Bio-Availability
A drug travels from the gut into the systemic circulation through the mucosa layer of GIT.
It also gauntlet the run of enzymes that may inactivates them in GIT or liver.
Bio-availability of a drug is defined as the amount or percentage of the drug that is absorbed from the given dosage and reaches the systemic circulation after oral administration. The bio-availability of intravenous injection is 100 %.
Bio-availability of a drug is related with only the conc. of drug that reaches plasma but the rate of absorption is not taken under consideration
For example: one drug is absorbed in GIT about 45 to 60 min. so its conc. is increased more highly in blood even the time taken for absorption is more. So, the drug may not be so effective but it may cause toxicity.
So, drugs are considered as bio-equivalents as if they have same ingredient and are identical in strength, conc. and dosage form. These types of drugs also have equal Bio-availability significantly.
.png)
