Makindo Medical Notes

Related Subjects: | Hypertension

📖 About

Always check the BNF link here (or local formulary) for prescribing advice.

• 💊 Potent vasodilator, originally developed for severe hypertension.
• 🧴 Topical formulations promote hair growth (male & female pattern baldness).

⚙️ Mode of Action

• Opens ATP-sensitive potassium channels in vascular smooth muscle → hyperpolarisation → relaxation.
• 🩸 Causes marked arteriolar vasodilatation → ↓ systemic vascular resistance & BP.
• Compensatory ↑ heart rate & cardiac output (sympathetic activation).

📋 Indications

• 🫀 Severe or resistant hypertension (usually with a diuretic & β-blocker to counter side effects).
• 💇‍♂️ Androgenic alopecia (male pattern baldness) – topical application.
• 👩‍🦰 Occasionally used in female pattern hair loss (topical).

💊 Dose

• Oral: 2.5–5 mg/day, titrated up; max 50 mg/day.
• Lower doses for elderly or dialysis patients.
• Topical: 2%–5% solution or foam, applied to scalp BD.

🔄 Interactions

• ⬇️ Additive hypotension with other antihypertensives.
• Combine with loop diuretic to avoid fluid retention & β-blocker to blunt reflex tachycardia.

⚠️ Cautions

• Ischaemic heart disease (risk of angina due to tachycardia).
• Porphyria.
• Renal impairment – may exacerbate fluid retention.

⛔ Contraindications

• 🚫 Phaeochromocytoma (risk of crisis from catecholamine surge).

⚠️ Side Effects

• 💇‍♂️ Hypertrichosis / hair growth (generalised, esp. face & arms, in systemic use).
• 💧 Fluid retention & oedema → always combine with a diuretic.
• ❤️ Reflex tachycardia, angina; risk of pericardial effusion.
• 🤢 GI upset.
• 🧔 Gynecomastia, breast tenderness (rare).