2. Clinical Pharmacokinetics And Pharmacodynamics Flashcards
What is bioavailability?
Measure of drug absorption where it can be used
What is bioavailability affected by?
Absorption - formulation, age, food, omitting/malabsorption, previous GI surgery
First pass metabolism (metabolism before reaching systemic circulation)
List some factors that can affect therapeutic agent distribution
Blood flow
Capillary structure
Lipophilicity and hydrophilicity
Protein binding - albumin, glycoproteins
What is volume of distribution equal to?
Dose/[drug]plasma
What does a smaller apparent volume of distribution suggest?
Drug is confined to plasma and extracellular fluid
What does a larger apparent volume of distribution suggest?
Drug is distributed throughout tissues
What can affect a drugs route and mechanism through metabolism?
Size
Lipophilicity
Hydrophobicity
Structural complexity
What factors can affect activity of CYP enzymes?
Increased age - decreased
Hepatic disease - decrease
Chronic alcohol - increase
Cigarette smoking - increase
What can influence CYP enzymes?
OTC/herbal preparations
Race
Sec
Species - drug development
Where are drugs in fluids eliminated from the body?
Kidney
Sweat, tears, genital secretions, saliva, breast milk
Where are drugs in solids eliminated from the body?
Faeces
Hair
Which metabolites are usually excreted via the kidney?
Low molecular weight polar metabolites
What is renal excretion of drugs affected by?
GFR and protein binding (gentamicin)
Competition for transporters such as OATS (penicillin)
Lipid solubility, pH, flow rate (aspirin)
What are drugs usually conjugated with in the liver?
Glucuronic acid
What is clearance?
Volume of blood cleared per unit time
