Fixed drug eruption due to acyclovir

Fixed Drug Eruption in a Patient Taking Valacyclovir without Cross-Reactivity to Acyclovir

Fixed drug eruption (FDE) is a well-defined hyperpigmented patch that recurs in a fixed location each time a particular drug is taken. Common causative agents of FDE are non-steroidal anti-inflammatory drugs, non-narcotic analgesics, sedatives, anticonvulsants, sulfonamides, and tetracycline. We report a 33-year-old male who presented with a recurrent, localized, brownish-to-erythematous macule and papules on the peri-philtrum area two hours after taking valacyclovir. Three episodes of valacyclovir ingestion for treatment of Herpes simplex virus infection provoked a similar skin rash at the same site. Histopathology results showed vacuolar degeneration in the basal layer of the epidermis, pigmentary incontinence, and perivascular inflammatory cell infiltration in the papillary dermis. Although patch test and skin prick test showed negative responses to acyclovir and valacyclovir, an intradermal test showed a positive reaction only to valacyclovir. The oral provocation test to acyclovir and valacyclovir showed a positive reaction only to valacyclovir. Through drug history, histopathological examination, patch test, intradermal test, and oral provocation test, we established a final diagnosis of FDE due to valacyclovir without cross-reactivity to acyclovir. To find alternative therapeutic drugs, we suggest diagnostic tests with not only the suspected drugs, but also other drugs in the same class.

Probable acyclovir-induced angioedema in a patient with HIV infection and suspected varicella-zoster virus encephalitis

PURPOSE

A probable acyclovir-associated hypersensitivity reaction resulting in severe facial angioedema and respiratory distress is reported.

SUMMARY

A 51-year-old woman with human immunodeficiency virus (HIV) infection and end-stage renal disease arrived at the emergency department (ED) with a diffuse rash on the chest and back; she was diagnosed with varicella-zoster virus infection, received one dose of i.v. acyclovir, and was discharged home with a prescription for valacyclovir. After taking one dose of the drug, she became confused and agitated. The next day the patient returned to the ED; she was confused and unresponsive, with signs and symptoms suggesting viral encephalitis. After a workup including lumbar puncture fluid, she was treated empirically with i.v. acyclovir for viral encephalitis. Within one hour of receiving the acyclovir infusion, the patient developed angioedema of the lips, tongue, and periorbital areas requiring intubation and transfer to the intensive care unit. Further acyclovir therapy was withheld, and foscarnet therapy was initiated for the presumptive treatment of viral encephalitis. Over the next few days, the patient's angioedema completely resolved; her mental status gradually improved while she completed a 14-day course of foscarnet therapy. The application of the Naranjo scale indicated a probable adverse reaction to acyclovir, likely mediated by acyclovir-specific immunoglobulin E, highlighting the need to consider alternative antiviral agents without cross-reactivity to acyclovir in patients with confirmed or suspected viral encephalitis.

CONCLUSION

A 51-year-old woman with HIV infection developed probable acyclovir-induced angioedema after receiving i.v. acyclovir therapy for suspected viral encephalitis.