A double-blind, placebo-controlled study of the safety, tolerability and pharmacokinetics of CP-101,606 in patients with a mild or moderate traumatic brain injury. Sample size review in a head injury trial with ordered categorical responses. Dexanabinol (HU-211) in the treatment of severe closed head injury: a randomized, placebo-controlled, phase II clinical trial. Failure of the competitive N-methyl-D-aspartate antagonist Selfotel (CGS 19755) in the treatment of severe head injury: results of two phase III clinical trials. The Selfotel Investigators.
CP-101,606 is a postsynaptic antagonist of the glutamate-mediated NR2B subunit of the N-methyl-D-aspartate (NMDA) receptor. When administered intravenously (i.v.) at the time of injury, CP-101,606 is neuroprotective in animal models of traumatic brain injury (TBI) and ischemia. Minimal adverse effects have been observed in normal human volunteers given i.v. doses of up to 3 mg/kg/hr for 72 hours. The objective of the present clinical trial was to assess the safety, pharmacokinetics, and tolerability of CP-101,606 infused for various times in patients who had suffered either an acute moderate or mild TBI (Glasgow Coma Score 9-14) or hemorrhagic stroke. Patients began receiving treatment within 12 hours of brain injury. A total of 53 subjects (45 with TBI and 8 with stroke) were randomized in a double-blind fashion to receive CP-101,606 or placebo (4 drug: 1 placebo). Drug/placebo was administered by i.v. infusion (0.75 mg/kg/hr) for 2 hours and then stopped (n = 25) or continued for 22 hours (n = 4) or 70 hours (n = 24) at a rate of 0.37 mg/kg/hr. Mean plasma drug concentrations were well above the predicted therapeutic concentration of 200 ng/ml within two hours of initiating treatment and were sustained as long as drug was infused. All the patients tolerated their drug/placebo treatment, and there were no clinically significant cardiovascular or hematological abnormalities in either group. A Neurobehavioral Rating Scale, used to detect personality changes and behavioral disturbances, indicated that all subjects showed an improvement from their postinjury, predosing baseline but did not significantly differ from each other with respect to type of head injury and/or treatment with drug or placebo. Modified Kurtzke Scoring also showed a similar pattern of improvement irrespective of type of head injury or drug/placebo treatment. This study suggests that CP-101,606, infused for up to 72 hours has no psychotropic effects and is well-tolerated in patients who have sustained a mild or moderate TBI or hemorrhagic stroke. Between 1993 and 1996, a total of 452 patients were entered into a randomized trial evaluating eliprodil (a non-competitive NMDA receptor antagonist) in patients suffering from severe head injury. The primary efficacy analysis concerned the Glasgow Outcome Score (GOS), six months after randomization. This outcome was classified into three ordered categories: good recovery; moderate disability, and the worst category made up by combining severe disability, vegetative state and dead. A sample size calculation was performed prior to the commencement of the study, using a formula which depends on the anticipated proportions of patients in the three different outcome categories, the proportional odds assumption and on the relationship between outcome and prognostic factors such as Glasgow Coma Score at entry. Owing to uncertainty about the influence of prognostic factors, and about the proportion of patients in the three GOS categories, a blinded sample size review was planned. This review was performed on the basis of the first 93 patients to respond, and this led to an increase in the sample size from 400 to 450. In this paper the pre-trial simulations showing that the type I error rate would be influenced and the power would be preserved will be presented, and the implementation of the procedure will be described. To establish the safety of intravenous dexanabinol in severe head injury.
                Prospective, randomized, double-blind, placebo- (vehicle) controlled, multicenter, escalating dose study of a single administration of drug (48 or 150 mg) or vehicle (1 or 3 mL).
                All Israeli neurosurgical intensive care units (a total of six units).
                Sixty-seven patients, aged 16-65 yrs, Glasgow Coma Scale score of 4-8, injured within 6 hrs of treatment.
                Intracranial pressure, cerebral perfusion pressure, blood pressure, and heart rate were measured continuously in the intensive care unit. Adverse medical events were recorded and clinical outcome was assessed by the Glasgow outcome scale throughout a 6-month follow-up period. A highly significant reduction in the percentage of time with intracranial pressure >25, cerebral perfusion pressure <50, and systolic blood pressure <90 mm Hg was observed in the drug-treated group. The nature and incidence of adverse medical events were similar in the two groups. The percentage of patients achieving good neurologic outcome on the Glasgow outcome scale was 21% and 14% higher in the drug-treated group at 3 and 6 months, respectively. Statistical analysis of these differences by a logistic model using dose, entry Glasgow coma scale score, and computed tomograph as covariates yielded p values for the effect of treatment of .03 and .14 at 3 and 6 months, respectively.
                Dexanabinol was safe and well tolerated in severe head injury. The treated patients achieved significantly better intracranial pressure/cerebral perfusion pressure control without jeopardizing blood pressure. A trend toward faster and better neurologic outcome was also observed. Excessive activity of excitatory amino acids released after head trauma has been demonstrated to contribute to progressive injury in animal models and human studies. Several pharmacological agents that act as antagonists to the glutamate receptor have shown promise in limiting this progression. The efficacy of the N-methyl-D-aspartate receptor antagonist Selfotel (CGS 19755) was evaluated in two parallel studies of severely head injured patients, defined as patients with post resuscitation Glasgow Coma Scale scores of 4 to 8.
                A total of 693 patients were prospectively enrolled in two multicenter double-blind studies. Comparison between the treatment groups showed no significant difference with regard to demographic data, previous incidence of hypotension, and severity of injury. As the study progressed, the Safety and Monitoring Committee became concerned about possible increased deaths and serious brain-related adverse events in the treatment arm of the two head injury trials, as well as deaths in the two stroke trials being monitored concurrently. The Selfotel trials were stopped prematurely because of this concern and because an interim efficacy analysis indicated that the likelihood of demonstrating success with the agent if the studies had been completed was almost nil.
                Subsequently, more complete data analysis revealed no statistically significant difference in mortality rates in all cases between the two treatment groups in the head injury trials. In this report the authors examine the studies in detail and discuss the potential application of the data to future trial designs.
The case for efficacy of excitatory amino acid inhibitor therapy remains unproven. To date, no product has proven to be efficacious (as determined by the criteria applied) for improving the outcomes of brain-injured patients. Early termination, unpublished, and underpowered studies limit a clear appreciation of the merits of this form of intervention. Additional studies, some of which remain in progress, may more clearly define the efficacy and effectiveness issues.