Development of a selective androgen receptor modulator for transdermal use in hypogonadal patients

We have identified a non-steroidal selective androgen receptor modulator (SARM), termed LY305, that is bioavailable through a transdermal route of administration while highly cleared via hepatic metabolism to limit parent compound exposure in the liver. Selection of this compound and its transdermal formulation was based on the optimization of skin absorption properties using both in vitro and in vivo skin models that supported PBPK modeling for human PK predictions. This molecule is an agonist in perineal muscle while being a weak partial agonist in the androgenic tissues such as prostate. When LY305 was tested in animal models of skeletal atrophy it restored the skeletal muscle mass through accelerated repair. In a bone fracture model, LY305 remained osteoprotective in the regenerating tissue and void of deleterious effects. Finally, in a small cohort of healthy volunteers, we assessed the safety and tolerability of LY305 when administered transdermally. LY305 showed a dose-dependent increase in serum exposure and was well tolerated with minimal adverse effects. Notably, there were no statistically significant changes to hematocrit or HDL after 4-week treatment period. Collectively, LY305 represents a first of its kind de novo development of a non-steroidal transdermal SARM with unique properties which could find clinical utility in hypogonadal men.

2-Chloro-4-[[(1R,2R)-2-hydroxy-2-methyl-cyclopentyl]amino]-3-methyl-benzonitrile: A Transdermal Selective Androgen Receptor Modulator (SARM) for Muscle Atrophy

A transdermal SARM has a potential to have therapeutic benefit through anabolic activity in muscle while sparing undesired effects of benign prostate hyperplasia (BPH) and liver-mediated decrease in HDL-C. 2-Chloro-4-[(2-hydroxy-2-methyl-cyclopentyl)amino]-3-methyl-benzonitrile 6 showed the desired muscle and prostate effects in a preclinical ORX rat model. Compound 6 had minimal effect on HDL-C levels in cynomolgus monkeys and showed human cadaver skin permeability, thus making it an effective tool for proof-of-concept studies in a clinical setting.

Preference for pharmaceutical formulation and treatment process attributes

PURPOSE

Pharmaceutical formulation and treatment process attributes, such as dose frequency and route of administration, can have an impact on quality of life, treatment adherence, and disease outcomes. The aim of this literature review was to examine studies on preferences for pharmaceutical treatment process attributes, focusing on research in diabetes, oncology, osteoporosis, and autoimmune disorders.

METHODS

The literature search focused on identifying studies reporting preferences for attributes of the pharmaceutical treatment process. Studies were required to use formal quantitative preference assessment methods, such as utility valuation, conjoint analysis, or contingent valuation. Searches were conducted using Medline, EMBASE, Cochrane Library, Health Economic Evaluation Database, and National Health Service Economic Evaluation Database (January 1993-October 2013).

RESULTS

A total of 42 studies met inclusion criteria: 19 diabetes, nine oncology, five osteoporosis, and nine autoimmune. Across these conditions, treatments associated with shorter treatment duration, less frequent administration, greater flexibility, and less invasive routes of administration were preferred over more burdensome or complex treatments. While efficacy and safety often had greater relative importance than treatment process, treatment process also had a quantifiable impact on preference. In some instances, particularly in diabetes and autoimmune disorders, treatment process attributes had greater relative importance than some or all efficacy and safety attributes. Some studies suggested that relative importance of treatment process depends on disease (eg, acute vs chronic) and patient (eg, injection experience) characteristics.

CONCLUSION

Despite heterogeneity in study methods and design, some general patterns of preference clearly emerged. Overall, the results of this review suggest that treatment process has a quantifiable impact on preference and willingness to pay for treatment, even in many situations where safety and efficacy were the primary concerns. Patient preferences for treatment process attributes can inform drug development decisions to better meet the needs of patients and deliver improved outcomes.

Design, synthesis and structure-activity-relationship of 1,5-tetrahydronaphthyridines as CETP inhibitors

This Letter describes the discovery and SAR optimization of 1,5-tetrahydronaphthyridines, a new class of potent CETP inhibitors. The effort led to the identification of 21b and 21d with in vitro human plasma CETP inhibitory activity in the nanomolar range (IC(50)=23 and 22nM, respectively). Both 21b and 21d exhibited robust HDL-c increase in hCETP/hApoA1 dual heterozygous mice model.

Regional-dependent intestinal absorption and meal composition effects on systemic availability of LY303366, a lipopeptide antifungal agent, in dogs

Low oral bioavailability and a negative meal effect on drug plasma levels motivated studies on formulation and meal composition effects on the absorption of LY303366, a poorly water-soluble, semisynthetic, cyclic peptide antifungal drug. Solid drug particle size and meal composition studies were evaluated in beagle dogs. Canine regional absorption studies were also carried out utilizing surgically implanted intestinal access ports, and Caco-2 studies were performed to evaluate drug candidate intestinal permeability. Particle size and Caco-2 data indicate that drug permeability limitations to absorption are more important than dissolution rate limits. Caco-2 cell-associated LY303366 approached 10% of incubation concentration that is in the range of the oral bioavailability of the drug. Canine regional absorption studies showed that the extent of LY303366 absorption following duodenal administration was similar to that following oral administration. Significantly lower drug plasma levels were obtained following administration through a colonic access port, a result consistent with poor membrane permeation. Administration of drug with meals of mixed composition, as well as simple fat and protein meals, resulted in significant reductions in AUC(0-48h) compared with results from fasted dogs. In contrast, carbohydrate meals did not reduce drug plasma levels compared to controls. Intravenous pretreatment with devazepide, a cholecystokinin (CCK) antagonist that blocks canine biliary secretion, did not reverse the negative effect of the fat meal on LY303366. Taken together, the results from the present study suggest that membrane-permeability-limited absorption is the cause of the observed regionally dependent absorption of LY303366 in the dog and that the observed negative meal effects depend on composition but are independent of biliary secretion.

Application of oral bioavailability surrogates in the design of orally active inhibitors of rhinovirus replication

Previous studies in rats and humans demonstrated poor oral bioavailability of potent in vitro 2-aminobenzimidazole inhibitors of rhinovirus replication due to significant first-pass elimination and possibly also to poor aqueous solubility. Estimations of aqueous solubility, as well as measurements of caco-2 permeability and NADPH dependent compound loss in rat liver microsomal incubations were employed alongside traditional in vivo experiments in rats to guide subsequent chemistry efforts. Retention of activity upon replacement of the metabolically labile vinyl oxime in the lead molecule with a vinyl carboxamide was a major breakthrough; however, oral bioavailability among the latter compounds was variable. Based on the ability to independently measure solubility, permeability, and metabolic stability of new compounds, variable solubility across the series (ranging from approximately 1 to 10 microg/mL) was identified as the cause of the inconsistent performance. Subsequent efforts to improve solubility led to the discovery of highly soluble (>10 mg/mL) and potent dessulfonyl vinyl carboxamide benzimidazoles. Determination of the metabolic stability of these compounds as a surrogate of the extent of their first-pass elimination supported a prediction of excellent oral bioavailability. In comparison to the sulfonyl-containing vinyl carboxamides, caco-2 permeabilities were reduced 5 to 10-fold; however, these were considered to be in the range of well-absorbed compounds based on comparison to a series of reference compounds of known percentage absorption in humans. Subsequent experiments in the rat verified the oral bioavailability of these N-alkyl compounds, with one compound (368177) having an absolute oral bioavailability of 89.4%. The application of solubility and caco-2 permeability as surrogates for oral absorption potential, in conjunction with the use of microsomal incubations as a surrogate for first-pass metabolism, was shown to augment a rational chemistry approach to discover orally bioavailable inhibitors of rhinovirus replication. Future expanded use of these surrogates is planned.

The effects of enprostil and RS-86505-007 on in-vitro intestinal permeability of rabbit and monkey

Enprostil is a prostaglandin E2 analogue characterized as a racemic mixture of four stereoisomers. Enprostil and a single isomer, RS-86505-007, were evaluated for their effects on the permeability of actively and passively transported compounds in segments of small intestine from rabbits and monkeys. Consistent with human in-vivo studies, which have demonstrated decreases in absorption of D-xylose, both compounds inhibited D-glucose transport. The passively transported compounds mannitol and progesterone were also less permeable in this model in the presence of enprostil or RS-86505-007. In contrast to the concentration-dependent inhibition displayed by ouabain, RS-86505-007 had no effect on purified Na+K(+)-ATPase. It is suggested that an effect of a general nature, possibly an increase in the barrier properties at the intestinal surface, may explain the transport inhibition. Of two other enprostil isomers, RS-86812-007 inhibited D-glucose transport in rabbit small intestine, while RS-86505-008 had no effect. The prostaglandin E1 analogue misoprostol was ineffective in monkey and poorly effective in rabbit. This suggests that the inhibition of D-glucose transport by enprostil and its active stereoisomers is mediated through some structurally specific receptor interaction.

A correlation of permeabilities for passively transported compounds in monkey and rabbit jejunum

Permeability measurements were conducted for a series of compounds using in vitro tissue sections from monkey and rabbit jejunum. Jejunal segments were stripped of serosal musculature and mounted in a diffusion-cell system, using previously described methods and equipment. Permeability determinations of radiolabeled compounds ranging over two orders of magnitude in molecular weight were conducted. For the compounds examined, the permeability of the rabbit jejunum was approximately twice that of the monkey. This was in contrast to the relationship implied by the stripped tissue thickness measurements of 0.92 and 0.83 mm for rabbit and monkey, respectively. An investigation of the size of the paracellular space in the jejunum was undertaken to account for this apparent discrepancy in tissue permeability. Scanning electron micrographs of intestinal sections revealed a similar packing density of cells between species; however, a difference was noted in the shape and number of villi per unit area. Comparative measurements of the paracellular volume in both species using mannitol and methoxyinulin as extracellular space markers further suggests that the paracellular junctions are similar in size but more numerous per unit area of rabbit jejunum than that of the monkey. In contrast to passively transported compounds, the active transport of D-glucose was greater in monkey jejunum compared to rabbit tissue segments. When active transport was inhibited by blockade of the sodium pump with ouabain, the passive component of D-glucose transport for both rabbit and monkey tissue was in agreement with the relationship demonstrated above for compounds which are solely transported by passive processes.

In vitro measurement of gastrointestinal tissue permeability using a new diffusion cell

A new diffusion cell, derived from the Ussing chamber, was developed for the measurement of tissue permeability. This cell incorporates the attributes of using a single material and laminar flow across the tissue surface. In addition, the design allows the cell to be manufactured in a wide range of sizes to allow optimization of surface area to volume for a variety of tissues. The apparatus is applicable to the evaluation of transport of compounds through mucosal/epithelial barriers, i.e., gastrointestinal tissue. Active transport, permeability enhancers, enzymatic degradation, and absorption in various tissue sections can be explored. Preliminary data are consistent with the expected effects of molecular size and partition coefficient of a transported molecule on permeability in epithelial tissue. In addition, active transport of D-glucose and inhibition by phloridzin and ouabain can be demonstrated.

Identification of new cactus alkaloids in Backebergia militaris by tandem mass spectrometry

Tandem mass spectrometry, applied to simple extracts of Backebergia militaris, indicated the presence of a number of new alkaloids, including fully aromatic oxygenated isoquinolines, their di- and tetra-hydro analogs, and beta-phenethylamines. These conclusions were supported by separation using radial tlc and comparison with authentic compounds. Traces of seven alkaloids new to this cactus species were identified; four (3,4,8,11) were known previously from other cacti. Three novel cactus alkaloids were identified and confirmed by synthesis as 7,8-dimethoxy-3,4-dihydroisoquinoline (12, dehydrolemaireocereine), 6,7-dimethoxyisoquinoline (13, backebergine), and 7,8-dimethoxyisoquinoline (14, isobackebergine). The last two compounds are the first simple, fully aromatic, isoquinoline alkaloids to be reported from the Cactaceae. The sensitivity of this approach to new alkaloid discovery is emphasized; the entire project consumed only 10 g of dried plant material.