Finasterida
Un comprimido diario, autorizado a 1 mg para la alopecia androgenética masculina y a 5 mg para la próstata: la misma sustancia a una dosis cinco veces mayor.
- Clase
- Inhibidor de la 5-alfa reductasa
- Se vende como
- Se vende como: Propecia, Proscar
- Solo con receta
De la ficha autorizada
Propecia
- Usos autorizados
- PROPECIA is a 5α-reductase inhibitor indicated for the treatment of male pattern hair loss (androgenetic alopecia) in MEN ONLY.
- Efficacy in bitemporal recession has not been established.
- PROPECIA is not indicated for use in women.
- Formas y dosis
- PROPECIA tablets (1 mg) are tan, octagonal, film-coated convex tablets with "stylized P" logo on one side and PROPECIA on the other. 1 mg tablets.
- Cómo se toma
- PROPECIA may be administered with or without meals.
- The recommended dose of PROPECIA is one tablet (1 mg) taken once daily.
- In general, daily use for three months or more is necessary before benefit is observed.
- Continued use is recommended to sustain benefit, which should be re-evaluated periodically.
- No debe usarse en caso de
- PROPECIA is contraindicated in the following: Pregnancy.
- Finasteride use is contraindicated in women when they are or may potentially be pregnant.
- Because of the ability of Type II 5α-reductase inhibitors to inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT), finasteride may cause abnormalities of the external genitalia of a male fetus of a pregnant woman who receives finasteride.
- If this drug is used during pregnancy, or if pregnancy occurs while taking this drug, the pregnant woman should be apprised of the potential hazard to the male fetus. In female rats, low doses of finasteride administered during pregnancy have produced abnormalities of the external genitalia in male offspring.
- Interacciones
- Cytochrome P450-Linked Drug Metabolizing Enzyme System No drug interactions of clinical importance have been identified.
- Finasteride does not appear to affect the cytochrome P450-linked drug-metabolizing enzyme system.
- Compounds that have been tested in man include antipyrine, digoxin, propranolol, theophylline, and warfarin and no clinically meaningful interactions were found. Other Concomitant Therapy Although specific interaction studies were not performed, finasteride doses of 1 mg or more were concomitantly used in clinical studies with acetaminophen, acetylsalicylic acid, α-blockers, analgesics,...
- Advertencias y precauciones
- PROPECIA is not indicated for use in women or pediatric patients.
- Women should not handle crushed or broken PROPECIA tablets when they are pregnant or may potentially be pregnant due to potential risk to a male fetus.
- PROPECIA causes a decrease in serum PSA levels.
- Any confirmed increase in PSA while on PROPECIA may signal the presence of prostate cancer and should be evaluated, even if those values are still within the normal range for men not taking a 5α-reductase inhibitor. 5α-reductase inhibitors may increase the risk of high-grade prostate cancer.
- Efectos adversos frecuentes
- most common adverse reactions, reported in ≥1% of patients treated with PROPECIA and greater than in patients treated with placebo are: decreased libido, erectile dysfunction and ejaculation disorder.
- Embarazo
- Pregnancy Category X. PROPECIA is contraindicated for use in women who are or may become pregnant. PROPECIA is a Type II 5α-reductase inhibitor that prevents conversion of testosterone to 5α-dihydrotestosterone (DHT), a hormone necessary for normal development of male genitalia.
- Mecanismo de acción
- Finasteride is a competitive and specific inhibitor of Type II 5α-reductase, an intracellular enzyme that converts the androgen testosterone into DHT. Two distinct isozymes are found in mice, rats, monkeys, and humans: Type I and II. Each of these isozymes is differentially expressed in tissues and developmental stages.
- Titular de la autorización:
- Organon LLC
- Versión de la ficha:
Las secciones anteriores están citadas de la ficha en inglés, porque es ese documento el que porta la autorización. Cuando una autoridad europea publica la misma información en español, el enlace figura en las fuentes. No traducimos por nuestra cuenta los textos reguladores: un error de traducción en una contraindicación sería más peligroso que una línea en otro idioma.
Esta sección recoge la ficha técnica autorizada. El texto está condensado a partir del resumen de la propia autoridad, y el documento completo figura en las fuentes.
Escrito por nosotros
Cómo funciona
La finasterida bloquea la enzima que convierte la testosterona en dihidrotestosterona, la hormona que miniaturiza los folículos en la alopecia androgenética. Si al folículo le llega menos, el proceso se frena y en parte del cuero cabelludo se revierte. No es un tratamiento que se aplique sobre el pelo: es un tratamiento hormonal en comprimidos, y esa distinción explica tanto su efecto como sus advertencias.
Original y genérico
Ambas dosis están fuera de patente y las farmacias dispensan por defecto finasterida genérica. Los comprimidos de 1 mg y de 5 mg contienen la misma sustancia; las fichas difieren porque se autorizaron para enfermedades distintas con datos distintos.
Cuánto cuesta
Es uno de los tratamientos continuados más baratos de este catálogo. La finasterida genérica de 1 mg cuesta unos pocos euros al mes a precios de farmacia europea, y la mayor parte de lo que cobra una clínica online es la consulta y el envío, no el comprimido.
Cómo conseguirlo legalmente
Requiere receta en la Unión Europea, el Reino Unido y Estados Unidos. La vía normal es la consulta online, y las preguntas que importan son las relativas a un embarazo previsto en casa, los antecedentes de ánimo y el control de la próstata, porque sobre esos tres puntos la ficha tiene algo que decir.
De la ficha autorizada
Proscar: autorizado para
- Usos autorizados
- PROSCAR, is a 5α-reductase inhibitor, indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to: Improve symptoms Reduce the risk of acute urinary retention Reduce the risk of the need for surgery including transurethral resection of the prostate (TURP) and prostatectomy.
- PROSCAR administered in combination with the alpha-blocker doxazosin is indicated to reduce the risk of symptomatic progression of BPH (a confirmed ≥4 point increase in American Urological Association (AUA) symptom score).
- Limitations of Use: PROSCAR is not approved for the prevention of prostate cancer.
- Formas y dosis
- 5-mg blue, modified apple-shaped, film-coated tablets, with the code MSD 72 on one side and PROSCAR on the other. 5-mg film-coated tablets.
- Cómo se toma
- PROSCAR may be administered with or without meals.
- Monotherapy: One tablet (5 mg) taken once a day.
- Combination with Doxazosin: One tablet (5 mg) taken once a day in combination with the alpha-blocker doxazosin.
- No debe usarse en caso de
- PROSCAR is contraindicated in the following: Hypersensitivity to any component of this medication.
- Finasteride use is contraindicated in females when they are or may potentially be pregnant.
- Because of the ability of Type II 5α-reductase inhibitors to inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT), finasteride may cause abnormalities of the external genitalia of a male fetus of a pregnant female who receives finasteride.
- If this drug is used during pregnancy, or if pregnancy occurs while taking this drug, the pregnant female should be apprised of the potential hazard to the male fetus. In female rats, low doses of finasteride administered during pregnancy have produced abnormalities of the external genitalia in male offspring.
- Interacciones
- Cytochrome P450-Linked Drug Metabolizing Enzyme System No drug interactions of clinical importance have been identified.
- Finasteride does not appear to affect the cytochrome P450-linked drug metabolizing enzyme system.
- Compounds that have been tested in man have included antipyrine, digoxin, propranolol, theophylline, and warfarin and no clinically meaningful interactions were found. Other Concomitant Therapy Although specific interaction studies were not performed, PROSCAR was concomitantly used in clinical studies with acetaminophen, acetylsalicylic acid, α-blockers, angiotensin-converting enzyme (ACE)...
- Advertencias y precauciones
- PROSCAR reduces serum prostate specific antigen (PSA) levels by approximately 50%.
- However, any confirmed increase in PSA while on PROSCAR may signal the presence of prostate cancer and should be evaluated, even if those values are still within the normal range for men not taking a 5α-reductase inhibitor.
- PROSCAR may increase the risk of high-grade prostate cancer.
- Females should not handle crushed or broken PROSCAR tablets when they are pregnant or may potentially be pregnant due to potential risk to a male fetus.
- Efectos adversos frecuentes
- The drug-related adverse reactions, reported in ≥1% in patients treated with PROSCAR and greater than in patients treated with placebo over a 4-year study are: impotence, decreased libido, decreased volume of ejaculate, breast enlargement, breast tenderness and rash.
- Embarazo
- PROSCAR is contraindicated in pregnant females and not indicated for use in females. Based on animal studies and the mechanism of action, PROSCAR may cause abnormal development of external genitalia in a male fetus if administered to a pregnant female.
- Mecanismo de acción
- The development and enlargement of the prostate gland is dependent on the potent androgen, 5α-dihydrotestosterone (DHT). Type II 5α-reductase metabolizes testosterone to DHT in the prostate gland, liver and skin. DHT induces androgenic effects by binding to androgen receptors in the cell nuclei of these organs.
- Titular de la autorización:
- Organon LLC
- Versión de la ficha:
Las secciones anteriores están citadas de la ficha en inglés, porque es ese documento el que porta la autorización. Cuando una autoridad europea publica la misma información en español, el enlace figura en las fuentes. No traducimos por nuestra cuenta los textos reguladores: un error de traducción en una contraindicación sería más peligroso que una línea en otro idioma.
Esta sección recoge la ficha técnica autorizada. El texto está condensado a partir del resumen de la propia autoridad, y el documento completo figura en las fuentes.
Comparación
Véase también
Preguntas
- ¿El efecto termina al dejar el comprimido?
- La ficha lo aborda directamente: el efecto se mantiene con el uso continuado. Lo que el tratamiento retiene, lo retiene solo mientras se toma.
- ¿Por qué hay un medicamento para la próstata en una página sobre el pelo?
- Porque la finasterida de 1 mg y la de 5 mg son la misma sustancia bajo dos autorizaciones. Aquí aparecen las dos fichas para que se vea qué dosis se autorizó para qué.
- ¿Por qué la ficha advierte sobre el embarazo si la toman hombres?
- Por el efecto de la sustancia sobre un feto masculino en desarrollo: por eso la ficha limita la manipulación de los comprimidos a quien esté o pueda quedarse embarazada. El texto exacto está en el apartado de la ficha, más arriba.
Fuentes
- PROPECIA: prescribing informationDailyMed, US National Library of Medicine. Versión de la ficha 14 de octubre de 2024
- PROSCAR: prescribing informationDailyMed, US National Library of Medicine. Versión de la ficha 18 de marzo de 2026
- Drugs@FDA: NDA020788US Food and Drug Administration
- Drugs@FDA: NDA020180US Food and Drug Administration
En esta categoría
- Minoxidil tópicoEl único tratamiento para la caída del cabello que se vende sin receta, se aplica en el cuero cabelludo y es también el único autorizado para mujeres además de para hombres.
- DutasteridaUn pariente más potente de la finasterida, autorizado para la próstata y recetado fuera de ficha para el pelo en la mayoría de los países.