A genetically determined sensitivity of the scalp hair follicles to adult levels of androgens.
Hairs become miniaturised in a symmetrical pattern.
Antiandrogen medications can sometimes be useful in treating hair lost in this way.
Both men and women can be affected with 80% of Caucasian men and 50% of women showing signs of AGA by 70 years of age.
Minoxidil is very helpful in androgenetic alopecia in both men and women. This can be purchased without a prescription. Treatment is twice daily and needs to be maintained for up to 6 months to notice any improvement. Any improvement is lost if treatment is discontinued.
Low Dose Oral Minoxidil
Hair Growth Cycle: There are a set number of anagen growth phases in any one persons lifetime.
1) Minoxidil can help to lengthen the anagen phase meaning more hair stays for longer.
2) The thickening affect it has on hair strands also helps to increase scalp coverage.
3) There is also a consensus that minoxidil may reduce hair follicle scarring.
Different forms of alopecia can also further shorten the average anagen phase.
Mechanism of action This is largely unknown, however minoxidil does cause potassium efflux that leads to peripheral vasodilation (which is speculated to alter blood flow to follicles) and increased hair growth stimulation.
This is important for a few weeks prior and upon initiation of minoxidil.
• Regular blood pressure and heart rate reading.
Oral Minoxidil Side effects
• Chest pain
• Excessive hair growth on body
• ECG abnormalities
• Fast heart rate
• Lower blood pressure
• Oedema and water retention
Maintain a healthy balanced diet. Minimise salt, caffeine and alcohol intake.
Side effects often go away with continued use as your body adjusts to the new medication. Shedding may occur for up to six weeks after initiation.
Oral minoxidil can be useful in nearly all forms of hair loss. These include androgenetic alopecia, alopecia areata and post chemotherapy induced alopecia (telogen effluvium). Androgenetic is the most common, affecting most males in their lifetime and half of women over the age of 65. In men this is characterised with hair loss beginning at the temples and crown eventually leading to complete loss of hair on the top of the scalp. Alopecia areata is caused by an individual’s own immune system attacking its hair follicles, this is often occurs in oval patches randomly positioned on the scalp.
Healthy male and female adults with no underlying health issues are the main candidates.
Heart and kidney problems can often rule out the use of this drug.
Females must be taking steps to prevent pregnancy.
For males suffering with androgenetic alopecia; monotherapy is not recommended, as it does not prevent the underlying cause of hair loss. However it can be an effective adjunct treatment option.
It is recommended to always try topical minoxidil first. However, this may not be tolerable or produce sufficient response in certain individuals. Tolerability may be an issue due to the topical causing greasy hair, and/or an itchy scalp. Even some preparations without propylene glycol (a known scalp irritant) yield the same result. In addition, some do not respond due to a lack of sulfotransferase enzyme activity in the scalp. This enzyme is required to turn minoxidil into its active from. However, patients taking the drug orally can bypass this barrier.
Studies have seen increased hair growth with doses ranging from 0.25mg to 5mg. This is substantially lower than the 10-40mg (and even up to 100mg) for which it is licensed for high blood pressure. 625mcg dose every day or every other day is a good starting point and is the lowest dose available after quartering the 2.5mg tablets available on the market. In general females require a lower dose to males but doses may be altered depending on response.
There is a minimum of four to six before initial results may be seen. Response rates to oral minoxidil seem to be high but there is limited data to give a definitive number. Minoxidil must be continually taken to maintain its benefit.