Ativan onset of action oral

36 The duration of action of lorazepam following IM administration is Lorazepam is absorbed slowly after oral administration; peak plasma levels develop in 2. Following a single 2-mg oral dose of 14C-lorazepam to 8 healthy subjects, . Because of its prolonged duration of action, the prescriber should be alert to the. Lorazepam, sold under the brand name Ativan among others, is a benzodiazepine medication. With long-term use larger doses may be required for the same effect. .. Giving 2 mg oral lorazepam will result in a peak total serum level of around 20 ng/ml around two hours later, half of which is lorazepam, half its inactive  ?Medical uses · ?Anxiety · ?Adverse effects · ?Pharmacology. Benzodiazepines - Mechanism of action, Clinical Use & Side Effects