Rx Update: July 2003
Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout,
R.Ph.
Peer Review Status: Internally Reviewed
Approximately 3% of the general population has a hypersensitivity reaction to sulfonamide antimicrobials. Sulfonamide allergic reactions range in severity from relatively mild cutaneous manifestations (e.g., maculopapular rash, fever) to serious and potentially life-threatening reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis, anaphylaxis). These rare but life-threatening allergic reactions make it important to recognize drugs that can cross-react with sulfonamide antibiotics.
A sulfonamide (SO2NH) is a chemical entity characterized by a sulfur dioxide and nitrogen moiety directly linked to a benzene ring. Many medication classes contain this chemical structure. A major difference between sulfonamide antimicrobials and other sulfonamide-containing mediations is the presence of an arylamine (NH2) side chain. This additional side chain may play an important role in the development of hypersensitivity reactions to the sulfonamides.
Generally, patients who state they have a "sulfa" allergy are referring to sulfonamide antimicrobials, such as sulfamethoxazole. Treatment of patients with sulfonamide allergies is particularly challenging because of the large number of sulfonamide-containing compounds available (see below). Fortunately, structural features of individual sulfonamide agents strongly influence the potential for adverse reactions. There is contradictory evidence for cross-sensitivity between sulfonamide antimicrobials and other sulfonamide-derivatives. For patients who have an established allergy to sulfonamide antimicrobials, the risk of cross-allergenicity with other sulfonamide-containing compounds is probably low. However, because additional drug allergies develop more frequently in patients with a preexisting history of drug allergy, patients with a history of an adverse reaction to sulfonamide antibiotics may be more likely to have adverse reactions to other sulfonamide derivatives.
Sulfones (dapsone) have structural similarities to sulfonamides. The incidence of cross-sensitivity between dapsone and sulfamethoxazole ranges from 0 to 55%. Although cross-sensitivity reactions can occur, dapsone is still considered a reasonable option for patients who experience a mild hypersensitivity reaction to sulfamethoxazole.
Sulfites are used in food and drugs as antioxidants (e.g., metabisulfite). Sulfates are used as salts to stabilize drugs (e.g., morphine sulfate, ferrous sulfate). Sulfites and sulfates contain sulfur, but these compounds do not cross-react with sulfonamides.
|
sulfacetamide, sulfadiazine, sulfamethoxazole, sulfapyridine, sulfasalazine, sulfisoxazole, mafenide, co-trimoxazole (sulfamethoxazole/trimethoprim, Bactrim®) Sulfonamide-Derivatives Carbonic Anhydrase Inhibitors: acetazolamide,# brinzolamide,# dorzolamide# Loop Diuretics: bumetanide,# furosemide,# torsemideb Sulfonylureas: acetohexamide, chlorpropamide, glimepiride, glipizide, glyburide, tolazamide, tolbutamide Thiazide Diuretics: chlorothiazide,* chlorthalidone,* hydrochlorothiazide,* indapamide,* metolazone# Miscellaneous: amprenavir,# celecoxib,* diazoxide,d probenecid,* valdecoxib,* zonisamide* |
* Medication that has a contraindication to use
in sulfonamide allergic patients in prescribing information.
# Medication that has a precaution/warning for use
in sulfonamide-allergic patients in prescribing information.
d Medication that has a contraindication to use in
thiazide allergic patients in prescribing information.
b Medication that has a contraindication to use in
sulfonylurea allergic patients in prescribing information.