Some Painkillers Linked To Small Risks Of Blood Disorders
BALTIMORE (AP) _ Certain widely used prescription pain-killing drugs have been linked to a small but distinct risk of severe blood disorders, according to a study to be published Friday.
The study, a multimillion-dollar effort conducted in eight countries, shows that the risk of these disorders is, however, much lower than many have feared.
One of the drugs, dipyrone, was banned in the United States in 1968 after inconclusive evidence from England suggested that the drug had a one-in-100 chance of causing agranulocytosis, a disorder marked by a lack of granulocytes, the white blood cells that fight acute infection.
The new study found that the chances dypirone would cause the disease are one in a million per week of drug use.
The study was coordinated by Dr. Samuel Shapiro of the Boston University Drug Epidemiology Unit. Its chairman was Dr. Micha Levy of Jerusalem.
Shapiro said dipyrone is used in Europe and all the other drugs in the study are used frequently in both the United States and Europe.
Shapiro and Levy and their collaborators found that indomethacin and the class of drugs called butazones - both of which are used in the United States - also appear to cause agranulocytosis, but at even lower rates.
Indomethacin has a risk of about one case per 2 million people who take it, and for butazones the increased risk is less than one case in 4 million people.
Indomethacin and butazones were also linked to aplastic anemia, a disorder in which the bone marrow stops producing blood cells altogether.
Indomethacin use appeared to cause approximately 10 cases of aplastic anemia per million people. Butazones were responsible for about 6 1/2 cases per million, according to the study to be published Friday in the Journal of the American Medical Association.
Shapiro described the principal findings Thursday at a news briefing sponsored by the American Medical Association and the Johns Hopkins Medical Institutions in Baltimore.
Another painkiller called diclofenac sodium was also found to produce an excess of nearly 7 cases of aplastic anemia per million.
Aspirin-related drugs were found to produce only borderline increases in risks of these disorders, and acetaminophen, the principal ingredient in Tylenol, had no link to these disorders, Shapiro said.
Gerald Faich of the U.S. Food and Drug Administration said the risk of these complications is much lower, for example, than the risk of dying in an automobile accident or from smoking-related illnesses, each of which, said Faich, occur with a probability of about 250 per million.
The chances of getting these disorders as the result of taking pain-killing drugs is comparable to that of being killed by lightning, which carries a risk of about one chance in a million per year, Faich said.
Furthermore, these drugs have other more common but less severe side effects which may be much more important when doctors are deciding whether to prescribe them, Faich said.
Among these side effects are irritation and bleeding in the stomach, Shapiro said.