Is Clot-Busting Drug Safe for Kids with Strokes?
New research looks at whether clot-busting drugs can safely be given to children who have strokes. The research was released today and will be presented at the American Academy of Neurology’s 64th Annual Meeting in New Orleans April 21 to April 28, 2012.
In adults, the clot-busting drugs can reduce disability if given within a few hours after stroke symptoms begin. But few studies have looked at whether the drugs are safe for children.
The study used a national database to look at all children admitted to a hospital with a diagnosis of ischemic stroke from 1998 to 2009. Only ischemic strokes can be treated with clot-busting drugs; they are the most common type of stroke.
Of the 9,367 children who were admitted with ischemic stroke, only 75 children, or 0.8 percent, received clot-busting drugs, also called thrombolytic therapy. Intracerebral hemorrhage, or bleeding in the brain, is a risk of thrombolytic therapy. The four percent rate of hemorrhage in the 75 kids who received thrombolytic therapy was higher than the 0.38 percent rate in kids who did not receive the therapy, but it was similar to the rate in adults who receive thrombolytic therapy.
Children who received thrombolytic therapy were no more likely to die following the stroke than those who did not receive the therapy.
About clot-busting drugs
Also known as thrombolytics, clot busters are medications given intravenously (I.V.) to a patient to break up a blood clot. If the patient is having a heart attack or an ischemic stroke, clot busters may reduce the damage to the heart or brain and prevent death.
Although blood clotting is a vital and natural bodily function, a blood clot can be deadly if it is large enough to block a blood vessel (thrombus), or if either part of the blood clot or the entire clot breaks off and travels through the bloodstream to lodge in a blood vessel elsewhere (embolism). Unlike anticoagulants, which can prevent blood clots from forming or becoming larger, clot busters are the only types of medication currently available that can actually destroy a blood clot.
Clot busters must be administered quickly and properly through several specifically timed I.V. infusions according to a rigid protocol established for each drug and the body weight of each patient. Research has shown that these medications are most effective when given within two hours of the onset of symptoms for heart attack or three hours for stroke. Therefore, better recognition of the signs and symptoms of these conditions could increase the number of patients who benefit from the use of clot-busting drugs.
The drugs are more likely than anticoagulants to cause bleeding problems, and errors in dosage or timing of delivery can be fatal. Because they are complicated drugs to administer, they are generally used only when the patient is in a hospital (although they could be used by emergency personnel outside the hospital). Emergency room teams must start the treatment as soon as possible, usually within a half-hour of the patient’s arrival. Treatments can remain effective for up to four hours after a heart attack or stroke.
An alternative approach to clot-busting therapy involves the use of a thin tube called a catheter. The catheter is threaded through a blood vessel to deliver the medication directly to the site of the blood clot. With this method, higher concentrations of clot busters can be used, and there may be fewer side effects than with the traditional I.V. infusion method.
Some types of clot busting drugs include:
alteplase (recombinant)
anistreplase
APSAC (anisoylated plasminogen-streptokinase activator complex)
rtPA or rt-PA (recombinant t-PA)
streptokinase
tenecteplase (TNK or TNK-tPA)
tPA or t-PA (tissue plasminogen activator)
retenplase (recombinant)
urokinase
A new type of thrombolytic medication called desmoteplase is currently being investigated for use in stroke treatment. The medication was created based on the saliva of vampire bats. While this medication will not likely be approved for general use for several years, results so far have been promise. Research has suggested that desmoteplase may be effective up to nine hours after the onset of stroke symptoms. Currently, the most commonly used clot busting medication (t-PA) needs to be given within three hours of symptoms starting to be most effective.
Researchers are also exploring the use of other medications in combination with clot busters. For instance, one study found that administering low doses of insulin along with clot busters and anticoagulants helped to decrease the inflammation of blood vessels in patients following a heart attack.
Combined therapies are also being researched, such as a study using clot busters in conjunction with stenting procedures for patients with ischemic stroke. Researchers found the combination to be beneficial in preventing or reducing damage caused by the stroke in most of the small number of patients studied.
“These findings provide evidence that clot-busting drugs can be safely used with children,” said study author Amer Alshekhlee, MD, of St. Louis University in St. Louis. “More research is needed to determine whether the drugs are as effective in preventing disability from stroke in children as they are in adults.”
The children in the study who received the therapy were older than those who did not, an average of 13 years old compared to eight years old. There were no differences in treatment regarding race, gender, or family income.
All the patients were treated in the same London medical center, where 20 percent suffered wake-up stroke. Researchers didn’t randomly assign patients to receive different treatments for comparison, which is the gold standard and, thus, a limitation of the study.
“Our study shows that administering clot-busting drugs to patients with wake-up stroke who have the same clinical and imaging features as those treated within current guidelines is feasible and safe,” Manawadu said.
Researchers analyzed information on patients who received the clot-buster alteplase, sold under the name Activase, between January 2009 and December 2010. Wake-up stroke patients received clot-busting treatments if their clinical presentation and early stroke changes on CT scan images were comparable to those treated with a known time of onset.
Both groups had similar blood pressure, blood sugar levels and scores on the National Institutes of Health Stroke Scale, which is a standardized method used by healthcare professionals to measure the level of impairment caused by a stroke.
After three months, the researchers found the wake-up stroke patients’ death rates, risk of bleeding inside the brain, and the proportion that made a good recovery were similar to those patients treated within a known 4.5 hours of stroke onset.
The American Academy of Neurology, an association of more than 25,000 neurologists and neuroscience professionals, is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer’s disease, epilepsy, Parkinson’s disease and multiple sclerosis.
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Source: American Academy of Neurology (AAN)