Fat Rats for Fat Cats

Just how representative of people are lab animals?

According to New Scientist’s Mark Mattson, there is a problem with pharmaceutical drug testing–and it is not lack of integrity. It is the use of fat rats and mice. Basically, he points out that lab animals are “couch potatoes”. They eat as much as they like, whenever they like, and rarely get any exercise. The result is that they develop typical obesity-related illnesses: high blood pressure, diabetes, kidney disease, low self-image (ok we made that one up).

Mr. Mattson then points out that the effect of a chemical differs depending on the recipient. For example, some cancer-causing agents are more potent in pudgy rats than in their more svelte counterparts. Therefore, the routine use of unhealthy animals may lead to spurious results in drug testing.

This is where there may be a problem. After all, Colorado is the only state in our country that boasts of an obesity rate of less than 20%. In comparison, about half a dozen states have an obesity rate of over 30% (CDC statistics). So, maybe we should have separate drug testing–on obese rats for those medications to be used on overweight individuals and on healthier rats for those medications to be targeted to a slimmer population. But then, what about using female rats for females and rats who like beer for those who like beer? It quickly becomes a rather unwieldy proposition. And, let’s face it, totally healthy people rarely need to use medicine anyway!

Maybe this is why medications undergo clinical trials before they are released onto the market? First, as Phase I, their safety is ascertained in healthy volunteers. In Phase II, the drug is given to patients with the condition of interest, again testing for safety, but also for the best dosage, drug efficacy, and more. Finally, the drug undergoes Phase III testing in a large group of patients (>1000). It is usually only after this that the drug is approved by the FDA. The final phase (IV) is conducted after release of the drug to monitor long-term or unexpected effects. Therefore, as long as the results are reported accurately, the original fat rats may not really matter.