Foscarnet therapy in five patients with AIDS and acyclovir-resistant varicella-zoster virus infection

To determine whether foscarnet has potential efficacy in the treatment of acyclovir-resistant mucocutaneous varicella-zoster infection in patients with the acquired immunodeficiency syndrome (AIDS).

Open-label study.

Three university medical centers.

Five patients with AIDS who were infected with thymidine-kinase-deficient or -altered strains of varicella-zoster virus.

Foscarnet, 40 mg/kg body weight every 8 hours in 1-hour infusions for 10 or more days.

Four patients had healing in response to foscarnet therapy, and each of four tested patients became culture negative for virus during foscarnet therapy. Results of fluorescent antigen testing remained positive during therapy in two patients; one of these patients had concomitant clinical failure but the other patient healed fully. One patient had complete healing despite the emergence of resistance to foscarnet in serial specimens obtained during foscarnet therapy.

Foscarnet is a potentially effective and tolerable antiviral agent for patients with acyclovir-resistant, varicella-zoster virus infection; however, the optimal dosage and duration of therapy require further study, as does the relation between clinical findings and in-vitro susceptibility results.