withdrawal symptoms (delirium tremens, or DTs”), and to stop convulsions in people Only your healthcare provider can determine the length of lorazepam treatment . The onset of action usually occurs within 20 to 60 minutes. Some pharmaceutical companies offer medication assistance programs to low-income. Lorazepam, sold under the brand name Ativan among others, is a benzodiazepine medication. When given by injection onset of effects is between one and thirty minutes and effects last for up to a day. .. The magnitude and duration of lorazepam effects are dose-related, meaning larger doses have stronger and Onset of action: 1–5 min (IV), 15–30 min (IM). Feb 18, - Barbara Ameer at Robert Wood Johnson Medical School, New When lorazepam and diazepam have been compared at a dosage ratio of 1: 5, . binding model to predict the onset and duration of pharmacological activity of.