以前拼高中/大學聯考, 每天只勉強睡到六小時. 要是持續兩天只睡四小時就一定會引發劇烈的偏頭痛.

http://en.wikipedia.org/wiki/Cafergot

Mechanism of action
The causes of migraine are not fully understood, but dilation of blood vessels in the brain may play a part in causing the headache pain. Ergotamine tartrate and caffeine both are vasoconstrictors, substances which act to constrict blood vessels.
偏頭痛的肇因仍未能完全理解, 但是在頭痛的起因上, 腦部血管(不正常)擴張可能扮演重要的角色. (Ergotamine taratrate) 酒石酸麥角胺和 (caffeine) 咖啡因這兩種化合物都是血管收縮劑, 能收縮血管.

Adverse effects
Because the vasoconstrictive effects of ergotamine and caffeine are not selective for the brain, adverse effects due to systemic vasoconstiction can occur. Cold feet or hands, angina pectoris or dizziness are some examples.
擷抗(反)效果
由於(Ergotamine taratrate) 酒石酸麥角胺和 (caffeine) 咖啡因是非選擇性(全面性/系統性)的血管收縮劑, 並非只有腦部血管收縮, 可能會發生 [全面/系統性的血管收縮] 所導致的反效果. 例如手腳發冷(末梢微血管過度收縮引起的血液循環不良), 舉例而言: 心臟供血(供氧)不足導致的劇烈胸痛或是暈眩.

P.S. 長期使用麥角胺的嚴重後果請參照 "St. Anthony's fire" 聖安東尼之火 (發病徵狀和烏腳病極為類似)

Ergotamine, if used frequently over a prolonged period of time, can cause dependence in the patient. If dependence occurs then cessation of ergotamine use can precipitate the same headaches which the drug was being used to treat. For this reason frequency of use must be restricted.

http://en.wikipedia.org/wiki/Imigran
Approval and availability

Several dosage forms for sumatriptan have been approved, including tablets, solution for injection, and nasal inhalers. Sumatriptan was the first triptan available (in 1991), and, in the United States and most developed countries, is available only by medical prescription. In the United Kingdom, sumatriptan is available over the counter, under the name of Imigran Recovery. It is sold in packs of two 50mg tablets for approximately £7.99 (about $15 US). Larger pack sizes, the nasal spray, and the liquid preparation for injection are still only available by prescription. Originally covered by UK Patent GB2162522, extended by supplementary protection certificate SPC/GB93/071, protection in the UK (as well as the rest of Europe), expired on 16 May 2006. Through patent litigation, Glaxo was able to extend their US patent considerably beyond this date. However, as the result of a lawsuit by the maker of a generic version of the injectable version of Imitrex, a settlement should allow this generic to come to the market in the US in August of 2008.
(Glaxo) 葛蘭素對Imigran的專利在 2006年5月16日過期. 經由專利訴訟的方式, (Glaxo) 葛蘭素延長美國專利有效期限. 由俗名藥廠發動的法律訴訟, 導致(非葛蘭素原廠生產的) 注射劑型 Imigran 應該可以在 2008 年 8 月之後在美國上市.

P.S. 買原廠藥付的錢主要用於****行銷 (根據 ACS 的研究報告, 大約 40% 的藥價被藥廠的業代拿來以各式各樣的方法 -- [教育/招待] 寫處方簽的醫師, 只有 10% 是真正用在研發/臨床試驗, 5% 用在生產製造包裝, 剩下 45% 中大部分進了藥廠高層的口袋 ) 別和自己錢包作對, 買俗名藥即可!

Mode of action
Often, serotonin levels in the brain become extremely erratic before the onset of a migraine. In an attempt to stabilize this, sumatriptan is administered to help aid in leveling the serotonin levels in the brain. Sumatriptan is structurally similar to serotonin, and is a 5-HT (5-HT1D) agonist, which is one of the receptors that serotonin binds to. The specific receptor subtype it activates is present in the cranial and basilar arteries. Activation of these receptors causes vasoconstriction of those dilated arteries. Sumatriptan is also shown to decrease the activity of the trigeminal nerve, which probably accounts for Sumatriptan's efficacy in treating cluster headaches. The injectable form of the drug has been shown to abort a cluster headache within fifteen minutes in 96% of cases.[1] This type of headache is extremely painful and debilitating, and sumatriptan injection is currently the only truly effective acute treatment.