CURRENT Essentials of Critical Care.pdf

270 Current Essentials of Critical Care■■■Phenytoin Hypersensitivity SyndromeEssentials of Diagnosis• High spiking fever, malaise, rash 2–3 weeks after starting phenytointherapy; sooner if prior exposure to drug• Patchy erythematous rash evolving into extensive pruritic maculopapularrash, occasionally with follicular papules and pustules;may evolve to exfoliative erythroderma, erythema multiforme,Stevens-Johnson syndrome, toxic epidermal necrolysis• Edema of palms, soles, and face• Tender localized or generalized lymphadenopathy• Mild to severe hepatic injury; mortality up to 20% with severeliver damage• Sometimes conjunctivitis, pharyngitis, diarrhea, myositis, andreversible acute renal failure• Leukocytosis with eosinophilia (5–50%); normal erythrocytesedimentation rate, serum complement• Adverse skin reactions in 3–15% of patients receiving phenytoin;smaller percentage develop syndrome of rash, fever, eosinophilia,hepatic injury• All age groups affected; incidence highest in blacks; likely immune-mediatedDifferential Diagnosis• Infectious mononucleosis• Other anticonvulsant medication reactions with rash and multisystemicinvolvement (phenobarbital)• Other drug reactions• VasculitisTreatment• Medication must be discontinued• Cross-reactivity among anticonvulsants possible; valproic acidor carbamazepine may be safer alternatives• General supportive care, especially with multisystem involvement• No demonstrated benefit of systemic corticosteroids■ PearlIn patients with anticonvulsant hypersensitivity syndrome to eitherphenytoin, phenobarbital or carbamazepine, up to 75% have demonstratedin vitro cross sensitivity to the other two drugs.ReferenceSchlienger RG, Shear NH: Antiepileptic drug hypersensitivity syndrome.Epilepsia 1998;39 (7 Suppl:)S3-7. [PMID: 9798755]