Pharmacokinectics Flashcards
Define pharmacokinetics.
The mathematical description of plasma concentration-time course
What are the factors for dose regimen?
1: Dosage
2: Route of administration
3: Frequency
4: Duration of administration
What are the factors for optimum dosage regimen?
1: Effective
2: Nontoxic
3: Without prolonged drug residues in tissues of food animals
Define rate of absorption.
The time to peak plasma concentration (tmax)
How is the extent of absorption measured?
By systemic bioavailability (F%)
Define systemic availability.
The fraction of the dose which reaches the systemic circulation intact
What is the formula for systemic availability?
F% = (Area under the curve X 100)/Area under the curve IV
Define compartment.
The tissues and organs for which the rates of uptake and subsequent clearance of a drug are similar
Define one-compartment model.
All tissues and organs which the drug penetrates as if they were in ready equilibrium with the blood.q
Define rate of distribution
Estimated by the distribution phase half-time (t1/2alpha) in the two-compartment model
How is the extent of distribution measured?
By the apparent volume of distribution
Define apparent volume of distribution.
The volumes of fluid which would be required to contain the amount of the drug in the body if it were uniformly distributes and the concentration in that fluid was equal to the concentration in the plasma.
Define dose IV
The amount of drug in the body
What is Vd (l/kg)?
amount of drug in the body (D)/plasma drug concentration (Cp)
What is the formula for IV the Vd (L/kg)?
Dose (mg/kg)/Cp (mg/L)
What is the formula for extravascular the Vd (L/kg)?
(D (mg/kg) X F%)/Cp (mg/L)
When Vd < 1L/kg, the drug _____.
Has a limited distribution (tends to stay in the plasma)
When Vd = 1L/kg, the drug _____.
Has a wide distribution
When the Vd > 1L/kg, the drug _____.
Has a very wide distribution