Testing the injectable dosage form of phenazepam showed no substantial pharmacokinetic differences in epileptic patients receiving a single intravenous and intramuscular doses of 2 mg. The bioavailability of the drug was 0.82. The individual and mean experimental stationary phenazepam concentration (157.3 ng/ml) in the patients' blood during course intramuscular therapy was found to be close to the theoretical stationary one (150.6 ng/ml). The pharmacokinetic findings allow one to optimize phenazepam therapy for epileptic patients.