Jack J. Kinsora

Activity profile of pregabalin in rodent models of epilepsy and ataxia

Pregabalin (Lyrica) is a novel amino acid compound that binds with high affinity to the alpha2-delta (alpha2-delta) auxiliary protein of voltage-gated calcium channels. In vivo, it potently prevents seizures, pain-related behaviors and has anxiolytic-like activity in rodent models. The present studies were performed to determine the profile of pregabalin anticonvulsant activity in a variety of mouse and rat models. In the high-intensity electroshock test, pregabalin potently inhibited tonic extensor seizures in rats (ED50 = 1.8 mg/kg, PO), and low-intensity electroshock seizures in mice. It prevented tonic extensor seizures in the DBA/2 audiogenic mouse model (ED50 = 2.7 mg/kg, PO). Its time course of action against electroshock induced seizures in rats roughly followed the pharmacokinetics of radiolabeled drug in the brain compartment. At higher dosages (ED50 1= 31 mg/kg, PO), pregabalin prevented clonic seizures from pentylenetetrazole in mice. In a kindled rat model of partial seizures, pregabalin prevented stages 4-5 behavioral seizures (lowest effective dose = 10 mg/kg, IP), and also reduced the duration of electrographic seizures. Pregabalin was not active to prevent spontaneous absence-like seizures in the Genetic Absence Epilepsy in Rats from Strasbourg (GAERS) inbred Wistar rat strain. Pregabalin caused ataxia and decreased spontaneous locomotor activity at dosages 10-30-fold higher than those active to prevent seizures. These findings suggest that pregabalin has an anticonvulsant mechanism different from the prototype antiepileptic drugs and similar to that of gabapentin except with increased potency and bioavailability. In summary, our results show that pregabalin has several properties that favor treatment of partial seizures in humans.

Oxadiazolone bioisosteres of pregabalin and gabapentin.

A series of oxadiazolone bioisosteres of pregabalin 1 and gabapentin 2 were prepared, and several were found to exhibit similar potency for the alpha(2)-delta subunit of voltage-gated calcium channels. Oxadiazolone 9 derived from 2 achieved low brain uptake but was nevertheless active in models of osteoarthritis. The high clearance associated with compound 9 was postulated to be a consequence of efflux by OAT and/or OCT, and was attenuated on co-administration with cimetidine or probenecid.