61 out of 75
All of the following statements regarding bioavailability of a drug are true except:
|A||It is the proportion (fraction) of unchanged drug that reaches the systemic circulation|
|B||Bioavailability of an orally administered drug can be calculated by comparing the Area Under Curve after oral and intravenous(iv) administration|
|C||Low oral bioavailability always and necessarily mean poor absorption|
|D||Bioavailability can be determined from plasma concentration or urinary excretion data)|
Ans. C i.e. Low oral bioavailability always and necessarily means poor absorption.
Term bioavailability is used to indicate the proportion of unchanged drug that passes into the systematic circulation after oral administration, taking into account both absorption and local metabolic degradation.
- Bioavailability is determined by the area under the plasma concentration time curve.
- Area under the curve of an orally administered drug when compared to the area under the curve for an IV administered drug (100%) can certainly give an idea of its bioavailability. Bioavailability of IV route is 100% and that of IM is less than that. Bioavailability of SC is in between IV and IM.