Pharmacokinetics of galanthamine hydrobromide after single subcutaneous and oral dosage in humans.

Galanthamine hydrobromide (Nivalin, dose 10 mg) was given subcutaneously and orally to 8 volunteers. Galanthamine and its metabolites were quantified in plasma and urine by reversed-phase HPLC. An unusual two-stage absorption and biexponential drug decline were observed. Galanthamine plasma peaks (1.24 micrograms/ml after subcutaneous and 1.15 micrograms/ml after oral doses) were reached 2 h following administration, the t1/2(beta) values being 5.70 and 5.26 h, respectively. Minor epigalanthamine and galanthaminone plasma levels were detected. An almost complete urinary recovery of galanthamine and its metabolites was obtained within 72 h. The plasma AUC, Cmax, tmax and ka suggest that the subcutaneous and oral Nivalin formulations are bioequivalent.