Generic Calan Sr

Common use

Calan Sr is used to treat hypertension, hypertensive crisis, primary pulmonary hypertension, stenocardia, supraventricular tachicardia, sinus tachycardia, atrial tachyarrhythmia, atrial flutter, atrial arrhythmia.



Dosage and direction

Patients with stenocardia or supraventricular tachicardia should take Calan Sr three times a day, those with arterial hypertension taken it twice a day. Dosage depends on the disease, age and should be individually administered depending on severeness of the condition. Consult your doctor before to take the medication.



Precautions

Calan Sr can influence thinking or reactions, thus special carefulness is necessary during driving or actions requiring concentration of attention and fast reaction. Do not get up too fast if you sit or lie as it may cause dizziness. Avoid drinking alcohol and consult your doctor if you drink grapefruit juice as its interaction with Calan Sr may lead to potentially dangerous effects.



Contraindications

Hypersensitivity, severe arterial hypotension pregnancy, breast-feeding, atrioventricular block (first and second degree), sinoatrial blockade, sick sinus syndrome (except of the patients with a cardiostimulator), Wolff-Parkinson-White syndrome (WPW), Lown-Ganong-Levine syndrome in combination with atrial fibrillation/flutter. Some other conditions require careful use of Calan Sr. Do not take the medication unless it is prescribed to you and take it only as it is administered by your physician.



Possible side effect

Usual side effects of Calan Sr are constipation, dizziness, nausea, low blood pressure, headaches. If more serious symptoms as chest pain, an irregular heart rhythm (arrhythmia) or a slow heart rate (bradycardia), heart attacks or strokes, significant water retention, especially accompanied by difficulty breathing, signs of very low blood pressure, such as dizziness, lightheadedness, or fainting, hallucinations or other psychotic problems, any signs of an allergic reaction, including an unexplained rash, hives, itching, unexplained swelling, wheezing, or difficulty breathing or swallowing are observed, seek for immediate medical attention.



Drug interaction

Dangerous heart slowing may appear if Calan Sr is taken concurrently with a beta blocker. This medication increases concentration of digoxin, theophylline, carbamazepine, myorelaxants in blood so levels of these drugs should be monitored to avoid toxicity. In some patients blood levels of lithium maybe reduced.



Missed dose

If you missed a dose take it as soon as you remember, but not if it is almost time of the next intake by your schedule. If so skip the missed dose. Do not try to compensate a missed dose by taking an extra one.



Overdose

If you suspect that you took too much of Calan Sr and feel slow heartbeat and fainting seek for immediate medical attention.



Storage

The medication should be stored at room temperature 15-30 C (59-86 F) in a light- resistant box.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)