Sulfonylureas and Sulfa allergy

[Robert Marshall <marshalr@OHSU.EDU>]

>From a Diabetes Newsletter distributed on the internet:
<snip>
> - -  Diabetes Q and A:
>      . What Are Diabetes Medications?
<snip>
> There are four major categories of oral hypoglycemics- sulfonylureas, 
> which are derived from sulfa drugs; and ...

In regards to Sulfonylureas being "derived from "sulfa  drugs" 
certainly they are derived from sulfonamides, and the chemical structure 
of each shown in the PDR and Goodman and Gillman contains an SO2 group 
tucked in the middle, but is this of clinical relevance?  This question 
came up when Celebrex was introduced.  A drug rep here for an older NSAID 
was bad-mouthing Celebrex saying its warnings regarding use in patients 
with sulfa allergy meant it could also not be used with sulfonylureas 
(this borderline unscrupulous rep was also using that erroneous NY Times 
article regarding MI's and ulcers in patients taking Celebrex to convince 
us not to use it).  But a Medline search revealed no case reports of 
sulfa-type allergic reaction, anaphylaxis, Stevens-Johnson Syndrome, 
TEN, etc with sulfonylureas.  The PDR and Drug Facts and Comparisons don't 
even mention sulfasensitivity or allergy as a contrandication or even a 
concern in the monographs for the sulfonylureas.  None of my colleagues 
could even remember ever being told in Med School, Residency, etc to even 
ask diabetics about allergy to sulfa before prescribing a sulfonylurea. 
(Do pharmacists ask about sulfa allergy before dispensing an Rx for 
Glipizide?)  Is there any reason to lump sulfonylureas with "sulfa drugs" 
in the sense of it being something to be concerned with in someone with 
allergy to sulfa?

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> End of Diabetes Digest V99 #100
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------------------------------
Robert Marshall, MD