VERELAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VERELAN (VERELAN).
Verapamil inhibits calcium ion influx across cardiac and smooth muscle cells, blocking L-type calcium channels, leading to vasodilation and negative chronotropic, dromotropic, and inotropic effects.
| Metabolism | Hepatic via CYP3A4, CYP1A2, CYP2C8; extensive first-pass metabolism. |
| Excretion | Renal excretion accounts for approximately 70% of elimination, with 3-4% as unchanged drug. Fecal elimination accounts for about 25%, predominantly via biliary secretion. |
| Half-life | Terminal elimination half-life is 2.8 to 7.4 hours in healthy adults, prolonged in hepatic impairment or elderly (up to 12 hours). |
| Protein binding | Approximately 83-93% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 2.7-4.3 L/kg, indicating extensive tissue binding. |
| Bioavailability | Oral bioavailability is 10-20% due to extensive first-pass metabolism; sustained-release formulations have comparable bioavailability but altered absorption profile. |
| Onset of Action | Oral: 30-60 minutes for immediate-release; extended-release: 2-4 hours for peak effect. |
| Duration of Action | Oral: 8-12 hours for immediate-release; extended-release: 24 hours. |
Hypertension: 120-240 mg ER orally once daily; maximum 480 mg/day. Angina: 80-120 mg IR orally three times daily; ER 180-360 mg once daily.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 25-50%; GFR <30 mL/min: use 50% of normal dose and monitor closely. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: reduce dose by 75% or avoid use. |
| Pediatric use | Not FDA-approved; limited data: 4-8 mg/kg/day IR divided every 6-8 hours; maximum 360 mg/day. Titrate cautiously. |
| Geriatric use | Start at low end of dosing range (e.g., 120 mg ER daily); titrate slowly due to increased bioavailability and reduced clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VERELAN (VERELAN).
| Breastfeeding | Verapamil is excreted into human breast milk with an M/P ratio of approximately 0.4. Infant exposure is low (estimated less than 0.1% of maternal weight-adjusted dose). No adverse effects have been reported in nursing infants. However, caution is advised due to potential for cardiovascular effects; monitor infant for bradycardia and hypotension. |
| Teratogenic Risk | Verelan (verapamil) is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses higher than human therapeutic doses. There are no adequate and well-controlled studies in pregnant women. First trimester: Potential risk of fetal cardiovascular and skeletal abnormalities; use only if benefit outweighs risk. Second and third trimesters: May cause maternal hypotension, fetal bradycardia, and reduced uterine blood flow; avoid in preterm labor as it may delay cervical dilation and prolong labor. |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
["Severe left ventricular dysfunction (ejection fraction <30%)","Cardiogenic shock","Sick sinus syndrome (unless pacemaker present)","Second- or third-degree AV block (unless pacemaker present)","Atrial fibrillation or flutter with accessory bypass tract (e.g., WPW syndrome)","Hypersensitivity to verapamil"]
| Precautions | ["Heart failure: May worsen heart failure due to negative inotropic effect.","Hypotension: Can cause symptomatic hypotension.","Bradycardia/AV block: May cause sinus bradycardia or AV block, especially with digitalis or beta blockers.","Hepatic impairment: Requires dose adjustment.","Drug interactions: Increased risk of toxicity with CYP3A4 inhibitors, beta blockers, digitalis, statins, etc."] |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and ECG for signs of bradycardia, hypotension, or arrhythmias. Fetal heart rate monitoring is recommended due to risk of fetal bradycardia. Assess fetal growth and amniotic fluid volume periodically, especially during third trimester. Monitor for signs of uterine atony postpartum. |
| Fertility Effects | Verapamil has been associated with reversible elevations in prolactin levels, which may cause gynecomastia or galactorrhea. In animal studies, it impaired fertility with reduced conception rates. In humans, no significant adverse effects on fertility have been reported, but caution is warranted in patients attempting conception. |