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Basic PK Definitions and
Principles

Volume of distribution (Vd)

Elimination constant (Ke) and half-life (t1/2)

“Steady state”

Loading dose
Volume of Distribution
• A proportional constant that relates the
amount of drug in the body to the serum
concentration
• If you know a drug’s Vd, you can
determine how much of the drug should
be given to achieve a desired plasma
concentration.
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Vd = Dose/CO
CONCETRATION OF
DRUG AT ZERO TIME
Co=
-If you know the dose and
the peak plasma
concentration, you can
calculate the patients Vd.
-If you know the Vd and
have a goal plasma
concentration, you can
calculate the dose
FACTORS AFFECTING THE RATE OF
DRUG DISTRIBUTION
LIPID SOLUBILITY (Kp)
2. IONISATION CONSTANT
3. MOLECULAR WEIGHT
4. BLOOD FLOW
1.
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FACTORS AFFECTING THE EXTENT
OF DRUG DISTRIBUTATION
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THANK YOU
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