Calan SR (Verapamil) – Patient Information (Australia)

Calan SR is a brand of verapamil in a sustained‑release (SR) form. It is used to treat certain heart rhythm problems and other cardiovascular conditions. This page explains how Calan SR works, how it is usually taken, what to expect, and what important safety considerations apply for people in Australia.

Note: Follow the instructions on your product label and any advice provided by your healthcare professional. If you have questions about your situation, ask a pharmacist or doctor.

Quick facts

• Active ingredient: Verapamil (as a sustained‑release tablet)
• Brand: Calan SR
• Medicinal class: Calcium channel blocker (non‑dihydropyridine)
• How it works: Slows electrical activity in the heart and helps relax blood vessels
• Common uses: Certain rhythm disorders (rate control) and angina (chest pain) in selected patients
• Form: SR (extended/sustained release) tablets

What is Calan SR?

Calan SR contains verapamil, a medicine belonging to the calcium channel blocker family. In the body, calcium helps muscle cells (including heart muscle and blood vessel muscle) contract. Verapamil reduces the movement of calcium into certain heart and blood vessel cells, which can:

• Slow the heart rate
• Reduce the heart’s workload
• Help prevent certain abnormal rhythms
• Relax blood vessels, which can improve blood flow

SR (sustained release): Calan SR is designed to release verapamil gradually over time, often allowing less frequent dosing than immediate‑release forms.

How Calan SR works (mechanism of action)

Verapamil blocks L‑type calcium channels. In practical terms for patients, this can lead to:

• Slower conduction through the AV node: This can help control certain supraventricular tachycardias (fast heart rhythms originating above the ventricles) and can assist with ventricular rate control in some conditions.
• Reduced contractility (negative inotropy): This may be relevant in people with certain types of heart failure or reduced pumping ability.
• Vasodilation: Relaxation of blood vessels may help reduce chest pain caused by reduced blood supply to the heart (angina) in appropriate patients.

Pharmacokinetics (how the body processes it)

Pharmacokinetics describes what the body does with the medicine—absorption, distribution, metabolism, and elimination.

• Absorption: Verapamil is absorbed from the gastrointestinal tract. The SR formulation releases the medicine gradually.
• Peak levels: With sustained‑release products, blood levels typically rise more gradually and peak later than immediate‑release forms.
• Protein binding: Verapamil binds to plasma proteins.
• Metabolism: Verapamil is extensively metabolised mainly in the liver.
• Elimination: Metabolites are excreted primarily by the kidneys and to a lesser extent via other routes.
• Half‑life: Verapamil’s apparent half‑life can vary between individuals and can be influenced by liver function and interacting medicines.

Because verapamil is metabolised in the liver and can interact with other medicines, dose adjustments may be needed in people with liver impairment and when certain drug interactions occur.

What is Calan SR used for?

Calan SR is used in selected patients for cardiovascular conditions where slowing the heart rate and/or reducing blood vessel tone can help. Your specific use depends on your diagnosis and overall health.

Common indications (examples)

• Supraventricular tachycardias: Used to help control certain fast heart rhythms.
• Rate control in selected arrhythmias: In some patients with atrial arrhythmias, verapamil may be used to help control heart rate.
• Angina (chest pain): Helps reduce the frequency or severity of angina episodes in appropriate patients.
• Hypertension: Verapamil can be used for blood pressure control in selected cases (depending on local prescribing practices and patient suitability).

Indications can vary based on product availability, formulation, and clinical guidelines. If you are unsure why you were prescribed Calan SR, ask your doctor or pharmacist.

When and how to take Calan SR

Calan SR should be taken exactly as advised. Because it is sustained‑release, the dosing routine and tablet handling are important.

Typical timing

• Frequency: Often taken once or twice daily depending on the prescribed strength and your response.
• Consistency: Try to take it at the same times each day.
• With or without food: It can usually be taken with food or on an empty stomach—see food interaction notes below.

How to take the tablet

• Swallow whole with water.
• Do not crush, split, or chew SR tablets. Breaking them can change how quickly the drug is released.
• If you miss a dose, do not double up unless your healthcare professional has advised that. Take the next dose at the usual time.

Dose information (general guidance)

Dosing depends on the condition being treated, your heart rate and blood pressure, kidney/liver function, and other medicines you take. The dosing below is general; always follow your local prescription/label directions and your clinician’s plan.

Do not adjust without advice

Because verapamil can affect heart conduction and blood pressure, changing the dose suddenly may increase the risk of side effects or symptoms such as dizziness, palpitations, or chest discomfort.

Food interactions

Grapefruit and grapefruit juice can increase verapamil levels in the blood in some people, which may raise the risk of side effects such as dizziness, low blood pressure, constipation, or slow heart rate. For many patients, it is best to avoid grapefruit while taking verapamil.

Taking with food: Some patients find taking SR tablets with food improves stomach comfort. In general, verapamil can be taken with or without food, but keep the routine consistent.

Alcohol in combination with meals: See the alcohol section below for general guidance.

Alcohol and medicine interactions

Alcohol

Alcohol may increase the risk of dizziness, drowsiness, and low blood pressure when combined with blood pressure–lowering or heart‑slowing medicines like verapamil.

• If you drink alcohol, consider limiting intake and monitoring how you feel.
• Avoid binge drinking, especially when starting or changing dose.

Important medicine interactions

Verapamil affects liver enzymes and can interact with other medicines that also influence heart rate, blood pressure, or liver metabolism. Tell your pharmacist or doctor about all medicines you take, including vitamins and herbal products.

• Other heart medicines: Combining with drugs that slow heart rate or affect conduction (such as certain beta‑blockers) can increase the risk of bradycardia or heart block in some people. Close monitoring is often required.
• Antiarrhythmics: Some rhythm medicines can increase the risk of excessive slowing or rhythm disturbances when combined.
• Digoxin: Verapamil can raise digoxin levels in some cases; monitoring may be necessary.
• Statins (cholesterol medicines): Some statins can interact via liver metabolism. Your clinician may choose a safer statin dose or monitor for muscle‑related effects.
• Certain antibiotics/antifungals and antivirals: Some can raise verapamil levels, increasing side‑effect risk.
• Rifampicin (TB treatment) and some anticonvulsants: These may lower verapamil levels, reducing effectiveness.
• Other blood pressure medicines: The combined effect may lead to more pronounced low blood pressure.
• Blood sugar medicines: In some patients, changes in blood pressure and overall metabolism may require closer monitoring of glucose control.

If you notice new symptoms after starting or changing another medicine, contact a pharmacist promptly.

Safety profile: who should be careful?

Calan SR may not be suitable for everyone. Safety depends on your heart rhythm, blood pressure, heart pumping strength, liver function, and interacting medicines.

Common side effects

Many side effects are dose‑related and may lessen as your body adjusts.

• Constipation (very common with verapamil)
• Dizziness or light‑headedness
• Headache
• Swelling of ankles or feet (peripheral oedema)
• Fatigue or weakness
• Nausea
• Low blood pressure symptoms (especially when standing)
• Slow heart rate (bradycardia)

Serious side effects (seek urgent help)

Contact emergency services or seek urgent medical attention if you experience:

• Fainting (syncope) or severe dizziness
• Very slow heartbeat or symptoms of heart block (e.g., feeling unusually unwell with a slow pulse)
• Chest pain that is new, worsening, or different from your usual pattern
• Breathing difficulties or sudden worsening of swelling
• Severe allergic reaction (swelling of face/lips, difficulty breathing, widespread rash)

Situations where verapamil requires extra caution

• Certain heart conduction problems: such as heart block or significant bradycardia
• Heart failure with reduced pumping function: verapamil can reduce heart contractility; suitability depends on the type and severity of heart failure
• Low blood pressure: may worsen symptoms of dizziness
• Liver disease: may increase verapamil levels
• Use of interacting medicines: particularly medicines affecting heart rhythm or metabolism

Practical use tips (how to get the best results)

• Track your pulse and blood pressure: If you are prone to dizziness or have a home blood pressure monitor, consider tracking and sharing readings with your clinician.
• Manage constipation early: Hydrate, include fibre, and discuss suitable stool‑softening options with your pharmacist if constipation occurs.
• Stay consistent with meals: Use the same timing with respect to food daily and avoid grapefruit products.
• Don’t crush SR tablets: Crushing can alter release and increase risk of side effects.
• Be cautious when standing up: Dizziness can occur—rise slowly from sitting or lying positions.
• Keep a medicine list: Carry a list (or use a phone note) of all medicines and supplements to reduce interaction risk.
• Ask before starting new treatments: This includes over‑the‑counter cold medicines and herbal supplements.

Alternative options (if Calan SR isn’t suitable)

Treatment depends on your condition (e.g., rhythm disorder, angina, or blood pressure). Alternatives may include other classes of medicines or different agents within the same class. Examples include:

• Other calcium channel blockers: such as diltiazem (in some rhythm/angina scenarios) or dihydropyridines (depending on the goal).
• Beta‑blockers: sometimes used for rate control or angina.
• Other antianginal or rhythm control medicines: your clinician will choose based on your ECG and overall health.
• Non‑medicine options: in selected rhythm problems, procedures such as cardioversion or catheter ablation may be considered depending on diagnosis.

If Calan SR causes troublesome side effects or is not appropriate, discuss options with your doctor or pharmacist. Do not stop abruptly without advice.

Market and legal context in Australia

In Australia, medicines are supplied under a regulated classification system. Verapamil products are generally available through pharmacy channels in accordance with Australian medicines scheduling and local prescribing rules. Availability of specific brands and strengths can vary across suppliers and wholesalers.

Healthcare professionals and pharmacists in Australia follow national safety policies, including requirements for:

• Correct identification of the product and strength
• Medication history and interaction screening
• Patient counselling and safety information delivery
• Pharmacist review when dispensing and when new medicines are added

Guidelines and prescribing practices may be updated over time based on evidence and national recommendations. Your pharmacist can also advise about current product availability and any changes to formulations.

Recent guidance and monitoring considerations

While individual care plans differ, many clinicians emphasise consistent monitoring when using verapamil, especially during:

• Initiation or dose increases: monitor for low blood pressure, dizziness, constipation, and slowed heart rate.
• Changes in other medicines: check for interaction risks.
• Symptoms of worsening heart disease: report breathlessness, swelling, fainting, or chest pain urgently.

Practical monitoring may include heart rate checks and blood pressure measurements, and in some cases ECG review, depending on the condition being treated. If you feel unwell after starting or modifying treatment, seek advice promptly.

Delivery and availability (online pharmacy)

Calan SR availability may vary by pharmacy and supplier. When ordering online in Australia, delivery times can depend on stock status and your location (metro vs regional).

• Stock checks: Many pharmacies confirm availability before dispatch.
• Packaging: Medicines are typically dispatched in tamper‑evident packaging to protect quality.
• Delivery updates: Tracking may be provided where available.
• Cold chain: Verapamil SR tablets generally do not require refrigeration unless specified for a particular product.

If you need help finding the correct strength or formulation (e.g., SR vs immediate‑release), contact the pharmacy before placing your order.

Frequently Asked Questions (FAQ)

1) How long does Calan SR take to work?

Many people notice effects such as improved heart rate control or angina symptom relief within hours to days. Because SR formulations release gradually, steady effects may take a little time. If you have not noticed any benefit after the expected period, consult your clinician rather than changing the dose yourself.

2) Can I stop Calan SR suddenly if I feel better?

Do not stop without medical advice. Stopping verapamil can lead to return of the symptoms it was controlling, such as chest pain or abnormal heart rate patterns.

3) What should I do if I miss a dose?

Take the next dose at the usual time. Do not double up. If you are unsure, ask your pharmacist, particularly if you missed more than one dose.

4) Why does constipation happen with verapamil?

Verapamil can slow gut movement and reduce bowel motility. Staying hydrated, eating fibre, and discussing suitable constipation management strategies with your pharmacist can help.

5) Is Calan SR safe to take with other heart medications?

It can be used in combination in certain cases, but the combination may increase risks such as slow heart rate or low blood pressure. Your clinician and pharmacist should review your medication list for interaction and dose suitability.

6) Can I drink alcohol while taking Calan SR?

Small amounts may be tolerated by some people, but alcohol can increase dizziness and low blood pressure. If you choose to drink, do so cautiously and monitor how you feel—especially after starting or increasing your dose.

7) Should I avoid grapefruit?

Grapefruit products may raise verapamil levels and increase side effects for some people. Avoiding grapefruit is commonly recommended.

8) What signs mean I should seek urgent help?

Seek urgent medical attention for fainting, severe dizziness, very slow heartbeat, worsening breathlessness, chest pain, or signs of a serious allergic reaction (such as facial swelling or trouble breathing).

9) Does Calan SR cause weight gain?

Some people may notice swelling of the ankles/feet, which can feel like weight gain. True weight gain isn’t a typical direct effect of verapamil. If swelling occurs or weight rises quickly, contact a healthcare professional.

10) Can I take Calan SR if I have liver problems?

Caution is required because verapamil is metabolised in the liver. Your clinician may adjust your dose or monitor you more closely. Tell your pharmacist about any liver disease.

Summary

Calan SR (verapamil sustained‑release) helps manage certain heart rhythm conditions and angina by blocking calcium entry into cardiac cells and relaxing blood vessels. It must be taken regularly and correctly—especially because SR tablets should be swallowed whole. As with all heart medicines, safety depends on your heart rate, blood pressure, liver function, and other medicines you use. If you notice concerning symptoms such as fainting, severe dizziness, or chest pain, seek urgent medical advice.