Temporal dependent neuroprotection with propentofylline (HWA 285) in a temporary focal ischemia model

Propentofylline (HWA 285, 3-methyl-1-(5-oxo-hexyl)-7-propylxanthine) is an adenosine uptake and phosphodiesterase inhibitor that has been shown to be neuroprotective in both global and permanent focal ischemia animal models. However, to date, the efficacy of propentofylline has never been examined in an animal model of temporary focal ischemia or the 'therapeutic window' systematically examined in a focal ischemia model. The present experiments were designed to investigate these. Temporary (3 h) middle cerebral artery occlusion was accomplished by the monofilament method. Infarct volumes were determined at 24 h from 2,3,5-triphenyltetrazolieum chloride (TTC) stained coronal slices. Animals were dosed with vehicle or propentofylline at 3 mg/kg bolus and/or a 6 mg/kg per h infusion (24 h infusion) at 30 min, 1 h or 3 h post ischemia onset. Physiological monitoring on a subset of animals indicated no changes in mean arterial pressure, blood gases, blood pH, and glucose levels with either ischemia or drug treatment. Propentofylline treatment resulted in a statistically significant decrease in infarct volume when an infusion dose of 6 mg/kg per h was initiated at 30 min or when a bolus of 3 mg/kg plus an infusion dose was initiated at 1 h but not 3 h post ischemia. Therefore, propentofylline is neuroprotective in a model of temporary focal ischemia. This suggests that combination therapy with propentofylline might lead to clinical improvement beyond that which would occur with thrombolytics alone. The apparent short window of opportunity for effective dosing is consistent with the proposed mechanism of action for propentofylline.