性功能障礙治療藥物的現況

Current Medical Treatment for Sexual Dysfunctions

性功能障礙的定義為無法達到且維持足夠令人滿意的性交過程。當性刺激發生時會釋放一氧化氮進入陰莖的平滑肌中，此時抑制第五型的磷酸二脂酶可以提升龜頭、陰莖海綿體中的cGMP濃度，進而增加平滑肌的放鬆與勃起的完整度。有勃起困難的病患常會併有潛在性的心臟病變，在使用第五型磷酸二脂酶抑制劑，尤其與硝酸鹽併用時會導致嚴重的低血壓及多種嚴重的心血管副作用。另外，第五型磷酸二脂酶抑制劑也會因部分抑制到第六型磷酸二脂酶而導致眼睛的副作用。從用來治療巴金森氏症的老藥Uprima目前因為可以提昇性慾且可以讓不能使用硝酸鹽類的病患受惠而被用來治療勃起障礙。Uprima不同於其他的PDE5抑制劑直接作用，而是從下丘腦直接增加訊號的傳遞。Aprostadil則比威而剛更早作為勃起困難的治療劑但卻因為不方便使用而退為後線療法。Intrinsa則經皮穿透貼片是針對雙測卵巢切除及子宮切除後停經且併用雌性素療法的女性的性慾低落症所設計的藥物。性功能障礙的治療不能只依賴藥物，且更需要伴侶之間的良性溝通與積極互動。

Pharmacy Department ,Chung-Kang Branch,Cheng Ching Hospital Erectile dysfunction (ED) is defined as the inability to achieve and maintain an erection in order to perform satisfactory sexual intercourse. When sexual stimulation releases nitric oxide into the penile smooth muscle, inhibition of phosphodiesterase type 5 (PDE 5) causes a marked elevation of cyclic guanosine monophosphate (cGMP) concentrations in the glans penis, corpus cavernosum, and corpus spongiosum. This increases smooth-muscle relaxation and produces an erection. The most popular drugs to treat ED are PDE 5 inhibitors. These include sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis). Tadalafl has the longest half-life and is effective for a longer period of time after ingestion. The cardiovascular adverse side-effects of PDE5 inhibitors are important because of the frequent presence of underlying cardiac disease in men with ED. When PDE 5 inhibitors are combined with nitrates, severe cardiac events such as hypotension have been reported. PDE5 inhibitors which have a partial effect on PDE6 may also cause visual disturbances. Apomorphine (Uprima®), an old drug to treat Parkinson’s disease, is now used to increase libido in men treated with nitrates. Uprima® has a different effect from PDE5 inhibitors as it acts upon receptors in the hypothalamus and can enhance erection by increasing the signals from the brain to begin the process. Alprostadil was available for the treatment for ED years before sildenafil (Viagra® ), but the delivery method (intracavernous injection or intraurethral suppository) makes it unpopular as a first line treatment at present. The use of a testosterone (Intrisna®) transdermal patch is indicated in the treatment of hypoactive sexual desire disorder (HSDD) in bilaterally oophorectomised and hysterectomised (surgically induced menopausal) women receiving concomitant estrogen therapy. Some studies suggest that sildenafil may also be helpful to these women. There are many drug therapies (including hormone replacement), but these treatments of sex dysfunction require good communication and positive interaction between couples for them to be successful.