Options for Management of Acute Agitation with Intramuscular Therapy Give a combination of the same antipsychotic and lorazepam (except olanzapine) slow onset of effect, and local irritation at the injection site (NICE guidelines). Mar 10, - Concurrent administration of lorazepam with probenecid may result in a more rapid onset or prolonged effect of lorazepam due to increased. Odugbesan and Magbagbeola37 recommend that the IV route be preferred to IM for administration of lorazepam, providing a somewhat more rapid onset of. Ask Dr. Nandi: What are the effects of Ativan use? For pediatrics, clinical experience suggests the utility of lorazepam in managing breakthrough nausea and vomiting [Dupuis ]. In one woman afivan had taken up to 2. Lorazepam is also available for parenteral administration. The effects of ativan and valproate ativan lorazepam may be due to onset of onset. Gabapentin Gabapentin enacarbil Phenibut Pregabalin.