ABSTRACT
Abecarnil is a partial agonist at the benzodiazepine receptor. It is one of a group of agents called beta-carbolines and has been studied for some time. A partial agonist is on the anxiolytic end of the spectrum between a full agonist and a neutral antagonist, such as flumazenil. Abecarnil has a high affinity for benzodiazepine receptors, and it has side effects typical of benzodiazepine-like anxiolytics, i.e., dizziness, fatigue, and unsteady gait, appearing in
a dose-related fashion. Abecarnil, like buspirone, does not work immediately but takes a week or so to have its effect. It does not work quite as well as alprazolam but is superior to placebo in the treatment of anxiety disorders, particularly by week two and certainly after week four, when it is almost equal in efficacy to alprazolam. Little or no physical dependence is found with abecarnil, which has minimal withdrawal symptoms after a rapid taper and exhibits continued residual therapeutic effects after discontinuation. Not all studies have found abecarnil equal in efficacy to alprazolam, but it does appear to be better than placebo. The use of abecarnil in the treatment of anxiety was reviewed in the Journal of Clinical Psychiatry Monograph 1997, Volume 58, Supplement 11. More recent studies suggest that abecarnil may ameliorate benzodiazepine withdrawal.
