AFEDITAB CR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AFEDITAB CR (AFEDITAB CR).
Nifedipine is a dihydropyridine calcium channel blocker that inhibits the influx of calcium ions through L-type channels in vascular smooth muscle and cardiac muscle, leading to vasodilation and reduced myocardial contractility.
| Metabolism | Primarily hepatic via CYP3A4; undergoes extensive first-pass metabolism. |
| Excretion | Renal (80% as inactive metabolites), fecal (15% as metabolites), unchanged drug (<1%) |
| Half-life | Terminal elimination half-life is 6-11 hours; prolonged in hepatic impairment and elderly due to reduced clearance |
| Protein binding | 92-98% bound to plasma proteins (primarily albumin) |
| Volume of Distribution | 0.5-0.9 L/kg; high distribution indicates extensive tissue binding |
| Bioavailability | Oral extended-release: approximately 50-60% due to first-pass metabolism; absolute bioavailability is 45-60% |
| Onset of Action | Extended-release: 30-60 minutes for detectable plasma levels; peak effect in 2-4 hours |
| Duration of Action | Antihypertensive and antianginal effects persist for 12-24 hours with once-daily dosing; therapeutic coverage maintained throughout dosing interval |
30-60 mg orally once daily, extended-release; maximum 90 mg/day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | No adjustment required for any degree of renal impairment, but use with caution in patients with severe renal failure due to risk of hypotension. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | Not recommended for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | Initiate at lower end of dosing range (30 mg once daily) due to increased sensitivity to hypotensive effects and potential for reduced hepatic clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AFEDITAB CR (AFEDITAB CR).
| Breastfeeding | Nifedipine excreted into breast milk; M/P ratio approximately 0.42-0.77; limited human data; no adverse effects reported in infants; use with caution during breastfeeding. |
| Teratogenic Risk | Teratogenic effects not established; first trimester: no data in humans, animal studies show no teratogenicity; second and third trimesters: risk of fetal hypoxia, intrauterine growth restriction (IUGR), and oligohydramnios; may cause neonatal hypotension, bradycardia, and hypoglycemia if used near term. Contraindicated in pregnancy for hypertension; use only if benefit outweighs risk (e.g., tocolysis). |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to nifedipine or any component","Cardiogenic shock","Concomitant use with strong CYP3A4 inducers (e.g., rifampin)","Kock pouch (ileostomy)"]
| Precautions | ["Hypotension, especially with immediate-release formulations","Peripheral edema","Hepatic impairment","Increased angina/acute MI upon withdrawal or dose escalation","Beta-blocker withdrawal","Congestive heart failure"] |
| Food/Dietary | Grapefruit juice increases nifedipine levels via CYP3A4 inhibition; avoid consumption. High-fat meals may delay absorption but do not alter overall exposure. Avoid alcohol as it can exacerbate vasodilation and hypotension. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, fetal heart rate, and ultrasound for amniotic fluid volume if used in pregnancy; assess for signs of fetal distress and neonatal effects. |
| Fertility Effects | No adverse effects on fertility reported; reversible inhibition of sperm motility in vitro; clinical significance unknown. |
| Clinical Pearls | AFEDITAB CR is a controlled-release formulation of nifedipine, a dihydropyridine calcium channel blocker. Avoid grapefruit juice as it inhibits CYP3A4 metabolism, increasing nifedipine levels. Use cautiously in patients with aortic stenosis or left ventricular dysfunction due to risk of hypotension. Do not crush or chew tablets; intact shell may appear in stool. |
| Patient Advice | Swallow the tablet whole; do not crush, chew, or break it. · Avoid grapefruit juice while taking this medication. · Do not discontinue abruptly; taper under medical supervision. · Report symptoms of hypotension like dizziness or fainting. · Limit alcohol intake as it may worsen side effects. · Monitor for fluid retention (ankle swelling) and notify doctor if worsening. |