Sensitivity to other Beta Lactam ABs

If pt has a hx of rxn to pen, they are allergic to derivative pen’s as well (eg Ticarcillin). Skin Testing (s.t.) for these drugs consists of major and minor determinants to benzyl penicillin and a s.t. to the desired drug, but the latter may cause a non-specific (+) rxn. There is no s.t. to Cephalosporins. The risk of having an IgE Cephalosporin rxn is 10-15% in pen allergic pts, so they sould not receive ceph’s unless there is no alternative. Use a test dose or modified desensitization (this is expensive, wont do it in dentistry. Keflex is a broad spectrum Cephalosporin brandname). 50% of PCN allergic pts are positive to imipenam, so don’t use Priaxin in pen allergics unless you desensitize. Aztreonam 9a monobactam) has negligible in-vitro or in-vivo reactivity to pen and ceph. Aztreo can be used in pen allergics.

Category: Pharmacology Notes