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Minoxidil

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Minoxidil, Loniten

  • See Also
  1. Topical Minoxidil
  2. Direct Acting Vasodilator
  • Indications
  1. Hypertension not controlled with other agents
    1. Not a first-line Antihypertensive (other agents are preferred)
    2. Oral Minoxidil as described on this page
  2. Alopecia
    1. See Topical Minoxidil
  • Contraindications
  • Systemic Minoxidil
  1. Ischemic Heart Disease (Minoxidil provokes Angina)
  2. Impaired Cardiac Function
  3. Impaired pulmonary function or preexisting Pulmonary Hypertension
  4. Severe renal Impairment (esp. CKD 5, GFR <10 ml/min)
  • Mechanism
  1. Potent Direct Acting Vasodilator (similar to Hydralazine)
    1. Decreases Blood Pressure with compensatory reflex Tachycardia
  2. Minoxidil metabolized to active form Minoxidil sulphate by sulphotransferase enzymes
    1. Minoxidil sulphate opens plasma membrane ATP-sensitive Potassium channels (KATP channels)
    2. Results in rapid, direct arteriole Smooth Muscle relaxation
    3. Reduces Peripheral Vascular Resistance and lowers both systolic and diastolic pressure
  1. Start 2.5 to 5 mg orally daily
  2. Titrate gradually no more often than every 3 days to 10 to 40 mg orally daily
  3. Maximum dose: 100 mg/day divided once to twice daily
  4. Renal Dosing
    1. GFR 10 to 50 ml/min: Dose only every 24 hours
    2. Avoid use in GFR <10 ml/min
  1. Start 0.2 mg/kg orally daily or divided twice daily
  2. Titrate gradually no more often than every 3 days to 0.25 to 1 mg/kg/day
  3. Maximum: 50 mg/day
  • Adverse Effects
  • Systemic Minoxidil
  1. Adverse Effects with systemic Minoxidil do not apply to Topical Minoxidil
  2. Similar to Hydralazine
  3. Reflex Tachycardia
    1. Beta Blockers are often used in combination with Beta Blockers to counter reflex Tachycardia
  4. Leg Edema
    1. Due to reflex Sodium and water retention
    2. Diuretics are often combined with Hydralazine
  5. Cardiac Muscle Lesions
  6. Pulmonary Hypertension
  7. Hirsutism
  8. Pericardial Effusion or Cardiac Tamponade (asscoiated with underlying renal disease)
  • Safety
  1. Pregnancy Category C
  2. Safe in Lactation
  • Metabolism
  1. Glucuronide Conjugation
  • Drug Interactions
  1. Guanethidine
    1. Severe Orthostatic Hypotension
  • Resources
  1. Minoxidil Tablet (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=0354a7f5-5917-44dc-9963-411104008cb5
  • References
  1. (2020) Med Lett Drugs Ther 62(1598): 73-80
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 68-9
  3. Hamilton (2020) Tarascon Pocket Pharmacopoeia