NZ724990B2

NZ724990B2 - Pharmaceutically active dimers linked through phenolic hydroxyl groups

Info

Publication number: NZ724990B2
Application number: NZ724990A
Authority: NZ
Inventors: Nikhilesh Singh
Original assignee: Dimerx Inc
Filing date: 2015-04-27
Publication date: 2024-01-04

Abstract

homo-dimer compound of a pharmaceutically active agent selected from the group consisting of naloxone and naltrexone, wherein two such agents are covalently ether-linked through phenolic hydroxyl groups of the agents by an ethylene residue, or a pharmaceutically acceptable salt or solvate thereof.

Description

PHARMACEUTICALLY ACTIVE DIMERS LINKED THROUGH PHENOLIC HYDROXYL GROUPS CROSS-REFERENCES TO RELATED APPLICATIONS This ation claims the bene?t of priority under 35 U.S.C. § ll9(e) to US.

Provisional Application Serial No. ,207, ?led April 28, 2014; US. Provisional Application Serial No. 62/101,768, ?led January 9, 2015; and US. Provisional ation Serial No. 62/176,883, ?led January 9, 2015, the disclosures of each being incorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT NOT APPLICABLE REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK NOT APPLICABLE BACKGROUND OF THE INVENTION Buprenorphine (Formula 1) is a semisynthetic opioid derivative of thebaine. It is a mixed agonist—antagonist opioid receptor modulator that is used to treat opioid addiction in higher s, to l moderate acute pain in non-opioid-tolerant individuals in lower dosages and to control moderate chronic pain in even r doses. Buprenorphine is absorbed in the gastrointestinal tract and acts systemically. ation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp ation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Formula 1 Naloxone (Formula 2) is a pure opioid antagonist. Naloxone is a medication used to reverse opioid-induced depression of the central nervous system, respiratory system, and nsion. Naloxone may be combined with opioids that are taken by mouth to decrease the risk of their misuse. Naloxone is absorbed in the gastrointestinal tract and may act systemically, leading to opioid awal symptoms.

Formula 2 Naltrexone (Formula 3) is an opioid antagonist used primarily in the management of alcohol dependence and opioid dependence. It is marketed in generic form as its hydrochloride salt, naltrexone hydrochloride. It is also absorbed in the intestinal tract and acts systemically. Like naloxone, naltrexone may induce opioid Withdrawal symptoms.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp ed set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Formula 3 Des-venlafaXine (Formula 4) also known as O-desmethylvenlafaxine, is an pressant of the serotonin-norepinephrine reuptake tor class. It has been considered for use in the treatment of chronic idiopathic constipation and paresis, but because it acts systemically and its CNS effects can include sexual dysfunction its use for those purposes in persons not ing from depression is contra-indicated.

Formula 4 Acetaminophen (Formula 5), chemically named N—acetyl-p-aminophenol, is one of the most Widely used medications in the United States. It is over-the-counter analgesic and antipyretic, commonly sold under the trade name Tylenol®. Acetaminophen is classi?ed as a mild analgesic. It is commonly used for the relief of hes and other minor aches and pains and is a major ingredient in numerous cold and ?u remedies. In combination with opioid analgesics, acetaminophen can also be used in the management of more severe pain such as post-surgical pain and providing palliative care in advanced cancer patients. The [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp quinone metabolite of inophen is hepatotoxic. While usual dosing of inophen is considered harmless, both acute and c overdoses can be fatal.

Hi?!" \?fff Formula 5 Albuterol (Formula 6) is a short-acting Bz-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It relaxes muscles in the airways and increases air ?ow to the lungs. Albuterol is also used to prevent exercise-induced bronchospasm. It is usually given by inhalation to sidestep high first pass metabolism in the liver. Its highly variable bioavailability has been attributed to its phenolic hydroxyl group.

What these agents have in common is a single phenolic hydroxyl group. Such groups confer photo instability and undergo rapid presystemic or first pass lism in the gastrointestinal tract, variously forming sulfate esters or glucourinide esters. Buprenorphine and desvenlafaxine are also subjected to enzymatic degradation (CYP3A4 and ). To sidestep consequent diminution in bioavailability, agents like buprenorphine and naloxone are most commonly administered by injection or sublingually.

Diarrhea-predominant irritable bowel syndrome (IBS—D) IBS-D is a highly prevalent gastrointestinal disorder that is often accompanied, in addition to diarrhea, by both al lgesia (enhanced pain from colorectal stimuli), discomfort, bloating, and gas.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Eluxadoline® (Forest Laboratories, Inc.) is a u opioid receptor agonist and 8 opioid receptor antagonist that has met primary endpoints of improvement in stool consistency and reduction of abdominal pain in Phase III g, albeit without a demonstrable effect on reducing colonic hypersensitivity that results in hyperalgesia. Moreover, several cases of pancreatitis, a potentially life threatening disease, were reported in Phase II trials. Cases of atitis were ed even after patients with a known history of biliary disease were excluded from clinical study enrollment. In general, u agonists have a icting effect on the ter of Oddi, a ar valve that regulates the ?ow of bile and pancreatic juice from the bile duct into the duodenum. It is very important that a drug with ptor agonist activity and that is prescribed for erm use, not lead to constriction of the Sphincter of Oddi.

There has accordingly been a long-standing need for a chronic treatment of IBS-D that decreases intestinal motility, thereby decreasing the incidence of diarrhea, is an sic, is not associated with pancreatitis, and more than merely treating symptoms, addresses underlying hypersensitivity and resulting hyperalgesia associated with IBS-D.

BRIEF SUMMARY OF THE INVENTION We have discovered that dimerization of a de?ned group of pharmaceutically agents by O-alkylation through their phenolic hydroxyl groups, such that the active agent residues are d by an ethylene linker, yields distinct advantages relative to the active monomers, while preserving their receptor pharmacology.

In opioids and other pharmaceutical agents characterized by a single phenolic hydroxyl group, the covalent linkage of two such agents via such groups by the ethylene linker yields homo-dimers which are essentially more resistant to presystemic metabolism than their parent molecules. The ethylene linkage is highly stable and in particular cases yields other distinct advantages as well.

In the case of the opioid compounds buprenorphine, naloxone, and naltrexone the corresponding dimers are ant to tampering, e.g., kitchen chemistry sion to drugs of abuse; and are substantially non-absorbed in the GI tract, permitting their peripheral use t entering the central nervous system with consequent adverse effects such as addiction or opiEwithdrawal.

The dimerization of des-venlafaxine prevents passage of the active agent across the blood brain barrier, and although the dimer is no longer ive in the ent of depression, that es CNS ation, its functional ligands remain active and act locally in the intestinal tract, thus avoiding all centrally mediated adverse events, including sexual dysfunction. The dimerization, therefore, permits the agent to be safely utilized in the treatment of paresis and chronic idiopathic constipation. The des-venlafaxine dimer is expected to function as a eral serotonin norepinephrine reuptake inhibitor. Unlike des-venlafaxine, the dimer is expected to act only peripherally in the gastrointestinal tract. Serotonin inherently has propulsive effect on the gastrointestinal tract and the dimer, therefore, could be used for treatment of intestinal conditions such as gastroparesis, chronic idiopathic constipation and pseudointestinal obstruction (ileus).

The effect of dimerizing acetaminophen, according to the invention, is to prevent formation of the quinone metabolite of the parent compound, which is hepatotoxic in acute and chronic use. In addition, blocking the phenolic yl of the monomer, zation reduces the ionic nature of the active agent, potentially enhancing transport through the brain barrier and hence, analgesia.

Dimerization of rol enhances resistance to gastrointestinal and c metabolism, increasing bioavailability of the drug when taken orally for the treatment of bronchospasm, which occurs in various ary conditions, including asthma and chronic obstructive pulmonary disease.

In at least the case of morphinan compounds and until the present time, conventional thought seems to have been, when derivatizing active agents in search of, e.g., prodrug activity, phenolic hydroxyl groups were to be avoided lest receptor binding be affected adversely.

Surprisingly, the compounds of the invention are ed to retain their characteristic activities despite derivatization involving the phenolic hydroxyl groups of the corresponding monomers. [0020a] The present invention as claimed herein is described in the following items 1 to 10: 1. A homo-dimer nd of a pharmaceutically active agent selected from the group consisting of naloxone and naltrexone, wherein two such agents are covalently ether-linked through phenolic hydroxyl groups of the agents by an ne residue, or a pharmaceutically acceptable salt or solvate thereof. 2. A homo-dimer compound according to item 1, wherein the compound is in the form of a pharmaceutically acceptable salt. 3. A pharmaceutical composition comprising a pharmaceutically acceptable carrier or excipient and a dimer compound ing to item 1 or item 2. 4. The pharmaceutical ition of item 3, wherein said composition is formulated as an oral tablet or extended release oral tablet.

. A ne dimer compound according to item 1 having the Formula: or a pharmaceutically acceptable salt or solvate thereof. 6. A naltrexone dimer nd according to item 1 having the Formula: or a pharmaceutically acceptable salt or solvate thereof. 7. A homo-dimer compound according to item 1, substantially as herein described with reference to any one of the es or Figures. 8. A pharmaceutical composition according to item 3, substantially as herein described with reference to any one of the Examples or Figures. 9. A ne dimer compound according to item 5, substantially as herein described with reference to any one of the Examples or Figures.

. A naltrexone dimer compound according to item 6, substantially as herein described with reference to any one of the Examples or Figures.

BRIEF PTION OF THE DRAWINGS Figure 1 provides a synthetic route to buprenorphine dimer HCl salt.

Figure 2 provides a synthetic route to naloxone dimer HCl salt.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Figure 3 provides a synthetic route to the naltrexone dimer HCl salt Figure 4 provides a synthetic route to des-venlafaxine dimer HCl salt.

Figure 5 provides a synthetic route to the acetaminophen dimer.

Figure 6 provides a synthetic route to the albuterol dimer. In Figure 6, DHP is DHP is dihydropyran, t-BuNHz is tert-butyl amine, TBSCI is tert-butyldimethylsilyl chloride; LAH is Lithium aluminium hydride; (Boc)20 is tert-butyl dicarbonate; and AcOH is acetic acid.

Figure 7 es a bar chart illustrating the stability of the buprenorphine dimer when exposed to CYP s in the ce and absence of a co-factor.

Figure 8 provides a bar graph showing the ity of the buprenorphine dimer to aqueous conditions, as well as acidic and basic condition, each at room temperature and at 140°F for the indicated period of time.

Figure 9 es the s of buprenorphine dimer receptor binding experiments — u receptor.

Figure 10 provides the results of orphine dimer receptor binding experiments — K receptor.

Figure 11 es u agonist ?anctional assay results for the buprenorphine dimer.

Figure 12 provides u antagonist ?anctional assay results for the orphine dimer.

Figure 13 provides the results of oral and IV bioavailability of the buprenorphine dimer Figure 14 provides the graphs for stress-induced fecal output of male CD-1 mice according to the evaluation of Example 7.

Figure 15 shows the buprenorphine dimer decreases fecal output in a dose- dependent manner.

Figure 16 shows the effect of the buprenorphine dimer on gastrointestinal motility in post in?ammatory models according to Example 7.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Figure 17 provides a bar chart illustrating the stability of the naloxone dimer salt when exposed to CYP enzymes in the presence and absence of a co-factor.

Figure 18 provides a bar graph showing the stability of the naloxone dimer salt to s ions, as well as acidic and basic condition, each at room temperature and at 140°F for the ted period of time.

Figure 19 provides the s of the human u opioid receptor binding assay of the naloxone dimer and naloxone.

Figure 20 provides a bar graph showing the effect of the naloxone dimer salt in alleviating loperamide-induced constipation in mice.

DETAILED DESCRIPTION OF THE INVENTION Pharmaceutical Compositions of the Dimers - General In certain embodiments, provided herein are pharmaceutical compositions comprising the dimers. A pharmaceutical composition can further comprise a pharmaceutically acceptable carrier. rative pharmaceutically acceptable carriers and formulations are described below.

As will be appreciated, a pharmaceutically acceptable salt of a dimer may be used instead of or in addition to a dimer in any or all of the compositions and methods of treating discussed herein. Thus, in c embodiments, a pharmaceutically acceptable salt of the dimer (i.e., any pharmaceutically acceptable salt of any of the ) is used in the methods of the invention. These salts can be prepared, for example, in situ during the ?nal ion and puri?cation of the compound or by separately reacting the puri?ed nd in its free base form with a le organic or inorganic acid and ing the salt thus formed. In some embodiments, the pharmaceutically acceptable salt of the dimer is prepared using acetic, alginic, anthranilic, benzenesulfonic, benzoic, camphorsulfonic, citric, ethenesulfonic, formic, fumaric, ?lroic, galacturonic, gluconic, glucuronic, glutamic, glycolic, hydrobromic, hloric, isethionic, lactic, maleic, malic, mandelic, esulfonic, mucic, nitric, pamoic, pantothenic, phenylacetic, phosphoric, propionic, salicylic, stearic, succinic, sulfanilic, sulfuric, tartaric acid, or enesulfonic acid. For ?lrther description of phamEutically acceptable salts that can be used in the methods described herein see, for [Annotation] jennyp None set by jennyp ation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp ation] jennyp Unmarked set by jennyp example, S.M. Berge et al., "Pharmaceutical Salts," 1977, J. Pharm. Sci. 66il-l9, which is incorporated herein by reference in its entirety.

The dimers of the invention can exist in unsolvated as well as ed forms with pharmaceutically acceptable solvents such as water, ethanol, and the like. In general, the solvated forms are considered equivalent to the unsolvated forms for the purposes of the present invention. In a speci?c embodiment, the solvated form of the dimer is a e.

In l, salt formation may improve shelf life of the resultant therapeutic agent.

Appropriate salt synthesis can afford products that are crystalline, less prone to oxidation and easy to . Various salts can be prepared that would afford stable and crystalline compounds. A few es are hydrochloric, sulfuric, p-toluenesulfonic, methanesulfonic, malonic, fumaric, and ascorbic acid salts.

In certain speci?c embodiments, such a pharmaceutical composition is formulated as oral tablet or capsule, extended release oral tablet or capsule (hard gelatin capsule, soft gelatin capsule), sublingual tablet or ?lm, or extended release sublingual tablet or ?lm.

Illustrative ceutically acceptable carriers and formulations are described in more detail below.

Pharmaceutical Compositions, Dosing and Routes of Administration The dimers provided herein can be administered to a subject orally in the conventional form of preparations, such as capsules, microcapsules, tablets, es, powder, troches, pills, suppositories, oral suspensions, syrups, oral gels, , solutions and emulsions. Suitable ations can be prepared by methods commonly ed using conventional, organic or inorganic additives, such as an excipient (e.g., sucrose, starch, mannitol, sorbitol, lactose, glucose, cellulose, talc, calcium phosphate or calcium carbonate), a binder (e.g., cellulose, methylcellulose, hydroxymethylcellulose, polypropylpyrrolidone, polyvinylpyrrolidone, gelatin, gum arabic, polyethyleneglycol, sucrose or starch), a disintegrator (e.g., starch, carboxymethylcellulose, hydroxypropylstarch, low substituted ypropylcellulose, sodium bicarbonate, calcium ate or calcium e), a lubricant (e.g, magnesium stearate, light anhydrous silicic acid, talc or sodium lauryl sulfate), a ?avoring agent (e.g., citric acid, menthol, glycine or orange powder), a preservative (e.g, sodium benzoate, sodium bisulf1te, methylparaben or paraben), a stabilizer (e.g. citric acid, sodium citrate or acetic acid), a suspending agent (e.g., methylcellulose, polyvinyl pyrroEne or aluminum stearate), a dispersing agent (6.g. , hydroxypropylmethylcellulose), [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp ation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp a diluent (e.g., water), and base wax (e.g., cocoa butter, white petrolatum or polyethylene glycol).

EXAMPLES The following examples are offered to illustrate, but not to limit the claimed invention.

Example 1 Buprenorphine Dimer HCl Salt The orphine dimer was sized as shown in Figure 1.

Synthesis of Intermediate 2: Buprenorphine HCl-salt (5.0 g, 10.68 mmol, 1 equiv) and potassium ate (42.73 mmol, 4 equiv) were charged in a 3-neck round bottom ?ask followed by anhydrous DMSO (50 ml, 10 vol). The mixture was heated to 60 oC and l,2-dibromoethane (3.7 mL, 42.72 mmol, 4 equiv) was added slowly. The reaction e was stirred at 60 0C for 16 h then cooled to room temperature, diluted with water and extracted with dichloromethane.

The organic layer was washed with brine, dried (anh. Na2SO4), ?ltered and concentrated under reduced pressure to afford a viscous liquid. The crude product was purified by silica gel chromatography using 0-5% MeOH/DCM to afford 4.2 g (69%) intermediate 2 as off- white foamy solid.

Synthesis of Intermediate 3: Buprenorphine HCl-salt (1.74 g, 3.72 mmol) and potassium carbonate (2.0 g, 14.87 mmol, 4 equiv) were charged in a 3-neck round bottom ?ask followed by anhydrous DMSO (10 mL). The mixture was heated to 60 0C and intermediate 2 (3 g, 5.22 mmol, 1.4 equiv) dissolved in 7 mL of anhydrous DMSO was added dropwise over a period of 2 h. The reaction mixture was stirred at 60 0C for 16 h then cooled to room temperature, diluted with water and ted with dichloromethane. The organic layer was washed with brine, dried (anh. Na2SO4), filtered and concentrated under d pressure to afford a viscous liquid.

The crude product was purified by silica gel chromatography using 0-5% MeOH/DCM to afford dimer 3 as a foamy solid (2.8 g, 77%).

[Annotation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp ation] jennyp Unmarked set by jennyp Synthesis of the Dimer HCl Salt: .5 g (5.7 mmol) of bi-conjugate 3 was dissolved in 50 mL of ethyl e at room ature under nitrogen. 3.43 mL (6.9 mmol, 1.2 equiv) of 2N HCl in ether was added drop-wise at room temperature. The reaction mixture wis stirred at room ature for an additional hour and ?ltered to obtain the solid. The solid was ?lrther washed with 100 mL of ethyl acetate and dried under vacuum to give white solid (5.8 g, 98 %). 1H NMR (300 MHz, DMSO-d6): 5 9.75 (br, 2H), 6.88 (d, J: 9.2 Hz, 2H), 6.67 (d, J: 9.2 Hz, 2H), 4.66 (s, 2H), 4.23-4.42 (m, 4H), 3.84-3.92 (m, 2H), 3.40 (s, 6H), 3.21-3.35 (m, 5H), 2.98-3.20 (m, 7H), 2.64-2.85 (m, 4H), 2.12-2.26 (m, 4H), 1.72-1.94 (m, 4H), 1.38-1.52 (m, 4H), 1.26 (s, 6H), 0.99 (s, 20H), 0.48-0.76 (m, 10H), 0.32-0.42 (m, 4H); MS: m/z 962 (M + 1)+ Example 2 In Vitro Assay: Metabolic Stability of Buprenorphine Dimer Incubations of the dimer (e.g., 1 MM) with human liver omes (e.g., 1 mg protein/mL) were carried out using a Tecan Liquid ng System (Tecan), or equivalent, at 37 :: 1°C in 0.2-mL incubation mixtures (?nal volume) ning potassium phosphate buffer (50 mM, pH 7.4), MgClz (3 mM) and EDTA (1 mM, pH 7.4) with and t a cofactor, generating system, at the ?nal concentrations indicated in a 96-well plate format. The NADPH-generating system consisted ofNADP (1 mM, pH 7.4), glucose phosphate (5 mM, pH 7.4) and glucosephosphate dehydrogenase (1 Unit/mL). The buprenorphine dimer was dissolved in aqueous methanolic solution (methanol 0.5% v/v, or less). Reactions were started typically by addition of the cofactor, and stopped at four designated time points (e.g., up to 120 min) by the addition of an equal volume of stop reagent (e.g., acetonitrile, 0.2 mL containing an internal standard). Zero-time incubations served as 100% value to determine percent loss of substrate. tions were carried out in triplicate with an exception for zero-time samples (which were incubated in quadruplicate).

Zero-cofactor (no NADPH) incubations were performed at zero-time and the longest time point. The samples were subjected to centrifugation (e.g., 920 x g for 10 min at 10°C) and the supernatant fractions analyzed by LC-MS/MS. Additional incubations were carried out with microsomes and a marker substrate (e.g., dextromethorphan to monitor substrate loss) as a ve control to determine if the test system was metabolically competent.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp ed set by jennyp ation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp The above samples were analyzed by an LC-MS/MS method. is was performed for the samples at each incubation solution. Results were determined by a comparison of peak ratios over the time course of the ment (typically reported as "% Parent Remaining").

Data were calculated with a LIMS (includes Galileo, Thermo Fisher Scienti?c Inc. and ing tool, Crystal Reports, SAP), the spreadsheet er program Microsoft Excel (Microsoft Corp.) or equivalent. The amount of unchanged parent compound was estimated (to determine approximate percent substrate remaining in each incubation) based on analyte/intemal standard (IS) peak-area ratios using a LIMS, Analyst Instrument Control and Data Processing Software (AB SCIEX), or equivalent.

Results: Results are shown in Figure 7 and indicate that the buprenorphine dimer was relatively stable in presence of omal enzymes for the duration of the assay. The microsomal enzymes are typically responsible for metabolism of drugs such as buprenorphine. [0056] The dimer was stable in presence of the microsomes, with or t the co-factor. The assay was terminated at 2 hours because enzymes are typically not stable beyond 2 hours at incubation temperatures of 37°C.

Example 3 Stress Stability Assay of the Buprenorphine Dimer This study facilitated the understanding of the ease with which a potential abuser could cleave the dimer using household chemicals such as baking soda, acid or simple heating in water. Buprenorphine dimer stability was assessed at room temperature in ted tap water and in ce of acid (lN HCl) or base (5% aqueous sodium bicarbonate). The dimer was relatively stable under those conditions and under these conditions did not degrade to buprenorphine. See Figure 8.

Results: As shown in Figure 8, the buprenorphine dimer ed stable and did not degrade to release buprenorphine either at room temperature or elevated temperature under e pH conditions even as long as 30 minutes.

These studies also facilitate the understanding of the stability of the dimer in the gastrointestinal tract which exhibits a gradient pH along its length in both patients with IBS- D and healthy subjects. The pH ranges from pH 1 due to excretion of hydrochloric acid from [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp ed set by jennyp the parietal cells of the stomach to pH 8 in the colon. The proximal portion of the gastrointestinal tract is most acidic where the distal end is the least acidic.

Example 4 or Binding Activity of the Buprenorphine Dimer This example illustrates the binding of the buprenorphine dimer provided herein to the following receptors: u-opioid receptor; K-opioid receptor; and S-opioid receptor.

Human u Opioid Receptor Binding Assay Membranes from Chinese Hamster Ovary cells expressing the human u opioid receptor (Perkin Elmer #RBHOMM400UA) were homogenized in assay buffer (50 mM Tris, pH 7.5 with 5 mM MgCl2) using glass tissue grinder, Te?on pestle and Steadfast Stirrer (Fisher Scienti?c). The concentrates of the membranes were adjusted to 300 ug/mL in assay plate, a 96 well round bottom polypropylene plate. Compounds to be tested were lized in DMSO (Pierce), 10 mM, then diluted in assay buffer to 3.6 nM. In a second 96 well round bottom polypropylene plate, known as the premix plate, 60 uL of 6X compound was combined with 60 uL of 3.6 nM 3H-Naloxone. From the premix plate 50 uL was transferred to the assay plate ning the nes, in duplicate. The assay plate was incubated for 2 h at room temperature. A GF/C 96 well ?lter plate (Perkin Elmer #6005174) was pretreated with 0.3% polyethylenimine for 30 min. The ts of the assay plate were ?ltered through the ?lter plate using a d Filtermate Harvester, and washed 3 times with 0.9% saline at 4°C. The ?lter plate was dried, underside , and 30 uL Microscint 20 (Packard #6013621) was added to each well. A Topcount-NXT Microplate Scintillation Counter (Packard) was used to measure emitted energies in the range of 2.9 to 35 KeV.

Results were compared to maximum binding, wells receiving no inhibitions. Nonspeci?c binding was determined in presence of 50 uM unlabeled ne. The biological activity of the buprenorphine dimer is shown in Figure 9.

Results: The graph in Figure 9 shows that the dimer has signi?cant af?nity for the opioid u receptor The opioid u receptor af?nity of the buprenorphine dimer at 10'8M (~10 ng) was r to that of buprenorphine .

Hum? Opioid or Binding Assay [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Membranes from cloned 3 cells expressing the human K opioid or (Amersham Biosciences UK Ltd. 6110558 200U) were homogenized in assay buffer (50 mM Tris, pH 7.5 with 5 mM MgCl2) using glass tissue grinder, Te?on pestle and Steadfast Stirrer (Fisher Scienti?c). The concentrates of the membranes were adjusted to 300 ug/mL in the assay plate, a 96 well round bottom polypropylene plate. nds to be tested were solubilized in DMSO (Pierce), 10 mM, then diluted in assay buffer to 3.6 nM. In a second 96 well round bottom polypropylene plate, known as the premix plate, 60 uL of 6X compound was combined with 60 uL of 3.6 nM 3H-Diprenorphine (DPN). From the premix plate 50 uL was transferred to the assay plate containing the membranes, in duplicate. The assay plate was incubated for 18 h at room temperature. A GF/C 96 well ?lter plate (Perkin Elmer #6005174) was pretreated with 0.3% hylenimine for 30 min. The contents of the assay plate were ?ltered through the ?lter plate using a Packard Filtermate Harvester, and washed 3 times with 0.9% saline at 4 OC. The ?lter plate was dried, underside sealed, and 30 uL Microscint 20 (Packard 21) was added to each well. A Topcount-NXT Microplate Scintillation Counter (Packard) was used to measure emitted energies in the range of 2.9 to KeV. s were compared to m binding, wells receiving no inhibitions.

Nonspeci?c binding was determined in the presence of 50 uM lled naloxone. The biological activity of the buprenorphine dimer is shown in Figure 10.

Results: Figure 10 bes the opioid K receptor agonist pro?le of the buprenorphine dimer. r the monomer nor the dimer of buprenorphine lost its af?nity for the K receptor. Qualitatively, as with buprenorphine, the binding of the buprenorphine dimer to opioid K receptor increases with concentration. It is estimated that at about 1 ug, the opioid K receptor af?nity of the dimer was similar to that of buprenorphine.

Human 6 Opioid Receptor Binding Assay The assay was ed to test the ability of a compound to interfere with the binding of tritiated naltrindole to the human 5 subtype 2 opioid receptor. Membranes from Chinese Hamster Ovary cells expressing the human 5 subtype 2 opioid receptor (Perkin Elmer #RBHODM400UA) were homogenized in assay buffer (50 mM Tris, pH 7.5 with 5 mM MgC12) using a glass tissue grinder, Te?on pestle and Steadfast r (Fisher Scienti?c). The concentration of membranes was adjusted to 100 ug/mL in the assay plate, a 96 well round bottom polypropylene plate. Compounds to be tested were solubilized in DMSEO mM, then diluted in assay buffer to 6x the desired ?nal concentration. The [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp ligand, 3H-natrindole (Perkin Elmer #NET-1065) was also diluted in assay buffer to 6 nM.

Aliquots of 3H-natrindole (50 uL) were transferred to the assay plate ning the membranes in duplicate. The assay plate was incubated for 30 minutes at room temperature.

A GF/C 96 well ?lter plate n Elmer #6005174) was pretreated with 0.3% polyethylenimine for 30 min. The contents of the assay plate were ?ltered through the ?lter plate using a Packard mate Harvester, and washed 3 times with 0.9% saline at 4° C .

The ?lter plate was dried, the underside sealed, and a 30 uL MictoS=scint 20 (Packard #6013621) was added to each well. A nt-NXT Microplate Scintillation Counter (Packard) was used to measure emitted energies in the range of 2.9 to 35 KeV. Results are compared to maximum binding, wells receiving no inhibitors. Nonspeci?c binding was determined in the presence of 1 uM unlabelled dole. The ical activity of the buprenorpine dimer is 7.6 nM (IC50) and 2.87 (Ki). Relative to the u and K opioid receptors, the dimer has poor af?nity for the 5 receptor.

Example 5 - Receptor Stimulation Activity u Opioid or Agonist and Antagonist Functional Assays: [35S]GTPyS Binding Assay in Chinese Hamster s expressing Human u Receptors (CHO-hMOR) cell membranes This e illustrates the ability of the buprenorphine dimer provided herein to stimulate the u-opioid receptor-mediated signaling. Brie?y, OR cell membranes were purchased from Receptor Biology Inc. (Baltimore Md). About 10 mg/ml ofmembrane protein was suspended in 10 mM TRIS-HCl pH 7.2 2 mM EDTA, 10% sucrose, and the suspension kept on ice. One mL of membranes was added to 15 mL cold binding assay buffer containing 50 mM HEPES, pH 7.6, 5 mM MgCl; 100 mM NaCl, 1 mM DTT and 1 mM EDTA. The membrane suspension was homogenized with a polytron and centrifuged at 3000 rpm for 10 min. The supernatant was then centrifuged at 18,000 rpm for 20 min. The pellet was resuspended in 10 mL assay buffer with a polytron.

The membranes were pre incubated with wheat germ agglutinin coated SPA beads (Amersham) at 25°C, for 45 min in the assay buffer. The SPA bead (5 mg/ml) coupled with nes (10 ug/ml) was then incubated with 0.5 nM [35S]GTPyS in the assay buffer. The basal binding is that taking place in absence of added test compound; this unmodulated binding was considered as 100%, with t stimulated binding rising to levels signifEtly above this value. A range of trations of receptor agonist SNC80 was [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp used to stimulate[3SS]GTPyS binding. Both basal and eci?c binding were tested in the absence of t; non-specific binding determination included 10 uM unlabeled GTPyS.

The buprenorphine dimer was tested for function as an antagonist by evaluating its potential to inhibit agonist-stimulated GTPyS binding using D-Phe-Cys-Tyr-D-Trp-Om-Thr- Pen-Thr-NH2 (CTOP) as the standard. Radioactivity was quanti?ed on a Packard Top Count. The following parameters are calculated: % Stimulation = [(test compound cpm- non-speci?c cpm)/(basal cpm — non-speci?c cpm)]* 100 % Inhibition = (% stimulation by 1 uM SNC80 -% stimulation by 1 uM SNC80 in presence of test compound)* lOO/(%stimulation by 1 uM SNC80-100).

EC50 was calculated using GraphPad Prism. Graphs for the compounds tested are shown in Figures 11 and 12.

Results: Data shown in Figure 11 tes that the buprenorphine dimer is a potent u agonist. The results also indicate that the opioid u receptor activity of the dimer at lO'6M (~l ug) is similar to that of buprenorphine. Data in Figure 12 shows that the buprenorphine dimer does not function as a u-antagonist.

Example 6 In Vivo Pharmacokinetic Study Animals used in these animal pharmacokinetic studies were CD-1 mice (about 35 gms, n = 3 per time point). Drugs tested were buprenorphine and the buprenorphine dimer.

Dose 10 mg/kg IV and oral gavage. Blood was collected at time 0, 30 min and l, 2, 6 and 24 hours. Blood samples for the drug were ed after ting the plasma and by MS as s: Standard curve was prepared in mouse plasma spiked with either the test drugs (10- 25000 nM). Plasma samples (50 uL) were extracted in 300 uL acetonitrile containing losartan or buprenorphine-d4 as internal standard. Extracts were centrifuged at 16000 x g at 4°C for 5 minutes. Supematants (250 uL) were transferred to a new tube and dried under N2 at 45°C for 1 hour. s were tituted with 100 uL of 30% acetonitrile, vortexed and centrifuged. tants (90 uL) were transferred to LC vials and 10 [LL is injected on LC/NE [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp ation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Results: Figures 13 depicts the plasma concentration pro?les of the dimer after 10 mg oral and IV dose. The graph indicates that the absolute bioavailability, measured as a ratio of the area under the concentration curve after oral and IV dose, of the dimer is 1% or less, whereas that of the r is about 30%.

Example 7 In Vivo Assay: Stress-Induced Fecal Output The animals used in the studies were male CD-1 mice, average weight about 30 to g, with an average of 5 mice per dose group. The mice were generally housed in colony g where they are housed 3 per cage in polycarbonate cages with access to food and water ad lib.

On the day of the experiment the mice were transported to the procedure room where they were individually housed in 20 cm wide x 20 cm deep x 15 cm tall cages, equipped with a wire mesh bottom after intragastric administration of test compounds.

During the test the animals were allowed access to water only ad lib. The wire mesh bottomed tall cage creates a novel environment which induces stress in mice. The number of pellets excreted was determined on an hourly basis. Results are shown in Figure 14.

Results: Figures 14 shows that oral dose of the dimer signi?cantly d the fecal output in mice versus placebo (vehicle). The doses igated were 25 and 50 mg per kg of mice. The results do not change even when the animals with zero fecal output, suggesting extreme sensitivity, were removed from the analysis. Figure 15 shows that fecal output in mice decreases with dose, which indicates a true pharmacological effect.

In Vivo Assay: Effect on post-in?ammatory altered GI transit time This test was designed to e the effect of test substance on intestinal hypersensitivity following ation. Post-in?ammatory altered GI transit was induced in male CD-1 mice by injecting freshly opened oil of mustard (95% pure allyl isothiocyanate, 0.5% in ethanol). The effect of stress on the post-in?ammatory GI tract was tested 3-4 weeks after dosing. At this point, the GI tract was in a hypersensitive state, i.e., having a significantly greater response to stimuli (hyperalgesia). The effect of the test substance was ed after oral stration (intragastric gavage) and subjecting animals to environmental stress by housing them in cages (20 cm wide x 20 cm deep x 15 cm tall), equipEwith a wire mesh bottom. During the test the animals were allowed access to water [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp ation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp ad lib. The wire mesh bottomed tall cage creates a novel environment which induces stress in mice. The number of pellets excreted is determined on hourly to two-hourly basis. See Figure 16.

Results: As shown in Figure 16, the buprenorphine dimer at 25 mg per kg signi?cantly decreases gastrointestinal motility in this model as ed by fecal output.

The graph also shows the fecal pellet output in the mice not treated with mustard oil is transient and does not last beyond 1 hour. The increase in pellet excretion in mustard oil treated animals persists even at 2 hours. The dimer continues to inhibit gastrointestinal motility with statistically signi?cant results even at 2 hours.

Example 8 Naloxone and Naltrexone Dimer HCl Salts The naloxone dimer HCl salt was synthesized as shown in Figure 2.

Synthesis of Intermediate 3: Naloxone (5.0 g, 15.27 mmol, 1 equiv) and potassium carbonate (6.32 g, 45.8 mmol, 3 equiv) were charged to a , 3-neck round bottom ?ask followed by anhydrous DMF (50 ml, 10 vol). The mixture was heated to 60°C and 1,2-dibromoethane (6.57 mL, 76.35 mmol, 5 equiv) was added to the reaction mixture via syringe. The on mixture was d at 110°C for 16 h. TLC analysis shows mostly intermediate 3. After the reaction was completed, the mixture was diluted with water (150 mL, 30 vol) and extracted with ethyl acetate (100 mL, 20 vol). The aq. layer was ted with ethyl e (100 mL). The combined c portions were washed with brine (100 mL), dried over magnesium sulfate and concentrated under reduced re. The crude product was puri?ed by silica gel tography using 0-5% MeOH/DCM to afford ediate 3 as viscous oil (1.25 g).

Synthesis of Intermediate 4: Intermediate 3 (1.25 g, 2.87 mmol) and potassium carbonate (1.59 g, 11.52 mmol, 4 equiv) were charged into a 3-neck round bottom ?ask containing compound 1 (0.57 g in 15 mL DMF). The mixture was heated at 60 OC and the reaction progress was monitored by TLC. The mixture was cooled to room temperature, diluted with water and extracted with ethyl acetate (50 mL X 2). The combined organic portions were dried over magnesium sulfatEltered and concentrated under reduced pressure to afford yellow syrup. The crude [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp product was puri?ed by silica gel tography using 0-4% MeOH/DCM to afford naloxone dimer 4 as a pale white solid (0.55 g).

Synthesis of Naloxone Dimer HCl—Salt 5: 0.55 g (0.8 mmol) of bi-conjugate 4 was dissolved in 10 mL of ethyl acetate at room temperature under nitrogen. 0.8 ml (3.2 mmol, 4.0 equiv) of 4M HCl in dioxane was added drop-wise at room temperature. The reaction mixture was stirred at room temperature for an additional hour and ?ltered to obtain the solid. The solid was ?lrther washed with 20 mL of MTBE and dried under vacuum to obtain a white solid (0.5 g). HPLC analysis shows 98.2% purity (AUC) at 235 Nm. 1H NMR (300 MHz, DMSO-d6): 1.41-1.63 (m, 4H, CH2), 1.98 (d, 2H, CH2), 2.14 (d, 2H, CH2), 2.63 (dt, 2H, CH2), 2.88-3.19 (m, 6H, CH2), 3.26-3.44 (m, 6H, CH2), 3.62 (d, 2H, CH), 3.72-3.84 (m, 2H, CH2), 3.85-3.98 (m, 2H, CH), 4.41 (dd, 4H, CH2), .09 (s, 2H, OH), 5.58 (dd, 4H, CH2), 5.82-6.02 (m, 2H, CH), 6.78 (d, 2H, Ar), 6.90 (d, 2H, Ar), 9.42 (s, 2H, NHCl).

The naltrexone dimer HCl salt is similarly synthesized, substituting for naloxone a molar equivalent of naltrexone, as shown in Figure 3.

Example 9 Metabolic stability of the Naloxone Dimer lic stability of the naloxone dimer was investigated using a protocol r to the buprenorphine dimer experiment discussed in Example 3. imately 1 uM of the dimer was incubated with human liver microsomes (1 mg n/ml) for up to 1 hour. The incubation medium was assayed by LC/MS/MS for the formation of naloxone over time. As shown in Figure 17, there was no evidence of formation naloxone over time.

Example 10 Stress Stability of the Naloxone Dimer Naloxone dimer stability was assessed at room ature in untreated tap water and in the ce of acid (lN HCl) or base (5% aqueous sodium bicarbonate). The protocol was similar to the buprenorphine dimer stress stability experiment described in [Annotation] jennyp None set by jennyp [Annotation] jennyp ionNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Example 3. The dimer was relatively stable under those conditions and under the described conditions does not appreciably degrade to ne, as shown in Figure 18.

Example 11 u Receptor binding assay of the Naloxone Dimer HCl Salt The ment was designed to determine the inhibition of tracer DAMGO syl-3,5-3H(N)]-[D-Ala2, N—Me-Phe,Gly5-ol]-Enkephalin acetate to the rat opiate u receptor by naloxone (1010’ 109, 19'8,10'7,10'6,and 10'5 mol/L) and naloxone dimer (1010, 10' 9, 108, 107, 10'6,and 10'5 mol/L). The test materials were incubated at 25°C for 60 min. The experiment was conducted with human u opioid receptors previously bound to [3H]N- DAMGO. DAMGO is a peptide with a high af?nity for human u opioid receptor. As the concentration of naloxone or the naloxone dimer was increased it gradually replaced the DAMGO bound to the receptor and thus the downward slope of the curves as shown in Figure 19. The binding ies of naloxone, the naloxone dimer, and other similar antagonists are provided in Table 1.

Table 1 Antagonist Ki nM Naloxone 0.5 Naloxone dimer 4.5 Pegylated naloxegol1 5 Methylnaltrexone Bromide2 42 1. Naloxegol®, AstraZeneca, Brie?ng Document 6 May 2014 to the Anesthetic and Analgesia Advisory tee to the FDA. 2. Relistor®, Salix tories, Brie?ng Document 8 May 2014 to the Anesthetic and Analgesia Advisory Committee to the FDA.

Example 12 Constipation Assay of the Naloxone Dimer HCl salt The naloxone dimer reversed the constipating effects of the opioid u t E'ie, as shown in Figure 20. In the study a group mice were subjected to mild stress, [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp which normally induces diarrhea and gastrointestinal motility measured by number of fecal s excreted per hour. The number of pellets expelled by the group treated with loperamide is signi?cantly less than the s excreted per hour by control le) animals. This observation con?rms the constipating effects of loperamide. In the group where the effect of loperamide was reversed by naloxone dimer the number of pellets ed per hour is more than the pellets excreted by loperamide-treated s and comparable to those of the control animals by hour 3 or later. The results demonstrate that the naloxone dimer effectively reversed the constipating effects of the human u opioid agonist loperamide.

The naloxone dimer offers signi?cant bene?t over naloxone, naltrexone, pegylated naloxone and methyl naltrexone as it is expected to act on the gastrointestinal tract receptors without being absorbed to treat opioid bowel disorder in general and opioid d constipation in particular. The naloxone dimer can also ?nd other therapeutic uses such as treatment of bloating, decreased gastric motility, abdominal cramping, and GERD (gastroesophagael re?ex disease.

Example 13 Des-venlafaxine Dimer HCl Salt The compound was sized as shown in Figure 4.

Synthesis of nd 2. Compound 1 (1 equiv) in DMF was reacted with 1,2- oethane (2 equiv) in the presence of anhydrous potassium carbonate (3 equiv) at 60 0C for 15 hours. TLC analysis tes complete ption of the starting compound. The mixture was diluted with MTBE and washed with water. The organic phase was separated, dried over magnesium sulfate, d and concentrated. The crude product was puri?ed by silica gel chromatography, affording pure product 2. Yield: 61%.

Synthesis of compound 3. Compound 2 (1 equiv) was added to sodium methoxide in methanol (5 equiv) at 5 0C and stirred at 0-5 0C for 2 hours. Cyclohexanone (2.5 equiv) was added and the mixture was stirred at 0-5 0C for 4 hrs. The reaction mixture was quenched with saturated ammonium chloride solution and concentrated. The resulting residue was dissolved in ethyl acetate and water. The organic phase was separated, dried over magnesium sulfate, ?ltered and concentrated. The crude t wis d by silica gel chromatography affording pure product 3. Yield: 74%.

[Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Synthesis of compound 4. Raney Nickel (30 wt%) was added to a mixture of nd 3 (1 equiv) in acetic acid (6 vol). The mixture was ?ushed with hydrogen (30 psi) then stirred under 140-150 psi of hydrogen at 55 0C for 3 hours, then cooled to room temperature. The mixture was ?ltered through a pad of celite and the ?ltrate was concentrated. The residue was ved in water and washed with MTBE to remove any unreacted materials. The t was extracted into ethyl acetate after neutralizing with bicarbonate solution. The ethyl acetate layer was dried over magnesium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel chromatography affording pure product 4. Yield: 85%.

Synthesis of nd 5. To a stirred solution of 4 (1 equiv) in water was added 37-40% formaldehyde (12 equiv) and formic acid (6 equiv). The reaction mixture was heated at 100 0C for 22 hours then cooled to room temperature. The mixture was washed with MTBE then basi?ed to pH 8-9 using 20% NaOH solution. The organic layer was dried over ium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel chromatography affording pure t 5. The product was dissolved in ethyl acetate and 2N HCl in ethyl acetate was added. The slurry was d for 30 s, ?ltered and dried to afford product 5. Yield: 79%. 1H NMR (300 MHz, DMSO-d6): 0.96-1.58 (m, 20H, CH2), 2.62 (s, 12H, CH3), 2.94 (dd, 2H, CH), 3.45 (dd, 2H, CH), 3.63 (dd, 2H, CH), 4.22 (s, 2H, OH), 4.36 (t, 4H, CH2), 6.76 (d, 4H, Ar), 7.06 (d, 4H, Ar).

Acetaminophen Dimer The compound was synthesized as shown in Figure 5.

Synthesis of Intermediate 3: Acetaminophen (1 equiv) and potassium carbonate (4 equiv) in a 3-neck round bottom ?ask was dissolved in anhydrous DMF (10 vol). The mixture was heated to 60 oC and l,2-dibr0m0ethane (4 equiv) was added. The reaction mixture was stirred at 60 0C for 16 h and TLC analysis showed consumption of acetaminophen. The e was diluted with MTBE, cooled to 10 0C, and washed with water. The organic phase was separated, dried over magnesium sulfate, ?ltered and trated. The crude product was puri?ed by silica gel chromatography affording pure product 3. Yield: 65%.

SyntlE of Compound 4: ation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp ed set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp Compound 3 (1 equiv), acetaminophen (1.2 equiv) and potassium carbonate (3 equiv) was dissolved in anhydrous DMF (10 vol) and the mixture was heated at 60 0C and stirred for 14 hours. TLC analysis showed consumption of intermediate 3. The mixture was diluted with MTBE and washed with water at 15-20 0C. The organic phase was separated, dried over magnesium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel tography affording pure product 4. Yield: 78%. 1H NMR (300 MHZ, DMSO-d6): 2.14 (s, 6H, CH3), 4.38 (t, 4H, CH2), 6.80 (d, 4H, Ar), 7.44 (d, 4H, Ar), 9.15 (s, 2H, NH).

Example 15 Albuterol Dimer The compound was synthesized as shown in Figure 6.

Synthesis of compound 2. Compound 1 (1 equiv) was reacted with 1.2 equiv of dihydropyran in the presence of 10 mol% PPTS in DCM at room temperature. The on was red by TLC analysis. The on mixture was washed with bicarbonate solution and the organic phase was dried over magnesium sulfate, ?ltered and concentrated. The crude product 2 was taken to the next step without ?lrther puri?cation. Yield: 95%. sis of compound 3. Compound 2 (1 equiv) in DCM was treated with 1.2 equiv of aluminum chloride followed by drop-wise addition of chloroacetyl chloride (1.5 equiv) at room ature. The reaction mixture was stirred at room temperature for 16 hours and TLC analysis indicated complete ption of the starting material. The reaction mixture was quenched with bicarbonate solution. The organic phase was separated and dried over magnesium sulfate, ?ltered and concentrated. The crude product 3 was puri?ed by silica gel chromatography to afford pure t 3. Yield: 72%.

Synthesis of Compound 4. nd 3 (1 equiv) was reacted with 2 equiv of butylamine in THF at room temperature. TLC analysis after 15 hours indicated complete consumption of the ng material. The reaction mixture was concentrated and the residue was puri?ed by silica gel chromatography to afford pure product 4. Yield: 96%.

Synthesis of compound 5. Compound 4 (1 equiv) was dissolved in THF and cooled to 0 0EAthium aluminum hydride (LAH) in THF (1 equiv) was added drop-wise and the [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp mixture stirred at room temperature for 3 hours. TLC analysis shows the consumption of the starting material. Saturated aqueous sodium sulfate was added until a white precipitate formed. The solid was ?ltered and the ?ltrate concentrated under reduced pressure to afford product 5. Yield (78%).

Synthesis of nd 6. nd 5 (1 equiv) in DCM was treated with 1.2 equiv of BOC-anhydride at room temperature followed by saturated sodium bicarbonate solution (2 equiv). The reaction mixture was stirred for 15 hours and TLC analysis indicated te consumption of the starting compound. The organic phase was separated and trated to afford product 6. Yield (94%).

Synthesis of compound 7. Compound 6 (1 equiv) in DCM was treated with imidazole (1.5 equiv) followed by TBDMSCl (l .2 equiv). The reaction e was stirred at room temperature for 12 hours and TLC analysis indicated complete consumption of the starting compound. Water was added to the reaction e and the organic phase was separated, dried over ium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel chromatography to afford pure product 7. Yield: 85%.

Synthesis of compound 8. Compound 7 (1 equiv) in 7:3 acetic acid/water was heated at 60 0C for 10 hours. TLC analysis indicated complete consumption of the starting compound. The mixture was concentrated and dissolved in MTBE, and washed with bicarbonate solution. The organic phase was separated, dried over magnesium sulfate, d and concentrated. The crude product was puri?ed by silica gel chromatography to afford pure product 8. Yield: 68%.

Synthesis of compound 9. Compound 8 (1 equiv) in DMSO was reacted with 1,2- dibromoethane (5 equiv) in the presence of anhydrous potassium carbonate (3 equiv) at 60 0C for 15 hours. TLC analysis ted te consumption of the starting compound. The mixture was diluted with MTBE and washed with water. The organic phase was separated, dried over magnesium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel chromatography to afford pure t 9. Yield: 62%.

Synthesis of compound 10. Compound 9 (1 equiv) in DMSO was reacted with compound 8 (l .2 equiv) in the ce of anhydrous potassium carbonate (2 equiv) at 50 0C for 15 hours. TLC analysis indicated complete ption of the starting compound 9. The mixture was diluted with MTBE and washed with water. The c phase was separated, [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp [Annotation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp dried over magnesium sulfate, ?ltered and concentrated. The crude product was puri?ed by silica gel chromatography to afford pure product 10. Yield: 74%.

Synthesis of compound 11. Compound 10 (1 equiv) in MTBE was reacted with 2N HCl in ethyl acetate (10 equiv) at room temperature for 12 hours. TLC analysis indicated complete consumption of the starting compound with solid itation. The solid was filtered and triturated with ethyl acetate to afford product 11. Yield: 88%. 1H NMR (300 MHz, DMSO-d6): 1.04 (s, 18H, CH3), 2.57 (d, 4H, CH2), 4.42 (t, 2H, CH), 4.45 (t, 4H, CH2), 4.49 (s, 4H, CH2), 4.63 (s, 6H, OH and NH), 6.71 (d, 2H, Ar), 7.01 (d, 2H, Ar), 7.29 (s, 2H, Example 16 Illustrative Pharmaceutical Compositions The pharmaceutical composition in Table 2 can be used for oral s of the dimers of the invention.

Table 2 Ingredients %w/w Dimer 2 Lactose 83.6 Colloidal Silicon dioxide 0.67 Microcrystalline cellulose 10 Croscarmellose sodium 3.4 Magnesium stearate 0.33 Example 17 Illustrative Doses The dose of the dimers provided herein to be stered to a patient is rather widely variable and can be subject to the nt of a health-care tioner. Dosage may be ly varied depending on the age, body weight and medical ion of the subject and the type of administration. In one embodiment, one dose is given per day. In any given case, Hmount of the dimer provided herein administered will depend on such factors as the ation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp ed set by jennyp ation] jennyp None set by jennyp [Annotation] jennyp MigrationNone set by jennyp [Annotation] jennyp Unmarked set by jennyp solubility of the active component, the formulation used and the route of administration. By "therapeutically effective dose" we mean a dose that yields an appreciable and beneficial effect in a statistically signi?cant number of patients. In certain embodiments, the patient is a mammal. In more specific embodiments, the patient is a human. In certain specific embodiments, the patient may be a domesticated mammal such as a dog, a cat, or a horse.

Preferred dosages for IBS-D ts, for e, are about 0.15 mg/kg of an IBS- D patient’s body weight to about 7.2 mg/kg of a patient’s body weight, more preferably from about 0.7 mg/kg of an IBS-D patient’s body weight to about 3.0 mg/kg of a patient’s body , and still more preferably about 1.5 mg/kg of a patient’s body weight in unit dosage for oral administration. Alternatively, from about 10 to about 500 mg, preferably from about 50 to about 200 mg, more preferably about 100 mg, will be administered to an IBS-D patient.

In Table 3 we provide putative dosages of dimers according to the invention for preferred indications, ed to those of the monomers for their own indications. The transformative effect of dimerization in extending the reach of these active agents will be apparent from the Table.

Table 3 Monomer Indication Dose Dimer Indication Dimer dose Buprenorphine Opioid addiction 2—32 mg/SL IBS—D 50—200 mg PO Naloxone Opioid abuse 0.5—2 mg IV/SC Opioid—induced 100—200 mg PO constipation Naltrexone Opioid abuse 50 mg PO Opioid—induced 100—200 mg PO pation Desvenlafaxine Anti—depressant 50 mg PO Gastroparesis, 50—200 mg PO constipation, ileus Albuterol ospasm 50 mg IN Bronchospasm 5—10 mg PO Acetaminophen Analgesia 500 mgs PO Liver—safe analgesia 500—1000 mg PO It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modi?cations or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this ation and scope of the appended claims. To the extent there is con?ict between the priority applications and the t application, any inconsistencies are to be resolved in favor of the present application. All publications and patents cited herein are hereby orated by reference in their entirety for all purposes.

Claims

WHAT IS CLAIMED IS:

1. A homo-dimer compound of a pharmaceutically active agent selected from the group consisting of naloxone and naltrexone, wherein two such agents are covalently ether-linked through phenolic hydroxyl groups of the agents by an ne residue, or a pharmaceutically able salt or solvate thereof.

2. A homo-dimer compound according to claim 1, wherein the compound is in the form of a pharmaceutically able salt.

3. A ceutical composition comprising a pharmaceutically acceptable carrier or excipient and a dimer compound according to claim 1 or claim 2.

4. The pharmaceutical composition of claim 3, wherein said composition is formulated as an oral tablet or extended release oral tablet.

5. A naloxone dimer compound according to claim 1 having the Formula: or a pharmaceutically acceptable salt or solvate thereof.

6. A naltrexone dimer compound ing to claim 1 having the Formula: 19757625_1 (WSMatters) P104283.NZ or a pharmaceutically acceptable salt or solvate thereof.

7. A homo-dimer compound according to claim 1, substantially as herein bed with reference to any one of the Examples or