Relative potencies of anti-herpes compounds.

Assessment of the relative potencies of compounds that inhibit the multiplication of herpesvirus is rendered difficult by the fact that they have been investigated by different workers who were not using comparable test systems. The relative and absolute potencies of idoxuridine, cytarabine, vidarabine, trifluorothymidine, and ara-DAP have therefore been evaluated by plaque inhibition, plaque reduction, and yield reduction tests, the most satisfactory dose-response lines being obtained by plaque reduction. The results obtained for five strains of type 1 and five of type 2 herpesvirus indicated that cytarabine was the most active compound, followed by idoxuridine and trifluorothymidine; vidarabine and ara-DAP were found to be the least active compounds. From comparisons of ED50 values derived from the dose-response lines it was found that the greater sensitivity of type 1 strains reported in the literature could only be confirmed with idoxuridine, since considerable overlaps in type sensitivity were observed with the other compounds.