Απ: Double A. Ίσως, από τις καλύτερες ιδιοκατασκευές.
Here's mention of this fact from Dr. Lee:
"HairlossTalk: The goal with Propecia obviously is a systemic altering of hormonal balances. It works from within the bloodstream to affect the levels of DHT throughout the whole body. It takes time for it to actually begin to affect the hormonal processes going on in the Scalp. It's not instant in the scalp even though its bloodstream effects are instant, and even when it has begun to work in the scalp, its even longer before you notice anything aesthetically as far as maintenance of hair or regrowth. Why is it that we have such an effective systemic DHT inhibitor, and the concept of systemic DHT inhibitors, especially with the upcoming release of Dutasteride is very clear to us that it works... but its so difficult for scientists to come up with a topical DHT inhibitor that comes anywhere near to working as well? It would seem to us that having to change your hormonal balances throughout your entire body would be incredibly unnecessary just to achieve the goal of making a change in the scalp. Why is it so hard for us to make something work *locally* in a topical formulation? Is it an issue of not enough absorption? Is it an issue of too much absorption which results in the active ingredient being "washed" away by the bloodstream, causing the treatment to not be present a sufficient number of hours out of the day to actually make a difference?
"Dr. Lee: Actually its both. By the way Finasteride (the active ingredient in Propecia) does work topically. When Merck was doing their trials, they had to make a decision as to what they felt would be a better selling product: A pill, or a topical applied solution. By far, people would rather take a pill, so this is the route they took. To answer your question: Why don't topicals work as well? It's for many reasons. One reason is that it doesn't stay in the skin long enough. That's the problem with progesterone. It's absorbed, metabolized, and carried away so quickly that it's not effective when it's applied topically. Another problem is absorption. There are very few things that get absorbed into skin very well at all. Its quite the protective device."
Excerpt from Merck's patent description:
"[0031] The present invention has the objective of providing methods of treating the hyperandrogenic conditions of androgenic alopecia, including male pattern baldness and female pattern baldness, acne vulgaris, seborrhea, female hirsutism, and polycystic ovary syndrome by systemic, oral, parenteral or topical administration of a 5.alpha.-reductase 2 inhibitor in a dosage amount under 5 mg/day, and particularly, from about 0.01 mg/day to 3.0 mg/day, and more particularly 0.05 to 1 mg/day. The invention is further illustrated by dosages of about 0.05 to 0.2 mg/day and specifically dosages of about 0.05, 0.1, 0.15 and 0.2 mg/day. Exemplifying the invention are dosages of 0.05 and 0.2 mg/day. The term "treating androgenic alopecia" is intended to include the arresting and/or reversing of androgenic alopecia, and the promotion of hair growth. Also, a 5.alpha.-reductase 2 inhibitor, e.g. finasteride, at a dosage under 5 mgs/day can be used in combination with a potassium channel opener, such as minoxidil or a pharmaceutically acceptable salt thereof, for the treatment of androgenic alopecia, including male pattern baldness. The 5.alpha.-reductase 2 inhibitor and the potassium channel opener may both be applied topically, or each agent can be given via different administration routes; for example, the 5.alpha.-reductase 2 inhibitor may be administered orally while the potassium channel opener may be administered topically.
"[0032] The present invention also has the objective of providing suitable systemic, oral, parenteral and topical pharmaceutical formulations for use in the novel methods of treatment of the present invention. The compositions containing 5.alpha.-reductase 2 inhibitor compounds as the active ingredient for use in the treatment of the above-noted hyperandrogenic conditions can be administered in a wide variety of therapeutic dosage forms in conventional vehicles for systemic administration. For example, the compounds can be administered in such oral dosage forms as tablets, capsules (each including timed release and sustained release formulations), pills, powders, granules, elixirs, tinctures, solutions, suspensions, syrups and emulsions. Likewise, they may also be administered in intravenous (both bolus and infusion), intraperitoneal, subcutaneous, topical with or without occlusion, or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. For oral administration, for example, the compositions can be provided in the form of scored or unscored tablets containing 0.01, 0.05, 0.1, 0.2, 1.0, 2.0 and 3.0 milligrams of the activtingredient for the symptomatic adjustment of the dosage to the patient to be treated.
"[0033] For the treatment of androgenic alopecia including male pattern baldness, acne vulgaris, seborrhea, and female hirsutism, the 5.alpha.-reductase 2 inhibitor compounds may be administered in a pharmaceutical composition comprising the active compound in combination with a pharmaceutically acceptable carrier adapted for topical administration. Topical pharmaceutical compositions may be, e.g., in the form of a solution, cream, ointment, gel, lotion, shampoo or aerosol formulation adapted for application to the skin. Topical pharmaceutical compositions useful in the method of treatment of the present invention may include about 0.001% to 0.1% of the active compound in admixture with a pharmaceutically acceptable carrier."
Where are getting your information that topical fin. is useless?
LEE TALKING......
ΤΟ μονο που συγκρατησα ειναι οτι αναφερει οτι τοπικα λογω προγεστερονης ειναι δυσκολο να κρατηθει η φιναστεριδη απο το δερμα....εκτος και αν μετεφρασα λαθος....