Clinical utility of oral valacyclovir compared with oral acyclovir for the prevention of herpes simplex virus mucositis following autologous bone marrow transplantation or stem cell rescue therapy

Oral acyclovir has been demonstrated to prevent reactivation of herpes simplex virus (HSV) infections when administered prophylactically to autologous bone marrow transplant (BMT) recipients or patients undergoing stem cell rescue therapy. Oral valacyclovir, which is converted in the body to acyclovir, has greater oral bioavailability than oral acyclovir and compared with oral acyclovir yields similar acyclovir plasma concentrations with less frequent (twice-daily) dosing. This study compared the efficacy of oral valacyclovir with that of oral acyclovir at preventing HSV mucositis in BMT recipients. A total of 60 HSV-1-positive patients scheduled for BMT or stem cell rescue therapy were treated prophylactically with valacyclovir 500 mg twice daily until resolution of neutropenia. Data from these patients were compared with those of a historical control group of 60 patients who had received acyclovir 600 mg every 6 h until resolution of neutropenia or acyclovir 125 mg/m(2) intravenously every 6 h. The results show that none of the patients developed oral or oropharyngeal HSV infection while receiving either treatment. Of the 60 patients receiving valacyclovir, 38 (63%) completed treatment without the need for intravenous acyclovir compared with 12 of 60 (20%) patients in the acyclovir group. Additionally, the total number of doses of drug administered to the valacyclovir group was significantly less than the number received by patients in the acyclovir group. No serious adverse events occurred in either group of patients. This study demonstrates that oral valacyclovir and acyclovir are comparably effective and safe in preventing reactivation of HSV infections in autologous BMT and stem cell recipients. The less frequent dosing schedule with valacyclovir compared with acyclovir offers a potential advantage for patients undergoing BMT who frequently suffer with severe mucositis and have difficulty taking oral medications.