Subduing Stroke

November 22, 2004

Stroke is one of the leading causes of death in America. Only heart disease and cancer kill more Americans. Doesn't it seem odd, then, that there is currently only one drug indicated to treat stroke? What's more, fewer than 5% of stroke patients ever receive this drug, according to the American Stroke Association (ASA). There are dozens of drugs for heart disease and cancer. Where are the drugs for stroke?

Stroke is one of the leading causes of death in America. Only heart disease and cancer kill more Americans. Doesn't it seem odd, then, that there is currently only one drug indicated to treat stroke? What's more, fewer than 5% of stroke patients ever receive this drug, according to the American Stroke Association (ASA). There are dozens of drugs for heart disease and cancer. Where are the drugs for stroke?

In the past 20 years, many drugs have been tested as neuroprotectives, Lapointe said. "The majority of them failed miserably when they hit phase III." Many clinicians are now skeptical of the hype surrounding new drugs for stroke.

There are two types of stroke: hemorrhagic and ischemic. Hemorrhagic stroke occurs when a blood vessel in the brain ruptures. Ischemic stroke, the most common form, occurs when a blood vessel in the brain is blocked, usually by a clot. Either way, the result is reduced blood flow to the brain. The greater the blood flow restriction, the greater the potential for severe, permanent, or even fatal damage.

A lone-wolf drug At present, tissue plasminogen activator (tPA) is the only drug approved to treat acute ischemic stroke. Named alteplase (Activase, Genentech), tPA binds to the fibrin in a thrombus (clot) and converts plasminogen to plasmin. The plasmin causes fibrinolysis and thus dissolves the clot. Sounds good so far, but there are some limits to the drug's use.

Because of its mechanism of action, tPA can cause bleeding, both internally and externally. Before patients receive tPA, they must be screened for any medications (such as anticoagulants) or conditions (such as ulcers, recent surgery, or advanced age) that could increase the risk for bleeding. They must also receive cranial CT scans to rule out hemorrhagic stroke. Furthermore, therapy must be initiated within three hours of symptom onset.