Opioids skin testing

The estimated sensitivity of skin tests for muscle relaxants is approximately 94-97%. Sensitivity for other substances varies. It is good for synthetic gelatins, (3-lactams, but poor for barbiturates, opioids and benzodiazepines dyes, and chlorhexidine. 

If appropriate OAD-reactive IgE antibody tests are available, they should be used as an adjunct to skin testing but an understanding of the immunochenucal basis of cross-reactivity between opioids and NMBDs shows that a cautionary approach to interpretation is necessary. For example, a morphine solid phase is routinely employed to detect NMBD-reactive IgE antibodies in the sera of subjects allergic to NMBDs (see Sect. 7.4.3.4.2). The structural basis of the cross-recognition is the tertiary methyl ammonium group of morphine and the substituted ammonium groups on NMBDs. 

Peptides with opioid activity have been isolated from sources other than mammalian brain. The heptapeptide p-casomorphin (Tyr-Pro-Phe-Pro-Gly-Pro-lle), found in cow s milk, is a p opioid agonist (11). Dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), a p-selective peptide isolated from the skin of South American frogs, is approximately 100-fold more potent than morphine in in vitro tests (12). 

Skin A 37-year-old woman developed generalized dermatitis, with pruritus, rash, and edema, after taking a codeine-containing cough mixture for a common cold [65 ]. A codeine-challenge test resulted in the same clinical picture. She had good tolerance to fentanyl and tramadol but not to other opioids. 

---