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Type IV allergy to amide-type local anesthetics
Contact Dermatitis
|July 1, 1991
Summary
A woman experienced severe itching and redness after a local anesthetic injection. This reaction was a delayed-type hypersensitivity to mepivacaine, confirmed by patch testing.
Area of Science:
- Dermatology
- Allergology
- Pharmacology
Background:
- Local anesthetics are widely used in medical procedures.
- Hypersensitivity reactions to local anesthetics, though rare, can occur.
- Delayed-type hypersensitivity is a T-cell mediated immune response.
Observation:
- A 45-year-old woman presented with intense erythema and itching.
- The reaction began 1 day after subcutaneous injection of a local anesthetic.
- The anesthetic contained mepivacaine and methylparaben.
Findings:
- Patch testing with mepivacaine showed a positive response.
- Subcutaneous challenges with mepivacaine elicited a delayed sensitivity reaction.
- Prick and patch tests with methylparaben were negative.
- Oral challenges with methylparaben did not provoke a reaction.
- The patient also exhibited sensitization to lidocaine, a previously encountered agent.
Implications:
- Mepivacaine can induce delayed-type hypersensitivity reactions.
- Patch testing is a valuable tool for diagnosing local anesthetic allergy.
- Cross-reactivity or prior sensitization to related compounds like lidocaine should be considered.
- This case highlights the importance of accurate diagnosis in adverse drug reactions.