Codeine-induced mast cell degranulation in human skin: effect of calcium channel blockers.

Codeine and other opiates can induce immediate type wheal and flare skin reactions. Calcium channel blockers including nifedipine have been shown to inhibit mast cell degranulation in different systems. The oral administration of nifedipine (10 mg) did not affect the size of codeine-induced skin reactions in ten normal volunteers. Mean wheal over flare sizes were 11.7 mm/29.2 mm before nifedipine and 11.5 mm/31.0 mm at peak nifedipine blood levels. Similar observations were made when codeine was injected locally with or without 20 micrograms nifedipine (12.1/29.2 mm and 13.2/29.2 mm, respectively). These data suggest that codeine-induced mast cell degranulation may be mediated by a calcium-independent mechanism. Alternatively, mast cells in the human skin may differ in their reactions to secretagogues when compared with basophils and mast cells from other human tissues or other species.