Calan SR Side Effects

Generic name: verapamil

Note: This document contains side effect information about verapamil. Some of the dosage forms listed on this page may not apply to the brand name Calan SR.

Some side effects of Calan SR 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 verapamil: oral capsule extended release, oral tablet, oral tablet extended release

Get emergency medical help if you have any of these signs of an allergic reaction while taking verapamil (the active ingredient contained in Calan SR) hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

• fast or slow heartbeats;

• feeling like you might pass out;

• fever, sore throat, and headache with a severe blistering, peeling, and red skin rash;

• restless muscle movements in your eyes, tongue, jaw, or neck;

• feeling short of breath, even with mild exertion;

• swelling, rapid weight gain; or

• nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects of verapamil may include:

• constipation, nausea;

• skin rash or itching;

• dizziness, headache, tired feeling; or

• warmth, itching, redness, or tingly feeling under your skin.

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 verapamil: compounding powder, intravenous solution, oral capsule extended release, oral tablet, oral tablet extended release

Gastrointestinal

Constipation due to verapamil (the active ingredient contained in Calan SR) appears to be related to a delay of colonic transit and not to an effect on upper gastrointestinal transit.

Gastrointestinal side effects have included constipation (up to 11.7%), nausea (up to 2.7%), dyspepsia (up to 2.7%), and diarrhea (up to 2.4%). Nausea (0.9%) and abdominal discomfort (0.6%) have been reported with intravenous verapamil. Nonobstructive, paralytic ileus (reversible upon discontinuation) has been reported infrequently. Diarrhea, dry mouth, gastrointestinal distress, and gingival hyperplasia have been reported during open trials/postmarketing experience.

Cardiovascular

Cardiovascular side effects have included hypotension (up to 2.5%), new or worsened congestive heart failure (CHF) or pulmonary edema (negative inotropism; 1.8%), bradycardia (heart rate less than 50/minute; 1.4%), atrioventricular (AV) block (first-degree; up to 1.7%), AV block (total first-, second-, and third-degree; 1.2%), AV block (second- and third-degree; 0.8%), and postural hypotension (up to 0.4%). Symptomatic hypotension (1.5%), bradycardia (1.2%), and severe tachycardia (1%) have been reported with intravenous verapamil (the active ingredient contained in Calan SR) In studies related to control of ventricular response in patients taking digoxin who had atrial fibrillation or atrial flutter, ventricular rate less than 50/minute at rest (15%) and asymptomatic hypotension (5%) were reported. Dizziness, hypotension, peripheral edema, and headache are not uncommon and are related to vasodilation of vascular smooth muscle. Verapamil may accelerate conduction of anomalous AV conduction tissue, as in the Wolff-Parkinson-White syndrome, which can result in worsened tachycardia, including malignant ventricular tachyarrhythmias or accelerated junctional tachycardia. Because of this potentially fatal side effect, verapamil is not recommended in patients with atrial fibrillation and premature ventricular depolarizations. Angina pectoris, AV block (second- and third-degree), atrioventricular dissociation, CHF, pulmonary edema, abnormal ECG, chest pain, claudication, hypertension, myocardial infarction, palpitations, and purpura (vasculitis) have been reported during open trials/postmarketing experience.

CHF or pulmonary edema may be particularly important in patients with poor left ventricular function.

Various conduction disturbances have been reported with verapamil therapy, including bradycardia, AV block, first-, second-, third-degree heart block, and left bundle branch block.

One study of patients with the Wolff-Parkinson-White syndrome (WPW) has shown that patients with a history of WPW complicated by atrial fibrillation and a history of reciprocating tachycardias with rapid conduction over an accessory pathway during atrial fibrillation are more susceptible to ventricular fibrillation after verapamil than those without a history of a rapid ventricular response. A small series of patients with WPW complicated by atrial fibrillation and a rapid ventricular response who developed cardiac arrest within 1 to 10 minutes after receiving intravenous verapamil has been reported.

The mechanism by which verapamil may enhance the ventricular rate response to atrial fibrillation is not known. Verapamil may directly shorten the refractory period of the accessory pathway or cause reflex tachycardia indirectly by causing peripheral vasodilation.

Nervous system

A 70-year-old man with supraventricular tachycardia began to experience uncontrollable, irregular, and symmetrical jerking movements in his extremities and torsional movements in his trunk 10 months after beginning verapamil (the active ingredient contained in Calan SR) Both myoclonic and dystonic movements occurred during activity and rest. An electroencephalogram was normal. The movements were not initiated by photic stimulation, hyperventilation, or acoustic stimuli. Once diltiazem was substituted, the movements gradually resolved over the ensuing three weeks. There was no rechallenge.

A 28-year-old woman was treated for supraventricular tachycardia with 10 mg of intravenous verapamil for 3 days in a row. After the third dose, the patient experienced involuntary movements in the buccolingual and neck muscles which made language articulation difficult. The patient also experienced episodes of compulsory neck extension and spasmodic movements of the eyes going upwards. The patient was treated with diazepam parenterally and the symptoms disappeared after 24 hours.

Nervous system side effects have included headache (up to 12.1%), dizziness (up to 4.7%), lethargy (up to 3.2%), fatigue (up to 4.5%), sleep disturbances (up to 1.4%), paresthesia (up to 1%), and rare neurologic complaints (including paresthesias, sleeping problems, and tremors; less than 1%). Dizziness (1.2%), headache (1.2%), sleepiness, vertigo, and rare cases of seizures during injection have been reported with intravenous verapamil. Rare cases of muscle fasciculations in patients with underlying neuromuscular diseases, stroke associated with verapamil-induced hypotension, exacerbation of myasthenia gravis, and myoclonic dystonia have been reported. Cerebrovascular accident, confusion, equilibrium disorders, extrapyramidal symptoms, insomnia, paresthesia, shakiness, somnolence, syncope, and tinnitus have been reported during open trials/postmarketing experience.

Other

Other side effects have included flu syndrome (up to 3.7%), peripheral edema (up to 3.7%), edema (up to 3%), pain (up to 2.4%), fatigue (1.7%), accidental injury (up to 1.5%), ankle edema (up to 1.4%), and flushing (up to 0.8%). Asthenia has been reported during open trials/postmarketing experience.

Immunologic

Immunologic side effects have included infection (up to 12.1%).

Respiratory

A 26-year-old man with rheumatic heart disease, mitral stenosis, and supraventricular tachycardia became apneic following a 5 mg intravenous bolus of verapamil (the active ingredient contained in Calan SR) His heart rhythm at the time was supraventricular tachycardia at 290 beats per min; his blood pressure is not reported. The patient responded to assisted ventilation, oxygen, and DC cardioversion. The authors of this case report have located two other such cases, one of which had "stable hemodynamics," but died due to intravenous verapamil-associated acute respiratory arrest.

A 66-year-old woman with a 10-year history of hypertension and bronchial asthma was switched from immediate-release verapamil to sustained-release verapamil. The patient developed dyspnea, cough, and wheezing after taking the first tablet. The patient experienced similar reactions on three subsequent occasions with verapamil sustained-release administration.

Respiratory side effects have included upper respiratory infection (up to 5.4%), pharyngitis (up to 3%), sinusitis (up to 3%), rhinitis (up to 2.7%), and dyspnea (up to 1.4%). Extremely rare cases of respiratory arrest have been associated with the use of intravenous verapamil. The mechanism is unknown. An acute asthma attack associated with sustained-release verapamil has been reported. Dyspnea has also been reported during open trials/postmarketing experience.

Hepatic

Hepatic side effects have included elevated liver enzymes (up to 1.4%), and elevated transaminases with or without elevated serum bilirubin and alkaline phosphatase. The mechanism of injury is not known. Verapamil-associated hepatotoxicity is considered to be idiosyncratic, although some cases indicate a probable hypersensitivity mechanism. Elevated liver enzymes have also been reported during open trials/postmarketing experience.

Transient increases in liver function tests may occur but generally resolve following discontinuation of verapamil, although these changes may abate even with continued administration. A hypersensitivity mechanism is suspected since some cases report eosinophilic infiltrations and moderate cholestasis on liver biopsy.

Hepatic side effects may be more likely and more severe in patients with liver disease. It is recommended that verapamil therapy be reconsidered if this patient's liver disease is severe. Monitoring liver function tests during therapy is recommended.

Dermatologic

Dermatologic side effects have included rash (up to 1.4%). Diaphoresis has been reported with intravenous verapamil (the active ingredient contained in Calan SR) Arthralgia and rash, exanthema, hair loss, hyperkeratosis, macules, sweating, urticaria, Stevens-Johnson syndrome, and erythema multiforme have been reported during open trials/postmarketing experience.

Endocrine

Due to verapamil-induced hyperprolactinemia, rare cases of galactorrhea have been reported in both sexes.

Endocrine side effects have rarely included interference with the release or synthesis of prolactin inhibitor factor in the hypothalamus; however, the mechanism is not known. A single case of hyperglycemic metabolic acidosis has been associated with sustained-release verapamil. Galactorrhea/hyperprolactinemia has been reported during open trials/postmarketing experience.

Renal

Rare cases of hypertensive patients with chronic renal failure who developed acute oliguric renal failure after receiving verapamil (the active ingredient contained in Calan SR) have been reported. These patients also developed symptomatic hypotension associated with slow cardiac arrhythmias.

Renal side effects have included rare cases of oliguria and worsened renal function in patients with preexisting chronic renal failure.

Genitourinary

After the onset of impotence, one patient elected to discontinue verapamil (the active ingredient contained in Calan SR) His impotence resolved upon drug discontinuation, and recurred upon rechallenge.

Genitourinary side effects have included rare cases of sexual impotence and loss of libido among males. Gynecomastia, galactorrhea/hyperprolactinemia, impotence, increased urination, and spotty menstruation have been reported during open trials/postmarketing experience.

Musculoskeletal

Three case reports have been found by one practitioner. In each case, unusual symptoms of cold extremities and paresthesias without objective evidence of a neuromuscular or cardiac etiology were described. The symptoms resolved upon discontinuation and, in each case, recurred upon drug rechallenge.

Musculoskeletal side effects have included myalgia (up to 1.1%) and bizarre perceptual symptoms most closely described as cold extremities. Muscle fatigue has been reported with intravenous verapamil. Arthralgia (with rash) and muscle cramps have been reported during open trials/postmarketing experience.

Psychiatric

Psychiatric side effects have included rare cases of depression. Emotional depression has been reported with intravenous verapamil (the active ingredient contained in Calan SR) Psychotic symptoms have been reported during open trials/postmarketing experience.

Hematologic

Hematologic side effects have included ecchymosis or bruising during open trials/postmarketing experience.

Hypersensitivity

Hypersensitivity side effects have included aggravated allergy during open trials/postmarketing experience. In rare cases of hypersensitivity, broncho/laryngeal spasm accompanied by itch and urticaria has been reported with intravenous verapamil (the active ingredient contained in Calan SR)

Ocular

Ocular side effects have included blurred vision during open trials/postmarketing experience. Rotary nystagmus has been reported with intravenous verapamil (the active ingredient contained in Calan SR)

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date, and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This information does not endorse drugs, diagnose patients, or recommend therapy. This drug information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug of drug combination is safe, effective, or appropriate for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of information provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse, or pharmacist.