FDA or any regulatory authority takes Safety first approach when dealing with drugs. They do not want to risk any human lives. Hence, a drug is studied in several hundreds if not thousands of patients before it is approved. That one thing that FDA looks into before it lets companies test drugs in humans is “Safety” of the drug.
How is it that FDA do not want to give approval before testing it in patients and how is it that they do not want to risk human lives? Aren’t they risking by testing drugs on humans in the first place without knowing how it behaves in humans? Sounds like a chicken and egg problem?
Not really!
Luckily, there is a work around to understand whether a drug is going to be safe or not before we can test it in human subjects. To understand those safety aspects of drug, companies test drugs in petridish and in animals (mice, rats, hamsters, dogs, monkeys etc). This part of testing is called Non-clinical testing.
As part of non-clinical testing, we get a preliminary understanding about drug in the following aspects:
- Whether a drug has intended effect or not – This translates to Pharmacology in technical terms.
- Whether a drug will affect any of the important physiological systems in the body (like Respiratory system, cardiovascular system and Nervous system) – This translates to Safety Pharmacology in technical terms.
- How is drug traveling inside the body and how is it going out – This translates to Pharmacokinetics that includes absorption, distribution, metabolism and excretion.
- Whether a drug shows any toxicity – This translates to Toxicology.
At the end of these preliminary non-clinical studies, scientists understand how much amount of drug is required to show intended effect and still be safe enough. Obviously, given the size and nature of human bodies, the amount of drug that is safe and effective enough in animals will not be same to show similar effect in humans. So, scientists use several factors to calculate the amount of drug that would be safe to start testing in humans (called as Human Equivalent Dose in technical terms).
Even after getting an understanding of human equivalent amount of drug that is safe, FDA suggests to start testing on humans with one tenth the amount of drug and slowly increase that amount as you gain better understanding of drugs in the human subjects.
Note: If you are interested in learning from FDA guidances about these aspects, look into these two documents.
