because it's an elimination process .... and it takes forever because different elements and compounds are used to treat that specific pathogen
Genetic disorders can have synthetic compounds designed in the lab too
After that are concerns about toxicity, attacks from the organisms antibodies etc all have to be considered...
Then tested over and over again.....with human subjects .......this takes years
You should see the pages on FDA drug approvals with the research included ...it can be bible sized
The equipment, salaries, rent and sterilization costs are high but if it pulls through