Comparative trial of acyclovir and adenine arabinoside in the treatment of herpes simplex corneal ulcers.

Recent work has shown that the new antiviral acyclovir (acycloguanasine) is a highly effective antiviral drug against the herpes simplex virus."2 It acts mainly on virally infected cells by blocking viral particle formation before the particles pass through the nuclear membrane3 by means of inhibiting viral DNA polymerase after being converted by virally specific thymidine kinase.4 In tissue culture it has been shown to have an antiviral potency greater than the currently available antivirals.5 It has been successfully used in the treatment of experimental herpes simplex infection,' being at least as effective as idoxuridine and triflurothymidine. ' Clinically in the topical treatment of dendritic ulcers after minimal debridement it prevents early recurrence," is at least as effective as idoxuridine,'213 and has been successfully used in ulcers due to either idoxuridine or adenine arabinoside clinical resistance.'4 Given parenterally it is effective in herpes simplex encephalitis (Punt, personal communication) and herpes simplex infection in patients with malignant disease." Currently available antivirals are not always successful in the treatment of herpes simplex comeal ulcers, with failure to heal, sometimes due to viral drug resistance arising,'6 hypersensitivity, or topical toxicity occurring. Thus there is a need for a potent antiviral which affects only virally infected cells and has little effect on normal cells. Acyclovir fulfils these criteria, and so in the treatment of herpes simplex corneal ulcers topical acyclovir has been compared with topical adenine arabinoside (ara-A), another active currently available antiviral,'7 by means of a comparative randomised clinical trial on 60 patients.