From the Guidelines
The peak effect of Ativan (Lorazepam) typically occurs within 1 to 2 hours after oral administration, but for intravenous administration, the peak effect is usually seen within 15 to 30 minutes 1.
Key Points
- The time to peak effect can vary depending on the route of administration, with intravenous administration resulting in a faster peak effect compared to oral administration 1.
- The duration of action is generally 6 to 12 hours, depending on the dose and individual factors, such as age and renal function 1.
- A typical dose of Ativan ranges from 0.5 to 4 milligrams, and it is essential to follow the prescribed dosage and administration instructions to ensure safe and effective use 1.
- It is also important to note that the metabolism of lorazepam can be affected by organ dysfunction and hypothermia, which may impact the time to peak effect and duration of action 1.
Administration Considerations
- For intravenous administration, the dose of lorazepam can range from 1 to 4 mg, with an infusion dose of 0.5 to 8 mg/h 1.
- The medication should be administered slowly and carefully, with close monitoring of the patient's vital signs and response to treatment 1.
From the FDA Drug Label
Following intramuscular administration, lorazepam is completely and rapidly absorbed reaching peak concentrations within 3 hours. A 4-mg dose provides a Cmax of approximately 48 ng/mL. Peak concentrations in plasma occur approximately 2 hours following administration
The time to peak effect of Ativan (Lorazepam) is:
- 2 hours for oral administration
- 15 to 20 minutes after intravenous injection for peak effect of sedation
- 3 hours for intramuscular administration to reach peak concentrations 2
From the Research
Time to Peak Effect of Ativan (Lorazepam)
- The time to peak effect of Ativan (Lorazepam) varies depending on the route of administration:
- Oral administration: peak concentrations are reached approximately 2 hours after administration 3, 4, 5
- Intramuscular administration: peak plasma levels are reached at 1.15 hours after dosage 4
- Sublingual administration: times of peak concentration were 2.25-2.35 hours postdose 4
- Intravenous administration: peak effect is immediate, but plasma levels decline rapidly with a half-life of approximately 2-3 hours 6, 7
- The peak effect of lorazepam is also influenced by the dose and individual factors, such as absorption and metabolism 3, 4, 6, 7, 5