How shelf life of a drug is fixed?

Answer 1

That is a good question! The scientists do the chemical testing of the drug periodically. Some drugs start to degrade faster than others. They have short shelf life. The product of degradation may be harmless or harmful. Depending on this the scientists probably decide the shelf life of the drug. The drug is declared as expired by the time it looses ten percent efficacy, probably. Some drugs do not expire and then they are declared as expired at the end of five years. So you have expiry of sodium chloride, potassium chloride and sterile water by five years in most countries. Though they can not expire.