Question

different between shelf half life and half life

Answer 1

Shelf Life - the time period from when the product was manufactured to it’s ‘expiry date’ -i.e. The time period the product is expected to be safe , effective and fit-for-purpose provided it has been packaged and stored in recommended conditions throughout this period. Shelf life: Time that something (e.g. food, batteries) can stay good in storage, unused (aka on the shelf). This is a rough estimate that depends on various conditions (e.g. temperature, humidity).

Half-life. This is usually a reference to the time taken for the body to eliminate 50% of the dose of drug after the time of administration. It varies with different drugs and between individual patients but ‘average’ half-lives’of drugs may be found in the literature. E.g. Most penicilllins - half lives around 20 mins , digoxin ( a heart medication) - half life = 36 hours - both assume normal kidney function etc. Half life: Time that something unstable (e.g. radioisotope) takes to decay to half its previous quantity. This is a physical constant for every item having this property.