Calan

Calan (verapamil hydrochloride) represents a cornerstone in cardiovascular pharmacotherapy as a Class IV antiarrhythmic and antihypertensive agent. This calcium channel blocker specifically inhibits the transmembrane influx of calcium ions into cardiac muscle and vascular smooth muscle cells, producing both negative chronotropic and vasodilatory effects. Its dual mechanism of action makes it particularly valuable for managing supraventricular tachyarrhythmias, chronic stable angina, and essential hypertension. With well-established efficacy and a predictable pharmacokinetic profile, Calan remains a first-line therapeutic option for physicians seeking to optimize cardiovascular outcomes through targeted ion channel modulation.

Features

• Contains verapamil hydrochloride as the active pharmaceutical ingredient
• Available in immediate-release (80 mg, 120 mg) and extended-release formulations (120 mg, 180 mg, 240 mg)
• Exhibits high oral bioavailability (20-35%) with extensive first-pass metabolism
• Demonstrates concentration-dependent calcium channel blockade with IC50 of approximately 100 ng/mL
• Protein binding exceeds 90%, primarily to albumin
• Elimination half-life ranges from 2.8-7.4 hours following single doses
• Undergoes hepatic metabolism via cytochrome P450 isoenzymes (primarily CYP3A4)
• Excreted predominantly in urine (70%) as metabolites with 3-4% as unchanged drug

Benefits

• Effectively reduces ventricular rate in atrial fibrillation and flutter through AV node conduction slowing
• Decreases myocardial oxygen demand via reduced afterload and contractility in angina management
• Provides sustained 24-hour blood pressure control with extended-release formulations
• Demonstrates antianginal efficacy through coronary and peripheral vasodilation
• Shows proven mortality benefit in certain cardiovascular patient populations
• Offers flexible dosing regimens compatible with various cardiovascular conditions

Common use

Calan is primarily indicated for the management of essential hypertension, either as monotherapy or in combination with other antihypertensive agents. It is equally effective for controlling chronic stable angina pectoris when beta-blockers are contraindicated or poorly tolerated. In cardiology practice, it serves as a first-line agent for rate control in atrial fibrillation and flutter, particularly when rapid ventricular response requires acute modulation. Off-label uses include prophylaxis of cluster headaches, hypertrophic cardiomyopathy management, and as an adjunct in manic episode treatment. The selection between immediate-release and extended-release formulations depends on the clinical scenario, with extended-release offering superior compliance for chronic conditions.

Dosage and direction

For hypertension management, initial dosing typically begins with 80 mg immediate-release tablets three times daily, titrating upward at weekly intervals based on therapeutic response. Most patients achieve adequate control at 360-480 mg daily divided into three or four doses. Extended-release formulations allow for once-daily dosing starting at 180-240 mg, with maximum recommended daily dose of 480 mg. For angina pectoris, initial dosing ranges from 80-120 mg three times daily. In atrial fibrillation, loading doses of 5-10 mg IV may be administered followed by oral maintenance therapy. Administration with food may enhance bioavailability while minimizing gastrointestinal discomfort. Tablets should be swallowed whole without crushing or chewing, particularly for extended-release formulations.

Precautions

Hepatic impairment necessitates dose reduction and careful monitoring due to verapamil’s extensive metabolism. Patients with renal dysfunction (creatinine clearance <30 mL/min) require 50% dose reduction. Regular monitoring of liver enzymes, renal function, and electrolyte levels is recommended during long-term therapy. Abrupt withdrawal should be avoided due to potential rebound hypertension or angina exacerbation. Patients should be cautioned about potential constipation and advised regarding dietary fiber supplementation. Regular blood pressure monitoring and ECG assessments are essential during dose titration periods. Elderly patients may exhibit increased sensitivity requiring lower initial doses.

Contraindications

Absolute contraindications include severe left ventricular dysfunction (ejection fraction <30%), cardiogenic shock, sick sinus syndrome (except with functioning pacemaker), second- or third-degree AV block, atrial flutter or fibrillation with accessory pathways (WPW syndrome), and hypersensitivity to verapamil or related compounds. Relative contraindications encompass moderate hepatic impairment, hypotension (systolic <90 mmHg), concomitant beta-blocker therapy, and neuromuscular disorders like myasthenia gravis. The combination with ivabradine is contraindicated due to additive heart rate reduction effects.

Possible side effect

Common adverse reactions (occurring in >5% of patients) include constipation (7.3%), dizziness (3.3%), nausea (2.7%), hypotension (2.5%), and peripheral edema (2.1%). Less frequent effects (1-5%) comprise headache, fatigue, flushing, and bradycardia. Serious but rare complications (<1%) include heart failure exacerbation, hepatotoxicity, gingival hyperplasia, and complete heart block. Approximately 15% of patients discontinue therapy due to adverse effects, primarily gastrointestinal complaints. Most side effects are dose-dependent and often diminish with continued therapy or dose adjustment.

Drug interaction

Calan exhibits numerous clinically significant interactions due to CYP3A4 inhibition and P-glycoprotein effects. Concurrent administration with beta-blockers may produce additive bradycardia and AV conduction abnormalities. Co-administration with digoxin increases digoxin levels by 50-75% through reduced renal clearance. Statins metabolized by CYP3A4 (atorvastatin, simvastatin) may experience increased exposure. Cyclosporine levels increase significantly, requiring 50% dose reduction. Verapamil potentiates neuromuscular blocking agents and enhances effects of alcohol and antihypertensive medications. Rifampin and phenytoin decrease verapamil concentrations through enzyme induction.

Missed dose

If a dose is missed within 4 hours of the scheduled time, patients should take the medication immediately. For extended-release formulations, if more than 4 hours have passed, the missed dose should be skipped and the regular schedule resumed. Doubling doses is strictly contraindicated due to risk of excessive hypotension or bradycardia. Patients using immediate-release formulations should maintain at least 4-hour intervals between doses. For those on multiple daily dosing, establishing reminder systems or pill organizers is recommended to maintain therapeutic consistency.

Overdose

Verapamil overdose presents with profound hypotension, bradycardia, and metabolic acidosis. Serum concentrations exceeding 1000 ng/mL typically produce life-threatening cardiovascular collapse. Management includes gastric lavage if presented within 1 hour, followed by activated charcoal administration. Calcium gluconate (1 g IV) serves as first-line antidote, repeated every 10-20 minutes as needed. Vasopressors (norepinephrine, dopamine) may be required for refractory hypotension. Temporary pacing is indicated for advanced heart block unresponsive to medical therapy. Glucagon (5-10 mg IV) has shown efficacy in reversing cardiovascular depression. Hemodialysis is ineffective due to high protein binding.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in original container with tight closure. Protect from moisture and light exposure. Keep blister packs intact until administration. Do not transfer to alternative containers as humidity may degrade formulation stability. Extended-release tablets particularly require protection from crushing or breaking. Discard any medication showing signs of discoloration, unusual odor, or physical deterioration. Keep securely closed and out of reach of children and pets. Proper disposal through medication take-back programs is recommended for unused portions.

Disclaimer

This information serves educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult qualified healthcare providers regarding medical conditions or before starting any new therapeutic regimen. Individual responses to medication vary based on genetic factors, concomitant conditions, and other medications. Never adjust dosage or discontinue therapy without medical supervision. The manufacturer provides complete prescribing information containing additional details, warnings, and precautions.

Reviews

Clinical studies demonstrate Calan’s efficacy with 70-80% of hypertensive patients achieving target blood pressure goals. In angina management, exercise tolerance improves by 40-60% in controlled trials. For rate control in atrial fibrillation, 85% of patients achieve ventricular rates <100 bpm at appropriate doses. Long-term studies show maintained efficacy over 5-year periods with consistent safety profiles. Patient satisfaction surveys indicate preference for once-daily formulations due to convenience and reduced side effect burden compared to immediate-release versions. Real-world evidence supports its position as a well-tolerated option in diverse patient populations.