Cognitive enhancement in man with ispronicline, a nicotinic partial agonist

Cholinergic mechanisms are clearly involved in memory deficits associated with Alzheimer's disease (AD) (Perry et al., 1977). Recently, there has been growing interest in the nicotinic approach to the treatment of AD; however, compounds have failed in the clinic because of a lack of separation between central and peripheral nicotinic effects (Potter et al., 1999). Ispronicline (TC-1734) is an orally active, selective, partial agonist of the central alpha4beta2 neuronal nicotinic acetylcholine receptor (nAChR), with high binding affinity to membrane preparations from rat brain or mammalian cells expressing recombinant human alpha4beta2 receptor (Gatto et al., 2004). Ispronicline has no detectable effects on muscle or ganglionic nAChRs, indicating a marked CNS over PNS selectivity. In animal models ispronicline potently improved cognitive function. A long duration of memory enhancement was displayed in object recognition and radial arm maze tests. Ispronicline pharmacokinetics (half-life of 2 h in rats) contrasts with the long-lasting improvement of working memory (18 h to 2 d) (Gatto et al., 2004).