Here is My Question:
Are you aware of any studies relating to Tecfidera where the efficacy of the drug was tested at half its potency? I understand from my own searches that Biogen conducted trials at double the current recommended strength but not at half the recommended strength. Do you have any understanding about why companies conduct their trials in this way?
The common paradigm for drug testing after preclinical evaluation (ie, animal testing) is to complete Phase 1 that looks at how the body handles the investigative therapeutic (ie, the pharmacokinetics and pharmacodynamics) which helps inform potential dosing for larger trials. Phase 2 may involve dose ranging studies based on Phase 1 and the goal is to get an idea if the medication will work for the disease being studied. Phase 3 testing confirms that the medication works but also gets a better sense of safety. The first 3 phases are required for consideration of approval by the FDA. Phase 4 is post-marketing safety evaluation (longer term safety). It is not surprising that pharmaceutical companies in general will seek to test the maximally tolerated dose because the thought is "more is better". If you give too little medication and it doesn't show benefit, that means they've lost a lot of money doing the experiment with no return on their investment (ie, greater chance they couldn't get it approved by the FDA). What you are getting at is doing experiments for the "lowest effective dose". I wish that would be part of the approval process (ie, mandatory dose ranging studies), but sadly, it is not.
A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente
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