Dose escalation safety and tolerance study of the competitive NMDA antagonist selfotel (CGS 19755) in neurosurgery patients.

Selfotel (CGS 19755), a competitive N-methyl-D-aspartate antagonist, is neuroprotective in experimental models of ischemic cerebral injury. We studied the safety and tolerability of a single intravenous dose (0.5 to 2.0 mg/kg) of selfotel in neurosurgery patients. Thirty-two neurosurgical patients undergoing intracranial surgery were given ascending doses of selfotel 2 to 14 h before surgery. Serum selfotel levels were measured over a period of 24 h. Cerebrospinal fluid (CSF) levels were measured 1.5 to 18 h after dosing. Frequent side effects included psychomimetic symptoms such as hallucinations, abnormal dreaming, agitation, and paranoia among 20 (66%) patients. Ataxia was seen among five (16%) and dizziness among eight (25%). Symptoms occurred 38 min to 40 h from administration and persisted 5 min to 4 days. Symptom severity worsened with increasing area under the curve measurements and doses above 1.0 mg/kg. All symptoms were reversible and easily treated with intravenous haloperidol. Modest elevations of hepatic enzymes were observed among four patients. No patient had severe adverse reactions. Maximum selfotel levels attained were 143 mumol (serum) and 4.76 mumol (CSF). Peak serum levels among six patients were within potentially neuroprotective ranges. CSF levels remained detectable up to 18 h after dosing. No obvious relationship was seen between CSF drug levels and symptoms. Selfotel in doses of 0.5 to 2.0 mg/kg can be administered safely to neurosurgical patients. Maximum serum levels attained were within the range shown to be neuroprotective in experimental studies. Side effects even at the highest levels are tolerable and reversible. Selfotel use in patients at risk for cerebral injury should be further explored.