快樂小藥師 Im pharmacist nichts glücklich

Zithromax（Azithromycin）這個算是很強效的巨環類抗生素

如果你想要複習一下機轉，可以參考這邊：點我

這個藥物其實已經用好久了，從最古早的膠囊，到後來的錠劑，緩釋錠劑還有懸液劑，不過有時候，你卻會聽到醫師或是藥師跟你說，吃Zithromax時要空腹，甚至要空腹半小時，真的有需要這樣嗎？

根據仿單描述：

I.V.: Infusate concentration and rate of infusion for azithromycin for injection should be either 1 mg/mL over 3 hours or 2 mg/mL over 1 hour. Other medications should not be infused simultaneously through the same I.V. line.

Ophthalmic: Shake bottle once prior to each administration. Wash hands before and after instillation.

Oral: Immediate release suspension and tablet may be taken without regard to food; extended release suspension should be taken on an empty stomach (at least 1 hour before or 2 hours following a meal), within 12 hours of reconstitution. 

除非你是服用緩釋懸液劑，不過台灣沒有賣，所以並沒有必要空腹服用

甚至，廠商的病患衛教區裡面，還有說到：

Take this medicine with or without food. Take with food if it causes an upset stomach.
（服藥時可以空腹也可以與食物並用，不過如果你服藥會引起腸胃不適，建議可以與食物並用）

又或者你是管灌病患，廠商也有說明：

Stop tube feeding for 2 hours before giving this medicine. Restart tube feeding 1 hour after giving.

不過這段說明是針對懸液劑的，因為本身Zithromax是不建議磨粉的（所以才推出懸液劑呀）

可是為何會有要空腹服用的說明呢？因為以前是膠囊的劑型，根據實驗，膠囊劑型的zithromax會因為食物影響吸收，所以才叫病患空腹，但是一來膠囊已經停產了

二來，錠劑等新劑型並不需要空腹，所以就不需要再提醒病患空腹服用了。

如果你覺得這樣還不夠，那就繼續看下去：

我們從藥物動力學的角度來解釋：

Micromedex綱要裡面就寫了：

Effects of food: minimal, no effect on AUC

接著我們看細項：

Effects of Food

1)  Oral suspension and tablets may be taken with or without food (Prod Info Zithromax(R), 2004; Simicevic et al, 1998). Bioavailability decreased with capsules (Drew & Gallis, 1992b; Hopkins, 1991c), which is not available in the U.S.

a)  The presence of food in the gastrointestinal tract may reduce the bioavailability of azithromycin CAPSULES by 50% (Drew & Gallis, 1992b; Hopkins, 1991c). Capsules should be taken at least 1 hour before or 2 hours after eating.
b)  The oral tablets may be taken with or without food. However, when a 500 mg dose (2 x 250 mg tablets) was administered with food, the peak concentration increased by 23%. There was no change in the area under the curve (Prod Info Zithromax(R), 2004).
c)  The oral suspension may be taken with or without food. However, when azithromycin suspension was administered with food to 28 healthy, adult males, the peak concentration increased by 56%. There was no effect on the area under the curve (Prod Info Zithromax(R), 2004).
d)  A high-fat meal does not significantly affect the bioavailability of the oral, 500-mg tablet. The peak concentration and area under the time-concentration curve for azithromycin is not significantly (p greater 0.05) altered by a high-fat meal; however, the time to peak concentration was slightly delayed (p less than 0.05) (Simicevic et al, 1998).

2)  Oral, extended-release suspension should be taken on an empty stomach (at least 1 hour before or 2 hours following a meal) (Prod Info Zmax extended-release oral suspension, 2005).

a)  Compared with the fasting state, a high-fat meal increased the mean azithromycin Cmax by 115% and the mean AUC by 23% and a standard-meal increased the mean Cmax by 119% and the mean AUC by 12% (Prod Info Zmax extended-release oral suspension, 2005).

最後我們還有一個問題要解決：zithromax磨粉以後，要空腹嗎？

這個問題在文獻中沒有解答，所以我直接問了輝瑞的開發人員：

答案是：不用，因為從膠囊到錠劑，不是只有劑型的改變，賦型劑也變了，所以現在不管你有沒有磨粉，都不需要空腹。（至於賦型劑是什麼，就是商業機密，別逼他們了）