Plasma lorazepam levels. A study following single dose administration of 2 and 4 mg by different routes

Plasma lorazepam levels were studied following single doses of 2 mg and 4 mg in patients and volunteers. There was a slightly more rapid uptake of drug following deep intramuscular injection than when taken by mouth. Plasma levels declined rapidly following intravenous injection (t1/2 of approximately 2-3 hours). Two hours after giving the drug the plasma levels were similar irrespective of the route of administration. The second phase decline was very slow and one third of the peak concentration was still in the blood at 24 hours.