Efavirenz Severe Hypersensitivity Reaction: Case Report and Rapid Desensitization Protocol Development

Abstract

Objective: Long-term efavirenz desensitization protocols have been reported; however, publication of a rapid desensitization protocol has not been noted to date. We report a case of severe hypersensitivity reaction that was successfully managed using a rapid desensitization protocol. Case Summary: In a 52-year old HIV-positive woman, antiretroviral therapy was started with lamivudine 150 mg twice daily, zidovudine 300 mg twice daily, and efavirenz 600 mg daily. Nine days after starting antiretroviral therapy, she developed a generalized maculopapular rash. Despite concomitant chlorpheniramine administration, the rash did not improve. With suspicion of efavirenz hypersensitivity reaction, efavirenz was discontinued for 5 days and when the patient's rash resolved, the drug was restarted at 600 mg daily. The patient developed a severe generalized pruritic rash the next day and all antiretroviral agents were discontinued. One week later, lamivudine and zidovudine were restarted and were well tolerated. An objective causality assessment revealed that an efavirenz hypersensitivity reaction was probable. A 7-hour efavirenz desensitization protocol, starting with a 1:20,000 solution of the target therapeutic dose, was successful. The patient was followed for 6 weeks and had no further signs or symptoms of a hypersensitivity reaction. Discussion: Efavirenz hypersensitivity reactions typically include cutaneous reactions that are observed in the first 2 weeks of treatment, are often mild to moderate without systemic manifestation, and improve with continued therapy. Previously, successful desensitization protocols have been described in patients receiving efavirenz who developed rash without systemic symptoms, but these protocols were carried out over 7 or 14 days. This case report indicates a rapid desensitization protocol that may be an available option for some patients. Conclusions: Considering that efavirenz can be the cornerstone of many antiretroviral therapy regimens and hypersensitivity reactions can restrict regimen options, effective desensitization protocols are valuable, especially in the developing countries with limited available antiretroviral drugs.