Verapamil
Class IV
| IV Dose | 0.075-0.150 mg/kg (max 10 mg) over 1-2 minutes. |
| Oral dose | 4-17 mg/kg/day divided q 8 hours (BID or QD with slow release form) |
| Levels | 0.1-0.3 ug/ml. |
| Kinetics | Zero-order (half-life related to dose). Extensive first-pass metabolism. Elimination half-life 12 hours on chronic oral therapy, but 6 hours after single dose. |
| Cautions | Do not use under 12 months of age, especially under 3 months, hypotension, CV collapse, death). Use with caution long-term in patients with manifest preexcitation. (conversion of SVT is OK). Do not pre-treat with calcium chloride, as it interferes with the therapeutic effect. Be prepared with calcium, fluids and dopamine if hypotension occurs following administration. |
| Interactions | Contraindicated with beta blockers, due to synergistic negative inotropy. Contraindicated with quinidine, due to synergistic negative inotropy. Increases digoxin levels 40-75% (quinidine-like). Therapeutic effect blocked by anticholinergic properties of disopyramide |
| Preparations | Calan scored tablets: 80, 120 mg. Calan SR scored tablets: 240 mg. Calan injection: 5 mg/2 ml, 10 mg/4 ml amps, vials. Isoptin: same Verelan pellet-filled capsules: 120, 240 mg. (QD dosing) |
| FDA approval in children | no |