【简要说明】
   AVODART 的成份为Dutasteride(度他雄胺)，是一种的双重5α-还原酶阻挡剂, 可阻断两种催化睾酮转化产生DHT的5α-还原酶。Dutasteride是2002年10月9日被美国食品药物管理局核准用于治疗前列腺肿大的新药，而针对脱发治疗的临床试验结果还处于等待FDA的核准中。5α-还原酶又分两种类型：第Ⅰ型和第Ⅱ型，5α-Ⅰ型还原酶主要是存在于毛囊基部的外鞘细胞以及基质细胞和毛囊旁边的皮脂腺内；5α-Ⅱ型还原酶主要存在于毛囊基部的内鞘细胞里面。如果只是抑制5α-Ⅱ型还原酶，只能挽救毛囊基部内鞘细胞免于死亡，而Dutasteride (药品名Avodart)则可以同时抑制伤害毛囊细胞组织的5α-Ⅰ型还原酶和5α-Ⅱ型还原酶，同时挽救外鞘细胞以及基质细胞，从而使毛囊得到更加周全的保护，脱发部位也可得到更高程度的恢复,根据国外初步的临床试验，用药六个月后，AVODART新生头发的效果比保法止多三分之一。
【适应症状】前列腺肿大、男性型脱发、脂溢性脱发、遗传性脱发 （女性及儿童切忌服用）
【注意事项】服药期间及停药后6个月之内,请勿捐血,或让女性怀孕。
【包装规格】AVODART (DUTASTERIDE) 0.5MG 30颗×3板￥2300元
                                                           0.5MG 30颗        ￥850元

Avodart – The effective treatment for enlarged prostate

Avodart is specifically designed to help men who suffer from an enlarging prostate gland and the problems associated with this condition. The prostate gland is a walnut-shaped organ that forms part of the male reproductive system. It sits at the base of the bladder with the urethra (the thin tube that allows urine and semen to pass out of the penis) running through it. The prostate gland plays an important role in male sexual function and reproduction. It produces a milky-coloured alkaline fluid that forms about 25-30% of the volume of a man’s semen. The fluid nourishes and transports sperm during ejaculation.

The prostate usually grows during specific periods of a man’s life. The first growth spurt is driven by the sex hormones produced by the testicles during puberty when the prostate doubles in size. Many men also experience a period of prostate growth beginning in their late 40s or 50s. At this time, cells in the central portion of the gland reproduce more rapidly, which results in prostate gland enlargement. The medical term given to this continued enlargement of the prostate gland is Enlarging Prostate or Benign Prostatic Hyperplasia (often referred to as BPH). BPH is very common and the likelihood of developing it increases with age. It is estimated that 50% of men over the age of 50 have BPH with this figure increasing to 90% of men over the age of 80! Prostate gland enlargement is not related to the development of prostate cancer.

BPH varies in severity among men and does not always cause any problems. Only about half the men with BPH experience signs and symptoms that become significant enough for them to seek medical treatment. Because of its position in the male anatomy, an enlarging prostate puts pressure on the urethra. This can cause a whole raft of urinary problems which, in rare cases, may result in the need for prostate surgery, particularly if left untreated (surgery is required in around 4 out every 100 untreated cases). 
Usually the first sign that something is wrong is the development of mild urinary symptoms. Many men may simply dismiss these problems as just being a part of the natural aging process and fail to seek medical help.  However, if left untreated, the prostate may continue to grow which results in worsening urinary symptoms which can impact upon many aspects of a man’s life.

Typical symptoms include:

• Urinating more than twice during the night
• Feeling the need to urinate frequently during the day
• Sudden strong urges to urinate
• Difficulty starting to urinate
• Weak urine stream that may also stop and start
• Difficulty in completely emptying the bladder - this may also cause urine to dribble afterwards

These types of urinary symptoms do not have to be simply part of growing older. Avodart has been proven to help men treat the symptoms of BPH and helps to reduce the risk of needing surgery for an enlarged prostate later in life.

Avodart also reduces the risk of developing acute urinary retention (AUR). AUR is the sudden inability to urinate and requires immediate medical attention if complications such as bladder damage and chronic kidney failure are to be avoided. It is an acutely painful condition producing severe lower abdominal pain and a distended abdomen. AUR is usually symptomatic of another condition that requires treatment. Although both men and women can develop AUR and there are a number of different causes for the condition, in men over 60 BPH is the most common cause.

The exact reason why the prostate should continue to enlarge as men grow older is not yet clear. However, dihydrotestosterone (DHT) is known to be implicated in the development of BPH. Avodart prevents the conversion of testosterone to DHT in the body. The active ingredient in Avodart is dutasteride, which belongs to a class of drugs called 5-alpha-reductase inhibitors. It’s the action of 5-alpha-reductase enzymes that leads to the conversion of testosterone into DHT.

By inhibiting both isoenzymes of 5-alpha-reductase enzymes, Avodart causes the prostate to shrink over time which in turn eases and improves the symptoms of BPH. However, patience is needed as shrinking the prostate cannot be achieved overnight. Although some men notice an improvement in their symptoms within three months, at least six months of treatment is usually necessary for symptom improvement.

Avodart and Hair Loss

Avodart has also proved to be very effective in treating male pattern hair loss on the top of the head and in the mid-scalp area. This is not surprising given that, in an adult male, DHT appears to be the main androgen responsible not only for prostate enlargement, but also for male pattern baldness, the shortening of the growing phase of hair, the progressive miniaturisation of hair follicles and a decline in the number of visible hairs. Avodart significantly reduces or delays this type of hair loss by increasing the number of scalp hairs and helps to fill thin areas on the scalp. It should be noted, however, that results do vary between individuals and, in general, men will not re-grow all the hair that they have lost.

Dosage

Your doctor will prescribe your dosage amount. The usual dosage is 0.5mg daily.

Avodart is sometimes prescribed with another medication called tamsulosin (Flomax).

Side effects

Avodart is generally well tolerated. If side effects are experienced at all, they tend to be mild in nature and usually go away during treatment. The most common side effects are impotence, decreased libido, breast tenderness and breast enlargement (gynecomastia) and a decline in ejaculate volume.

Caution and warnings

Avodart should never be taken, or handled, by a woman or a child. The active ingredient, dutasteride, can be absorbed through the skin, and women or children should not be permitted to handle the capsules. Avodart can cause birth defects if a woman is exposed to it during pregnancy. This is because DHT is responsible for the development of the external genitals in the male foetus. If a woman accidentally comes into contact with this medication from a leaking capsule, wash the area with soap and water right away.

Blood should not be donated whilst taking Avodart and for at least 6 months after treatment has ended. Avodart can be carried in the blood and could cause birth defects if a pregnant woman received a transfusion with blood that contained Avodart.

Avodart (Dutasteride) Results

Scientists have evaluated the effectiveness of Avodart at different daily dosage, ranging from 0.01 mg, 0.05 mg, 0.5 mg, 2.5 mg, and 5.0 mg per day. It was found that the highest suppression of DHT was achieved with 2.5 mg or 5.0 mg per day. At a daily dosage of 2.5 mg or 5.0 mg, Avodart suppresses 99% of the DHT whereas 5.0 mg daily dosage of Finasteride only blocking 70% of the DHT. According to information provided by GlaxoSmithKline, the level of DHT suppression does not seem to different significantly between 2.5 mg and 5.0 mg. The daily dose of 0.5 mg (recommended starting dose of Avodart), DHT inhibiton is 90%.

A comparative phase II evaluation of dutasteride and finasteride in a double-blind placebo-controlled trial clearly demonstrates that serum dihydrotestosterone (DHT) suppression is significantly greater with dutasteride (0.5 mg daily) than with finasteride (5 mg daily).

Before treatment with Avodart	After 6 months with Avodart
		In the first 6 months of the study 90% experienced visibly more hair. After six months of treatment, the hair counts measured in a 1 inch diameter circle increased by about 96 hairs with 0.5mg Avodart, compared to about 72 hairs with 5mg Finasteride Dutasteride (0.5 mg daily) has been shown to decrease levels of DHT with 90%, about 30% more than Propecia.

2002年10月9日有一种被美国食品药物管理局核准用於治疗摄护腺肥大的新药Dutasteride(药品名为AVODART)，该药已经於2002年11月底在美国上市，也可能於不久的将来正式核准使用於雄性秃的治疗。到底这种药的效果怎麼样呢？它和保法止比较起来如何？有没有什麼副作用？
　 雄性秃的主要原因是秃发部位的毛囊裡面DHT(二氢睪固酮)【註:DHT是一种雄性荷尔蒙的衍生物,作用的强度为雄性荷尔蒙的五倍】含量太高所起，而DHT的浓度太高主要是因为这些毛囊裡面的5α还原酵素浓度太高的缘故；5α还原酵素的主要功能是将雄性贺尔蒙代谢变成DHT，5α还原酵素的浓度太高导致DHT的產量也太高，根据莎瓦雅(Sawaya)最近有关毛囊分子生化学的研究，毛囊内DHT的浓度太高，会造成毛囊基部细胞内bax蛋白及Caspases 3蛋白酵素的连锁性毁灭作用被活化【註：Caspases 3蛋白酵素是一种细胞内的恐怖杀手, 它一旦被诱发作用，就可以肆无忌惮的直接或间接把细胞核内的DNA切碎、破坏细胞核、崩解细胞膜；Bax蛋白则是Caspases 3 的前导帮兇】，最后导致毛囊基部细胞凋亡(apoptosis)的数目增加，毛囊逐渐变小甚至死亡。

　 5α还原酵素又分两种类型：第一型及第二型。根据一九九五年淮廷(Whiting)及艾契勒(Eicheler)的报告，第一型主要是存在於毛囊基部的外鞘细胞以及基质细胞和毛囊旁边的皮脂腺内；第二型5α还原酵素主要存在於毛囊基部的内鞘细胞裡面。Finasteride (保法止)只能抑制第二型5α还原酵素，亦即挽救毛囊基部内鞘细胞免於死亡，而Dutasteride (药品名AVODART)则可以同时抑制含有第一型的5α还原酵素，同时挽救外鞘细胞以及基质细胞。据一些研究报告，Finasteride服用六个月左右可以减少DHT浓度百分之七十六。而据莎瓦雅(Sawaya)的报告每天服用0.5毫克的Dutasteride，持续六个月，可以减少DHT的浓度百分之九十四。若以增加的发量来比较，结果发现地中海雄性秃直径1英吋的圆圈范围(约五平方公分)内可以增加96根头发(註:正常人头发五平方公分约有650至750根)，而每天服用Finasteride持续六个月的效果只有增加72根毛发。此外，Dutasteride对位於头顶部位的地中海秃的生发效果比较好。

　 在副作用方面，根据2002年10月美国德州大学Roehrborn教授两年的研究报告,发现每天服用Dutasteride 0.5毫克,会引起阳萎的比例是4.7%、性慾减退 3.0%、男性女乳症0.5%、射精困难1.4%。其副作用发生的机率比保法止高。但是其中大部分都是暂时性的，且发生的机率随服用期的增长而减少。

　 此外，Roehrborn教授建议， Dutasteride的服用者不要捐血给孕妇；如果要捐的话，也要在停药后半年才可以，因为Dutasteride停药之后4至6个月在血液中还可以测出其浓度，孕妇接受这种血液可能造成男性胎儿生殖器发育畸形。有肝机能问题者，也建议不要使用. 据Glaxosmithkline药厂的报告,Avodart 预定2003年1月3日在美国上市 。(註：美国FDA目前对AVODART用於治疗雄性秃发是採取负面表列使用)

　 据莫斯科医科大学的Konstantinova教授2001年6月的报告，雄性秃发时间超过30个月，可能会造成毛囊无法回復的伤害，因此雄性秃的早期治疗是非常重要的，一但有掉发的现象出现就须考虑药物治疗。韩国仁荷大学最近的研究也显示，合併使用口服Finasteride(保法止)和外用Minoxidil(落建)生发水的生发效果，要比单独使用其中一种好。由於不明原因，目前的治疗药物只对地中海秃的效果较好，前额秃较差。然而目前的这些药物一个很确定的作用是让那些还属於早期伤害的毛囊可以免於进一步受损而恢復生机，不会继续恶化掉发。

　 对於已经有很明显的雄性秃头而且使用药物之后仍无法有效长出头发的患者而言，如果想要改变现状，以组合疗法，也就是口服Finasteride(保法止)或外用Minoxidil(落建)生发水，加上自体毛囊单位移植术，是目前最有效的治疗方式。这种组合疗法的好处是药物可维持秃发部位残餘毛囊的生机，同时，密集植入健康毛囊，使秃发患者只施行一次植发手术即可有明显的新毛发持续不断的生长，雄性秃因而得到根本的改善。

注意

根据GSK的研究结果 5mg finasteride(保法止的主成分)阻挡了 70% of DHT,(一般的日用量为1mg), 0.5mg的 dutasteride阻挡了92%的DHT

换言之 一天吃五颗保法止(或 一颗波斯卡的)的效果 还比部上每日 0.5mg的 dutasteride(一颗AVODART).

注意事项:服药期间及停药后6个月之内,请勿捐血,或让女性怀孕
【包装规格】AVODART (DUTASTERIDE) 0.5MG 90颗(三盒装)
AVODART (DUTASTERIDE) 0.5MG 30颗(一盒装)
【使用方法】见包装使用说明