Pharmacokinetics Flashcards
What is pharmacokinetics?
What the body does to a drug.
What happens to a drug in the body is divided into 4 stages. ADME
A: Absorption from the site of administration.
D: Distribution within the body.
M: Metabolism within the body.
E: Excretion
What are the 4 movements across cell membrane.
- Diffusion through lipid
- Diffusion through aqueous channels.
- Carrier
- Pinocytosis
Diffusion through lipid is determined by what?
Permeability coefficient (P)
Drugs can be uncharged or charged. Which forms is more lipid soluble?
Uncharged or ionized
Do weak or strong acids and bases absorb best from intestines?
Weak, as they will not be ionized.
What is Bioavailability?
The fraction (F) of an orally administered drug that reaches the systemic circulation.
What is Bioequivalence?
A formulation of a drug can be substituted for another with similar clinical outcomes expected.
What is Volume of distribution? Equation?
Total amount of a drug in the body (Q or dose) divided by the plasma concentration (Cp).
Vd= Q/Cp
What are prodrugs?
Inactive precursors that activate inside the body by enzymatic processes.
Drug metabolism involves 2 kinds of reactions. What is involved in Phase I? what can it create? What compound is involved?f
Catabolic reactions like oxidation, reduction, hydrolysis. Can cause a more toxic form of the chemical. P450 enzymes are involved.
What is phase II of drug metabolism? where does this mainly take place? What can it do to a prodrug in some cases.
Anabolic reactions, which involves attachment of a chemical group to change the compound. Mainly in the liver. Can activate a prodrug.
What is first-pass metabolism?
Some drugs are metabolized so efficiently that the bioavailability is lower than absorbed dose.
What is Glomerular Filtration of drugs?
Size based filtration. Most drugs are small enough to be filtered.
What is tubular secretion of drugs?
Unfiltered drugs can be actively transported form the peritubular capillaries in the renal tubules.
