Bioavailability of intranasal neostigmine: comparison with intravenous route.

The pharmacokinetics of intranasal (i.n.) neostigmine was compared with the intravenous (i.v.) route in 6 healthy volunteers with a mean age of 25.5 years and a mean weight of 65.8 kg in a crossover design. The doses used were 0.5 mg i.v. and 21.6 mg i.n. Neostigmine was determined by HPLC. The plasmatic profiles of the two routes were similar. An early peak of plasmatic concentration after i.n. administration was observed. The absolute bioequivalence of the i.n. route was ten-fold greater than the oral one.