Hypotension beta-blocker-induced

PO/IV. Well absorbed, 80% metabolized in first pass. 90% protein bound. Metabolites are active. Half-life is 5 hrs but may be up to 20 hrs in patients with cirrhosis. Patient on IV blockers or digitalis. A-V node block, sick sinus syndrome, cardiogenic shock, heart failure, hypotension. Beta blockers or digitalis Increases likelihood of bradycardia or A-V blockade. Quinicfine or prazosin Increases hypotension. Digoxin levels are increased. Cimetidine reduces verapamil clearance. Calcium supplements may inhibit actions of verapamil. Depolarization (leading to contraction) of vascular smooth muscle is dependent on calcium entry. Vasodilation is induced by calcium entry blockers because they inhibit calcium influx. 

Terazosin is an alpha-adrenoreceptor blocker that causes vasodilation and is used in the management of hypertension and benign prostatic hypertrophy. Beta-blockers and alpha-blockers can interact to induce hypotension since both act to reduce the blood pressure. Patients already on beta-blockers and who are started on alpha-blockers such as terazosin should be advised to take the terazosin dose at night to reduce the implications (falls) of first-dose hypotension. 

Eor preventive treatments, the adverse effects of the beta blockers are classical for this class bradycardia, bronchospasm, hypotension, nightmares and depression. Indoramine induces neuropsychiatric effects (sedation, asthenia) and cardiovascular disorders (hypotension). Eluanarizine is strictly contraindicated in patients with Parkinsonism and depression. 

Direct vasodilators frequently produce baroreflex-induced tachycardia, but rarely orthostatic hypotension. They are usually prescribed with a beta blocker or a centrally acting antihypertensive to minimize the reflex increase in heart rate and cardiac output. It should be noted that another member of the directly acting class of antihypertensives is minoxidil. This potent, long-acting drug has gained considerable notoriety for its use as a topical hair-restorer. Oral use can result in hirsutism (unwanted hair growth over the face as well as other parts of the body). 

Eight out of 42 patients taking unnamed beta blockers given atracurium developed bradycardia (less than 50 bpm) and hypotension (systolic pressure less than 80 mniHg). Most of them had been premedicated with diazepam, induced with methohexital, and maintained with droperidol, fentanyl and nitrous oxide/oxygen. A further 24 showed bradycardia, associated with hypotension on 9 oeeasions. All responded promptly to 300 to 600 micrograms of intravenous atropine. ... 

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