A Disturbing Reality: How Prescribed Doses are Determined for New Drugs
Posted by Adrienne Choma on Tue, Jul 05, 2011 @ 01:10 PM
Do you know how pharmaceutical companies determine the prescribed dose for new drugs? It’s really pretty scary! The maximum tolerated dose (MTD) for a new cancer drug is established in Phase I clinical trials, often using the Fibonacci 3+3 Schema.
It works like this: First, several dosing levels are targeted by the pharmaceutical company for testing. Three patients are administered the new drug at each of these targeted dosing levels. If one of the three patients at any dose level displays undue toxicity, an additional three patients are administered the drug at the same dose. If one of the three new patients again displays high toxicity, the next lower dosing level being tested in the Phase I clinical trial becomes the recommended dose.
What this means is that the recommended dose of a new drug can be established on the basis of testing only six patients!
Given that there can be more than a 10-fold variability in drug blood levels of patients receiving the identical dose of a chemotherapy drug, this hardly seems justifiable or clinically sound. It can also help explain why cancer drugs are not as effective in combating disease as they could be. The pharmaceutical industry offers us a lot of beneficial drugs – but often, they can be more effective if dosed correctly to meet the needs of the individual patient. The body of knowledge in pharmacokinetics and newly available dose monitoring tools are now available to make personalized dosing a reality for better patient care.
Adrienne Choma, Vice President, Marketing & Sales