Oral Severe hypertension unresponsive to standard therapy
Adult: In combination with a β-blocker or appropriate alternative (e.g. methyldopa), and a diuretic: Initially, 5 mg daily. Dose may be gradually increased in increments of 5-10 mg daily at intervals of at least 3 days according to response until optimum control is achieved. Usual effective dose range: 10-40 mg daily. Max: 100 mg daily. Daily doses may be given as a single dose or in 2 divided doses, depending on the patient's blood pressure response. If the desired reduction of diastolic blood pressure is >30 mmHg, the daily dose must be divided into 2 equal doses. If more rapid blood pressure control is needed, dose increments of 5 mg 6 hourly may be given with continuous blood pressure monitoring. Dosage recommendations may vary among countries and between individual products (refer to specific product guidelines). Elderly: In combination with a β-blocker or appropriate alternative (e.g. methyldopa), and a diuretic: Initially, 2.5 mg daily, then increase gradually. Child: In combination with a β-blocker or appropriate alternative (e.g. methyldopa), and a diuretic for patients with severe hypertension associated with target organ damage when another therapy has failed: <12 years Initially, 0.2 mg/kg daily. Carefully increase the dose in increments of 0.1-0.2 mg/kg daily at intervals of at least 3 days according to response. Usual effective dose range: 0.25-1 mg/kg daily. Max: 50 mg daily. Daily doses may be given as a single dose or in 2 divided doses, depending on the patient's blood pressure response; ≥12 years Same as adult dose. Dosage recommendations may vary among individual products or between countries (refer to detailed product information or local treatment guidelines).
Topical/Cutaneous Androgenetic alopecia
Adult: In males: As 2% or 5% topical solution or spray: Apply 1 mL to affected areas of the scalp bid. Max: 2 mL daily. As 5% topical foam: Apply 1 g (1/2 capful) to affected areas of the scalp bid. Max: 2 g daily. In females: As 2% topical solution or spray: Apply 1 mL to affected areas of the scalp bid. Max: 2 mL daily. As 5% topical foam: Apply 1 g (1/2 capful) to affected areas of the scalp once daily. Max: 1 g daily. Onset and hair regrowth response may vary on an individual basis; therefore, 2-4 months of treatment may be needed before signs of hair growth appear. Continuation of once daily or bid application without interruption is recommended to maintain the effect. Available percentage formulations and dosage forms may vary among individual products and between countries (refer to detailed product guidelines).
What are the brands available for Minoxidil in Malaysia?
Oral:
Patients with renal failure or those undergoing dialysis: Dose reduction may be required.
Administration
Minoxidil May be taken with or without food.
Contraindications
Oral: Phaeochromocytoma. Topical: Hypertension (treated or untreated); scalp abnormality (including sunburn and psoriasis) and shaved, inflamed, infected, irritated or painful scalp. Concomitant use with other topical agents or occlusive dressings applied on the scalp.
Special Precautions
Oral: Patient with CHF, ischaemic heart disease, recent MI, and pulmonary hypertension associated with mitral stenosis. Patients with malignant hypertension and those receiving guanethidine are recommended to have initial treatment in the hospital setting to ensure that blood pressure is not reduced too rapidly. Minoxidil must be used concomitantly with therapeutic doses of β-blockers (if not contraindicated) or an appropriate substitute (e.g. methyldopa) to prevent reflex tachycardia and to increase myocardial workload, and with a diuretic to control fluid retention. Reserved for hypertensive patients who do not adequately respond to Max therapeutic doses of a diuretic and 2 other antihypertensive drugs. Topical: Patient with CV disease, including cardiac arrhythmia. Minoxidil should not be used in other types of hair loss (e.g. hair loss without a family history, hair loss is sudden/patchy or for unknown reason). Products intended to be applied on the scalp must not be used on other areas of the body. Children and elderly. Significant renal impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Pericarditis, pericardial effusion which may progress to tamponade and exacerbate angina pectoris; reflex tachycardia, ECG alterations in T wave direction and magnitude; may precipitate syncope, CVA, MI and/or ischaemia of special sense organs resulting in vision or hearing loss (due to rapid blood pressure control in severe hypertension); salt and water retention leading to oedema; hypertrichosis, changes in hair colour or texture; temporary increase in hair shedding upon treatment initiation (topical). Blood and lymphatic system disorders: Rarely, thrombocytopenia, leucopenia (oral). Gastrointestinal disorders: Nausea, vomiting. General disorders and administration site conditions: Application site reactions (e.g. irritation, pruritus, dry skin, erythema, erythematous rash). Investigations: Weight gain; transiently increased serum creatinine and BUN levels (oral). Nervous system disorders: Headache (topical). Reproductive system and breast disorders: Breast tenderness (oral). Skin and subcutaneous tissue disorders: Rash, pruritus, dermatitis, acne (topical). Rarely, Stevens-Johnson syndrome (oral).
Topical: If fingertips are used to facilitate application, wash hands thoroughly after use since unwanted hair growth may be caused by transfer to other areas of the scalp. Avoid contact with eyes. For the spray, avoid inhaling the spray mist.
Monitoring Parameters
Closely monitor blood pressure, fluid and electrolyte balance, and body weight. Any test performed (e.g. ECG, echocardiogram, renal function test, chest X-ray) with abnormal results at treatment initiation may be repeated every 1-3 months, then every 6-12 months once the patient is stable. Closely assess for signs and symptoms of pericarditis, pericardial effusion, cardiac tamponade, or angina.
Overdosage
Symptom: Exaggerated hypotension (most likely associated with residual sympathetic nervous system blockade). Management: Give NaCl 0.9% IV infusion to help maintain blood pressure. Administer phenylephrine, dopamine and vasopressin only if inadequate vital organ perfusion is evident. Avoid sympathomimetic agents (e.g. epinephrine, norepinephrine) due to excessive cardiac stimulation.
Drug Interactions
May result in excessive blood pressure reduction or increased risk of orthostatic hypotension with sympathetic blocking agents (e.g. guanethidine, betanidine). Additive effects with other antihypertensive agents and other drugs that lower blood pressure. May lead to increased absorption of topical minoxidil when used with other topical agents (e.g. tretinoin, dithranol, corticosteroids, petrolatum) applied on the scalp.
Action
Description: Mechanism of Action: Minoxidil, a pyrimidine derivative direct-acting peripheral vasodilator, is used orally for severe hypertension and topically for androgenetic alopecia. When taken orally, it lowers peripheral vascular resistance and blood pressure through direct vasodilation on vascular smooth muscles. When applied topically, minoxidil stimulates hair growth secondary to its vasodilating effect, increases cutaneous blood flow, and stimulates the resting hair follicles. Onset: Hypotensive effect: Approx 30 minutes (oral). Duration: Up to 2-5 days (oral). Pharmacokinetics: Absorption: Rapidly and well absorbed from the gastrointestinal tract; minimal absorption after topical scalp application. Bioavailability: 90% (oral). Distribution: Widely distributed into body tissues. Enters breast milk. Metabolism: Extensively metabolised in the liver predominantly via glucuronidation to form minoxidil O-glucuronide (primary metabolite). Excretion: Mainly via urine (mostly as metabolites). Elimination half-life: 3.5-4.2 hours.
Chemical Structure
Minoxidil Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 4201, Minoxidil. https://pubchem.ncbi.nlm.nih.gov/compound/Minoxidil. Accessed Oct. 28, 2024.
Storage
Tab: Store between 20-25°C. Protect from light or moisture. Topical spray, solution, or foam: Store between 20-25°C. Do not expose to extreme heat and keep away from naked flames.
C02DC01 - minoxidil ; Belongs to the class of pyrimidine derivative agents acting on arteriolar smooth muscle. Used in the treatment of hypertension. D11AX01 - minoxidil ; Belongs to the class of other dermatologicals.
References
5% Minoxidil Spray (Consilii LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/09/2024.Anon. Minoxidil (Systemic). AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 03/09/2024.Anon. Minoxidil (Topical). AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 03/09/2024.Brayfield A, Cadart C (eds). Minoxidil. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/09/2024.Hirsutin Tablet 5 mg (Zontron Pharmaceuticals Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/09/2024.Jewim Minoxidil Topical Solution 2% w/v and 5% w/v (Medispec [M] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/09/2024.Joint Formulary Committee. Minoxidil. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/09/2024.Minoxidil (Systemic). UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 03/09/2024.Minoxidil (Topical). UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 03/09/2024.Minoxidil 10 mg Tablets (Roma Pharmaceuticals Ltd). MHRA. https://products.mhra.gov.uk. Accessed 03/09/2024.Minoxidil 5% (for Women) Aerosol, Foam (Aurohealth LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/09/2024.Minoxidil 5% Cutaneous Solution (Careforsons Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/09/2024.Minoxidil Dermapharm 20 mg/mL Cutaneous Spray, Solution (Mibe Pharma UK Ltd). MHRA. https://products.mhra.gov.uk. Accessed 03/09/2024.Minoxidil Tablet (Actavis Pharma, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/09/2024.Paediatric Formulary Committee. Minoxidil. BNF for Children [online]. London. BMJ Group, Pharmaceutical Press, and RCPCH Publications. https://www.medicinescomplete.com. Accessed 03/09/2024.Pfizer New Zealand Limited. Loniten 10 mg Tablets data sheet 20 May 2019. Medsafe. http://www.medsafe.govt.nz. Accessed 03/09/2024.Regaine for Men Extra Strength Scalp Foam 5% w/w Cutaneous Foam (McNeil Products Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/09/2024.Regaine for Women Once a Day Scalp Foam 5% w/w Cutaneous Foam (McNeil Products Limited). MHRA. https://products.mhra.gov.uk. Accessed 20/09/2024.Regaine for Women Regular Strength (McNeil Products Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/09/2024.Remixdil Hair Regrowth Treatment for Women (Rida LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/09/2024.
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