I suppose the patent of terfenadine is expiring soon. The market, if
anything, is expanding for drugs in that cateory. If I were the
manufacturer of terfenadine and had a similar product (fexofenadine) in
the pipeline, I would have tried to discredit terfenadine and make it
disappear from the market. Best of all would be if I could make a
regulatory authority do it for me. In this way there will be no generic
competition for the new, and most likely considerably higher priced
product, fexofenadine.
This trick with antihistamines really began with hydroxyzine
(Atarax (ucb, or Searle). This drug has been on the market for
decades. It has a long-lived metabolite which must be taken
into account in designing the drug washout period prior to allergy
testing.
This metabolite now is a best-selling antihistamine called cetirizine
(Zyrtec). There's really nothing new about it. It must be due to some
flaw in the patent legislation that the manufacturer was granted a
patent for this product. But it seems true that the metabolite is
less sedating than hydroxyzine, which has been used as a sedative
more than as an anti-allergic drug.
Now the manufacturers of terfenadine try to repeat the success - but
with the help of the FDA and a number of other regulatory agencies
by removing the parent drug for safety reasons.
Arrythmias are really dangerous when they occur, I have no doubt about
that - but this danger can be minimised by sensible labelling, and by
never granting terfenadine OTC status. Keep it away from people with
hepatic cirrhosis, keep the doses within the recommended range, and
beware of interactions!
By following the FDA in this case one does not work so much for
drug safety, really, but more for the successful marketing of another
me-too-metabolite, fexofenadine.
Another element to consider, is the fixed combination of antihistmines
with norephedrine or pseudoephedrine. I know these products are popular
in the USA and elsewhere. In Norway we managed to remove this type of
combinations from the market some years ago. I wonder for how long.
If the combination is really needed, the components could easily be
taken separately.
Gaut Gadeholt
National Insurance Administration
Oslo, Norway
E-mail: gaut@online.no
--
Send mail for the `E-Drug' conference to `e-drug@usa.healthnet.org'.
Mail administrative requests to `majordomo@usa.healthnet.org'.
For additional assistance, send mail to: `owner-e-drug@usa.healthnet.org'.