First I would like to thank you for your great blog which is extremely helpful. I am a medical school student and I was doing some research on the documentation of Merck for approval of Propecia. Some data which was submitted to FDA brought my interest toward these documents. [Link: PDF file]
As you can see in the link above there are some figures regarding the DHT in scalp as well at T serum. I can see clearly that 0.05mg of finasteride would significantly lower T and DHT levels in scalp while this dosage does not effect the hormone levels as much in the rest of the blood (although the numbers are lower for 0.05mg,but still they are very close to 1mg and look very effective). Now my question to you is that why aren’t we using 0.05mg dosage instead of 1mg? 1mg finasteride seems to lower DHT and T levels a lot more in the blood which causes uncomfortable side effects; and we also know that once we lower 1mg to 0.5 (half a pill) or 0.25mg the side effect tend to subside, so we do know that the side effects of finasteride are dosage dependent.
Also I would like to add that I am at one of the UC system medical schools and we have been running and experiment on MPH sufferers and so far (within 1.5 years of our study) we have been successful up to 88.5% to get the same results of finasteride 1mg by using 0.2mg dosage on 749 men. unfortunately I am not allowed to release more information about out experiment, but the results are very convincing and our study will continue for another 3-5 years on these patients.
It has been known that a 1/2 dose of Propecia (finasteride 0.5mg) and even 1/10 dose (finasteride 0.1mg) showed efficacy on androgenic alopecia. I am aware of the study you’re referencing, and we’ve written in the past about how the 1/2 dose of Propecia is about 80% as effective as the full dose. So I believe your study! I do wonder why your school would be conducting a study that has already been published and established or why you would not be able to publish your results. I must not have all the story here.
I would say in the real world many patients with side effects elect to take 1/2 dose Propecia and see benefits for their hair. It is my understanding the 1mg finasteride was chosen for Propecia to give maximum benefits for a wide percentage of the general population while maintaining the lowest side effect profile balance. You said yourself, 88.5% get same results on 0.2mg finasteride. Maybe Merck wanted that number a bit higher for the general public.
I would be curious to know the reduction in side effects from 1mg to 0.2mg. If the reduction was not significant then I could understand why a drug company would choose the 1mg option. I do not know if this is what really happened, but it is my speculation and logical guess. Perhaps you should find this information or add it to your experiment/research and publish the data. Good luck!