The effects of nicardipine given after 10-minutes complete global cerebral ischemia on neurologic recovery in dogs

Nicardipine: a hypotensive dihydropyridine-type calcium antagonist with a peculiar cerebrovascular profile

Control of blood pressure protects against the development of cerebrovascular lesions, stroke, and vascular dementia (VaD). Cerebrovascular disease is increasingly recognized as a cause of cognitive impairment and dementia primarily in the elderly. Nicardipine is a dihydropyridine-type calcium channel blocker (CCB) with a peculiar cerebrovascular profile developed approximately 30 years ago. This study has reviewed the main controlled clinical studies investigating the use of nicardipine in pathologies associated with cerebrovascular injury, such as subarachnoid haemorrhage (SAH), acute stroke, and VaD. SAH is a main cerebrovascular indication of CCBs. In this indication, CCBs prevent vasospasm and improve clinical outcomes. Nimodipine represents the CCB more investigated in this indication. Former studies did not demonstrate a clear advantage of nicardipine versus nimodipine in SAH. A more recent approach using implants of nicardipine prolonged-release showed a decreased incidence of vasospasm, delayed ischemic deficits, and improved clinical outcome after severe SAH. Controlled trials have shown the effectiveness of the drug in preventing stroke. Increasing evidence suggests some benefit of some CCBs in VaD or mixed degenerative and vascular dementia. In this setting, nicardipine has been investigated in approximately 6,000 patients, with an improvement of cognitive deterioration in more than 60% of patients treated. The pronounced anti-hypertensive activity of nicardipine and its safety and effectiveness in cognitive domain suggest its reconsideration in the treatment of cognitive impairment of vascular origin as well as for reducing the risk of recurrent stroke in patients at high risk of it.

The effects of a thromboxane A2 receptor antagonist on neurologic recovery after 15 min complete global brain ischemia in dogs

The effects of a thromboxane A(2) receptor antagonist (anti-TXA(2); ONO-3708) on the neurologic recovery after 15 min complete cerebral ischemia were investigated in dogs. Complete cerebral ischemia was achieved by occlusion of the trunk of the aorta, the superior and the inferior caval vein. Seventeen dogs were divided into 2 groups; 1) control group (no drug, n = 9), 2) Anti-TXA(2) group (anti-TXA(2) 200 mcg.kg(-1) in iv bolus soon after recirculation followed by continuous infusion at a rate of 10 mcg.kg(-1).min(-1) for 3 days, n = 8). EEG, auditory brainstem response (ABR), middle latency response (MLR), and somatosensory evoked potential (SEP) recordings were obtained before ischemia, 120 min after re-circulation and on the 7th day after ischemia. The neurologic recovery score (NRS) were determined on the 3rd and the 7th day. Impaired EEG score was significantly higher in the anti-TXA(2) group on 7th day after ischemia ( P < 0.05). Anti-TXA(2) increased the reappearance rates of the ABR-Vth ( P < 0.05) and the SEP-N(3) waves ( P < 0.01) at 120 min after ischemia. The survival rate tended to be higher in the anti-TXA(2) group. However, NRS did not significantly differ in the groups.

Nicardipine and treatment of cerebrovascular diseases with particular reference to hypertension-related disorders

Nicardipine is a second generation dihydropyridine-type Ca2+ antagonist with high vascular selectivity and strong cerebral and coronary vasodilatory activity. The compound is used in the treatment of hypertension, primarily in the elderly. In this review the main evidence of the cerebrovascular activity of nicardipine in preclinical studies using in vitro and in vivo models is detailed. A particular physico-chemical property of nicardipine is the almost complete protonation in acid environment. This allows its accumulation in ischemic brain regions and makes it a candidate for the treatment of cerebrovascular disorders characterised by impaired brain perfusion. The main clinical data on the use of nicardipine in cerebral ischemia and related disorders, subarachnoid haemorrhage and stroke, are also reviewed. These studies included 5940 patients affected by chronic cerebrovascular insufficiency (cerebral ischemia, cerebral atherosclerosis mainly associated with hypertension, transient ischemic attacks, sequelae of cerebral infarction, thrombosis or embolia, hypertensive encephalopathy), 1540 patients affected by sequelae of subarachnoid haemorrhage and 206 patients affected by stroke. Both preclinical studies and clinical trials have shown that nicardipine is a safe Ca2+ antagonist with powerful cerebrovascular activity. This suggests its possible use in cerebrovascular disorders in which blockade of Ca2+ channels of the L-type and/or selective cerebral vasodilatation is desirable. Further studies are necessary to establish if modulation of neuronal Ca2+ channels of the L-type by nicardipine may have a neuroprotective effect independent by the cerebrovascular activity of the compound.

A randomized clinical study of a calcium-entry blocker (lidoflazine) in the treatment of comatose survivors of cardiac arrest

BACKGROUND

Abnormalities of cellular calcium homeostasis have been implicated in the pathophysiology of postischemic encephalopathy. Calcium-entry-blocking drugs inhibit the influx of calcium into cells and have been shown to mitigate postischemic encephalopathy in animal models.

METHODS

Five hundred twenty patients with cardiac arrest who remained comatose after the restoration of spontaneous circulation were randomly assigned to receive three doses of lidoflazine, an experimental calcium-entry blocker, or a placebo and were followed for six months. Four patients were lost to follow-up. Treated patients received an intravenous loading dose (1 mg per kilogram of body weight) of lidoflazine and two subsequent doses (0.25 mg per kilogram) 8 and 16 hours after resuscitation. The investigators were blinded to treatment assignment.

RESULTS

There was no statistically significant difference between the lidoflazine group (n = 259) and the placebo group (n = 257) in the proportion of patients who died during the six-month follow-up (82 vs. 83 percent), who survived with good cerebral recovery (15 vs. 13 percent), or who survived with severe neurologic deficit (1.2 vs. 1.9 percent). Analysis of the best level of recovery achieved at any time during follow-up also did not show a difference between the treatment groups: 24 percent of those given lidoflazine and 23 percent of those given placebo recovered good cerebral function (normal or only moderately disabled cerebral performance) at some time.

CONCLUSIONS

The administration of lidoflazine after cardiac arrest was not found to be beneficial. Our data do not support the routine use of this calcium-entry-blocking drug in comatose survivors of cardiac arrest.

The effects of calcium antagonists on EEG, evoked potentials and neurologic recovery after complete global brain ischemia for 15 minutes in dogs

The effects of three calcium antagonists on the recovery from neurologic damages after complete global brain ischemia were examined by evaluating the change of a electroencephalogram (EEG), evoked potentials (EP) and a neurologic recovery score (NRS) in dogs. Fifteen minutes global brain ischemia was achieved by occluding the ascending aorta and the caval veins. Nicardipine (NC), flunarizine (FL) and diltiazem (DL) were administered with continuous infusions for three days after the ischemia. The EEG-EP scores (0 : no response - 6 : normal) 3 hr after the ischemia were 1.4 +/- 0.4 (mean +/- SE) in the control, 2.2 +/- 0.3 in the NC, 2.2 +/- 0.4 in the FL and 2.1 +/- 0.2 in the DL. There were no significant differences between the 4 groups. The survival rates on the 7th day after the ischemia were 67% (6/9) in the control, 78% (7/9) in the NC, 56% (5/9) in the FL and 89% (8/9) in the DL. No significant differences were presented between the 4 groups. The NRSs (0 : death - 100 : normal) on the 7th day were 40.3 +/- 7.3 in the control, 59.0 +/- 8.5 in the NC, 63.2 +/- 9.7 in the FL and 55.7 +/- 3.3 in the DL. Each treated group showed a tendency to have a higher NRS than that in the untreated control group. The NRS in all dogs treated by the Ca(++) antagonists on the 7th day was 58.7 +/- 4.1, which was significantly higher than that in the control group ( P < 0.05). We conclude that the continuous administration of calcium antagonists for three days after the global brain ischemia would be beneficial for the neurologic recovery.