Generic Calan Sr (Verapamil)

Introduction

Calan Sr is a prescription pill that contains the calcium-channel blocker verapamil. It is supplied in 120 mg and 240 mg tablets and belongs to the class of nondihydropyridine calcium-channel antagonists. The drug is primarily indicated for the management of certain cardiovascular conditions, notably hypertension, angina pectoris, and supraventricular tachyarrhythmias such as atrial fibrillation. Verapamil is also marketed under brand names such as Calan, Isoptin, and Verelan. In addition to its approved uses, clinicians sometimes employ verapamil for off-label indications, which are discussed later in this article.

What is Calan Sr?

Calan Sr is the generic formulation of the active compound verapamil. It is produced by several licensed manufacturers worldwide; the exact commercial source may vary by region. The tablet is designed for oral administration and contains either 120 mg or 240 mg of verapamil hydrochloride, together with inactive excipients that aid tablet integrity and dissolution.

• Classification: Nondihydropyridine calcium-channel blocker (CCB).
• Therapeutic group: Antihypertensive and anti-arrhythmic agents.
• Development history: Verapamil was first synthesized in the early s and received FDA approval in 1981 for the treatment of hypertension and angina. Since then, it has become a cornerstone therapy for rate control in supraventricular tachycardia.

How Calan Sr Works

Verapamil blocks L-type calcium channels located on cardiac myocytes, vascular smooth muscle, and the nodal tissue of the heart. By inhibiting calcium influx, the drug produces three key physiological effects:

1. Vasodilation: Reduced calcium entry into arterial smooth muscle leads to relaxation of peripheral vessels, lowering systemic vascular resistance and consequently blood pressure.
2. Negative inotropy and chronotropy: In the myocardium, decreased calcium limits contractile force (negative inotropic effect) and slows conduction through the atrioventricular (AV) node (negative chronotropic effect). This slows heart rate and reduces the frequency of premature beats.
3. Prolongation of AV nodal refractory period: The slowed AV nodal conduction is particularly useful in controlling ventricular response during atrial fibrillation or flutter.

The onset of action after oral dosing occurs within 1-2 hours, with peak plasma concentrations at 2-4 hours. Verapamil’s elimination half-life ranges from 3 to 7 hours, allowing twice-daily dosing for most indications. Renal excretion accounts for roughly 70 % of the drug’s clearance, while hepatic metabolism (via CYP3A4) handles the remainder.

Conditions Treated with Calan Sr

1. Hypertension - By dilating systemic arterioles, verapamil reduces both systolic and diastolic blood pressure. It is especially useful in patients who require additional rate-control properties.

2. Chronic Stable Angina - The combination of decreased myocardial oxygen demand (due to reduced heart rate and contractility) and improved coronary blood flow alleviates exertional chest pain.

3. Supraventricular Tachyarrhythmias - Verapamil is FDA-approved for rate control in atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia (PSVT). Its AV-nodal blocking action prevents excessively rapid ventricular responses, improving symptoms and reducing the risk of tachycardia-mediated cardiomyopathy.

Each of these conditions benefits from the dual antihypertensive and anti-arrhythmic profile of verapamil, making Calan Sr a versatile therapeutic option for many cardiovascular patients.

Off-Label and Investigational Uses of Calan Sr

Important: None of the above uses are officially approved by the U.S. Food and Drug Administration (FDA) or the European Medicines Agency (EMA). Patients should discuss any off-label consideration with a qualified healthcare professional, and therapy should only be initiated under direct medical supervision.

Is Calan Sr the Right Medication for You?

Calan Sr is most appropriate for adults who:

• Have confirmed hypertension, stable angina, or documented supraventricular tachyarrhythmia requiring rate control.
• Need an alternative to beta-blockers, especially if bronchospastic disease (e.g., asthma) precludes beta-blocker use.
• Have preserved left-ventricular function, as the negative inotropic effect may exacerbate heart failure with reduced ejection fraction.

Contraindications and cautions

• Severe left-ventricular systolic dysfunction (EF < 35 %).
• Second- or third-degree AV block without a permanent pacemaker.
• Hypotension (systolic < 90 mm Hg).
• Sick sinus syndrome unless a paced rhythm is established.
• Significant hepatic impairment (due to reduced metabolism).

Patients with these conditions should seek alternative therapies or undergo careful monitoring if verapamil is deemed necessary.

Risks, Side Effects, and Interactions

Common

• Headache - Often mild and transient.
• Dizziness or light-headedness - Related to blood pressure lowering.
• Constipation - Occurs in up to 15 % of patients; dietary fiber can help.
• Peripheral edema - Usually mild, resolves with dose adjustment.

Rare

• Bradycardia - Heart rate < 50 bpm, may require dosage reduction.
• Hypotension-related syncope - Less common when taken with other antihypertensives.
• Erythema or mild rash - Generally manageable with antihistamines.

Serious

• Severe bradyarrhythmias (complete heart block).
• Heart failure exacerbation due to negative inotropic effect.
• Liver toxicity (transaminase elevations).
• Life-threatening allergic reactions (anaphylaxis, angioedema).

Drug-Drug Interactions

• Beta-blockers - Additive negative chronotropic effect; monitor heart rate.
• Digoxin - Increases serum digoxin concentration; check levels.
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) - Raise verapamil levels, increasing toxicity risk.
• CYP3A4 inducers (e.g., rifampin, carbamazepine) - Lower verapamil exposure, reducing efficacy.

Drug-Food Interactions

• Grapefruit juice - Potently inhibits CYP3A4 in the gut, leading to higher plasma verapamil concentrations; avoid large amounts.
• High-fat meals - May delay absorption but do not significantly alter overall exposure.

Patients should inform all healthcare providers of concomitant medications, over-the-counter products, and supplements.

Use: Dosing, Missed Dose, Overdose

Standard dosing

• Hypertension: 120 mg orally twice daily; may increase to 240 mg twice daily based on response.
• Angina: 120 mg three times daily (total 360 mg/day) or a sustained-release formulation of 240 mg once daily.
• Atrial fibrillation/flutter: 120 mg twice daily; some clinicians start at 80 mg twice daily in frail patients.

Dosage adjustments are necessary in renal impairment (creatinine clearance < 30 mL/min) and in the elderly; reduce by 25-50 % and monitor plasma levels if available.

Missed dose

If a dose is missed and the scheduled time is more than 6 hours away, take the missed tablet as soon as remembered. If it is within 6 hours of the next dose, skip the missed tablet to avoid excessive dosing. Do not double-dose.

Overdose

Signs of verapamil overdose include severe hypotension, ventricular bradyarrhythmias, cardiac arrest, and respiratory depression. Immediate actions:

• Call emergency services (e.g., 911).
• If trained, administer activated charcoal within 1 hour of ingestion.
• In a medical setting, treatment may involve intravenous calcium, atropine, high-dose insulin-glucose therapy, and advanced cardiac life-support measures.

FAQ

• Can I travel internationally with Calan Sr?

  • Yes. Keep the medication in its original labeled container, carry a copy of the prescription (if applicable), and store it in your carry-on luggage to avoid temperature extremes.

• Does alcohol affect the efficacy of Calan Sr?

  • Moderate alcohol consumption can potentiate verapamil-induced hypotension and dizziness. Patients should limit intake and avoid driving if they feel unsteady.

• What does the tablet look like?

  • The 120 mg tablet is typically round, film-coated, and pink; the 240 mg tablet is larger, round, and light-blue. Appearance may vary by manufacturer.

• Are there any sugar substitutes in the tablet?

  • In most formulations, the inactive ingredients are lactose, magnesium stearate, and microcrystalline cellulose. Patients with lactose intolerance should verify the specific batch composition.

• Will Calan Sr show up on a drug test?

  • Verapamil is not screened for in standard employment drug tests. However, specialized toxicology panels could detect it if specifically requested.

• Is it safe to use Calan Sr during pregnancy?

  • Animal studies have not demonstrated teratogenicity, but human data are limited. The drug is classified as pregnancy category C; it should only be used if the potential maternal benefit justifies the potential fetal risk.

• How should I store Calan Sr in a hot climate?

  • Keep tablets below 30 °C (86 °F). In regions with high ambient temperatures, store the medication in a climate-controlled drawer or a sealed container with a desiccant pack.

• Can I crush or split the tablet?

  • Verapamil tablets are not recommended for crushing because this can alter absorption and increase the risk of rapid onset of side effects. Splitting is permissible only for the 240 mg tablet if a scored line is present; otherwise obtain a lower-strength formulation.

• What is the difference between immediate-release and sustained-release forms?

  • Immediate-release tablets deliver the full dose quickly, requiring multiple daily dosing. Sustained-release (SR) tablets release the drug gradually over 24 hours, allowing once-daily administration and often resulting in smoother plasma concentration profiles.

• Do calcium-channel blockers interact with dietary calcium supplements?

  • Calcium supplements taken simultaneously can mildly reduce verapamil absorption. Separate dosing by at least 2 hours to minimize this effect.

Glossary

Calcium-channel blocker (CCB)

A class of drugs that inhibit the flow of calcium ions through L-type channels in cardiac and smooth-muscle cells, leading to vasodilation and reduced heart rate.

Negative chronotropic effect

A reduction in heart rate caused by a medication’s action on the cardiac conduction system, particularly the AV node.

Pharmacokinetic half-life

The time required for the plasma concentration of a drug to decrease by 50 % after reaching steady state.

Off-label use

Prescription of a medication for an indication, dosage, or patient population that has not received formal regulatory approval.

Buying Calan Sr from Our Online Pharmacy

Patients who encounter limited availability or high out-of-pocket costs for verapamil can obtain Calan Sr through our online pharmacy. Our service offers several advantages:

• Cost-effective pricing - We source the generic product directly from licensed manufacturers, allowing us to sell it at prices close to the wholesale rate.
• Verified quality - Every batch is inspected for compliance with international pharmacopeial standards and is shipped from certified, audited facilities.
• Reliable delivery - Discreet packaging and tracked shipping options ensure that the medication arrives safely; express delivery typically reaches most destinations within 7 days, while standard airmail takes about 3 weeks.
• International access - For patients residing in regions where Calan Sr is not stocked locally, our pharmacy broker service connects you with overseas licensed pharmacies, maintaining full regulatory compliance.
• Privacy protection - Orders are processed with strict confidentiality. Personal information is encrypted, and packaging contains no identifying markings beyond the necessary shipment details.

By choosing our online pharmacy, patients gain a convenient, secure pathway to receive the medication they need without compromising on safety or affordability.

Disclaimer

The information presented about Calan Sr is intended solely for general educational purposes and does not replace professional medical assessment. All therapeutic decisions, including considerations of off-label applications, must be made under the direct supervision of a qualified healthcare provider. Readers are presumed to be competent adults capable of informed health choices. Our online pharmacy provides access to Calan Sr for individuals who may encounter limited availability through conventional pharmacies, insurance-based dispensing, or who seek cost-effective generic alternatives. Always discuss any medication changes, initiations, or discontinuations with a qualified clinician before proceeding.