Clinical evaluation of injectable lorazepam as a premedicant: the effect on recall

Intravenous benzodiazepines as anaesthetic agents: pharmacokinetics and clinical consequences

Despite extensive and numerous pharmacokinetic studies on benzodiazepines, the published pharmacokinetic data do not adequately explain the clinical differences found between different benzodiazepine derivatives after intravenous administration. Especially, correlations between initial drug responses and distributional changes of the benzodiazepines are limited. However, during the elimination phase some relationships exist between the kinetic and dynamic phenomena. Age, sex, diseases and concomitantly given drugs cause clinically important alterations in the pharmacokinetics of benzodiazepines. Generally these anxiolytics and sedatives should be considered as adjuvants to general anaesthesia, but not primarily as routine induction agents. The major reasons for this limitation are a high variability in drug response, a relatively slow onset of action and long-lasting residual effects. However, benzodiazepines have many important advantages (see Table 5) when used as intravenous inducing agents of general anaesthesia.

Lorazepam and diazepam as adjuncts to epidural anaesthesia for caesarean section

Lorazepam 0.05 mg X kg-1 and diazepam 0.1 mg X kg-1 administered intravenously were compared as sedatives for 42 patients undergoing Caesarean Section under epidural anaesthesia. After receiving the drug, 15 per cent of the diazepam patients and 32 per cent of the lorazepam patients were still agitated. Ten per cent of the diazepam patients and 36 per cent of the lorazepam patients had severe symptoms of delirium. These included hallucinations, confusion, agitation, restlessness, inappropriate weeping and repetitive hand movements. Memory impairment was greater with lorazepam. Thirty-five per cent of the diazepam patients had pain at the injection site. None of the lorazepam patients had such pain. Respiratory rate, heart rate and mean blood pressure did not change significantly in either group. Half the patients who had been given lorazepam had side effects that were bothersome enough to cause them to complain the following day. Lorazepam and diazepam were both unsatisfactory as sedatives for patients having Caesarean Section.

Clinical pharmacokinetics of lorazepam. III. Intravenous injection. Preliminary results

Four healthy male volunteers received 5 mg lorazepam as a single intravenous injection. Concentrations of lorazepam and its glucuronide metabolite were determined in multiple venous blood samples drawn during the 48 hours after dosing and in all urine collected during 96 hours after the dose. Mean pharmacokinetic parameters for lorazepam were: apparent elimination half-life, 13.2 hours; volume of distribution, 0.84 liter/kg; total clearance, 55.3 ml/min. Lorazepam glucuronide, the major metabolic product of lorazepam, promptly appeared in blood, reached peak levels within 6 hours of the dose, then declined in parallel with the parent compound. A mean of 69 per cent of the dose was recovered in urine as lorazepam glucuronide.