British journal of clinical pharmacology
-
1 The circulatory effects of labetalol 25 mg intravenously in six patients during 1% halothane anaesthesia were studied. 2Labetalol caused a marked decrease in arterial pressure and a consistent but modest (20%) decrease in cardiac output. Heart rate was slowed and stroke volume did not change significantly. Central venous pressure increased and peripheral resistance decreased. 3 Increasing the halothane concentration of 3% led to marked myocardial depression as evidenced by reduced cardiac output and increased central venous pressure with increasing arterial hypotension. 4 Labetalol may be a suitable drug for controlling induced hypotension under general anaesthesia, although high concentrations of halothane should be used with care.
-
A survey of one hundred patients submitted to autopsy has been carried out to assess the contribution of investigational procedures, surgery and drug therapy to death. In nineteen patients drug therapy, usually appropriate and necessary therapy, was thought to have contributed to death. In five patients failure to continue therapy properly contributed to death. The survey was not representative either of patients dying in hospital or in the community, but it suggests that a larger and more comprehensive survey should be undertaken.
-
1 The disposition and metabolism of labetalol and either 14C- or 3H-labetalol has been studied in mouse, rat, rabbit, dog and man. 2 Radiolabelled labetalol was administered orally at doses of 100 mg/kg to the mouse, up to 50 mg/kg to the rat and rabbit, 20 mg/kg to the dog and 200 mg to man. From measurements of the total plasma radioactivity it was shown that labetalol was well absorbed by all the species. When the measurements of plasma radioactivity and labetalol concentrations were compared, it was found labetaol had been extensively metabolized by the first-pass effect in rat, rabbit and man. ⋯ This was probably formed through conjugation of glucuronic acid was the secondary alcohol group of labetalol. The major metabolite present in human urine was an unidentified conjugate of labetalol. Minor metabolites of labetalol present in rat, rabbit and dog urine were hydroxylabetalol and its glucuronyl conjugate.