Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Labetalol is a drug possessing both alpha and beta adrenergic receptor blocking properties. Its possible use in induced hypotension during halothane anaesthesia has been investigated. It causes a satisfactory decrease in arterial pressure unaccompanied by tachycardia. The circulatory effects of the drug during halothane anaesthesia, both with spontaneous and controlled respiration, have been measured and compared with those of halothane alone. In patients anaesthetised with 1% halothane, labetalol, with both spontaneous and controlled ventilation, was associated with a reduction in MAP from 71.5 mmHg to 54.0 mmHg (P less than 0.001) and 66.8 mmHg to 50.4 mmHg (P less than 0.001) respectively. This reduction was associated with decreases in Qt of 18% and 12% respectively. In the presence of labetalol, with 3% halothane and spontaneous respiration, the depressant effects of the anaesthetic on the heart became rapidly apparent: Qt was reduced by a further 28%. In patients not receiving labetalol, the depressant effects of 3% halothane were frequently countered by the positive inotropic effects of hypercarbia.
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PMID:Circulatory effects of labetalol during halothane anaesthesia. 63 71

Hypertensive emergencies are uncommon and physiologically diverse. Consequently, it is difficult for most physicians to develop a familiarity with all the different hypertensive crises and with all drugs available for treating them (Table 4). Clinicians should not agonize over which is the perfect therapeutic agent for a particular emergency, but instead, they should focus on scrupulous monitoring and familiarize themselves with a few agents that will serve in most situations. Generally, these agents will be sodium nitroprusside and nitroglycerin. Vigilant neurologic monitoring is mandatory in all hypertensive emergencies. The early symptoms and signs of cerebral hypoperfusion can be vague and subtle, but if recognized, serious complications of therapy can be avoided. Remember, the patient may still be hypertensive. Avoid acute (during the first hour) reductions in MAP of more than 20% whenever possible; subsequent reductions should be gradual. In patients known to have markedly elevated ICP and who need acute reductions in their BP, serious consideration should be given to direct monitoring of the ICP so that CPP can be maintained within safe limits. In general, oral agents should not be used for the treatment of hypertensive emergencies. Intravenous Labetalol and intravenous nicardipine are not suitable for general use in hypertensive emergencies. In special situations (e.g., perioperative hypertension and subarachnoid hemorrhage), however, they may be employed. Their role may expand with further study. Trimethaphan may be superior to nitroprusside for hypertension complicated by elevated ICP or cerebral dysfunction. Realistically, most physicians will continue to use nitroprusside. Intense neurologic monitoring is more important than the specific agent used. Nitroglycerin is the agent of choice for acute ischemic heart disease complicated by severe hypertension; if it fails, use nitroprusside. For aortic dissection, the combination of nitroprusside and IV propranolol is the therapy of choice; beta-blockade must be achieved rapidly or the dissection may worsen. Trimethaphan is also an agent for first-line therapy. Esmolol is an alternative to IV propranolol for the treatment of aortic dissection, if prolonged beta-blockade might seriously jeopardize the patient. For eclampsia, unless an expert in hypertension during pregnancy has established an alternative, the therapy of choice is hydralazine and magnesium. The treatment of subarachnoid hemorrhage is in flux; calcium channel blockers are used to prevent spasm, not to lower BP. If the BP must be lowered immediately, use nitroprusside.
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PMID:Hypertensive emergencies. 758 98