LONITEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LONITEN (LONITEN).
Minoxidil is a potassium channel opener that causes direct vasodilation of peripheral arteries. It reduces peripheral vascular resistance and blood pressure by hyperpolarizing vascular smooth muscle cells via activation of ATP-sensitive potassium channels.
| Metabolism | Primarily metabolized by the liver via glucuronidation (UGT1A1) to inactive metabolites; less than 20% excreted unchanged in urine. |
| Excretion | Renal: 85% (12% unchanged, 73% as glucuronide conjugates); biliary/fecal: 3% |
| Half-life | Terminal elimination half-life: 4.2 hours (range 3.5–5.5); clinically, half-life extends to 14–23 hours after chronic dosing due to drug accumulation. |
| Protein binding | No significant plasma protein binding (<1%); binds to vasular smooth muscle tissue. |
| Volume of Distribution | 1.5 L/kg (range 1.2–2.0); large Vd indicates extensive tissue binding, primarily to arteriolar smooth muscle. |
| Bioavailability | Oral: 95% (rapidly and completely absorbed). |
| Onset of Action | Oral: within 30 minutes; IV: within 5 minutes. |
| Duration of Action | Oral: 8–12 hours; IV: 2–5 hours. Hypotensive effect may persist for ≥24 hours after single dose due to prolonged vasodilation. |
10 mg orally twice daily, titrated to 40 mg twice daily for hypertension; for heart failure, start at 2.5-5 mg orally twice daily, max 20 mg twice daily.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment needed for mild to moderate renal impairment (GFR >30 mL/min). For severe renal impairment (GFR <30 mL/min), reduce dose by 50% and monitor closely. |
| Liver impairment | No specific Child-Pugh based guidelines; use with caution in severe hepatic impairment as drug may accumulate. Reduce initial dose by 50% in Child-Pugh class C. |
| Pediatric use | For hypertension: 0.1-0.2 mg/kg orally once daily, titrate to max 0.5 mg/kg/day divided every 12-24 hours, max 50 mg/day. |
| Geriatric use | Start at lower end of dosing range (2.5-5 mg twice daily) due to increased sensitivity; titrate slowly. Monitor for orthostatic hypotension and renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LONITEN (LONITEN).
| Breastfeeding | Excreted in breast milk; M/P ratio unknown. Avoid use while breastfeeding due to potential adverse effects (e.g., hypotension) in the infant. |
| Teratogenic Risk | Pregnancy Category C. Fetal risks: First trimester - limited human data; animal studies show fetal resorptions and cardiovascular anomalies at high doses. Second/third trimesters - possible fetal hypotension, oligohydramnios, and hypertrichosis. Use only if benefit outweighs risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
Must be administered under close medical supervision; may cause pericardial effusion, occasionally progressing to cardiac tamponade, especially in patients with renal impairment or those on dialysis.
| Serious Effects |
["Hypersensitivity to minoxidil or any component of the formulation.","Pheochromocytoma (due to risk of catecholamine release)."]
| Precautions | ["Monitor for pericardial effusion and tamponade; discontinue if effusion occurs and treat appropriately.","May cause severe fluid retention and congestive heart failure; administer with a diuretic.","Can exacerbate angina; use with caution in patients with coronary artery disease.","Hypertrichosis (excessive hair growth) is common; reversible upon discontinuation.","Monitor blood pressure closely; avoid abrupt withdrawal to prevent rebound hypertension."] |
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| Monitor maternal blood pressure, heart rate, weight, and signs of edema; fetal monitoring with ultrasound for growth, amniotic fluid index, and nonstress test in pregnancy. |
| Fertility Effects | No known effect on human fertility; animal studies show no impairment of fertility at therapeutic doses. |