Drug Breakdown / CPD

Drug Breakdown: Minoxidil

02 May 2023
Prescribing
02 May 2023
Volume 5 · Issue 5

Abstract

In this column, Sharon Rees aims to refresh knowledge and interest in some of the commonly used drugs in a series of tweets. This month she is talking about #minoxidil

Dr Sharon Rees @reesprescribe

Day 1: A vasodilator derived from diallylmelamine in 1960s was found to have a BP lowering effect & #minoxidil was licensed 1970s. Long-term use revealed side-effect of hypertrichosis & trials for alopecia & male pattern baldness ensued. Licensed for male hair loss in 1988 as a topical formulation, then 1992 for female hair loss

Dr Sharon Rees @reesprescribe

Day 2: #minoxidil topical 5% solution is licensed for (wo) men aged 18-65 years. It is applied x 1-2/day when the reason for hair loss is known (OTC/private prescription); 5% foam can be prescribed on NHS. Full effect can take 6 months+. Low dose oral #minoxidil (0.625-2.5mg) is used by specialists off-label e.g for alopecia, including for children over 12 years (topical use not recommended in children). Oral 1mg approx equivalent to 5% solution

Dr Sharon Rees @reesprescribe

Day 3: Oral version is a prodrug & genetics determine breakdown response (weak in 50% as less active drug released (if low SULT1A1)). Avoid if severe hepatic impairment. Topical absorption is minimal from intact skin (1-2% of applied dose). All routes metabolised in liver & renal excretion.T½ 4-5 hrs

Dr Sharon Rees @reesprescribe

Day 4: #minoxidil MOA: How stimulation of hair growth occurs is not fully understood & may differ between systemic/topical formulations. #minoxidil increases vascular supply & promotes survival & growth cycle of follicles, as well as increasing the size of the hair follicles

Dr Sharon Rees @reesprescribe

Day 5: #minoxidil ADRs (topical) include local irritation (discontinue), initial increased hair shedding (usually temporary), unwanted hair growth, headache & dyspnoea. Rarely hypotension/cardiovascular ADRs. Topical #minoxidil contraindicated with hypertension (treated or not) & cardiovascular disease caution. Unknown effects in pregnancy. Cannot be used on a shaved or inflamed/ damaged scalp (NOT exhaustive). NOTE product is flammable

Dr Sharon Rees @reesprescribe

Day 6: #minoxidil drug-drug interactions. Absorption could be increased if used with other topical products. Synergistic effects with other anti-hypertensives (NOT exhaustive)

Dr Sharon Rees @reesprescribe

Day 7: #minoxidil does not cure hair loss & the effects only last while using the medication

Earn Your CPD Certificate

With the help of Prescribing and Therapeutics Training Ltd and the Journal of Prescribing Practice, you can earn your 1-hour CPD certificate

In addition to the tweets, read the BNF treatment summary on scalp and hair conditions, the monograph on minoxidil and the SPCs for oral and topical minoxidil. Once you have completed this, answer the 10 questions. Submit your answers to reesprescribe@gmail.com. If you answer at least eight out of 10 questions correctly, you will receive your CPD certificate via email.

  • Minoxidil was originally licensed for, and can still be used as, an anti-hypertensive TRUE or FALSE?
  • Minoxidil is suitable for all types of alopecia TRUE or FALSE?
  • Minoxidil can be used in all age groups TRUE or FALSE?
  • When used for hair loss, the oral formulation is usually used TRUE or FALSE?
  • Which of the following best describes the mechanism of action for minoxidil?
  • Minoxidil increases the size of the hair follicles and prolongs the lifespan of the hair
  • Minoxidil decreases the size of the hair follicles but improves the anchorage to the skin
  • Minoxidil enlarges the hair shaft so existing hair appears thicker
  • Minoxidil stimulates the growth of more hair follicles
  • Side effects from topical application are unlikely, due to minimal systemic absorption TRUE or FALSE?
  • Which of the following is FALSE?
  • You cannot use topical minoxidil on a shaved head
  • Local skin reactions can occur with topical use
  • Other topical treatments can increase the absorption of minoxidil making ADEs more likely
  • You can use as much of the product as needed to stimulate hair growth
  • Increased hair shedding can occur in the first few weeks of treatment TRUE or FALSE?
  • Minoxidil foam may be better tolerated than the solution as it does not contain propylene glycol TRUE or FALSE?
  • Minoxidil can cure some types of hair loss TRUE or FALSE?

Further reading on #minoxidil

  • Scalp and hair conditions: https://bnf.nice.org.uk/treatment-summaries/scalp-and-hair-conditions/
  • Minoxidil: https://bnf.nice.org.uk/drugs/minoxidil/
  • Minoxidil 10 mg tablets: https://www.medicines.org.uk/emc/product/13823/smpc
  • Regaine for Men Extra Strength Scalp Foam 5% w/w Cutaneous Foam (GSL): https://www.medicines.org.uk/emc/product/5781/smpc#gref
  • Regaine for Women Once a Day Scalp Foam 5% w/w Cutaneous Foam: https://www.medicines.org.uk/emc/product/5082/smpc#gref