AMLODIPINE BENZOATE
Clinical safety rating: safe
Weak CYP3A4 inhibitors may increase levels but no dosage adjustment is typically needed Monitor for hypotension and peripheral edema dose-related side effects.
Dihydropyridine calcium channel blocker; inhibits transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle, leading to peripheral vasodilation and reduced systemic vascular resistance.
| Metabolism | Hepatic metabolism via CYP3A4; undergoes extensive first-pass metabolism. |
| Excretion | Renal: 60% (10% unchanged), biliary/fecal: 20-25% as metabolites |
| Half-life | Terminal: 30-50 hours (steady state achieved after 7-8 days; prolonged in elderly, hepatic impairment) |
| Protein binding | 93-98% bound to plasma proteins (albumin) |
| Volume of Distribution | 21 L/kg (extensive extravascular distribution; high tissue affinity) |
| Bioavailability | Oral: 64-90% (first-pass metabolism minimal; no significant food effect) |
| Onset of Action | Oral: 30-60 minutes; gradual onset with peak effect at 6-12 hours |
| Duration of Action | 24 hours (supports once-daily dosing; antihypertensive effect persists beyond 24h with consistent trough-to-peak ratio) |
Oral: 5-10 mg once daily. Initial dose 5 mg once daily, titrate up to 10 mg once daily as needed. Maximum 10 mg daily.
| Dosage form | SUSPENSION |
| Renal impairment | No dose adjustment required for any degree of renal impairment. Not dialyzable. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): Initial dose 2.5 mg once daily, titrate slowly to a maximum of 10 mg once daily. Severe hepatic impairment (Child-Pugh C): Use with caution, initial dose 2.5 mg once daily; maximum dose not established. |
| Pediatric use | For hypertension in children ≥6 years: Oral 2.5-5 mg once daily. Initial dose 2.5 mg once daily, may increase to 5 mg once daily if needed. For children 1-5 years: safety and efficacy not established. |
| Geriatric use | For patients ≥65 years: Initial dose 2.5 mg once daily due to increased bioavailability and prolonged half-life. Titrate slowly to a maximum of 10 mg once daily. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Weak CYP3A4 inhibitors may increase levels but no dosage adjustment is typically needed Monitor for hypotension and peripheral edema dose-related side effects.
| FDA category | Animal |
| Breastfeeding | Amlodipine is excreted in human milk; M/P ratio is not established. The relative infant dose is estimated to be 3-7% of maternal weight-adjusted dose. Caution is advised; monitor infant for hypotension and tachycardia. |
| Teratogenic Risk | Amlodipine benzoate is classified as FDA Pregnancy Category C. First trimester: Animal studies have shown delayed parturition and increased fetal death; human data are limited. Second and third trimesters: Use only if benefit outweighs risk; potential for hypotension and reduced uterine blood flow. No adequate well-controlled studies in pregnant women. |
■ FDA Black Box Warning
None
| Common Effects | angina |
| Serious Effects |
["Hypersensitivity to amlodipine or any dihydropyridine derivative","Severe hypotension","Shock (including cardiogenic shock)","Acute myocardial infarction with pulmonary congestion"]
| Precautions | ["Peripheral edema","Hypotension","Increased angina or myocardial infarction on initiation or dose titration","Severe left ventricular dysfunction","Hepatic impairment","Aortic stenosis"] |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 metabolism of amlodipine, increasing plasma concentrations and risk of adverse effects. No other significant food interactions. Alcohol may potentiate hypotensive effects; limit intake. |
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| Fetal Monitoring | Monitor maternal blood pressure and fetal heart rate regularly. Assess for signs of hypotension in mother and potential fetal distress. Consider ultrasound to assess fetal growth if used long-term. |
| Fertility Effects | Animal studies suggest no effect on fertility; human data are minimal. No significant impact on male or female reproductive function reported. |
| Clinical Pearls | Amlodipine benzoate is a dihydropyridine calcium channel blocker used for hypertension and angina. Its long half-life (~30-50 hours) allows once-daily dosing. Peripheral edema is a dose-dependent side effect, more common in women and older adults. Can be used with ACE inhibitors or ARBs to reduce edema. Avoid grapefruit juice as it increases amlodipine levels. Onset of action is gradual; do not titrate more frequently than every 1-2 weeks. |
| Patient Advice | Take exactly as prescribed, usually once daily, with or without food. · Do not consume grapefruit or grapefruit juice while taking this medication. · Common side effects include swelling of the ankles/feet, dizziness, flushing, and headache. · Avoid sudden discontinuation; talk to your doctor before stopping. · Check blood pressure regularly and keep a log to share with your healthcare provider. · Inform your doctor if you experience severe dizziness, fainting, or irregular heartbeat. · This medication does not cure your condition but helps control it; continue use even if you feel well. |