5α-reductase, the enzyme responsible for converting testosterone to dihydrotestosterone, exists in 2 forms: Type 1 and Type 2. Finasteride selectively inhibits Type 2 whereas dutasteride inhibits both forms. Dutasteride curbs 20 to 24 percent more 5a enzyme; consequently, prevents more DHT conversion (94%) than finasteride(70%) in the scalp. DHT in the scalp causes hereditary hair loss in men, and male pattern baldness(MPB) is the most prevalent cause of hair loss.
Different Factors that Cause Androgenetic Alopecia or MPB
The medical term Androgenetic Alopecia (AGA) points to the role of androgens and genetic factors causing progressive hair loss in men. DHT is a potent form of testosterone, the androgenic hormone that defines male characteristics and plays an important role right from fetal stage to old age in men. But DHT in the scalp causes hair loss to those who have the gene that makes them susceptible.
Here is a caveat. Although a gene is responsible for hair loss, and is inherited, the trigger that releases the gene can be unhealthy lifestyles - Late nights, junk food, sedentary habits. So if baldness does not run in the family and just the one case this may be the reason.
How are Type-1 and Type-2 5a Reductase Enzymes Different?
Type 1 5AR enzyme is mostly found in the liver and skin, and a bit in the prostate as well. It is also the dominant isoform or protein variant in sebaceous glands. The face and scalp have the highest amount of sebaceous glands, and they are found around hair follicles.
Dutasteride is three times more effective than finasteride in inhibiting TYPE-1 and one hundred times more effective against Type-2. Another reason why dutasteride prevents more DHT conversion than finasteride.
Type 2 5AR enzyme is the dominant isoenzyme in the prostate, and is minimally present in the liver and skin.
The primary function of both type 1 and type 2 5a reductase enzyme is to convert testosterone to DHT.
Half-Life
Dutasteride also has a longer half-life of 5 weeks compared to the half-life of 5-6 hours for finasteride. This can also factor in the higher efficacy of dutasteride to mop up DHT.
Drug Development and FDA Approval
Dutasteride is the new kid on the block, extremely enthusiastic and too good at the job, while Finasteride is the mature adult who does what is required. Finasteride has been well researched, studied since it was patented in the 70s and FDA approved for hair loss in 1998.
Dutasteride is a new drug approved to treat Benign Prostate Hyperplasia(BPH) in 2001, and is not yet FDA approved for hair loss. It is prescribed off label to treat hair loss from male pattern baldness for now. It will be approved as more trial data is assimilated and long-term effects, adverse side effects are well established.
Forms of Drug Delivery and Dosage
Oral (1mg/day pill) and topical finasteride(.5 mg with minoxidil) is a well established treatment for alopecia (hair loss) The treatment can be only topical as well depending on when treatment started. If treatment started early in 20s as a preventive measure the need to take both forms might not be necessary. If treatment starts later it benefits to use both forms of medication. Some topical finasteride solutions can be a bit higher than .5 mg.
Due to the high potency of dutasteride, .5 mg is prescribed for hair loss and the 5 mg tablet for treating Benign Prostate Hyperplasia(BPH).
Liposomal drug delivery of topical dutasteride and finasteride is another form which is coming into vogue. It has not become mainstream yet. Results from a few studies demonstrate that the skin permeability or rate of absorption in the skin is much higher using this drug delivery method. This was established by growing hair on excised abdominal mice cells. The liposomal formulation showed a seven fold higher deposition of drug in skin as compared to hydro-alcoholic solution and conventional gels. Overall the study proved improved and localized drug action in the skin and thus could be formulated as a better option to cure androgenetic alopecia.
What is Liposomal Drug Delivery?
Liposomal drug delivery is a process where fatty (lipids) medium is used to form a multi-layered envelope or bubble to target drug delivery to specific parts of the body, to prevent adverse side effects or damage other parts of the body.
Nano-Particle Drug Delivery
Several studies have suggested that nanoparticles are able to deeply penetrate into hair follicles after topical application to human and animal skin, with some researchers suggesting that follicular delivery is more efficient with nanoparticles with diameters under 300 nm compared to larger nanoparticles. Mostly in the experimental stage these are the future in hair loss treatments.
Side Effects
Both medications work similarly, and have similar side effects. Dutasteride with its higher rate of efficiency might increase estrogen, with higher chances of gynecomastia, breast tenderness. But with right dosage, and active monitoring of the doctor, side effects are manageable.
In long term studies of finasteride and dutasteride treating BPH, feeling dizzy while sitting up was noted as a side effect.
Most noted side effects are loss of libido which can be reversed by stopping usage, watery sperm, and watery ejaculation.
Side effects do go away after the body adjusts to the medication, or can be safely managed.
Important point to note: while those suffering from MPB hair loss, and those who do not have comparable levels of DHT, it is the scalp concentration of DHT that really matters.
While topical solutions stay on the scalp itchiness from the Poly propylene glycol, and ethanol, dryness can be a bother for sensitive skin. Water based formulations should be used to avoid itchiness.
If pregnant women come into contact with finasteride or dutasteride, they should immediately wash the area with soap and water. It might affect the development of a male fetus.
Considering dutasteride is highly potent, and DHT is an essential hormone for the male body to function effectively, prescribing dutasteride will be under doctor's discretion depending on medical necessity weighing pros and cons of both medications.
