2018-11-05 14:24:17 来源：网络专四专八资料下载
How Safe Are KIDS' Prescription Drugs?
Drugs prescribed to children and adolescents have been much in the news lately.Health Canada has issued warnings about some drugs that both patients and physicians trusted,and it has withdrawn others from the market.What's going on?Parents should understand these complicated and confusing issues.
How Are Prescription Drugs Approved in Canada?
When a pharmaceutical company has a new drug.it applies to Health Canada for a licence to sell it.Based oninformation the company provides,including the results of clinical trials,the drug is either approved or the application is rejected.
Is There a Difference in the Way Drugs Are Approved for Children and Adults?
Normally.drugs are tested in adults first.Dr.Denis Daneman.a clinical investigator at The Hospital for Sick Children in Toronto,says,“we have to be remarkably careful because children are physiologically different than adults and are seen by physicians as a highly vulnerable group.”
What Happens Once a Drug Is Approved?
“Once approved,” explains Daneman.“it's available on the market and doctors can prescribe it for any indication they'd like to.” Even if it has not been tested specifically in children.he says.“physicians may start to use it either in small trials or what we call off-label (use of a prescription drug to treat a condition for which the drug has not been approved) in children.”
How Common Is Off-label Use?
Dr.Michael Rieder. director of the Adverse Drug Reaction Clinic at the Children's Hospital of Western Ontario,says,“drugs commonly used in children，such as antibiotcs and asthma drugs,are tested in children.” But,he says,“there is a misconception that children take only those drugs.We did a study looking at a million kids in Canada over a year.It turns out they used l,400 different drugs,of which 60 percent have not been tested,or approved for use in children.”
If a Drug Is Safe in Adults,Why Do You Need to Test It in children?
Health Canada's Dr.Siddika Mithani says.“children are not small adults.”Their physiology is different.That goes for adolescents.too.Dr.Eric Wookltorton.an Ottawa-based family physician who writes a column on adverse events for the Canadian Medical Association Journal,says,“Depo Provera is an injectable birth-control product used by women of all ages.No one thought to test it in adolescents until recently.Teenagers arelaying down bone density and this drug decreased bone density.”
Are Older Drugs Safer?
“If I were to use a medication off-label that's been around for some time,I'd be less concerned about it.” advises Dr.Peter Nieman.a Calgary pediatrician.“But if you use a medication that's being promoted as che best thing since sliced bread,and you know it's fairly new and are using it off-label,you are a bit nervous.”
How Many Side Effects Are Reported?
In 2004 Health Canada received 10,238 reports of adverse reactions in people of all ages.The number of reports has been increasing since 1999,when just under 6,000 were sent in.However.Dr.Bruce Carleton.of the pharmaceutical outcomes program at the Children's and Women's Health Centre of British Columbia，says,“95 percent of negative reactions are never reported.”Wooltorton explains:“how do you track the more minor,long-term side effects,the ones where kids are a little bit stunted in growth or they are having learning problems in school.There's no regulation and no financial incentive to report anything at all.”
Should We Be More Careful with Some Drugs?
Dr.Jack Uetrecht,a Canada Research Chair in adverse drug reactions,advises extra caution with drugs that affect the central nervous system.“The effects and long-term outcomes of giving these types of drugs aren't totally understood. Make sure the appropriate tests are given to make as clear a diagnosis as possible.and that the appropriate treatment is given based on that diagnosis.Talking to the patient for a few minutes and prescribing a drug would not be the best method.If there is a severe clinical problem and a clear clinical benefit,then the benefit is worth the risk.”