ADVERSE CUTANEOUS DRUG REACTIONS ICD:10: T88.7
Adverse cutaneous drug reactions (ACDRs) are unpredictable They affect 2 to 3% of inpatients and lead to 0.1 to 0.3% of hospital fatalities1.
In the United States, adverse drug events account for up to 140,000 deaths and $136 billion in costs annually.
Most reactions are mild, accompanied by pruritus, and resolve promptly after the offending drug is discontinued.
Drug eruptions can mimic virtually all the morphologic expressions in dermatology and must be the first consideration in the differential diagnosis of a suddenly appearing eruption.
Drug eruptions are caused by immunologic or nonimmunologic mechanisms and are provoked by systemic or topical administration of a drug.
The majority are based on a hypersensitivity mechanism and are thus immunologic and may be of types I, II, III, or IV.
IMMUNOLOGICALLY MEDIATED ACDR (see Table 23-1) It should be noted that in most reactions both cellular and humoral immune reactions are involved. Nonimmunologic reactions are summarized in Table 23-2.
TABLE 23-1Immunologically Mediated Adverse Cutaneous Drug Reactions* ||Download (.pdf) TABLE 23-1 Immunologically Mediated Adverse Cutaneous Drug Reactions*
|Type of Reaction ||Pathogenesis ||Examples of Causative Drug ||Clinical Patterns |
|Type I ||IgE-mediated; immediate-type immunologic reactions ||Penicillin, other antibiotics ||Urticaria/angioedema of skin/mucosa, edema of other organs, and anaphylactic shock |
|Type II ||Drug + cytotoxic antibodies cause lysis of cells such as platelets or leukocytes ||Penicillin, sulfonamides, quinidine, isoniazid ||Petechiae due to thrombocytopenic purpura, drug-induced pemphigus |
|Type III ||IgG or IgM antibodies formed to drug; immune complexes deposited in small vessels activate complement and recruitment of granulocytes ||Immunoglobulins, antibiotics, rituximab, infliximab ||Vasculitis, urticaria, serum sickness |
|Type IV ||Cell-mediated immune reaction; sensitized lymphocytes react with drug, liberating cytokines, which trigger cutaneous inflammatory response** ||Sulfamethoxazole, anticonvulsants, allopurinol ||Morbilliform exanthematous reactions, fixed drug eruption, lichenoid eruptions, Stevens–Johnson syndrome, toxic epidermal necrolysis |TABLE 23-2Nonimmunologic Drug Reactions ||Download (.pdf) TABLE 23-2 Nonimmunologic Drug Reactions
|Idiosyncrasy ||Reactions due to hereditary enzyme deficiencies |
|Individual idiosyncrasy to a topical or systemic drug ||Mechanisms not yet known |
|Cumulation ||Reactions are dose dependent, based on the total amount of drug ingested: pigmentation due to gold, amiodarone, or minocycline |
|Reactions due to combination of a drug with ultraviolet irradiation (photosensitivity) ||Reactions have a toxic pathogenesis but can also be immunologic in nature (see Section 10) |
|Irritancy/toxicity of a topically applied drug ||5-Fluorouracil, imiquimod |
|Atrophy by topically applied drug ||Glucocorticoids |
GUIDELINES FOR ASSESSMENT OF POSSIBLE ACDRS
Exclude alternative causes, especially infections (most commonly viral).
Examine interval between introduction of a drug and onset of the reaction.
Note any improvement after drug withdrawal.
Determine whether similar reactions have been associated with the same compound.
Note any reaction on ...