VERELAN PM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VERELAN PM (VERELAN PM).
Verapamil is a calcium channel blocker that inhibits the influx of calcium ions across the cardiac and vascular smooth muscle cells, thereby reducing myocardial contractility, sinoatrial and atrioventricular node conduction, and vascular tone.
| Metabolism | Hepatic metabolism primarily via CYP3A4, CYP1A2, and CYP2C8; forms several metabolites including norverapamil (active). |
| Excretion | Primarily hepatic metabolism (>95%), with 3-4% excreted unchanged in urine; biliary/fecal excretion accounts for <1% of unchanged drug. |
| Half-life | Terminal elimination half-life 7.2 ± 1.5 hours after oral administration, prolonged in hepatic impairment (up to 14-16 hours) and elderly; steady-state achieved after 3-4 days. |
| Protein binding | 90% bound to plasma proteins (primarily albumin and alpha-1-acid glycoprotein). |
| Volume of Distribution | 3-4 L/kg (mean 3.4 L/kg), indicating extensive tissue distribution; higher Vd with cirrhosis. |
| Bioavailability | Oral (extended-release): 40-50% due to first-pass hepatic metabolism; food slightly increases AUC (10-15%) but not clinically significant. |
| Onset of Action | Oral (extended-release): 1-2 hours for detectable serum concentrations, 2-4 hours for measurable reduction in blood pressure or angina symptoms. |
| Duration of Action | 24 hours with once-daily dosing; antihypertensive effect maintained over 24-hour dosing interval, but variability exists; food may prolong duration slightly. |
Verelan PM (verapamil hydrochloride) is an extended-release oral capsule administered once daily at bedtime. Typical adult dose for hypertension is 200 mg to 400 mg once daily at bedtime. Initial dose is 200 mg, titrated upward as needed. Maximum recommended dose is 400 mg daily.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | No specific dose adjustment is recommended for renal impairment. However, verapamil is not significantly removed by hemodialysis. Use with caution in patients with impaired renal function as they may be more sensitive to antihypertensive effects. |
| Liver impairment | In patients with impaired hepatic function (Child-Pugh score A or B), dose should be reduced by 50% to 70% of normal dose as verapamil is extensively metabolized by the liver. For Child-Pugh class C, use is contraindicated or avoid if possible; if necessary, use lowest possible dose with careful monitoring. |
| Pediatric use | Pediatric use is not recommended as safety and efficacy in children have not been established. No official weight-based dosing guidelines exist for Verelan PM in pediatric patients. Alternative formulations (e.g., immediate-release verapamil) are used off-label with dosing based on weight (e.g., 4-8 mg/kg/day in divided doses) but not for Verelan PM specifically. |
| Geriatric use |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VERELAN PM (VERELAN PM).
| Breastfeeding | Verapamil is excreted into human breast milk. The milk-to-plasma (M/P) ratio is approximately 0.6. Infant daily dose is estimated at <0.1% of maternal weight-adjusted dose, considered low. However, monitor infant for bradycardia and hypotension. Use with caution, especially in preterm neonates or those with renal impairment. |
| Teratogenic Risk | Verapamil (VERELAN PM) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies have shown embryotoxicity and teratogenicity (skeletal abnormalities) at high doses. Second and third trimesters: Can cause maternal hypotension, which may reduce uteroplacental blood flow; potential for fetal hypoxia and growth restriction. Risk of neonatal bradycardia and hypoglycemia if used near term. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Severe left ventricular dysfunction","Hypotension (systolic <90 mmHg)","Cardiogenic shock","Sick sinus syndrome (unless pacemaker present)","Second- or third-degree AV block (unless pacemaker present)","Atrial fibrillation/flutter with accessory bypass tract (e.g., WPW syndrome)","Concurrent use of IV beta-blockers (within a few hours)","Known hypersensitivity to verapamil"]
| Precautions | ["Heart failure: May worsen heart failure due to negative inotropic effects.","Hypotension: May cause excessive hypotension, especially with IV use.","Bradycardia and AV block: Risk of bradycardia and AV block, especially in patients with sick sinus syndrome or pre-existing conduction defects.","Hepatic impairment: Use with caution; doses may need reduction.","Neuromuscular transmission: May potentiate neuromuscular blocking agents."] |
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| In elderly patients, start with the lowest available dose (200 mg once daily at bedtime). Titrate slowly due to increased sensitivity to antihypertensive effects and higher risk of bradycardia, constipation, and hypotension. Maximum dose may be lower than in younger adults. Monitor renal and hepatic function as age-related decline may require dose adjustment. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate regularly. Fetal heart rate monitoring during labor if used for preterm labor. Assess fetal growth via ultrasound if long-term use. Neonatal monitoring for bradycardia, hypotension, and hypoglycemia after delivery. |
| Fertility Effects | In animal studies, verapamil did not impair fertility. In humans, no significant effects on female fertility reported. Limited data on male fertility; theoretical risk of reversible sperm motility impairment due to calcium channel blockade. |