Definitions
Biopharmaceutics:-
Definition:- Study of interrelationship of physio-chemical properties of drug, the dosage form in which drug is given and route of administration on the rate and extent of systemic absorption.
Factor Influencing Drug Elimination :-
Product Design
Stability
Drug Release
Absorption
Bioavailability:- Definition:- “Measurement of rate and extent of active drug that become available at the site of action is called bioavailability.”
How much drug is available for therapeutic use of site of action?
1. Absolute
When we administer drug through route other than IV we compare it with the standard for maximum
bioavailability
2. Relative
Comparison of different formulation with standard, same route
Methods to Assess Bioavailability:-
• Dissolution (In vitro)
• Animal Models (In vivo)
• Onset of Action
• Duration of Action
• Intensity
• Clinical Trails
Factor Effecting Availability of Drug
• Protein Binding
• First Pass Effect
Bioequivalence:
Pharmaceutical equivalence or pharmaceutical alternatives whose rate and extent of absorption do
not show a significant difference, when administer at same molar dose of therapeutic moiety (API)
under similar experimental conditions.
Volume of Distribution VD:-
Apparent volume in which drug is dissolved
OR
A volume that must be considered in estimating the amount of drug found in sampling compartments
Dose = Vp Cp
VD = Dose / Cp
Clearance:-
It's a measurement of drug elimination from body without identifying the mechanism or process
OR
Fixed volume of fluid, cleared of drug per unit time. (mL/min or L/hr)
Elimination:
Fixed amount of drug removed from body per unit time (mg/min or g/hr)