During the course of our research efforts to develop a potent and selective γ-secretase inhibitor for the treatment of Alzheimer's disease, we investigated a series of carboxamide-substituted sulfonamides. Optimization based on potency, Notch/amyloid-β precursor protein selectivity, and brain efficacy after oral dosing led to the discovery of 4 (BMS-708163). Compound 4 is a potent inhibitor of γ-secretase (Aβ40 IC50 = 0.30 nM), demonstrating a 193-fold selectivity against Notch. Oral administration of 4 significantly reduced Aβ40 levels for sustained periods in brain, plasma, and cerebrospinal fluid in rats and dogs.

To identify novel targets for neuropathic pain, 3097 mouse knockout lines were tested in acute and persistent pain behavior assays. One of the lines from this screen, which contained a null allele of the adapter protein-2 associated kinase 1 (AAK1) gene, had a normal response in acute pain assays (hot plate, phase I formalin), but a markedly reduced response to persistent pain in phase II formalin. AAK1 knockout mice also failed to develop tactile allodynia following the Chung procedure of spinal nerve ligation (SNL). Based on these findings, potent, small-molecule inhibitors of AAK1 were identified. Studies in mice showed that one such inhibitor, LP-935509, caused a reduced pain response in phase II formalin and reversed fully established pain behavior following the SNL procedure. Further studies showed that the inhibitor also reduced evoked pain responses in the rat chronic constriction injury (CCI) model and the rat streptozotocin model of diabetic peripheral neuropathy. Using a nonbrain-penetrant AAK1 inhibitor and local administration of an AAK1 inhibitor, the relevant pool of AAK1 for antineuropathic action was found to be in the spinal cord. Consistent with these results, AAK1 inhibitors dose-dependently reduced the increased spontaneous neural activity in the spinal cord caused by CCI and blocked the development of windup induced by repeated electrical stimulation of the paw. The mechanism of AAK1 antinociception was further investigated with inhibitors of α2 adrenergic and opioid receptors. These studies showed that α2 adrenergic receptor inhibitors, but not opioid receptor inhibitors, not only prevented AAK1 inhibitor antineuropathic action in behavioral assays, but also blocked the AAK1 inhibitor–induced reduction in spinal neural activity in the rat CCI model. Hence, AAK1 inhibitors are a novel therapeutic approach to neuropathic pain with activity in animal models that is mechanistically linked (behaviorally and electrophysiologically) to α2 adrenergic signaling, a pathway known to be antinociceptive in humans.

Abstract. Food can impact the pharmacokinetics of a drug product through several mechanisms, including but not limited to, enhancement in drug solubility, changes in GI physiology, or direct interaction with the drug. Significant food effects complicate development of new drugs, especially when clinical plans require control and/or monitoring of food intake in relation to dosing. The prediction of whether a drug or drug product will show a human food effect is challenging. In vitro models which consider physical-chemical properties can classify the potential for a compound to demonstrate a positive, negative or no food effect, and may be appropriate for screening compounds at early stages of drug discovery. When comparing various formulations, dissolution tests in biorelevant media can serve as a predictor of human drug performance under fasted and fed conditions. Few in vivo models exist which predict the magnitude of change in pharmacokinetic parameters in humans when dosing in the presence of food, with the dog appearing to be the most studied species for this purpose. Control of gastric pH, as well as the amount and composition of the fed state in dogs are critical parameters to improving the predictability of the dog overall as a food effect model. No single universal model is applicable for all drugs at all stages of drug development. One or more models may be required depending whether the goal is to assess potential for a food effect, determine the magnitude of change in pharmacokinetic parameters in the fed/fasted state, or whether formulation efforts have the ability to mitigate an observed food effect.

Recently 2 QSPR-based in silico models were developed in our laboratories to predict the aqueous and non-aqueous solubility of drug-like organic compounds. For the intrinsic aqueous solubility model, a set of 321 structurally diverse drugs was collected from literature for the analysis. For the PEG 400 cosolvent model, experimental data for 122 drugs were obtained by a uniform experimental procedure at 4 volume fractions of PEG 400 in water, 0%, 25%, 50%, and 75%. The drugs used in both models represent a wide range of compounds, with log P values from -5 to 7.5, and molecular weights from 100 to >600 g/mol. Because of the standardized procedure used to collect the cosolvent data and the careful assessment of quality used in obtaining literature data, both data sets have potential value for the scientific community for use in building various models that require experimental solubility data.

The objective of this work was to design an acyclovir prodrug that would utilize the human apical sodium-dependent bile acid transporter (hASBT) and enhance acyclovir oral bioavailability. Using each chenodeoxycholate, deoxycholate, cholate, and ursodeoxycholate, four bile acid prodrugs of acyclovir were synthesized, where acyclovir was conjugated to a bile acid via a valine linker. The affinity of the prodrug for hASBT was determined through inhibition of taurocholate uptake by COS-7 cells transfected with hASBT (hASBT-COS). The prodrug with the highest inhibitory affinity was further evaluated in vitro and in vivo. The prodrug acyclovir valylchenodeoxycholate yielded the highest affinity for hASBT (Ki = 35 microM), showing that chenodeoxycholate is the free bile acid with the greatest affinity for hASBT. Acyclovir valylchenodeoxycholate's affinity was similar to that of cholic acid (Ki = 25 microM). Further characterization showed that acyclovir was catalytically liberated from acyclovir valylchenode-oxycholate by esterase. Relative to cellular uptake studies of acyclovir alone, the cellular uptake from the prodrug resulted in a 16-fold greater acyclovir accumulation within hASBT-COS cells, indicating enhanced permeation properties of the prodrug. Enhanced permeability was due to hASBT-mediated uptake and increased passive permeability. The extent of acyclovir uptake in the presence of sodium was 1.4-fold greater than the extent of passive prodrug uptake in the absence of sodium (p = 0.02), indicating translocation of the prodrug by hASBT. The prodrug also exhibited an almost 12-fold enhanced passive permeability, relative to acyclovir's passive permeability. Oral administration of acyclovir valylchenodeoxycholate to rats resulted in a 2-fold increase in the bioavailability of acyclovir, compared to the bioavailability after administration of acyclovir alone. Results indicate that a bile acid prodrug strategy may be useful in improving the oral bioavailability of intestinal permeability-limited compounds.