Unpredictable central nervous system effects after lorazepam premedication for neurosurgery

Area of Science:

• Anesthesiology
• Pharmacology
• Neuroscience

Background:

• Lorazepam is commonly used as a preanesthetic medication.
• It is generally expected to induce amnesic effects.
• The relationship between lorazepam plasma levels and clinical effects requires further investigation.

Purpose of the Study:

• To evaluate the relationship between plasma levels of lorazepam and its clinical effects.
• To assess the incidence of amnesia and degree of drowsiness after lorazepam administration.
• To investigate potential variability in lorazepam's central nervous system effects.

Main Methods:

• Two studies were conducted involving neurosurgical patients receiving lorazepam.
• Patients received lorazepam intramuscularly (i.m.) or intravenously (i.v.) at specific doses.
• Plasma lorazepam levels were measured using gas chromatography, and clinical effects like amnesia and drowsiness were assessed.

Main Results:

• No significant relationship was observed between lorazepam dose or plasma levels and the incidence of amnesia.
• Similarly, no correlation was found between lorazepam levels and the degree of drowsiness.
• A subset of patients receiving a higher i.m. dose experienced prolonged drowsiness, complicating post-operative assessment.

Conclusions:

• The study suggests that lorazepam's amnesic and sedative effects in neurosurgical patients are variable.
• This variability may be attributed to differences in the drug's ability to cross the blood-brain barrier.
• Further research is needed to understand the factors influencing lorazepam's central nervous system penetration and effects.