Calan (verapamil hydrochloride) represents a cornerstone in cardiovascular pharmacotherapy as a Class IV antiarrhythmic and antihypertensive agent. This calcium channel blocker exerts its therapeutic effects through selective inhibition of calcium ion influx across cardiac and vascular smooth muscle cell membranes, resulting in decreased peripheral vascular resistance and reduced myocardial oxygen demand. Clinically validated through decades of rigorous research, Calan demonstrates particular efficacy in managing supraventricular tachyarrhythmias, chronic stable angina, and essential hypertension. Its well-characterized pharmacokinetic profile and established safety record make it a preferred choice among cardiologists for long-term cardiovascular management across diverse patient populations.

Features

• Contains verapamil hydrochloride as active pharmaceutical ingredient
• Available in immediate-release (80mg, 120mg) and extended-release formulations (120mg, 180mg, 240mg)
• Exhibits selective inhibition of L-type calcium channels
• Demonstrates high oral bioavailability (20-35%) with extensive first-pass metabolism
• Shows protein binding approximately 90%
• Features elimination half-life of 2.8-7.4 hours following single dose
• Provides hepatic metabolism via cytochrome P450 system (CYP3A4, CYP2C9)
• Presents renal excretion as primary elimination pathway (70% as metabolites)

Benefits

• Effectively reduces elevated blood pressure through vasodilation of peripheral arteries
• Decreases myocardial oxygen demand by reducing afterload and contractility
• Controls ventricular rate in atrial fibrillation and flutter through AV node conduction slowing
• Prevents angina episodes by improving coronary blood flow and reducing cardiac workload
• Demonstrates proven long-term cardiovascular protection in hypertensive patients
• Offers convenient once-daily dosing with extended-release formulations

Common use

Calan is primarily indicated for the management of essential hypertension, either as monotherapy or in combination with other antihypertensive agents. It is extensively used for controlling ventricular rate in patients with chronic atrial fibrillation and atrial flutter. The medication demonstrates significant efficacy in the prophylactic treatment of chronic stable angina pectoris, particularly in patients who cannot tolerate beta-blockers or nitrates. Off-label applications include migraine prophylaxis, hypertrophic cardiomyopathy management, and reduction of esophageal spasm in achalasia. Clinical practice typically reserves Calan for patients requiring specific calcium channel blockade effects rather than first-line therapy in uncomplicated hypertension.

Dosage and direction

Dosage must be individualized based on therapeutic response and tolerability. For hypertension: Initial dose of 80mg three times daily (immediate-release) or 180-240mg once daily (extended-release), titrating upward at weekly intervals. Maximum daily dose should not exceed 480mg. For angina: 80-120mg three times daily (immediate-release) or 180-480mg once daily (extended-release). For arrhythmias: 240-480mg daily in divided doses (immediate-release) or once-daily extended-release formulation. Administer with food to minimize gastrointestinal upset. Extended-release tablets must be swallowed whole without crushing or chewing. Regular monitoring of blood pressure and heart rate is essential during dosage titration.

Precautions

Exercise caution in patients with impaired hepatic function due to reduced metabolism and potential accumulation. Monitor patients with renal impairment closely as verapamil may decrease renal perfusion. Use cautiously in patients with neuromuscular transmission disorders (myasthenia gravis, Duchenne muscular dystrophy) due to potential exacerbation. Avoid rapid dosage escalation in elderly patients due to increased sensitivity. Regular ophthalmological examinations recommended due to potential effects on intraocular pressure. Patients should be advised about potential constipation and appropriate management strategies. Periodic monitoring of liver function tests and electrolyte levels is recommended during long-term therapy.

Contraindications

Absolute contraindications include severe left ventricular dysfunction (ejection fraction <30%), cardiogenic shock, sick sinus syndrome or second- or third-degree AV block without functioning ventricular pacemaker, atrial flutter or fibrillation with accessory pathway (WPW syndrome), hypotension (systolic <90 mmHg), and known hypersensitivity to verapamil or any component of the formulation. Concurrent administration with ivabradine is contraindicated due to additive heart rate lowering effects. Use is contraindicated in patients with severe hepatic impairment (Child-Pugh class C).

Possible side effect

Common adverse reactions include constipation (7-25%), dizziness (3-10%), nausea (2-7%), hypotension (2-5%), headache (2-8%), and peripheral edema (1-5%). Less frequent effects include fatigue (1-3%), bradycardia (1-2%), flushing (1-2%), and AV block (0.5-1%). Rare but serious adverse events include heart failure exacerbation, hepatotoxicity, gingival hyperplasia, and Stevens-Johnson syndrome. Most side effects are dose-dependent and often diminish with continued therapy. Constipation can usually be managed with appropriate dietary measures or stool softeners.

Drug interaction

Significant interactions occur with beta-blockers (additive bradycardia and AV conduction depression), digoxin (increased serum concentrations 50-75%), statins metabolized by CYP3A4 (increased risk of myopathy), cyclosporine (increased nephrotoxicity risk), and lithium (increased neurotoxicity potential). Potent CYP3A4 inhibitors (ketoconazole, clarithromycin) significantly increase verapamil concentrations. Concurrent use with disopyramide or flecainide may produce excessive negative inotropic effects. Alcohol may enhance vasodilation and hypotensive effects. Grapefruit juice may increase bioavailability through CYP3A4 inhibition.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next scheduled dose. Do not double the dose to make up for a missed administration. For once-daily formulations, if missed within 12 hours of scheduled time, take immediately and resume regular schedule. If beyond 12 hours, skip the missed dose and resume normal dosing schedule. For multiple daily dosing regimens, if remembered within 4 hours of scheduled time, take immediately and continue regular schedule. Maintain consistent dosing intervals to ensure stable therapeutic effects.

Overdose

Overdose manifestations include severe hypotension, bradycardia, heart failure, and junctional escape rhythms. Management involves cardiovascular support with IV fluids and vasopressors (norepinephrine preferred over dopamine). Calcium gluconate (1g IV) may reverse hemodynamic effects. Atropine may be effective for bradycardia. Temporary cardiac pacing may be required for high-grade AV block. Glucagon has been used successfully in some cases. Hemodialysis is not effective due to high protein binding and extensive tissue distribution. Gastric lavage may be considered if presentation occurs within 1-2 hours of ingestion.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) with excursions permitted between 15-30°C (59-86°F). Protect from moisture and light. Keep in original container with tight closure. Do not transfer to other containers as this may affect stability. Keep out of reach of children and pets. Do not use if tablets show evidence of discoloration, cracking, or other physical deterioration. Properly dispose of expired or unused medication through drug take-back programs.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Individual therapeutic responses may vary. Healthcare professionals should exercise clinical judgment when prescribing Calan based on individual patient characteristics. Patients should not alter dosage or discontinue medication without consulting their healthcare provider. The prescribing information provided here may not include all possible uses, directions, precautions, or interactions. Always refer to the official prescribing information for complete details.

Reviews

Clinical studies demonstrate Calan’s efficacy with 70-80% of hypertensive patients achieving blood pressure control (<140/90 mmHg) at appropriate doses. In angina management, studies show 50-60% reduction in angina episodes and nitroglycerin consumption. For rate control in atrial fibrillation, successful ventricular rate reduction (<100 bpm) achieved in 85% of patients. Long-term studies indicate maintained efficacy over 5-year periods with consistent safety profile. Patient satisfaction surveys indicate high compliance rates due to generally favorable side effect profile compared to other antihypertensive classes.