Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Labetalol is a combined alpha- and beta-adrenoceptor blocking agent for oral and intravenous use in the treatment of hypertension. It is a nonselective antagonist at beta-adrenoceptors and a competitive antagonist of postsynaptic alpha 1-adrenoceptors. Labetalol is more potent at beta that at alpha 1 adrenoceptors in man; the ratio of beta-alpha antagonism is 3:1 after oral and 6.9:1 after intravenous administration. Labetalol is readily absorbed in man after oral administration, but the drug, which is lipid soluble, undergoes considerable hepatic first-pass metabolism and has an absolute bioavailability of approximately 25%. There are no active metabolites, and the elimination half-life of the drug is approximately 6 hours. Unlike conventional beta-adrenoceptor blocking drugs without intrinsic sympathomimetic activity, labetalol, when given acutely, produces a decrease in peripheral vascular resistance and blood pressure with little alteration in heart rate or cardiac output. However, like conventional beta-blockers, labetalol may influence the renin-angiotensin-aldosterone system and respiratory function. Clinical studies have shown that the antihypertensive efficacy of labetalol is superior to placebo and to diuretic therapy and is at least comparable to that of conventional beta-blockers, methyldopa, clonidine and various adrenergic neuronal blockers. Labetalol administered alone or with a diuretic is often effective when other antihypertensive regimens have failed. Studies have shown that labetalol is effective in the treatment of essential hypertension, renal hypertension, pheochromocytoma, pregnancy hypertension and hypertensive emergencies. In addition, preliminary studies indicate that labetalol may be of value in the management of ischemic heart disease. The most troublesome side effect of labetalol therapy is posture-related dizziness. Other reported side effects of the drug include gastrointestinal disturbances, tiredness, headache, scalp tingling, skin rashes, urinary retention and impotence. Side effects related to the beta-adrenoceptor blocking effect of labetalol, including asthma, heart failure and Raynaud's phenomenon, have been reported in rare instances.
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PMID:Labetalol: a review of its pharmacology, pharmacokinetics, clinical uses and adverse effects. 631 May 29

An 82-year-old man was admitted to the hospital in the summer of 1995 due to dyspnea, peripheral edema, and a tingling sensation and muscle weakness in all extremities. Physical examination showed heart failure and polyneuropathy. Laboratory data showed a low concentration of vitamin B1 (10 ng/ml normal 23.8-45.9 ng/ml) and a low level of erythrocyte transketolase activity (0.58 IU/gHb normal 0.75-1.30 IU/gHb). A chest X-ray film revealed cardiomegaly (cardiothoracic ratio 57.1%) and ultrasonic cardiography revealed increased motion of the left ventricle. A diagnosis of beriberi was made. The disease in this case may have been caused by hard work in the summer heat. The patient was treated with thiamine and his symptoms and signs resolved within a few weeks. A search of the literature revealed no previous report of beriberi in a patient of this age, but reports of beriberi in older patients in Japan are more common now than in previous years. Beriberi should be included in the differential diagnosis of polyneuropathy in elderly patients.
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PMID:[An elderly patient with beriberi]. 926 56