Minoxidil

# Minoxidil ## Overview - **Classification:** Peripheral vasodilator; topical hair growth stimulant - **Mechanism:** Opens ATP-sensitive potassium channels causing arteriolar vasodilation to lower blood pressure; topical form converted to minoxidil sulfate stimulates hair follicle growth by prolonging the anagen (growth) phase and increasing scalp blood flow[1][3][4]. ## Primary Indications 1. **Severe hypertension (resistant/high blood pressure):** Oral minoxidil used when other antihypertensives fail 2. **Androgenetic alopecia (male/female pattern hair loss):** Topical minoxidil to promote hair regrowth 3. **Off-label hair loss types:** Sometimes used for other hair loss disorders (off-label) ## Adult Dosing ### Standard Dosing **Hypertension (oral)** - **Dose:** Start 5 mg daily, may increase weekly by 5 mg - **Frequency:** 1-2 times daily (usually divided doses) - **Route:** Oral - **Max Dose:** Up to 100 mg/day (divided doses) with close monitoring - **Notes:** Usually combined with beta-blockers and diuretics to counter reflex tachycardia and fluid retention[5][6]. **Androgenetic alopecia (topical)** - **Dose:** 1 mL of 2% or 5% solution or equivalent foam - **Frequency:** Twice daily for men; once daily for women - **Route:** Topical scalp application - **Duration:** Continuous for at least 4 months for hair growth effects[1]. ### Dose Adjustments - **Renal Impairment:** Absorption may be delayed; no specific dose changes but monitor closely - **Hepatic Impairment:** Metabolized primarily by liver; use caution, no clear dose adjustment guidelines - **Elderly:** Start at lower doses; monitor blood pressure and cardiac status closely ## Pediatric Dosing ### Neonates (0-28 days) - **Use:** Not routinely recommended; no established dosing - **Notes:** Safety not established; use only if benefits outweigh risks under specialist supervision ### Infants (1-12 months) - **Use:** Not routinely recommended; no clear dosing information ### Children (1-12 years) - **Use:** Occasionally used for severe hypertension under specialist guidance - **Dose:** Start low, e.g., 0.1-0.2 mg/kg/day orally divided doses; titrate carefully - **Max:** Adult equivalent dose dependent on response and tolerance ### Adolescents (13-18 years) - **Dose:** Typically approach adult dosing with careful titration and monitoring - **Max:** Same as adult dose ## Safety Information ### Contraindications - **Absolute:** Hypersensitivity to minoxidil - **Absolute:** Pheochromocytoma (may cause hypertensive crisis) - **Relative:** Severe tachycardia, pericardial effusion without drainage (due to fluid retention risk) ### Common Adverse Effects - **Very Common (>10%):** Hypertrichosis (excessive hair growth on body), Skin irritation (topical) - **Common (1-10%):** Dizziness, tachycardia, edema, headache - **Serious but Rare:** Pericardial effusion, angina exacerbation, severe hypotension, reflex tachycardia[5]. ### Key Drug Interactions - **Beta-blockers:** Usually co-administered to prevent reflex tachycardia - **Diuretics:** Essential to prevent sodium and fluid retention - **Other antihypertensives:** Additive hypotensive effects — monitor blood pressure closely[5]. ## Monitoring & Follow-up - **Before Treatment:** Baseline BP, heart rate, renal function, electrolyte levels, cardiac evaluation if indicated - **During Treatment:** Frequent BP and HR monitoring (weekly during titration), watch for edema, pericardial effusion signs - **Clinical Signs:** Monitor for chest pain, shortness of breath, swelling, dizziness, excessive hair growth (topical) ## Clinical Pearls - 💡 **Oral minoxidil requires concurrent beta-blocker and diuretic therapy** to prevent tachycardia and edema - 💡 **Topical minoxidil must be applied consistently** for several months before assessing efficacy in hair growth - 💡 **Patient counseling:** For topical use, avoid contact with eyes and other body areas; wash hands after application > **⚠️ Important**: This information is educational only. Consult current guidelines and product labels before prescribing.