ADALAT
Clinical safety rating
cautionComprehensive clinical and safety monograph for ADALAT (ADALAT).
Dihydropyridine calcium channel blocker; inhibits calcium ion influx across cardiac and vascular smooth muscle cells, reducing peripheral vascular resistance and blood pressure.
| Metabolism | Hepatic via CYP3A4; extensive first-pass metabolism; metabolites are inactive. |
| Excretion | Renal: 70-80% as metabolites; Fecal: 15-20% as metabolites; <1% unchanged in urine |
| Half-life | Terminal elimination half-life: 2-5 hours (immediate-release); 8-14 hours (extended-release). Context: shorter half-life necessitates multiple daily dosing for immediate-release; extended-release allows once-daily dosing. |
| Protein binding | 92-98% bound to plasma proteins (albumin and alpha-1-acid glycoprotein) |
| Volume of Distribution | 0.8-1.2 L/kg. Clinical meaning: indicates extensive tissue distribution, consistent with high lipophilicity. |
| Bioavailability | Oral immediate-release: 45-60% (due to first-pass metabolism); extended-release: 60-85% (due to slower release and reduced first-pass effect). |
| Onset of Action | Oral immediate-release: 20-30 minutes; sublingual: 1-5 minutes. Context: sublingual onset is rapid for hypertensive crises, but not recommended due to risk of severe hypotension. |
| Duration of Action | Immediate-release: 4-6 hours; extended-release: 24 hours. Clinical note: extended-release provides consistent blood pressure control over 24 hours. |
| Molecular Weight | 346.38 |
10-20 mg orally three times daily; extended-release: 30-60 mg orally once daily; maximum 120 mg/day.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min; for GFR <30 mL/min, use with caution and reduce initial dose by 50%. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce by 75%. |
| Pediatric use | 0.25-0.5 mg/kg/dose orally every 6-8 hours; maximum 3 mg/kg/day. Extended-release not recommended. |
| Geriatric use | Start at 10 mg orally twice daily; titrate slowly due to increased sensitivity and risk of hypotension. |
| 1st trimester | Avoid use; associated with fetal abnormalities in animal studies, limited human data. |
| 2nd trimester | Use only if clearly needed; may cause fetal hypoxia, reduced placental perfusion. |
| 3rd trimester | Avoid use; may cause fetal hypoxia, premature labor inhibition, and maternal hypotension. |
Clinical note
Comprehensive clinical and safety monograph for ADALAT (ADALAT).
| Placental transfer | Crosses placenta; fetal plasma concentrations approximately 40-60% of maternal levels. |
| Breastfeeding | Present in breast milk in low concentrations; monitor infant for hypotension and bradycardia. Consider alternative agents with more safety data. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Limited human data; animal studies show embryotoxicity. Second/third trimester: May cause fetal hypoxia due to maternal hypotension; risk of preterm labor inhibition. Category C. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate; fetal heart rate and uterine activity; assess for signs of fetal distress. |
| Fertility Effects | Reversible impairment of spermatogenesis in animal studies; no significant human data on fertility. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to nifedipine or any dihydropyridineCardiogenic shockAcute myocardial infarction within previous 4 weeksUnstable angina (except under controlled conditions)Concomitant use with strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin)
| Precautions | May cause hypotension, especially in patients on beta-blockers or with poor cardiac reserve, Risk of increased angina and/or myocardial infarction upon initiation or dose increase, Peripheral edema, Stevens-Johnson syndrome and toxic epidermal necrolysis (rare), Hepatic impairment, Exacerbation of angina on withdrawal |
| Food/Dietary | Avoid grapefruit and grapefruit juice; they inhibit CYP3A4 and increase nifedipine serum concentrations, leading to enhanced hypotensive effects and risk of toxicity. Grapefruit interaction persists for 24 hours; separate consumption by at least 4 hours if unavoidable, but preferable to avoid entirely. Avoid alcohol which can increase hypotension. High-fat meals may reduce absorption of extended-release formulations; take consistently with or without food. |
| Clinical Pearls | Adalat (nifedipine) is a dihydropyridine calcium channel blocker. Use immediate-release capsules only for hypertensive emergencies, not chronic treatment due to risk of reflex tachycardia and unpredictable hypotension. Extended-release formulations are preferred for stable angina and hypertension. Avoid grapefruit juice as it increases nifedipine levels via CYP3A4 inhibition. Monitor for peripheral edema, gingival hyperplasia, and constipation. Contraindicated in cardiogenic shock, severe aortic stenosis, and within 4 weeks of myocardial infarction. |
| Patient Advice | Swallow extended-release tablets whole; do not crush, chew, or split. · Avoid grapefruit and grapefruit juice while taking this medication. · Report persistent swelling of ankles/feet, gum tenderness or bleeding, or severe dizziness. · Do not stop abruptly; taper under medical supervision to avoid rebound hypertension. · Take at the same time each day; if a dose is missed, skip it if near next dose. · May cause dizziness; avoid driving until you know how it affects you. · Increase fluid and fiber intake to prevent constipation. · Store at room temperature away from light and moisture. |
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