Pharmacodynamics and kinetics Flashcards
Kinetics and Dynamics
a. intravenous drugs have bioavailability of 50%
a. False, IV drugs have 100% bioavailability
b. topical administration is a type of parenteral administration
b. False, parenteral administration results in systemic effects and topical administration will cause local effects
c. sodium bicarbonate increases the pH of the stomach
c. True, bicarb will make the stomach more basic and thus, increase the pH
d. first-pass metabolism refers to renal elimination of water soluble drugs
d. False, first pass metabolism Refers to the elimination that occurs when a drug is first absorbed from the intestine & passes through the liver via the portal circulation
e. adrenaline is a alpha-1 receptor agonist
e. True, acts on alpha and beta-adrenergic receptors
Pharmacokinetics and Pharmacodynamics
a. in first-order kinetics, the rate of elimination of a drug is constant
A. False, in first order kinetics a constant fraction of the drug in the body is eliminated. The rate of elimination is proportional amount to the drug in the body
Pharmacokinetics and Pharmacodynamics
b. a non-competitive antagonist shifts the dose response curve to the left
B. False, a non-competitive antagonist does not shift the curve. It reduces the maximal response
Pharmacokinetics and Pharmacodynamics
c. a competitive antagonist binds irreversibly to the receptor
C. False, a non-competitive antagonist binds irreversibly to the receptor
Pharmacokinetics and Pharmacodynamics
d. the higher the affinity of a drug for its receptor, the higher its potency
D. True. Affinity is the ability to bind a receptor.
Pharmacokinetics and Pharmacodynamics
e. second messengers relay signals from receptors on the cell surface to target molecules inside the cell
E. True, second messengers Relay signals received at the surface to target molecules in cytosol or nucleus
Pharmacokinetics
a. bioavailability refers to the elimination rate of a drug per unit time
A. False, bioavailability is the fraction of drug absorbed into systemic circulation
Pharmacokinetics
b. rifampicin is a cytochrome P450 enzyme inhibitor
B. False, rifampicin induces P450 enzymes
Pharmacokinetics
c. the non-ionized form of a drug readily diffuses easily across cell membranes
C. True, The un-ionized form is usually lipid soluble (lipophilic) and diffuses readily across cell membranes
Pharmacokinetics
d. lipophilic drugs have a high volume of distribution
D. True, Drugs that are highly lipid soluble, such as digoxin, have a very high volume of distribution
Pharmacokinetics
e. IV administered drugs have a higher 1st pass metabolism than orally administered drugs
E. False, IV administered drugs will have no first pass metabolism as the drug won’t pass through the GIT
Pharmacokinetics and Pharmacodynamics
a. in zero-order kinetics, the rate of elimination of a drug is proportional to the drug concentration
a. False, in zero-order kinetics a constant amount of drug is eliminated per unit time. In first order kinetics, elimination is proportional to drug in the body
Pharmacokinetics and Pharmacodynamics
b. a non-competitive antagonist binds irreversibly to the receptor
b. True
Pharmacokinetics and Pharmacodynamics
c. a competitive antagonist shifts the dose response curve to the left
c. False, a competitive antagonist shifts the dose response curve to the right
Pharmacokinetics and Pharmacodynamics
d. the higher the affinity of a drug for its receptor, the higher its potency
d. True
Pharmacokinetics and Pharmacodynamics
e. a partial agonist has less intrinsic activity than a full agonist
e. True. agonist has affinity plus intrinsic activity. partial agonist has affinity and less intrinsic activity
Pharmacokinetics
a. bioavailability (F) refers to the fraction of the dose of a drug absorbed into the systemic circulation
a. True, bioavailability (F) refers to the fraction of the dose of a drug absorbed into the systemic circulation
Pharmacokinetics
b. drugs with a high apparent volume of distribution (> 500ℓ) are confined to the plasma
b. False, increased VD means increased lipid solubility. The higher the lipid solubility. The lower the VD, the lower the lipid solubility. Decreased lipid solubility will confine a drug to the plasma.
Pharmacokinetics
c. a greater proportion of an acidic drug is in its unionized form in an acidic medium
c. True, acidic drugs will be unionized in an acidic medium
Pharmacokinetics
d. topically administered drugs undergo first-pass metabolism in the liver
d. False, topically administered drugs will not pass through the GIT
