Penbutolol Side Effects

Some side effects of penbutolol may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to penbutolol: oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking penbutolol: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• slow or uneven heartbeats;

• feeling short of breath, even with mild exertion;

• swelling, rapid weight gain; or

• feeling like you might pass out.

Less serious side effects of penbutolol may include:

• headache;

• feeling tired;

• dizziness;

• nausea, diarrhea, upset stomach;

• decreased interest in sex; or

• cold symptoms such as stuffy nose, sneezing, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to penbutolol: oral tablet

General

Penbutolol is generally well tolerated in selected patients. In one study of 111 hypertensive patients who took penbutolol for eight weeks, 12% reported side effects. The incidence of side effects appeared to decrease with continued therapy. Less than 1% of patients discontinue therapy due to side effects.

Nervous system

Nervous system are the most common. General tiredness is reported in 7%, headache in 3%, and dizziness in 5% of patients. Dizziness may be related to orthostatic hypotension. Peripheral paresthesias are rarely described, and may be due to the peripheral cardiovascular side effects of the drug. Penbutolol may rarely be associated with sleeping problems.

Cardiovascular

One double-blinded, placebo-controlled study in 10 hypertensive patients who suffered recurrent bouts of Raynaud's phenomenon showed that penbutolol 20 mg twice a day did not produce any additional vasoconstrictor effect on digital circulation as measured by skin thermometry, time to induce symptoms, or superficial skin blood flow.

Cardiovascular effects of penbutolol (decreased blood pressure or heart rate) can be problematic. Bradycardia and postural hypotension occur in approximately 2% and 4% of patients, respectively. Dizziness is reported in 5% of patients and may be related to hypotension or bradycardia in some cases. Because penbutolol decreases myocardial contractility, new or worsened heart failure is seen in rare, isolated cases, usually in patients with preexisting left ventricular systolic dysfunction. Dyspnea on exertion or AV block have been associated with penbutolol in rare cases.

Penbutolol can have a deleterious effect on the serum lipid profile, which may be important in some patients with or at risk for coronary artery disease.

Peripheral cardiovascular effects usually present as cold extremities or paresthesias.

Respiratory

Respiratory side effects including respiratory insufficiency can develop due to beta-2-adrenergic receptor blockade (inhibition of bronchial dilation). This can result in asthmatic symptoms in 1% of patients and can be more likely or more severe in patients with preexisting reactive airways disease.

Gastrointestinal

Gastrointestinal side effects include nausea or vomiting in 5%, abdominal pain in 2%, flatulence in 1%, and dry mouth in 1% of patients.

Endocrine

Endocrine side effects have been reported. Some patients with diabetes or thyrotoxicosis are at risk for masking the signs or symptoms of their diseases (sweating, tachycardia, hypoglycemia) during penbutolol therapy. Like some other beta-blockers with intrinsic sympathomimetic activity, penbutolol may cause significant increases in serum triglycerides and decreases in HDL cholesterol.

Renal

Renal side effects of penbutolol appear to be of no significance. Data show that glomerular filtration rate and renal plasma blood flow are not significantly affected when blood pressure is lowered using therapeutic doses in patients with chronic renal insufficiency.

Musculoskeletal

Musculoskeletal side effects including muscular fatigue or cramping is rare. No other musculoskeletal complaints have been reported.

Hypersensitivity

Hypersensitivity reactions have not been reported during penbutolol therapy, but have been associated with other beta-blockers. These reactions have presented as erythema, fever with sore throat, laryngospasm, and respiratory distress.

Hematologic

Hematologic side effects (including laboratory abnormalities) have not been associated with penbutolol. The manufacturer, however, states that agranulocytosis and both thrombocytopenic and nonthrombocytopenic purpura have been associated with other beta-blockers.

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