Internal Medicine

P1: RLJ/OZN P2: KUF

0521779407-D-01 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:41

Drug Allergy 499

■Pulmonary

➣Cough, infiltrates on radiograph, fever

■Hepatic

➣Cholestasis, hepatocellular damage

tests

■Blood: eosinophilia in <10%

■Serum tryptase to detect mast cell degranulation in suspected ana-

phylaxis

■Complement levels in serum sickness, other suspected immune

complex-mediated reactions

■Skin biopsy if vasculitis suspected

■Specific identification of responsible drug by skin testing if possible

➣Standardized reagents available only for penicillin & derivatives

➣Positive reaction to intradermal test w/ non-toxic dose of other

drugs may have value

differential diagnosis

■Increased sensitivity to known pharmacologic action of the drug

common in elderly

■Nonallergic adverse reactions to drugs

➣Flushing, hypotension w/ radiocontrast media; less frequent w/

isotonic contrast media

➣Aspirin-induced asthma

➣Assoc w/ rhinosinusitis

➣Virtual complete cross-reactivity w/ other NSAIDs implicates

pharmacologic action of these drugs

➣Hemolytic anemia w/ G6PD deficiency

➣Primaquine, other antioxidants

➣Opiate-related urticaria

➣Hepatitis caused by reactive drug metabolites (eg, isoniazid)

➣Syncope, usually vasovagal, mimicking anaphylactic reaction to

local anesthetics in dentistry

management

What to Do First

■Recognize that symptoms & signs are cause by drug allergy, identify

the offending agent, discontinue it.

General Measures

■Support blood pressure, maintain airway in anaphylaxis

■Maintain skin integrity w/ local treatment in cutaneous disease