We all remember the drug Seldane. It was an anti-histamine used for allergies and allergic conditions. The drug was pulled off the market in 1998 because of potential life threatening reactions. Basically, drink a glass of grapefruit juice, pop a Seldane, go cut some grass and your life could end. The generic name for Seldane is Terfenidine. The parent drug Terfenidine had a first metabolite that was also effective for allergies but did not have the drug interaction problem like Terfenidine. It was called Nor-Terfenidine. The drug manufacturer of Seldane didn't want to lose all of their revenue from the drug when it was pulled off the market so they decided to market the first metabolite Nor-Terfenidine for allergies. There was such a negative stigma towards Terfenidine that they couldn't market that drug as Nor-Terfenidine, they had to go another route. They opted to change the name of the metabolite to Fexofenadine. This is how the drug Allegra was created. It's the first metabolite of Terfenidine. And now you know the rest of the story.
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