Money for old drugs

The wikipedia article on drug trial phases which indicates sizes and groups types is an interesting starter on clinical trials, and there are some links to approval and success rates.


This is a table of clinical trial approval rates at each stage:

Stage of Development               Probability of Approval

• Phase 1                                                       9%
• Phase 2                                                     15%
• Phase 3                                                    44%
• Submission                                            80%

So basically only 9% of candidate drugs make it through the phase 1 trial, so there is massive attrition. my rudimentary calculations make that if you start with 1000 phase 1 trials then 90 make it to phase 2, of those 13.5 make it to phase 3, and then .44 of those.

Hence only ~6 make it to the application for approval to the FDA (this is US data, but its broadly similar over here)



However I think its worth looking at the success rate of those trials;
Clinical Trial Phase      Probability of Success

• Phase 1                                    63%
• Phase 2                                    33%
• Phase 3                                    55%
• Approval                                 80%

I understand the "success rate" to mean "did it work", as opposed to "approval rate" as "was it safe", but I am still looking for an authoritative definition for that.

But loads of drugs have some biological effect, but can't be used because they kill you as well. (but these drugs have been tested on humans, so they are not arsenic or rat-poison etc)

Many of these problems are that the drug might work on hypertension but it also toxic, hence if some company can develop novel delivery methods to for example selectively deliver a drug to the liver or the heart, and avoid the kidneys, then loads of those "non-approvals" but "successful phase-1" drugs get another chance.

ie, the pharmas would pay a fortune, because they have cupboards full of these fucking drugs which they can't use because of the above reasons.

One technique is construct a drug with two parts, the one with the biological active site, and then make that bound to a big fat sweaty molecule that is known to be excreted by the kidneys, but not effects the target organ.

Then, badda-bing, let the cash roll in.