Clinical trials ischemic stroke

This section will review the phase III clinical trials of IV thrombolytic agents for acute ischemic stroke, organized by the type of agent and the time window from stroke onset to study drug delivery (Table 3.1). The 1995 National Institute of Neurological Disorders and Stroke (NINDS) rt-PA trial is presented first because it showed that IV rt-PA, given within 3 hours of stroke onset, reduced stroke-related disability. This trial was the basis for the United States Food and Drug Administration (FDA) approval for rt-PA for use in acute ischemic stroke. 

Adams HP, Jr., Bendixen BH, Kappelle LJ, Biller J, Love BB, Gordon DL, Marsh EE, 3rd. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke. 1993 24 35 1. 

Kent DM, Price LL, Ringleb P, Hill MD, Selker HP. Sex-based differences in response to recombinant tissue plasminogen activator in acute ischemic stroke A pooled analysis of randomized clinical trials. Stroke. 2005 36 62-65. 

No direct comparison trials have been reported between the different thrombolytic agents in acute ischemic stroke. In a retrospective review of the results for acute stroke lAT performed at our center, we have found significantly higher rates of recanalization and good clinical outcome in the era in which lA UK was used versus the era in which UK was not available and lAT with rt-PA was the primary treatment. Conversely, in another retrospective study, Eckert et al. found no major difference between the recanalization rates of UK and rt-PA. 

In rodent stroke models, statin pretreatment has been shown to reduce infarct volumes and improve outcomes. Similarly, several clinical studies have shown that prior statin use reduced the severity of acute ischemic stroke and myocardial infarction. Recent studies indicate that beneftt can be achieved even when treatment is initiated after the onset of symptoms. In rodents, atorvastatin and simvastatin have been shown to reduce the growth of ischemic lesions, enhance functional outcome, and induce brain plasticity when administered after stroke onset. A retrospective analysis of the population-based Northern Manhattan Stroke Study (NOMASS) showed that patients using lipid-lowering agents at the time of ischemic stroke have a lower incidence of in-hospital stroke progression and reduced 90-day mortality rates. Retrospective analysis of data of the phase III citicoline trial showed... 

Yamaguchi T, Sano K, Takakura K, Saito I, Shinohara Y, Asano T, Yasuhara H. Ebselen in acute ischemic stroke a placebo-controlled, double-blind clinical trial. Ebselen study group. Stroke 1998 29 12-17. 

Davalos A, Castillo J, Alvarez-Sabin J, Secades JJ, Mercadal J, Lopez S, Cobo E, Warach S, Sherman D, Clark WM, Lozano R. Oral citicoline in acute ischemic stroke an individual patient data pooling analysis of clinical trials. Stroke 2002 33 2850-2857. 

Clinical Trials of Aspirin in Acute Ischemic Stroke... 

Ticlopidine inhibits the P2Yj2 platelet ADP receptor, thus inhibiting ADP-dependent activation of the GP Ilb/IIIa receptor. It has a slow onset of action and takes 3-7 days to reach its maximal antiplatelet effect. It is inactive in vitro and must undergo activation by the hepatic cytochrome p450 enzyme system. Secondary prevention trials have found that ticlopidine-treated patients have an estimated RRR of 33% for the composite endpoint of stroke, myocardial infarction, or vascular death after ischemic stroke. Significant adverse effects include bone marrow depression, rash, diarrhea, and thrombotic thrombocytopenic purpura. No clinical trials have studied ticlopidine for the treatment of stroke in the acute phase. 

One clinical trial showed that the combination of an ACE inhibitor and thiazide diuretic reduces the incidence of recurrent stroke in patients with a history of ischemic stroke or transient ischemic attacks. 

For some of these diseases, such as hypertension and heart disease, drugs such as ACE inhibitors and beta-blockers are available for treatment. For some other diseases, such as Alzheimer s disease, more effective drugs have yet to be discovered. For stroke, two late stage (Phase III) trials of NXY-059 and desmoteplase failed to meet the trial criteria. Other clinical trials in progress for ischemic stroke are presented in Table 11.1. 

Senn S (1997) Statistical Issues in Drug Development Chichester. John WUey Sons, Ltd Senn S (2002) Cross-Over Trials in Clinical Research (2nd edn) Chichester John WUey Sons Senn S (2003) Disappointing dichotomies. Pharmaceutical Statistics, 2, 239-240 Sherman DG, Atkinson RP, Chippendale T et al (2000) Intravenous ancrod for treatment of acute ischemic stroke the STAT study a randomised controUed trial. Journal of the American Medical Association, 283, 2395-2403... 

Recombinant t-PA has also been approved for use in acute ischemic stroke within 3 hours of symptom onset. In patients without hemorrhagic infarct or other contraindications, this therapy has been demonstrated to provide better outcomes in several randomized clinical trials. The recommended dose is 0.9 mg/kg, not to exceed 90 mg, with 10% given as a bolus and the remainder during a 1 hour infusion. Streptokinase has been associated with increased bleeding risk in acute ischemic stroke when given at a dose of 1.5 million units, and its use is not recommended in this setting. 

PCP inhibits brain nitric oxide synthase irreversibly (Osawa and Davila, 1993 Jewett et al., 1996 Klamer et al., 2005). Depending upon its levels, nitric oxide acts as a neuroprotective or neurodestructive molecule (Lipton, 1993 Lipton et al., 1998). NMDA receptor antagonists that have treated ischemic injury of the brain in animal models with some benefit are presented in Tables 10.1 and 10.2. All studies on their use in humans have been unsuccessful because they not only block normal neuronal function, but also produce serious side effects such as headache, anxiety, agitation, nausea, vomiting, hallucinations, dizziness, and coma (Schehr, 1996 Koroshetz and Moskowitz, 1996 Ratan et al., 1994). Clinical trials of NMDA antagonists for stroke and traumatic brain injury have been abandoned (Kemp and McKeman, 2002 Lees et al., 2000 Sacco et al., 2001). 

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