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Dr. Bob is Robert Hsiung, MD,
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Posted by djmmm on February 3, 2007, at 16:52:21
Follow-on Drugs: Therapeutic Benefit or Economic Burden?
full article:
When a drug patent approaches expiration, manufacturers may market a metabolite, isomer, or new salt form of the original drug to retain their market share. These new versions of old drugs are sometimes called "follow-on" drugs.
Many drugs are marketed as mixtures (usually 50:50) of two drug isomers. For example, Celexa is a mixture of S-citalopram (Lexapro) and R-citalopram. Isomers look identical, except that they are mirror images of each other (like a left and right shoe). Isomers can differ in efficacy, adverse effects, or drug interactions. One isomer may even antagonize the effect of the other. Therefore, a single isomer product may provide a therapeutic advantage over the mixture.1
Follow-on drugs may also be active metabolites of other drugs. For example, desloratadine (Clarinex) is the primary active metabolite of loratadine (Claritin, Alavert).2
Follow-on drugs are relatively easy to market. Prescribers have, in essence, already been prescribing the new drug for years, so they are familiar with it. And a lot of data already exists for the follow-on drug, so approval is relatively quick and inexpensive.3
Some follow-on drugs offer an advantage over the original product in terms of safety, efficacy, or pharmacokinetics. However, the advantage may be small and prescribers and patients may not deem it worth the extra cost.
SEE chart here:
Follow-on drugs: therapeutic benefit or economic burden? Pharmacist's Letter/Prescriber's Letter 2007;23(2):230201.
Posted by Phillipa on February 3, 2007, at 17:27:25
In reply to article on Marketing drug metabolites/isomers..., posted by djmmm on February 3, 2007, at 16:52:21
Can't believe how expensive resperidol is wow!!!!Love Phillipa
This is the end of the thread.
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