Flunarizine, a calcium channel antagonist, is partially prophylactically neuroprotective in hypoxic-ischemic encephalopathy in the fetal sheep.

Calcium antagonist therapy has been reported to reduce neuronal death after hypoxia-ischemia; however, its potential use in prenatal hypoxic-ischemic events has received little attention. We examined the effect of pretreatment with flunarizine in chronically instrumented late gestation fetal sheep subjected to 30 min of cerebral ischemia. Eight fetuses were given 0.11 mmol (45 mg) of flunarizine over 2 h preischemia (high dose), 10 were given 0.07 mmol (30 mg) over 3 h preischemia (low dose), 17 were given nothing (ischemia controls), and 5 received neither the ischemic insult nor any treatment (sham controls). The fetal electrocorticogram was monitored for 3 d postinsult. Histologic outcome was quantified after 72 h. Low-dose, but not high-dose, flunarizine therapy was associated with an overall reduction in cerebral damage (p < 0.01), a greater final electrocorticogram intensity, and a reduction in the incidence of seizures (p < 0.02) compared with ischemia controls. High-dose, but not low-dose, flunarizine was associated with a significant acute mortality and a decrease in fetal blood pressure (p < 0.05) at the time of occlusion, although there was no effect on the initial hypertensive response to occlusion. These observations suggest that flunarizine is partially neuroprotective when given before severe global ischemia in utero, but that its hypotensive effects make it unsuitable for prophylactic administration in utero.