Penbutolol

Pronunciation

(pen BYOO toe lole)

U.S. Brand Names

Levatol®

Synonyms

Penbutolol Sulfate

Generic Available

Canadian Brand Names

Levatol®

Use

Treatment of mild to moderate arterial hypertension

Pregnancy Risk Factor

C (manufacturer); D (2nd and 3rd trimester - expert analysis)

Lactation

Enters breast milk/use caution

Contraindications

Hypersensitivity to penbutolol or any component of the formulation; uncompensated congestive heart failure; cardiogenic shock; bradycardia or heart block (except in patients with a functioning artificial pacemaker); sinus node dysfunction; asthma; bronchospastic disease; COPD; pulmonary edema; pregnancy (2nd and 3rd trimester)

Warnings/Precautions

Avoid abrupt discontinuation in patients with a history of CAD; slowly wean while monitoring for signs and symptoms of ischemia. Use caution with concurrent use of beta-blockers and either verapamil or diltiazem; bradycardia or heart block can occur. Use caution in patients with PVD (can aggravate arterial insufficiency). Use cautiously in diabetics because it can mask prominent hypoglycemic symptoms. Can mask signs of thyrotoxicosis. Can cause fetal harm when administered in pregnancy. Beta-blockers with intrinsic sympathomimetic activity (including penbutolol) do not appear to be of benefit in CHF.

Adverse Reactions

1% to 10%:

Cardiovascular: CHF, arrhythmia

Central nervous system: Mental depression, headache, dizziness, fatigue

Gastrointestinal: Nausea, diarrhea, dyspepsia

Neuromuscular & skeletal: Arthralgia

<1% (Limited to important or life-threatening): AV block, bradycardia, bronchospasm, cold extremities, confusion, cough, edema, hypoglycemia, hypotension, insomnia, lethargy, ischemic colitis, mesenteric arterial thrombosis, nightmares, purpura, Raynaud's phenomena, thrombocytopenia

Overdosage/Toxicology

Enhancement of elimination: Charcoal hemoperfusion can be used to lower serum levels. Treatment is symptom-directed and supportive.

Drug Interactions

Alpha-blockers (prazosin, terazosin): Concurrent use of beta-blockers may increase risk of orthostasis.

Albuterol (and other beta2 agonists): Effects may be blunted by nonspecific beta-blockers.

Clonidine: Hypertensive crisis after or during withdrawal of either agent.

Drugs which slow AV conduction (digoxin): Effects may be additive with beta-blockers.

Epinephrine (including local anesthetics with epinephrine): Penbutolol may cause hypertension.

Glucagon: Penbutolol may blunt the hyperglycemic action.

Insulin and oral hypoglycemics: May mask symptoms of hypoglycemia.

NSAIDs (ibuprofen, indomethacin, naproxen, piroxicam) may reduce the antihypertensive effects of beta-blockers.

Penbutolol masks the tachycardia that usually accompanies insulin-induced hypoglycemia.

Salicylates may reduce the antihypertensive effects of beta-blockers.

Sulfonylureas: beta-blockers may alter response to hypoglycemic agents.

Verapamil or diltiazem may have synergistic or additive pharmacological effects when taken concurrently with beta-blockers.

Mechanism of Action

Blocks both beta1- and beta2-receptors and has mild intrinsic sympathomimetic activity; has negative inotropic and chronotropic effects and can significantly slow AV nodal conduction

Pharmacodynamics/Kinetics

Absorption: ~100%

Protein binding: 80% to 98%

Metabolism: Extensively hepatic (oxidation and conjugation)

Bioavailability: ~100%

Half-life elimination: 5 hours

Excretion: Urine

Dosage

Adults: Oral: Initial: 20 mg once daily, full effect of a 20 or 40 mg dose is seen by the end of a 2-week period, doses of 40-80 mg have been tolerated but have shown little additional antihypertensive effects; usual dose range (JNC 7): 10-40 mg once daily

Patient Education

Take exactly as directed. Do not increase, decrease, or adjust dosage without consulting prescriber. Take pulse daily, prior to medication and follow prescriber's instruction about holding medication. Do not take with antacids. Do not use OTC medications (eg, cold remedies) without consulting prescriber. If you have diabetes, monitor serum glucose closely (drug may alter glucose tolerance or mask signs of hypoglycemia). May cause fatigue, dizziness, or postural hypotension; use caution when changing position from lying or sitting to standing, when driving, or when climbing stairs until response to medication is known. May cause alteration in sexual performance (reversible). Report unresolved swelling of extremities, respiratory difficulty or new cough, unresolved fatigue, unusual weight gain, unresolved constipation, or unusual muscle weakness. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Consult prescriber if breast-feeding.

Nursing Implications

Advise against abrupt withdrawal

Monitor orthostatic blood pressures, apical and peripheral pulse and mental status changes (ie, confusion, depression)

Anesthesia and Critical Care Concerns/Other Considerations

Penbutolol possesses intrinsic sympathomimetic activity. While beta-blockers with intrinsic sympathomimetic activity induce fewer side effects, the cardiovascular benefits are less clear.

Surgery: Atenolol has also been shown to improve cardiovascular outcomes when used in the perioperative period in patients with underlying cardiovascular disease who are undergoing noncardiac surgery. Bisoprolol in high-risk patients undergoing vascular surgery reduced the perioperative incidence of death from cardiac causes and nonfatal myocardial infarction.

Withdrawal: Beta-blocker therapy should not be withdrawn abruptly, but gradually tapered to avoid acute tachycardia and hypertension.

Cardiovascular Considerations

This drug possesses intrinsic sympathomimetic activity. While beta-blockers with intrinsic sympathomimetic activity induce fewer side effects, the cardiovascular benefits when used in patients with hypertension or heart failure are less clear than for beta-blockers without intrinsic sympathomimetic activity.

Hypertension: Beta-blocker therapy in the treatment of hypertension has been associated with improved cardiovascular outcomes. This class of drug is beneficial for elderly patients with hypertension. A recent UKPDS study showed that beta-blocker therapy (atenolol) was as effective as an ACE inhibitor in reducing cardiovascular events and that the benefits of therapy were related more to the degree of antihypertensive efficacy rather than the class of drug used.

Surgery: Atenolol has also been shown to improve cardiovascular outcomes when used in the perioperative period in patients with underlying cardiovascular disease who are undergoing noncardiac surgery. Bisoprolol in high-risk patients undergoing vascular surgery reduced the perioperative incidence of death from cardiac causes and nonfatal myocardial infarction.

Angina: Beta-blockers are effective in the treatment of angina as monotherapy or when combined with nitrates and/or calcium channel blockers. In patients with severe intractable angina requiring negative cardiac chronotropic medications, pacemaker placement has been carried out to maintain heart rate in the setting of large doses of beta-blockers and/or calcium channel blockers. Beta-blockers are ineffective in the treatment of pure vasospastic (Prinzmetal) angina.

Unstable angina/non-ST-segment elevation MI: In the treatment of unstable angina/non-ST-segment elevation MI, a beta-blocker, with the first dose administered intravenously if there is ongoing chest pain, followed by oral administration, is recommended (in the absence of contraindications).

Withdrawal: Beta-blocker therapy should not be withdrawn abruptly, but gradually tapered to avoid acute tachycardia and hypertension.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation). Penbutolol is a nonselective beta-blocker and may enhance the pressor response to epinephrine, resulting in hypertension and bradycardia. Many nonsteroidal anti-inflammatory drugs, such as ibuprofen and indomethacin, can reduce the hypotensive effect of beta-blockers after 3 or more weeks of therapy with the NSAID. Short-term NSAID use (ie, 3 days) requires no special precautions in patients taking beta-blockers.

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause dizziness or depression; may rarely cause insomnia, confusion, or nightmares

Mental Health: Effects on Psychiatric Treatment

Concurrent use with phenothiazines may potentiate hypotensive effects of penbutolol

Dosage Forms

Tablet, as sulfate: 20 mg

References

Braunwald E, Antman EM, Beasley JW, et al, "ACC/AHA 2002 Guideline Update for the Management of Patients With Unstable Angina and Non-ST-Segment Elevation Myocardial Infarction - Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina)," J Am Coll Cardiol , 2002, 40(7):1366-74. Available at: http://www.acc.org/clinical/guidelines/unstable/incorporated/index.htm. Accessed May 20, 2003.

Chobanian AV, Bakris GL, Black HR, et al, "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report," JAMA , 2003, 289(19):2560-71.

"Consensus Recommendations for the Management of Chronic Heart Failure. On Behalf of the Membership of the Advisory Council to Improve Outcomes Nationwide in Heart Failure," Am J Cardiol , 1999, 83(2A):1A-38A.

Gibbons RJ, Abrams J, Chatterjee K, et al, "ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina - Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Chronic Stable Angina)," J Am Coll Cardiol , 2003, 41(1):159-68.

Mokhlesi B, Leikin JB, Murray P, et al, "Adult Toxicology in Critical Care: Part II: Specific Poisonings," Chest , 2003, 123(3):897-922.

International Brand Names

Betapressin® (DE); Hostabloc® (AR); Levatol® (CA)

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