Penbutolol Sulfate
Pronouncation: (pen-BYOO-toe-lole SULL-fate)Class: Beta-adrenergic blocking agent
Trade Names:
Levatol
- Tablets 20 mg
Pharmacology
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Nonselectively blocks beta-adrenergic receptors, primarily affecting the CV system (eg, decreased heart rate, decreased cardiac contractility, decreased BP) and lungs (promotes bronchospasm).
Pharmacokinetics
Absorption
Absorption is rapid and complete (100%). The t max is 2 to 3 h.
Distribution
Protein binding is 80% to 98%. Penbutolol crosses the placenta.
Metabolism
Hepatic metabolism is by conjugation and oxidation.
Elimination
Urine (90% excreted in urine, 1/ 6 as penbutolol conjugate). Penbutolol plasma t ½ is approximately 5 h; conjugated penbutolol is approximately 20 h, 25 h in elderly patients, and approximately 100 h in patients on renal dialysis.
Special Populations
Renal Function ImpairmentAccumulation of penbutolol conjugates may be expected.
Indications and Usage
Management of mild to moderate hypertension.
Contraindications
Greater than first-degree heart block; CHF unless secondary to tachyarrhythmia or untreated hypertension treatable with beta-blockers; overt cardiac failure; sinus bradycardia; cardiogenic shock; hypersensitivity to beta-blockers; untreated bronchial asthma or bronchospasm, including severe COPD.
Dosage and Administration
AdultsPO 20 mg every day.
General Advice
Administer without regard to meals. Administer with food if GI upset occurs.
Storage/Stability
Store tablets at controlled room temperature (59° to 86°F). Protect from light.
Drug Interactions
ClonidineMay attenuate or reverse antihypertensive effect; potentially life-threatening increases in BP, especially on withdrawal.
EpinephrineInitial hypertensive episodes followed by bradycardia may occur.
Ergot derivativesPeripheral ischemia, manifested by cold extremities and possible gangrene.
InsulinProlonged hypoglycemia with masking of symptoms.
LidocaineIncreased lidocaine levels, leading to toxicity.
NSAIDsSome agents may impair antihypertensive effects.
TheophyllineElimination of theophylline may be reduced; effects of both drugs may be reduced by pharmacologic antagonism.
VerapamilEffects of both drugs may be increased.
Laboratory Test Interactions
None well documented.
Adverse Reactions
Cardiovascular
Bradycardia; hypotension; CHF; edema; worsening angina, atrioventricular (AV) block.
CNS
Dizziness; tiredness; fatigue; headache; insomnia; depression; short-term memory loss; emotional lability.
Dermatologic
Sweating.
EENT
Dry eyes; visual disturbances.
GI
Diarrhea; nausea; dyspepsia.
Genitourinary
Impotence.
Hematologic
Agranulocytosis; nonthrombocytopenic and thrombocytopenic purpura.
Metabolic
May increase or decrease blood sugar.
Respiratory
Cough; dyspnea; bronchospasm.
Precautions
Pregnancy
Category C .
Lactation
Undetermined.
Children
Safety and efficacy not established.
CHF
Administer cautiously in CHF patients controlled by digitalis and diuretics.
Diabetics
May mask signs and symptoms of hypoglycemia (eg, tachycardia, BP changes). May potentiate insulin-induced hypoglycemia.
Nonallergic bronchospasm
Give drug with caution to patients with bronchospastic disease.
Thyrotoxicosis
May mask clinical signs of developing or continuing hyperthyroidism (eg, tachycardia). Abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm.
Abrupt withdrawal
A beta-blocker withdrawal syndrome (eg, hypertension, tachycardia, anxiety, angina, MI) may occur 1 to 2 wk after sudden discontinuation of systemic beta-blockers. If possible, gradually withdraw therapy over 1 to 2 wk.
Anaphylaxis
May be unresponsive to usual doses of epinephrine; aggressive therapy may be required.
Peripheral vascular disease
May precipitate or aggravate symptoms of arterial insufficiency.
Overdosage
Symptoms
Bradycardia, hypotension, CHF, AV block, intraventricular conduction defects, asystole, coma.
Patient Information
- Warn patient to never stop taking this medication suddenly. Rebound effects can produce angina, and even MI. Explain that medication will be tapered slowly before discontinuation.
- Instruct patient to take medication at the same time every day.
- Advise patient not to take any OTC medications such as nasal decongestants, diet aids, cold preparations, or antihistamines without consulting the health care provider first.
- Teach patient and family how to take pulse. Instruct them to check it before taking the medication. If the pulse is irregular or has a rate less than 60 bpm, notify health care provider before taking the medication.
- Instruct patient and family on how to take BP. If BP is markedly lower than normal, notify health care provider.
- Warn patient that sudden position changes may cause dizziness caused by postural hypotension.
- Instruct patient to notify health care provider if any of the following occur: confusion, depression, memory loss, rash, shortness of breath, slowed pulse rate, or unusual bruising or bleeding.
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