Most of the information doctors receive about prescription drugs comes from the companies making the product, a doctor said Wednesday, pointing to a possible reason doctors continue to prescribe dangerous drugs to seniors.

Dr. John Haggie, a Canadian Medical Association board member who chairs its ad hoc working group on pharmaceutical issues, said government warnings often get lost in the stack of documents physicians routinely receive.

"The average physician is bombarded with written and faxed material in the course of a week.… [Government warnings] tend to get buried sometimes in the noise," Haggie said in an interview with CBC News from Gander, N.L., on Wednesday.

Two years ago, CBC first reported more than a million seniors were being prescribed dangerous drugs, including atypical antipsychotics, which are considered by many experts to be ineffective and even dangerous for elderly patients.

Health Canada then issued a warning about atypical antipsychotics and their greater risk of death for elderly patients. The warning cautioned physicians against relying heavily on the drugs to treat dementia.

Many atypical antipsychotics, which include drugs such as risperidone (Risperdal), quetiapine (Seroquel), olanzapine (Zyprexa) and clozapine (Clozaril), have never been tested on seniors.

They are intended to treat severe mood disorders, symptoms of schizophrenia and bipolar disorder in adults under 65.

But despite the warning, the number of such prescriptions for seniors has since shot up by as much as 40 per cent in some cases.

Haggie warned there is a lack of impartial information available to doctors.

"Most of the information the physician would receive in the general course of a week on medication by and large tends to come from material from drug companies," he said.

Drug companies have an active sales and marketing team, he said, and they follow Health Canada warnings by issuing their own.

Health Canada warnings are sent out to physicians by fax, e-mail and mail, but are often one among many documents received.

Haggie said the CMA is trying to work with the academic community to provide doctors with unbiased education material to replace documents received from drug companies.

The association is also trying to get tools on its website so doctors can quickly access the latest peer-reviewed information on what drugs are safe and which need to be used with caution.