II. Indications
-
Hypertension not controlled with other agents
- Not a first-line Antihypertensive (other agents are preferred)
- Oral Minoxidil as described on this page
- Alopecia
III. Contraindications: Systemic Minoxidil
- Ischemic Heart Disease (Minoxidil provokes Angina)
- Impaired Cardiac Function
- Impaired pulmonary function or preexisting Pulmonary Hypertension
- Severe renal Impairment (esp. CKD 5, GFR <10 ml/min)
IV. Mechanism
- Potent Direct Acting Vasodilator (similar to Hydralazine)
- Decreases Blood Pressure with compensatory reflex Tachycardia
- Minoxidil metabolized to active form Minoxidil sulphate by sulphotransferase enzymes
- Minoxidil sulphate opens plasma membrane ATP-sensitive Potassium channels (KATP channels)
- Results in rapid, direct arteriole Smooth Muscle relaxation
- Reduces Peripheral Vascular Resistance and lowers both systolic and diastolic pressure
V. Dosing: Hypertension in Adults
- Start 2.5 to 5 mg orally daily
- Titrate gradually no more often than every 3 days to 10 to 40 mg orally daily
- Maximum dose: 100 mg/day divided once to twice daily
-
Renal Dosing
- GFR 10 to 50 ml/min: Dose only every 24 hours
- Avoid use in GFR <10 ml/min
VI. Dosing: Hypertension in Children (Not FDA approved)
- Start 0.2 mg/kg orally daily or divided twice daily
- Titrate gradually no more often than every 3 days to 0.25 to 1 mg/kg/day
- Maximum: 50 mg/day
VII. Adverse Effects: Systemic Minoxidil
- Adverse Effects with systemic Minoxidil do not apply to Topical Minoxidil
- Similar to Hydralazine
- Reflex Tachycardia
- Beta Blockers are often used in combination with Beta Blockers to counter reflex Tachycardia
-
Leg Edema
- Due to reflex Sodium and water retention
- Diuretics are often combined with Hydralazine
- Cardiac Muscle Lesions
- Pulmonary Hypertension
- Hirsutism
- Pericardial Effusion or Cardiac Tamponade (asscoiated with underlying renal disease)
VIII. Safety
- Pregnancy Category C
- Safe in Lactation
IX. Metabolism
- Glucuronide Conjugation
X. Drug Interactions
XI. Resources
- Minoxidil Tablet (DailyMed)
XII. References
- (2020) Med Lett Drugs Ther 62(1598): 73-80
- Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 68-9
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
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Related Studies
| minoxidil (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| MINOXIDIL 10 MG TABLET | Generic | $0.21 each |
| MINOXIDIL 2.5 MG TABLET | Generic | $0.11 each |