Page 23 - Interactive Theoritical Notes of Bioharmaceutics and pharamcokinetics.docx compressed

PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

 Relationship between the administered dose and amount of drug in the body

✓ Only the bioavailable drug will produce the therapeutic activity

Intravenous solution Extravenous route

∞
∞
= = ( ) = = (

)
Where; Where;
∞
∞
✓ ( ) is the area under the ✓ ( ) is the area under the curve of
0
0
curve of plasma drug plasma drug concentration versus
concentration versus time (AUC) time (AUC) from time zero to time
from time zero to time infinity infinity

✓ K is the first-order elimination ✓ K is the first-order elimination rate
rate constant constant

✓ V (or V d) is the drug’s volume of ✓ V (or V d) is the drug’s volume of

distribution. distribution.
✓ F bioavailable fraction

Notes

Only that fraction of the administered dose that reaches the systemic circulation

will be available to elicit a pharmacological effect.

For an IV solution, the amount of drug that reaches general circulation is the

dose administered.

For the extravascular route, the amount of drug that reaches general circulation

is the product of the bioavailable fraction (F) and the dose administered.

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