Usefulness of intradermal test and patch test in the diagnosis of nonimmediate reactions to metamizol.
BACKGROUND
Metamizole is a pyrazolone derivative, and its most common reactions are IgE-mediated reaction and idiosyncratic reactions. Non-immediate reactions are poorly described and there are very few reports on non-immediate reactions to pyrazolones.


METHODS
We evaluated 12 patients (nine men) who consulted for a non-immediate reaction after metamizol administration. We performed cutaneous tests (skin prick tests and immediate and delayed intradermal tests) and epicutaneous tests, and, if necessary, an oral challenge test.


RESULTS
All skin prick and intradermal tests, if necessary, were negative in immediate reading. Delayed intradermal tests were positive in six of 10 patients (60%) and epicutaneous tests were positive in four of 11 patients (36%). Three cases (25%), were diagnosed by a positive oral challenge test.


CONCLUSIONS
Delayed-reading intradermal tests and patch tests are useful tools in the diagnosis of nonimmediate reactions to pyrazolones and should be considered the first step when evaluating these type of reactions. Intradermal test appears to be more sensitive than patch test. The positivity of skin tests suggests an immunological reaction, probably mediated by T lymphocytes, but further studies are required.
Macías
E
E
Immunoallergy Service, University Hospital of Salamanca, Salamanca, Spain.
Ruiz
A
A
Moreno
E
E
Laffond
E
E
Dávila
I
I
Lorente
F
F
D000328:Adult; D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D004177:Dipyrone / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000175:diagnosis* / Q000276:immunology; D007428:Intradermal Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000379:methods*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004177:Dipyrone