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Qsymia: One Pill or Two?

Qsymia, one pill that combines phentermine (PHEN) and topiramate in an extended release formulation (TPM-ER), raises a question for doctors and pharmacists who have a preference for generic drugs. Can’t we just use generic phentermine or topiramate pills and get the same effect?

Well, not exactly. First of all, a new study published for early view online in Obesity shows that the combination product, Qsymia, works better than even higher doses of phentermine or topiramate individually. Specifically, the combination of PHEN 7.5mg and and TPM-ER 46mg was more effective than either PHEN or TPM-ER by themselves, even at twice the dose used in the combination.

The next question is invariably, why not mix and match with the generic forms of PHEN and TPM-ER? And the short answer is that you can’t get the same dosage forms. Generic phentermine is only available in 15mg and 30mg strengths. Extended-release topiramate is not available in a generic form. For that matter, even in a recently approved branded form (Trokendi XR), it’s not yet widely available. And when it is available, the dosage strengths will be different.

So, long story short, the combination of drugs in Qsymia works better than the individual components of it by themselves. And there’s no generic equivalent available.

Click here to read the new study in Obesity by Aronne et al.

One, photograph © ISOtob / flickr

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