Timolol induces HSV-1 ocular shedding in the latently infected rabbit.

Timolol iontophoresis into the eye can induce herpes simplex virus type 1 (HSV-1) shedding in rabbits latently infected with HSV-1 strain McKrae. Anodal iontophoresis of 0.01% timolol was done at 0.8 mAmp for 8 min once a day for 3 consecutive days. Viral shedding was determined by the presence of HSV-1 in the preocular tear film obtained by eye swabs. In two experiments, iontophoresis of 0.01% timolol resulted in all eyes (18/18) shedding HSV-1 for an average duration of 4.3 days. When 5.0% timolol was applied topically to rabbit eyes supersensitized by iontophoresis of 6-hydroxydopamine (6-HD), all eyes (10/10) shed virus for an average duration of 2.9 days. All eyes (12/12) receiving iontophoresis of 6-HD, pre- and posttreatment with topical application of 5.0% timolol, and posttreatment with topical application of 1.0% epinephrine shed virus for an average duration of 3.6 days. Eyes treated with topical application of 5.0% timolol alone showed no difference in HSV-1 ocular shedding, compared with untreated eyes. We concluded that both iontophoresis of 0.01% timolol and topical application of 5.0% timolol to adrenergically supersensitized eyes induced HSV-1 shedding reliably and with a high frequency, and that topically applied timolol does not block the HSV-1 ocular shedding induced by epinephrine in adrenergically supersensitized eyes.