Tuesday, November 27, 2007

How Do Drug Work - NEW Non Sedating Antihistamine

Hello Everyone,

On a previous post I wrote about Zyrtec (cetirizine) now being available over the counter (OTC).
There is now another non sedating antihistamine on the market.

YXZLAR (levocetirizine) was approved by the Food and Drug Administration (FDA) as a once-daily prescription antihistamine. It is classified as a non sedating antihistamine and indicated for the the relief of symptoms associated with seasonal or perennial allergic symptoms. It is also indicated for non complicated skin allergies. When a drug is INDICATED for a certain condition, that means that the FDA has approved that drug for that specific use.

The most common side effects of Xyzlar in adults were drowsiness, fatigue and dry mouth.

Here is an interesting medication phenomenon. See if you can see any similarities here.



Are they the same drug? No, not exactly. On a molecular level, in the world on medicinal chemistry, levocetirizine is an ENANTIOMER of cetirizine. More specifically, it is the active R-enantiomer. Think of your left hand as being an enatiomer of your right hand. They are the same, but reversed. Being the active enantiomer means that it is the levocetirizine molecule that actually provides the antihistmine effects.If anyone would like more information on the specifics of stereo-chemistry, please email me.

Anyway, I got carried away there.

So, if your allergy symptoms are being well controlled by Zyrtec (cetirizine) and since it is now over the counter (OTC), you may want to look for a prescription product. XYZLAR may be a good candidate to ask your physician about.

Thanks for your interest,

Dr. Paul

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