Summary
Zyrtec (cetirizine) is a second generation nonsedating antihistamine that has enjoyed wide popularity. Zyrtec will become available generically in late 2007 and the generic form is expected to be significantly cheaper. To virtually extend the patent, the manufacturer is marketing the active enantiomer, levocitirizine (Xyzal) as a replacement for Zyrtec. This required only a fraction of the R&D costs that developing a new drug would entail. While this could be a boon to the pharmaceutical companies involved in the release, patients have little to benefit from the increased cost.
Analysis
This is only one of the tricks pharmaceutical companies have come up with to prolong their patents without giving patients more for their money.
This is exactly what happened in 1990 when the "purple pill" Prilosec went off patent. We now have a new "purple pill" esomeprazole (Nexium) which does exactly the same thing for a lot more money. See this link for more info
http://en.wikipedia.org/wiki/Omeprazole
Another favorite trick is to combine 2 effective medications about to go off patent into 1 tablet to prolong the patent at a much greater cost than the 2 medications individually.
Xyzal (levocetirizine) is the active R-enantiomer of cetirizine (Zyrtec). The present formulation also contains the inactice enantiomer in equal proportions. This is not truely a new drug and is expected to be no more effective than Zyrtec and much more expensive.
