Studies of Drugs Given Before Anaesthesia Xxvi: Lorazepam

Abstract

Lorazepam has been studied as preanaesthetic medication given by mouth, i.m. and i.v. Sediation and side-effects and the incidence of anterograde amnesia in patients having a standard operation under methohexitone-nitrous oxide-oxygen anaesthesia were assessed. In a preliminary study of three i.m. (2-, 4- and 8-mg) and six oral (1-,2-,2.5-,4-,5- and 8-mg) doses, the optimum dose was found to be 4 mg for patients with an average weight of 60 kg. This dose was studied in detail when given by all three routes and compared with the commercially available 2.5- and 5-mg tablets. Even when given i.v., there was a delay of 30-40 min in the onset of maximum sedative effect and drowsiness persisted for at least 4 h. Although the onset of action by i.m. injection was slightly faster than when the drug was given by mouth this advantage was more than offset by the high frequencies of pain at the site of injection and restlessness which persisted for 20-40 min. Oral lorazepam in doses of 2.5-5.0 mg was a reliable, effective sedative which could be recommended for routine preanaesthetic medication, provided rapid recovery was not essential. Its soporific effect was accompanied by an appreciable incidence of anterograde amnesia.

Interactive effects of subanesthetic ketamine and subhypnotic lorazepam in humans

“…Lorazepam doses that produce anxiolysis, amnesis, and sedation were not e¤ective in preventing ketamine psychosis. However, the anesthesia literature suggests that the IV administration of lorazepam at a higher dose than employed in the current study, 4 mg, reduces ketamine psychosis (Dundee et al 1977). At this lorazepam dose, sedative e¤ects interfere with prospective behavioral assessments and amnestic e¤ects could interfere with retrospective self-reports.…”

Analgesia, Sedation, and Therapeutic Paralysis in the Critically Ill

“…Lorazepam has a slower onset and longer duration of action than midazolam. 96 It is the high affinity of lorazepam for cellular receptors that produces its intermediate to long duration of action. Because lorazepam does not require hepatic metabolism and does not yield active hepatic metabolites, it may be a better benzodiazepine choice for the patient with liver disease.…”

Comparative Study of Lorazepam and Trimeprazine for Oral Premedication in Paediatric Anaesthesia

“…The frequency of vomiting after anaesthesia in the trimeprazine group was similar to that reported after trimeprazine in previous studies. The frequency of postoperative vomiting after premedication with lorazepam was 39.3%, which is greater than the 10.4% (Dodson and Eastley, 1978) and 15% (Dundee et al, 1977) frequency observed in adults. Both groups received equal amounts of analgesic, following surgery, but whereas trimeprazine has a well recognized antiemetic effect, opinion is divided concerning lorazepam, with both antiemetic and emetic properties reported (Dodson et al, 1976).…”

“…The frequency of anterograde amnesia for the venepuncture was less than the 28% rate reported in adults (Dundee et al, 1977). However, amnesia following oral lorazepam is greater for nonemotional or visual events than for painful stimuli (McKay, Dundee and George, 1978;Studd and Eltringham, 1980).…”

“…surgery. Lorazepam possesses the advantage of greater anxiolysis than narcotic premedication (Wassenaar et al, 1977), lack of respiratory depression (Dodson et al, 1976;Cormack, Milledge and Hanning, 1977), anterograde amnesia, long duration of action (Dundee et al, 1977) and an antiemetic effect (Loach and Fisher, 1975).…”