Dosing and uses of Isradipine
Adult dosage forms and strengths
capsule
- 2.5mg
- 5mg
tablet, extended release
- 5mg
- 10mg
Hypertension
Capsule: 2.5 PO q12hr; may increase dose q2-4week at 2.5-5 mg increments to maximum 20 mg/day (most patients show no improvement with doses >10 mg/day); maximum in older adults is 10 mg/day
Controlled release tablet: 5 mg PO qDay; may increase dose by 5 mg q2-4week; not to exceed 20 mg/day (freqency of adverse effects increases with doses >10 mg/day)
Pediatric dosage forms and strengths
capsule
- 2.5mg
- 5mg
tablet, extended release
- 5mg
- 10mg
Hypertension (Off-label)
Capsule: 0.15-0.2 mg/kg PO qDay or divided q8-12hr, not to exceed 0.8 mg/kg/day (20 mg/day)
Controlled release tablet: 0.15-0.2 mg/kg PO qDay or divided q12hr
Geriatric dosage forms and strengths
Capsules: 2.5 mg PO q12hr initially
Controlled release tablet: 5 mg PO qDay initially
The bioavailabilty of isradipine is increased in the elderly population
Isradipine adverse (side) effects
>10%
Headache (2-22%)
1-10%
Edema (1-9%)
Dizziness (2-8%)
Palpitation (1-5%)
Flushing (1-5%)
Tachycardia (1-3%)
Chest pain (2-3%)
Rash (2%)
Nausea (1-5%)
Vomiting (≤1%)
Diarrhea (≤ 3%)
Weakness (≤1%)
Dyspnea (1-3%)
Urinary frequency (1-3%)
<1%
Drug-induced gingival hyperplasia
Angioedema
Drowsiness
Hyperhidrosis
Leg pain
Nasal congestion
Drug fever
Dysuria
Impotence
Pruritus
Urticaria
Weight gain
Myocardial infarction
Warnings
Contraindications
Hypersensitivity to isradipine or other calcium channel blockers; hypotension (<90 mm Hg systolic)
Cautions
Use caution in CHF, aortic stenosis, hypotension (initially or after dose increases), persistent progressive dermatologic reactions, exacerbation of angina (during initiation of treatment, after dose increase, or withdrawal of beta blocker), liver impairment
Reflex tachycardia resulting in angina and/or MI in patients with obstructive coronary disease reported
Peripheral edema may occur within 2-3 weeks of initiating therapy
Hypotension with or without syncope is possible (particularly with severe aortic stenosis)
Avoid taking with grapefruit juice
Pregnancy and lactation
Pregnancy category: C
Lactation: not known if excreted into breast milk
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Isradipine
Mechanism of action
Ca channel blocker: inhibits the transmembrane influx of extracellular Ca ions across the membranes of myocardial cells and vascular smooth muscle cells, without changing serum calcium concentrations, resulting in inhibition of cardiac and vascular smooth muscle contraction, thereby dilating the main coronary and systemic arteries
Pharmacokinetics
Onset: 1 hr (initial response; regular release); 2 hr (SR)
Peak response: 2-3 hr (regular release); 8-10 hr (SR)
Excretion: Urine (60-65%); feces (30%)
Peak plasma time: 1.5-3 hr (regular release); 7-18 hr (SR)
Bioavailability: 15-24%
Protein Bound: 95-97%
Vd: 3 L/kg
Metabolism: Hepatic P450 enzyme CYP3A4
Metabolites: Mono acids and a cyclic lactone product (inactive)
Clearance: 40 L/hr
Half-Life: 5-10.7 hr
Duration: 12 hr (regular release); 24 hr (SR)
