Practical constraints. The main contributor to the cost of a lifespan study is the cost of upkeep for the mice—so it’s proportional to number of mice and length of the study. Testing 50 compounds at once means raising 50x the money at once (which is out of reach at the moment) and may also run into constraints of the capacity of labs/CROs.
What’s the point in testing them individually? Why not simply do a multivariate test with all 50 compounds?
Practical constraints. The main contributor to the cost of a lifespan study is the cost of upkeep for the mice—so it’s proportional to number of mice and length of the study. Testing 50 compounds at once means raising 50x the money at once (which is out of reach at the moment) and may also run into constraints of the capacity of labs/CROs.