Side Effects of Inderal (propranolol)

Inderal (propranolol) is a beta-adrenergic blocking agent (beta-blocker) used to treat

• high blood pressure (hypertension),
• heart pain (angina),
• abnormal rhythms of the heart, and
• some neurologic conditions. 

Norepinephrine is a neurotransmitter used by the sympathetic nervous system, a portion of the involuntary nervous system. Nerves of the sympathetic nervous system release norepinephrine that binds to beta receptors on other cells. 

Inderal inhibits the sympathetic nervous system by blocking the beta receptors on the nerves of the sympathetic system. Since stimulation of the sympathetic nervous system is responsible for increasing the heart rate, by blocking the action of these nerves Inderal reduces the heart rate and is useful in treating abnormally rapid heart rhythms. 

Inderal also reduces the force of contraction of heart muscle and thereby lowers blood pressure. By reducing the heart rate and the force of muscle contraction, Inderal reduces the need for oxygen by heart muscle. 

Heart pain (angina pectoris) occurs when oxygen demand of the heart muscle exceeds the supply of oxygen, so Inderal, by reducing the demand for oxygen, is helpful in treating heart pain.  

Common side effects of Inderal include

• abdominal cramps,
• diarrhea,
• constipation,
• fatigue,
• insomnia,
• nausea,
• depression,
• dreaming,
• memory loss,
• fever,
• impotence,
• lightheadedness,
• slow heart rate,
• low blood pressure,
• cold extremities,
• sore throat, and
• shortness of breath or wheezing.

Serious side effects of Inderal include

• aggravation of breathing difficulties in patients with asthma, chronic bronchitis, or emphysema;
• dangerously slow heart rates and even shock in patients with existing slow heart rates and heart blocks, and
• aggravation of symptoms of heart failure.

In patients with coronary artery disease, abruptly stopping Inderal can suddenly worsen angina, and occasionally precipitate heart attacks. 

Drug interactions of Inderal include calcium channel blockers and digoxin, which can lower blood pressure and heart rate to dangerous levels when administered together with Inderal.

Inderal can mask the early warning symptoms of low blood sugar (hypoglycemia) and should be used with caution in patients receiving treatment for diabetes.

Inderal reduces the metabolism of thioridazine, increasing the concentration of thioridazine in the body and potentially causing abnormal heartbeats.

Safe use of Inderal during pregnancy has not been established. Growth retardation and congenital abnormalities have been reported in infants whose mothers received Inderal during pregnancy.

Infants whose mothers received Inderal during labor have exhibited

• slow heart rate,
• hypoglycemia, and/or
• respiratory depression.

Inderal is secreted into breast milk. It should be avoided or used with caution in breastfeeding women.

Common side effects are:

• abdominal cramps,
• diarrhea,
• constipation,
• fatigue,
• insomnia,
• nausea,
• depression,
• dreaming,
• memory loss,
• fever,
• impotence,
• lightheadedness,
• slow heart rate,
• low blood pressure,
• cold extremities,
• sore throat, and
• shortness of breath or wheezing.

Propranolol can aggravate breathing difficulties in patients with

• asthma,
• chronic bronchitis, or
• emphysema.

In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), propranolol can cause dangerously slow heart rates, and even shock. Propranolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure.

In patients with coronary artery disease, abruptly stopping propranolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue propranolol, its dosage should be reduced gradually over several weeks.

The following adverse reactions have been observed, but there is not enough systematic collection of data to support an estimate of their frequency.

Within each category, adverse reactions are listed in decreasing order of severity. Although many side effects are mild and transient, some require discontinuation of therapy.

Propranolol hydrochloride (Inderal (propranolol) )

Cardiovascular: Congestive heart failure; hypotension; intensification of AV block; bradycardia; thrombocytopenic purpura; arterial insufficiency, usually of the Raynaud type; paresthesia of hands.

Central Nervous System: Reversible mental depression progressing to catatonia; mental depression manifested by insomnia, lassitude, weakness, fatigue; an acute reversible syndrome characterized by disorientation for time and place, short-term memory loss, emotional lability, slightly clouded sensorium, decreased performance on neuropsychometrics; hallucinations; visual disturbances; vivid dreams; light-headedness.

Total daily doses above 160 mg (when administered as divided doses of greater than 80 mg each) may be associated with an increased incidence of fatigue, lethargy, and vivid dreams.

Gastrointestinal: Mesenteric arterial thrombosis; ischemic colitis; nausea, vomiting, epigastric distress, abdominal cramping, diarrhea, constipation.

Allergic: Hypersensitivity reactions, including anaphylactic/anaphylactoid reactions; laryngospasm and respiratory distress; pharyngitis and agranulocytosis; fever combined with aching and sore throat; erythematous rash.

Respiratory: Bronchospasm.

Hematologic: Agranulocytosis; nonthrombocytopenic purpura; thrombocytopenic purpura.

Autoimmune: In extremely rare instances, systemic lupus erythematosus has been reported.

Miscellaneous: Male impotence. Alopecia, LE-like reactions, psoriasiform rashes, dry eyes, and Peyronie's disease have been reported rarely. Oculomucocutaneous reactions involving the skin, serous membranes, and conjunctivae reported for a beta blocker (practolol) have not been associated with propranolol.

Skin: Stevens-Johnson Syndrome; toxic epidermal necrolysis; exfoliative dermatitis; erythema multiforme; urticaria.

Hydrochlorothiazide

Cardiovascular: Orthostatic hypotension (may be aggravated by alcohol, barbiturates or narcotics).

Central Nervous System: Dizziness, vertigo, headache, xanthopsia, paresthesias.

Gastrointestinal: Pancreatitis; jaundice (intrahepatic cholestatic jaundice); sialadenitis; anorexia, nausea, vomiting, gastric irritation, cramping, diarrhea, constipation.

Hypersensitivity: Anaphylactic reactions; necrotizing angiitis (vasculitis, cutaneous vasculitis); respiratory distress including pneumonitis; fever; urticaria, rash, purpura, photosensitivity.

Hematologic: Aplastic anemia, agranulocytosis, leukopenia, thrombocytopenia.

Skin: Erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis.

Miscellaneous: Hyperglycemia, glycosuria; hyperuricemia; muscle spasm; weakness; restlessness; transient blurred vision.

Whenever adverse reactions are moderate or severe, thiazide dosage should be reduced or therapy withdrawn.

Propranolol hvdrochloride (Inderal [propranolol])

Patients receiving catecholamine-depleting drugs such as reserpine should be closely observed if Inderide is administered. The added catecholamine-blocking action may produce an excessive reduction of resting sympathetic nervous activity, which may result in

• hypotension,
• marked bradycardia,
• vertigo,
• syncopal attacks, or
• orthostatic hypotension.

Caution should be exercised when patients receiving a beta blocker are administered a calcium-channel blocking drug, especially intravenous verapamil, for both agents may depress myocardial contractility or atrioventricular conduction.

On rare occasions, the concomitant intravenous use of a beta blocker and verapamil has resulted in serious adverse reactions, especially in patients with

• severe cardiomyopathy,
• congestive heart failure, or
• recent myocardial infarction.

Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia.

Blunting of the antihypertensive effect of beta-adrenoceptor blocking agents by nonsteroidal anti-inflammatory drugs has been reported.

Hypotension and cardiac arrest have been reported with the concomitant use of propranolol and haloperidol.

Aluminum hydroxide gel greatly reduces intestinal absorption of propranolol.

• Alcohol, when used concomitantly with propranolol, may increase plasma levels of propranolol.
• Phenytoin, phenobarbitone, and rifampin accelerate propranolol clearance.
• Chlorpromazine, when used concomitantly with propranolol, results in increased plasma levels of both drugs.
• Antipyrine and lidocaine have reduced clearance when used concomitantly with propranolol.
• Thyroxine may result in a lower than expected TS concentration when used concomitantly with propranolol.
• Cimetidine decreases the hepatic metabolism of propranolol, delaying elimination and increasing blood levels.
• Theophylline clearance is reduced when used concomitantly with propranolol.

Hydrochlorothiazide

• Thiazide drugs may increase the responsiveness to tubocurarine.
• Thiazides may decrease arterial responsiveness to norepinephrine. This diminution is not sufficient to preclude effectiveness of the pressor agent for therapeutic use.
• Insulin requirements in diabetic patients may be increased, decreased, or unchanged. Hypokalemia may develop during concomitant use of corticosteroids or ACTH.

Drug/Laboratory Test Interactions

Hydrochlorothiazide

• Thiazides may decrease serum FBI levels without signs of thyroid disturbance.
• Thiazides should be discontinued before carrying out tests for parathyroid function.