Another Unnecessary Expensive Drug

[Edward]

如果把xyzal 和 zyrtec 比
可能還成立

但是xyzal 和 atarax 比
應該可以看到她們之間的差異吧
單單嗜睡程度, 口乾舌燥的程度就有差很多

[ceciltcy]

Xyzal我是沒在用，
但是如果患者都像本文作者一樣，
願意使用一天要吃3-4次，每次都昏昏欲睡、口乾舌燥的藥，
那麼這些Long-acting的Anti-histamine就會被自然淘汰。

[poki]

Xyzal我是沒在用，
但是如果患者都像本文作者一樣，
願意使用一天要吃3-4次，每次都昏昏欲睡、口乾舌燥的藥，
那麼這些Long-acting的Anti-histamine就會被自然淘汰。

外國人的評論很多只談事情的某一面向,
xyzal 和 zyrtec qd服用比較方便, 又比較不嗜睡, 完全不提,

不過外國的藥廠真的很奸詐, 藥價爆貴,
專利過期, 又出個slow rease 劑型又來削錢

[robert shi]

Dear Sir:

Levocetirizine can not be compared with hydoxyzine. They are two different type of compound. One is amino-alcohol, the other is amino-carboxylic acid. Chemical property is quite different. Cetirizine is a metabolite of hydroxyzine. Hydroxyzine has an alcoholic group in chemical structure and easily penetrate into central nerve system, causing drowsiness. However the cetirizine has a carboxylic (COOH) group, the alcoholic group in hydroxyzine has been changed to carboxylic acid group. The COOH group will be ionized to carboxylate(COO-) in body biological fluid under pH 7, and the ionized compound is hard to penetrate into central nerve system. So, cetirizine is much weaker in causing drowsiness than hydroxyzine does. Cetirizine is effective and safe and less drowsiness. Recently, this drug had been approved by FDA as an over the counter, non-prescription drug.

Turning (oxidizing) alcohol to carboxylic acid is body's nature response to drug .It is called drug metabolism. If the product of metabolism is also active (most of time is not or less active), then the metabolite might be a better drug. Loratadine turning to desloratadine, terfenadine( an alcohol form) turning to fexofenadine( a carboxylic acid form) and hydroxyzine turning to cetirizine are good examples. In addition, the metabolite bypass the liver metabolism process, avoid the unnecessary advert effect to liver, if any.

Regarding to the levocetirizine comparing to cetirizine, it is not really meaningless. Cetirizine is a 1:1 mixture of dextro form and levo form, called racemate. The levo form is active form. So, at least the dose can be half of cetirizine. The major side effect, drowsiness, will be less, although not half. In addition, levocetirizine avoid the unnecessary adverse effects of dextro form, if any.

In pharmaceutical business, there is a trick called "chiral switch". The company switches the originally marketed racemate mixture into an active form (levo or dextro form) as a new drug in order to occupy the market longer time. Sometimes it shows some benefit, like omeprazole switching to esomeprazole(claimed less interindividual variability) and cetirizine switching to levocetirizine. Some times it doesn’t work, like one of anti-obesity drug fenfluramine switching to dexfenfluramine.


So, in this issue I do not completely agree with what WorstPill claimed.

[wwl2008]

Dear Sir:

Levocetirizine can not be compared with hydoxyzine. They are two different type of compound. One is amino-alcohol, the other is amino-carboxylic acid. Chemical property is quite different. Cetirizine is a metabolite of hydroxyzine. Hydroxyzine has an alcoholic group in chemical structure and easily penetrate into central nerve system, causing drowsiness. However the cetirizine has a carboxylic (COOH) group, the alcoholic group in hydroxyzine has been changed to carboxylic acid group. The COOH group will be ionized to carboxylate(COO-) in body biological fluid under pH 7, and the ionized compound is hard to penetrate into central nerve system. So, cetirizine is much weaker in causing drowsiness than hydroxyzine does. Cetirizine is effective and safe and less drowsiness. Recently, this drug had been approved by FDA as an over the counter, non-prescription drug.

Turning (oxidizing) alcohol to carboxylic acid is body's nature response to drug .It is called drug metabolism. If the product of metabolism is also active (most of time is not or less active), then the metabolite might be a better drug. Loratadine turning to desloratadine, terfenadine( an alcohol form) turning to fexofenadine( a carboxylic acid form) and hydroxyzine turning to cetirizine are good examples. In addition, the metabolite bypass the liver metabolism process, avoid the unnecessary advert effect to liver, if any.

Regarding to the levocetirizine comparing to cetirizine, it is not really meaningless. Cetirizine is a 1:1 mixture of dextro form and levo form, called racemate. The levo form is active form. So, at least the dose can be half of cetirizine. The major side effect, drowsiness, will be less, although not half. In addition, levocetirizine avoid the unnecessary adverse effects of dextro form, if any.

In pharmaceutical business, there is a trick called "chiral switch". The company switches the originally marketed racemate mixture into an active form (levo or dextro form) as a new drug in order to occupy the market longer time. Sometimes it shows some benefit, like omeprazole switching to esomeprazole(claimed less interindividual variability) and cetirizine switching to levocetirizine. Some times it doesn’t work, like one of anti-obesity drug fenfluramine switching to dexfenfluramine.


So, in this issue I do not completely agree with what WorstPill claimed.

+1 很好的解釋。個人服用三週感覺：鼻子：Xy優於Zy 優於Hy，止癢(尤其花粉季的眼睛鼻子或皮膚癢)：Hy優於Xy優於Zy。僅供參考。

[blind faith]

Sorry to be a moron who could not catch your point.

You mean Xyzal (levocetrizine) is no better than Zyrtec (cetrizine) in regard to effectiveness and safety?

But all this discussion here focused on Xyzal causing less side effect, such as drowsiness.

About the price, I just check the Drug Reference to see the price in US

Xyzal (Sanofi) 5 mg: 267.05 USD/ 90# = 2.967/each
Zyrtec (Pfizer) 5 mg: 277.5 USD/ 100# = 2.775/each

So, the pharmacy industry is really evil bastard?

[xkuk]

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