Methods: We reported a case of Tenofovir-induced non-immediate hypersensitivity reaction desensitized, proceeded under a slow oral protocol and obeying the European Network for Drug Allergy (ENDA) recommendations.
Results: A female nonatopic, 69 year-old patient, was diagnosed as having hepatitis B virus infection and started antiretroviral scheme with Lamivudine and Adenovir in 1999. This treatment was kept for ten years without success on controlling the viral replication. Therefore, the previous treatment was substituted for Tenofovir (150mg/day). Twenty days after starting the new treatment, the patient developed mild itchy rash on face and neck without systemic symptoms. As this drug showed to be successful on itchy rash on the viral replication, it was decided to keep it with concomitant use of systemic antihistamine drugs.
In May 2012, the dose of Tenofovir has been increased to 300mg/day once the follow-up tests showed the increase of viral replication. After one month, the patient developed a maculopapular pruritic diffuse exanthema without systemic involvement. The antiretroviral drug was withdrawn and systemic corticosteroids (prednisone) and anti-histamine (fexofenadine) drugs were administered until the complete recovery in 20 days.
The re-introduction was tried in August 2012, the hypersensitivity manifestation reappeared and the drug has been withdrawn again.
Based on the lack of therapeutic options for this patient, the desensitization with Tenofovir and the cumulative dose has been discussed with the Infectious Diseases staff. The patient agreed with the procedure and signed a consent form.
The desensitization protocol started with 9 mg/day administered for 2 days and advanced increasing the dose each 2 days to reach the dose of 200 mg/day. No evidences of renal and hepatic dysfunction were noticed during and after the process. The patient was seen 3 weeks after the desensitization and monthly. Presented good response for the treatment without further reactions.
Conclusions: This slow oral desensitization protocol showed to be successful and appears to be effective on inducing tolerance to Tenofovir, permitting continuation of a first-line antiretroviral therapy.