PHARMACODYNAMICS AND PHARMACOKINETICS OF EPTASTIGMINE IN ELDERLY SUBJECTS

Eptastigmine is a new cholinesterase inhibitor, which may be potential ly useful for the symptomatic treatment of Alzheimer's disease. A prel iminary evaluation of its pharmacodynamic and pharmacokinetic profiles in the elderly has now been made in 6 healthy subjects (63-84 years o f age) given 30 mg eptastigmine as a single oral dose. Blood was colle cted prior to and 1, 2,3,4, 6, 8, and 12 h after eptastigmine administ ration for measurement of cholinesterase inhibition in plasma and red blood cells and the plasma drug concentrations. The maximum plasma cho linesterase inhibition was 17%, which was reached 2.7 h after treatmen t. In red cells the maximum inhibition of the enzyme was 29% after 3.8 h. The estimated half-time of cholinesterase recovery was 12.4 h in p lasma and 13.6 h in red blood cells. The peak plasma concentration of eptastigmine of 0.86 ng . ml-1 was reached after 1.4 h. Following abso rption the drug was rapidly distributed into tissues (t1/2alpha = 0.44 h) and then eliminated with a half-life of 12.1 h. The drug was well tolerated in all but one subject, who showed bradycardia with hyperten sion and nausea for about 2 h after the dose. The results indicate tha t oral administration of eptastigmine to elderly subjects produces lon g lasting inhibition of cholinesterase activity in plasma and in red b lood cells.