英文药名: Propecia(Finasteride Tablets)

中文药名: 保法止（非那雄胺片）

品牌药生产厂家: Merck & Co. Inc.

保法止（非那雄胺片）：简介

本品适用于治疗男性秃发（雄激素性秃发），能促进头发生长并防止继续脱发。主要成分及其化学名称：非那雄胺，其化学名称为N-（1，1-二甲基乙基）-3-氧-4-氮杂-5α-甾-1-烯-17β-酰胺.

作用机理

非那雄胺是一种合成的甾体类化合物，它是雄激素睾酮代谢成为双氢睾酮过程中的细胞内酶Ⅱ型5α-还原酶的特异性抑制剂。非那雄胺对雄激素受体没有亲和力，也没有雄激素样、抗雄激素样、雌激素样、抗雌激素样或促孕作用。对该酶的抑制能阻碍外周组织中睾酮向雄激素双氢睾酮的转化，使血清及组织中双氢睾酮浓度显著下降。与安慰剂相比，可使血循环中睾酮的水平升高约10%-15%，但仍在生理范围内。非那雄胺能使血清中双氢睾酮浓度迅速下降，在给药后24小时内使之显著减少。

适应症

保法止适用于治疗男性秃发（雄激素性秃发），能促进头发生长并防止继续脱发。保法止不适用于妇女（参见孕妇和临床研究部分）和儿童。

用法用量

推荐剂量为每天1次，1次1片（1mg），可与或不与食物同服。一般在连续用药三个月或更长时间才能观察到头发生长增加，头发数目增加和/或防止继续脱发的效果。建议持续用药以取得最大疗效，停止用药后疗效可在12个月内发生逆转。

不良反应

保法止一般耐受性良好，副作用通常轻微，一般不必中止治疗。上市后报告的不良事件如下：射精异常、乳房触痛和肿大、过敏反应（包括皮疹、瘙痒、荨麻疹和口唇肿胀）和睾丸疼痛。
禁忌症

止禁用于：

孕妇或可能怀孕的妇女
对本品任何成分过敏者
不适用于妇女和儿童
注意事项

在对18至41岁男性进行的临床研究中，应用本品12个月后血清前列腺特异抗原（PSA）从0.7ng/ml的基础水平降至0.5ng/ml。本品在用于治疗患有良性前列腺增生（BPH）的老男年性秃发病人时必须考虑到前列腺特异性抗原水平会降低约50％。
药物相互作用

临床尚未发现重要的药物相互作用。非那雄胺不影响与细胞色素P450有关的药物代谢酶系。已在男性中研究过的药物包括安替比林、地高辛、优降糖、普奈洛尔、茶碱和华法令，未发现相互作用。虽然尚未进行专门的相互作用研究，但在临床研究中，将1mg或大于1mg剂量的非那雄胺与血管紧张素转化酶抑制剂、对乙酰氨基酚、α受体阻断剂、苯二氮卓类、β受体阻断剂、钙通道阻滞剂、硝酸酯类、利尿剂、H2受体拮抗剂、β-羟基-β-甲基戊二酸单酰辅酶A还原酶抑制剂、前列腺素合成酶抑制剂及喹诺酮类合用，均未见重要的不良相互作用。
药物过量

临床研究中非那雄胺单次剂量达400mg或多次服药，每天总量达80mg，连续用药三个月，均未产生副作用。保法止过量时无推荐的特效治疗措施。
Propecia (finasteride) was the first approved male pattern baldness treatment. It remains the most effective; clinical trials have shown that the active ingredient finasteride stopped hair loss in over 90% of men, and a further two-thirds actually saw some hair growth.

Propecia has been an established hair loss medication since 1997 and has been put under many clinical studies, including some that lasted five years. It’s a well known and understood medication that can help you see your hair grow back.

Most men will see the benefits of this treatment within three to six months of using it, with their hair loss being reduced and even some hair growing back. After nine months of using Propecia (finasteride), you can expect to be maintaining the amount of hair you have, and you could possibly see a regrowth.

How does it work?
The active ingredient in Propecia is finasteride. This is a 5-alpha reductase inhibitor, and it works to stop the process that stops your hair from re-growing.

Male pattern baldness is caused by testosterone breaking down in your body. It’s a natural process that happens in every male - it’s what gives you masculine characteristics - but some men have a markedly increased sensitivity to the product of this process, which causes hair loss.

This process creates what is known as DHT, dihydrotestosterone, which makes the hair follicle smaller and reduces the size of the hair root. This means the new hair that grows through will be much thinner. When this hair is shed, the root becomes a little thinner again. It’s a process that repeats until the hair follicle is so small that hair can’t grow out of it.

Finasteride works to stop the action of DHT, preventing the follicles from minimising so hair can still grow.

Who can take it?
Men suffering from male pattern baldness can take Propecia (finasteride), but there are certain conditions which may prevent you from being able to buy this medication. These can include active or historical liver disease, prostate cancer and bladder muscle disorder, for example.

This medication should never be taken by women or children.

How do you take Propecia?
You should take Propecia exactly as prescribed by your doctor. You need to take the medication with a full glass of water, but it can be taken with or without food.

You need to use this medication regularly to experience the effect. If you stop using it, the finasteride will leave your system and any benefits you have seen are likely to disappear.

Are there any side effects?
There is always a risk of developing side effects when you use prescription medication. The more commonly reported side effects that are caused by finasteride include swelling in the hands and feet; pain in the testicles; abnormal ejaculation; dizziness, headaches and skin rashes; and impotence, reduced libido or difficulty having an orgasm.