Varicella-zoster virus and subcutaneous cytarabine: correlation of in vitro sensitivities to blood levels.

The susceptibility of 26 strains of varicella-zoster virus to cytarabine was tested in vitro by measuring reduction in number and size of plaques using human foreskin fibroblast cells. Most strains showed 50% reduction of plaque number by 0.125 mug of cytarabine per ml or less. Cytarabine levels in sera of 12 patients after a single subcutaneous injection of 50 mg/M(2) exceeded this inhibitory level for a period of 75 min. Thus, the subcutaneous route is a potentially useful method of administration of cytarabine for antiviral drug trials.