Nimodipine tested in a human model of cerebral ischaemia. Electroencephalographic and transcranial Doppler ultrasound investigations in normal subjects during standardized hyperventilation.

The anti-ischaemic properties of nimodipine 30 mg and 60 mg t.i.d. for 4 days has been tested in a double-blind, placebo-controlled, cross-over study based on the use of hyperventilation to reduce flow velocity in cerebral arteries. Whether the anti-ischaemic properties were due to a vasodilatator action on cerebral blood vessels or to an anti-ischaemic effect on cerebral neurons was studied. There was a slight cardiovascular effect, without any significant change in the EEG at rest. During standardized hyperventilation, there was no difference in the reduction in the blood flow velocity in the nimodipine and placebo groups (namely 56%, 56% and 59%). Both doses of nimodipine, however, significantly attenuated the hyperventilation-induced increase in slow EEG activity in the 1.5-6.0 Hz range. It is concluded that the anti-ischaemic properties of nimodipine are due to an effect on the central nervous system rather than to an effect on cerebral blood flow.