Dutasteride is a 5a reductase enzyme inhibitor. It acts to stop the conversion of testosterone to DHT. It has been established that DHT destroys hair follicles in the scalp and hence by preventing the conversion of testosterone to DHT hair loss can be prevented. Dutasteride is more potent than finasteride since it can block type I and type II 5 a reductase enzymes whereas finasteride only blocks the type II 5 a reductase enzyme.
Studies have demonstrated that dutasteride is more effective than finasteride in preventing hair loss. In a study by Olsen et al., (2006), which compared finasteride and dutasteride when used for the treatment of male pattern baldness. They found that a 2.5mg dose of dutasteride increased target hair area count versus placebo and it demonstrated superiority over finasteride at 12 weeks and 24 weeks.
Dutasteride is given in a dose of 0.5mg daily or twice a day. However, the twice daily dosing did prove to be more effective at reducing hair loss but was associated with more side effects. Due to its potency, there is a greater risk of suffering from the side effects associated with the 5 a reductase blockers. However, these side effects can be mitigated by using a topical solution rather than the oral capsules. At present only specialist compounding pharmacies can prepare and dispense topical dutasteride solutions.
Olsen, E.A., Hordinsky, M., Whiting, D., Stough, D., Hobbs, S., Ellis, M.L., Wilson, T., Rittmaster, R.S. and Dutasteride Alopecia Research Team, 2006. The importance of dual 5α-reductase inhibition in the treatment of male pattern hair loss: results of a randomized placebo-controlled study of dutasteride versus finasteride. Journal of the American Academy of Dermatology, 55(6), pp.1014-1023.