Most people assume that doctors prescribe drugs based on how they will help their patients. Some doctors, however, prescribe drugs that, while they might help their patients, also help the doctor reap big cash payments from drug manufacturers.

Some recent reports suggest some doctors have prescribed drugs in dosages that may actually harm the patients, while making the doctors' bank accounts healthier.

The increasingly cozy — and troubling — relationship between big pharmaceutical companies and doctors is illustrated in a recent New York Times story revealing that some doctors have earned millions of dollars in payments from Amgen and Johnson & Johnson, manufacturers of particular anemia drugs (Aranesp, Epogen and Procrit) that are often prescribed to people undergoing cancer treatments or dialysis.

The newspaper report revealed that a single practice in the Pacific Northwest with six cancer doctors made $2.7 million for prescribing $9 million worth of Amgen's drug.

One of the larger dialysis chains in the U.S. earns about 25 percent of its revenue from money paid by drug companies for prescribing their particular anemia drugs.

The federal Food and Drug Administration reported recently that there is no evidence that the drugs improve the quality of life or extend the patients' survival. The FDA also reported that some studies suggest that the drugs can actually shorten patients' lives, when given in higher doses.

Yet, the arrangment with the drug manufacturers rewards doctors for prescribing the drug. More prescriptions and higher doses mean more money for the doctors.

The payments are legal. But given the potential for distorting a doctor's motivation for prescribing the most effective drug and dosages — to the most profitable drug for the doctor — suggests the generally secretive practice should be banned.

The Miami Herald reports that federal law prohibits such payments for drugs sold in pill form that are purchased at a pharmacy, but not for drugs that are administered intravenously in a doctor's office.

That loophole should be closed.

The drug market is highly competitive — and highly profitable. Doctors certainly need to be informed by drug companies about the effectiveness (and potential side effects) of the drugs they are prescribing. But they should not be paid to prescribe one drug over another.

The decision to prescribe medicine should be based solely on what's best for the patient. Financial considerations for the doctor should not be part of the decision.