Isoptin (Verapamil Hydrochloride)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Isoptin Used For?
Isoptin contains verapamil hydrochloride and belongs to a group of medicines called calcium channel blockers. It helps treat heart and blood pressure conditions by opening up blood vessels.
Primary Uses
Isoptin is used to treat high blood pressure (hypertension), angina (chest pain), and irregular heartbeats (arrhythmias). The SR (sustained release) version is not recommended for children under 18 years old.
How It Works
Isoptin works by opening up blood vessels, which allows more blood and oxygen to reach the heart while lowering high blood pressure. The regular tablets also help control fast or irregular heartbeats. It does not change the amount of calcium in your blood or bones, and dietary calcium will not interfere with how it works.
Good to know: There is no evidence that Isoptin is addictive, and calcium in your diet or supplements will not interfere with how the medicine works.
How to Take Isoptin
Your doctor will determine the right dose and timing for you based on your condition and other medicines you may be taking. Treatment is usually long-term.
Dosage Instructions
Regular Isoptin tablets are usually taken 2-3 times daily and can be taken with or without food. Isoptin SR tablets are usually taken once daily or twice daily and should be taken with food. Swallow all tablets whole with water. Regular tablets should not be broken, but SR tablets can be broken in half if prescribed. Never crush or chew SR tablets.
What If You Miss a Dose?
If it’s almost time for your next dose, skip the missed dose and take your next dose as scheduled. Otherwise, take it as soon as you remember and return to your normal schedule. If you miss more than one dose or are unsure what to do, contact your doctor or pharmacist.
Important: Never take a double dose to make up for a missed dose, as this may increase your chance of unwanted side effects.
Available Tablet Strengths
Side Effects
Like all medications, this medicine can cause side effects. Most are mild and temporary, but some require medical attention.
Common Side Effects
These side effects occur relatively frequently and usually don’t require emergency care:
- Constipation
- Dizziness
- Light-headedness
- Feeling sick
- Upset stomach
- Headache
- Tiredness
- Flushing
Seek immediate medical attention if you experience:
- Chest pain
- Fainting or collapse
- Slow, fast, or irregular heartbeat
- Shortness of breath with swelling of feet and legs due to fluid buildup
- Severe blisters, skin rash, itching or flaking skin
- Fever, upper stomach pain, feeling generally unwell
- Swollen eyes and mouth
- Muscle weakness
Important Warnings
Certain people should not take Isoptin, and others need special monitoring. Always inform your healthcare providers about all your medical conditions.
Who Should Not Take Isoptin
Do not use Isoptin if you are allergic to verapamil hydrochloride or any ingredients, have certain heart conditions (heart failure, very slow heart rate, heart conduction problems, some irregular heartbeats, or heart muscle disease), have low blood pressure, are taking ivabradine or certain blood thinners like dabigatran, or if the packaging is damaged.
Medical Conditions to Discuss
Tell your doctor if you have any heart problems, blood vessel disease or stroke history, liver or kidney problems, or neuromuscular conditions such as Duchenne muscular dystrophy, myasthenia gravis, or Lambert-Eaton syndrome.
Pregnancy and Breastfeeding
Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding. Isoptin may affect your baby during pregnancy and passes into breast milk. Your doctor will discuss the risks and benefits with you.
Elderly Patients: If you are over 65 years of age, you may have an increased chance of getting side effects. Report any side effects to your doctor promptly.
Drug Interactions
Many medicines can interact with Isoptin and affect how it works. Always tell your doctor about all medicines, vitamins, and supplements you take.
Grapefruit interaction: Avoid grapefruit juice as it may increase blood levels of verapamil. Do not take Isoptin with grapefruit or its juice.
- Beta-blockers (atenolol, propranolol, metoprolol)
- Ivabradine
- Digoxin
- Heart rhythm medicines (quinidine, flecainide, amiodarone, disopyramide)
- Blood pressure medicines (prazosin, terazosin)
- Cholesterol medicines (atorvastatin, simvastatin)
- Blood thinners (dabigatran, aspirin)
- Gout medicines (colchicine, sulfinpyrazone)
- Depression/psychiatric medicines (St John’s Wort, imipramine, buspirone, midazolam, lithium)
- Seizure medicines (phenytoin, carbamazepine, phenobarbital)
- Transplant rejection medicines (cyclosporin, everolimus, sirolimus, tacrolimus)
- Antibiotics (erythromycin, clarithromycin, telithromycin, rifampicin)
- HIV medicines (ritonavir)
- Surgical medicines (general anesthetics, muscle relaxants)
- Theophylline (asthma medicine)
- Doxorubicin (cancer medicine)
- Cimetidine (stomach ulcer medicine)
- Diabetes medicines (metformin, glibenclamide)
- Almotriptan
Alcohol & Driving
Isoptin can affect your ability to drive and may interact with alcohol, so take precautions to stay safe.
Alcohol
Avoid alcohol while using Isoptin. Drinking alcohol while taking Isoptin may make dizziness or light-headedness worse and cause greater blood pressure lowering effects than usual.
Driving and Operating Machinery
Be careful driving or operating machinery until you know how Isoptin affects you. Isoptin may cause dizziness, light-headedness, or tiredness in some people. If this occurs, do not drive, operate machinery, or do anything else that could be dangerous. Dizziness or fainting may occur especially when getting up quickly from sitting – getting up slowly may help.
Storage
Store Isoptin tablets below 25°C in a cool, dry place away from moisture, heat, and sunlight. Do not store in the bathroom, near a sink, in the car, or on window sills. Keep tablets in their original pack until it’s time to take them. Keep all medicines where children cannot reach them. Take any unwanted or expired medicine to a pharmacy for safe disposal.
Overdose Information
If you think you have taken too much Isoptin, seek urgent medical attention immediately. Call the Poisons Information Centre (Australia 13 11 26, New Zealand 0800 POISON or 0800 764 766), contact your doctor, or go to the nearest hospital Emergency Department, even if you feel fine. Overdose symptoms may include difficulty breathing, slow heartbeat, chest pain, feeling very faint, or collapse. With SR tablets, symptoms may be delayed due to the extended release formula.
Frequently Asked Questions
The source doesn’t specify exact timing, but treatment with Isoptin is usually long-term. Your doctor will monitor your progress with regular visits to check how well the medicine is working for your condition.
Yes, regular Isoptin tablets (40mg and 80mg) can be taken with or without food. However, Isoptin SR tablets should be taken with food.
No, there is no evidence that Isoptin is addictive.
Do not stop taking Isoptin or lower the dosage without checking with your doctor first. Treatment is usually long-term, so keep taking Isoptin for as long as your doctor recommends.
No, you should avoid alcohol while using Isoptin. Drinking alcohol while taking Isoptin may make dizziness or light-headedness worse and cause greater blood pressure lowering effects than usual.
No, avoid grapefruit juice as it may increase the blood levels of verapamil. Do not take Isoptin with grapefruit or its juice.
If it’s almost time for your next dose, skip the missed dose and take your next dose as scheduled. Otherwise, take it as soon as you remember. Never take a double dose to make up for a missed dose, as this may increase your chance of unwanted side effects.
Important Disclaimer
This information is intended for general educational purposes only and should not be considered medical advice. Always consult your healthcare provider or pharmacist before starting, stopping, or changing any medication.
If you think you may have a medical emergency, call your doctor or emergency services immediately.