Penbutolol

Oral
Hypertension

May be taken with or without food.

AV block (2nd and 3rd degree), sinus bradycardia, bronchial asthma, cardiogenic shock.

Bronchospastic disease, compensated heart failure, DM, myasthenia gravis, untreated phaeochromocytoma, peripheral vascular disease including Raynaud's disease. May mask signs and symptoms of hyperthyroidism and acute hypoglycaemia. Avoid abrupt withdrawal as it may precipitate thyroid storm, exacerbate angina, HTN and MI. Patients undergoing surgery involving general anaesth. Pregnancy and lactation.

Headache, dizziness, fatigue, insomnia, asthenia, arrhythmia, diaphoresis, CHF, nausea, diarrhoea, dyspepsia, upper resp tract infection, dyspnoea, cough, chest and limb pain, excessive sweating, impotence.

Monitor BP and heart rate.

Symptoms: Bradycardia, hypotension, bronchospasm and acute cardiac failure. Management: Consider gastric emptying. IV atropine sulfate may be given to induce vagal blockade, and if bradycardia persists, administer IV isoproterenol HCl cautiously. For hypotension, sympathomimetic drugs (e.g. dobutamine, dopamine, levarterenol) may be given. IV glucagon may be useful in refractory cases. For bronchospasm, a β₂-agonist and/or IV aminophylline may be considered.

Concomitant use w/ digitalis glycosides may increase the risk of bradycardia. Hypoglycaemic effects of insulin and antidiabetics may be prolonged. Coadministration w/ Ca antagonist may lead to synergistic hypotensive effects, bradycardia and arrhythmias. Additive effects w/ anaesth agents that depress the myocardium (e.g. cyclopropane, ether, trichloroethylene). Catecholamine-depleting drugs (e.g. reserpine) may enhance hypotensive effects. May enhance the rebound hypertensive effect of clonidine.

Description: Penbutolol is a non-cardioselective β-blocker w/ some intrinsic sympathomimetic activity but lacks membrane-stabilising properties.
Onset: 1.5-3 hr.
Duration: >20 hr.
Pharmacokinetics:
Absorption: Readily absorbed from GI tract. Bioavailability: Approx 100%. Time to peak plasma concentration: Approx 1-3 hr.
Distribution: Plasma protein binding: 80-98%.
Metabolism: Undergoes extensive hepatic metabolism via hydroxylation and glucuronidation.
Excretion: Via urine (as metabolites). Elimination half-life: Approx 20 hr.

Store between 20-25°C. Protect from light.

Beta-Blockers

Anon. Penbutolol. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 28/11/2013.

Buckingham R (ed). Penbutolol Sulfate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 28/11/2013.

Levatol (Actient Pharmaceuticals, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 28/11/2013.

Wickersham RM. Penbutolol Sulfate. Facts and Comparisons [online]. St. Louis, MO. Wolters Kluwer Clinical Drug Information, Inc. https://www.wolterskluwercdi.com/facts-comparisons-online/. Accessed 28/11/2013.