Pharmacodynamics describes the effect of drugs quantitatively in order to determine _______________.
A. efficacy
B. potency
C. toxicity
D. All of the above are correct.
Which of the following statements is correct with respect to the relationship between drugs and their receptors?
A. The first step in initiating a drug-induced effect is the formation of a complex between the drug and a cell component known as the drug receptor.
B. Drug receptors may be metabolic or regulatory enzymes or co-enzymes; proteins or glycoproteins associated with transport mechanisms; and structural and functional components of lipid membranes or nucleic acids.
C. The molecular events that follow drug-receptor interactions are called the mechanisms of action of drugs.
D. All of the above are correct.
Which of the following statements is correct with respect to the relationship between drugs and their affinity for their receptors?
A. Drugs attach to their receptors by covalent, ionic, hydrogen, hydrophobic, and Van der Waals binding.
B. The affinity of a drug for a particular receptor and the type of bond formed is intimately related to the drug’s chemical structure.
C. Affinity is expressed as the drug’s dissociation constant (Kd ), i.e., the concentration of the drug required in solution to achieve 50 percent occupancy of its receptors.
D. All of the above are correct.
Which of the following types of chemical bonding is the least likely to be involved in a drug-receptor interaction?
A. Covalent bonding
B. Hydrogen bonding
C. Electrostatic bonding
D. Van der Wall’s forces
Which of the following statements is correct with respect to a drug, which has a direct stimulatory effect on a receptor?
A. A strong agonist produces a significant physiologic response when only a relatively small number of receptors are occupied, i.e. the drug has good intrinsic activity.
B. A weak agonist must be bound to many more receptors to produce the same effect, i.e., the drug has low intrinsic activity.
C. A partial agonist will never produce the same effect as a strong or a weak agonist even when all receptors are occupied, i.e., the drug has very low intrinsic activity.
D. All of the above are correct.
All of the following statements related to antagonists are correct EXCEPT which one?
A. An antagonist interacts with the agonist-binding domain of a receptor and blocks the agonist from interacting with it.
B. A chemical antagonist either alters the Kd for the agonist or inhibits the receptor from responding to the agonist.
C. A reversible antagonist binds to the agonist-binding domain of the receptor, but high concentrations of the agonist can overcome the antagonism.
D. An allosteric antagonist binds to a receptor at a site other than the agonist-binding domain and produces a conformational change in the receptor.
Which of the following statements is correct with respect to the efficacy of a drug?
A. The magnitude of a physiological/pharmacological response obtained from optimal receptor occupancy by a drug reflects its efficacy.
B. The graded dose-response relationship is the quantification of a specific response elicited by a drug over a range of dosages.
C. The dose of a drug that produces maximal effect (Emax ) is the ceiling dose of that drug.
D. All of the above are correct.
Which of the following statements is correct with respect to a drug’s potency?
A. Potency of a drug is defined as that concentration at which the drug elicits 50 percent of its Emax , i.e., EC50 .
B. Potency reflects the affinity of a drug to its receptor as well as its intrinsic activity.
C. The concept of potency is important in determining drug dosage.
D. All of the above are correct.
The Therapeutic Index of a drug is defined as the _______________.
A. median effective dose (ED50 ) of the drug
B. LD1 /ED99
C. the ratio of LD50 /ED50
D. the therapeutic window of the drug
There are several mechanisms by which drugs translocate across biological membranes, but the most important one is _______________.
A. active transport
B. facilitated transport
C. passive diffusion
D. pinocytosis
Primary determinants of passive diffusion include the drug’s _______________.
A. molecular weight
B. concentration gradient
C. pKa and lipid solubility
D. All of the above are correct.
Which of the following statements related to the dissociation constant (pKa) is correct?
A. The pKa is that pH at which a drug is 50% ionized and 50% unionized.
B. When the pH of the environment is increased above the pKa of a weak acid, over 50% of the drug will be ionized.
C. When lidocaine with a pKa of 7.9 is deposited into an infected (acidic) milieu more than 50% of its molecules will be ionized.
D. All of the above are correct.
Which of the following is an example of an enteral route of drug administration?
A. Oral
B. Sublingual
C. Subcutaneous
D. Intramuscular
All of the following statements related to plasma protein binging of drugs are correct EXCEPT which one?
A. Only the free form of a drug is capable of diffusion, plasma protein binding reduces a drug’s availability to cross biological membranes.
B. Albumin is the most abundant protein in plasma and it is responsible for most plasma protein binding of drugs.
C. Highly protein bound drug have a high volume of distribution (Vd ).
D. Plasma protein binding is also an important mechanism for drug-drug interactions.
All of the following statements relate to metabolism/biotransformation are correct EXCEPT which one?
A. Phase I reactions are mediated by the hepatic microsomal CYP450 enzyme system and involve metabolic modification of a drug by oxidation and reduction.
B. In Phase II reactions drugs are either hydrolyzed or conjugated to endogenous macromolecules.
C. Phase II reactions can be “induced” to increase or reduce the rate of a drug’s metabolism and is responsible for many drug-drug interactions.
D. There is much genetic variability (polymorphism) with the CYP450 enzyme system.
Renal excretion may involve _______________.
A. glomerular filtration which depends on fractional plasma protein binding and filtration rate
B. active tubular excretion, a non-selective carrier system for organic ions
C. passive tubular reabsorption of unionized drugs, which result in net passive reabsorption
D. All of the above are correct.
All of the statements relative to the excretion of drugs are correct EXCEPT which one?
A. Most drugs are excreted by zero-order kinetics.
B. First-order kinetics implies that a constant fraction of the drug is eliminated per unit time.
C. Zero-order kinetics, implying that a constant amount of the drug is eliminated per unit time.
D. Zero-order kinetics tend to predominate in overdose as a result of saturation of metabolic and/or elimination pathways.
All of the following statements about drug clearance and/or dosing requirements are correct EXCEPT which one?
A. Following drug administration, the initial rapid clearance of the drug from the vascular compartment reflects the distribution of the drug to various tissues.
B. The time it takes to distribute 50% of a drug from the circulation throughout the body is the drug’s distribution half-life (t1/2 ).
C. The time required for metabolizing and clearing 50 percent of the drug from the body is the drug’s elimination half-life (t1/2 ).
D. The distribution half-life (t1/2 ) determines the dosing interval.
Assuming first-order kinetics, _______________.
A. dosage intervals shorter than the drug’s elimination half-life lead to steady-state concentration (accumulation) of the drug in approximately four half-lives
B. at steady-state concentration, the rate of drug administration is equal to the rate of drug clearance
C. after the administration of a single dose or the last dose of a drug, it will take approximately four half-lives to eliminate the drug from the body
D. All of the above are correct.
All of the following statements about drug dosing are correct EXCEPT which one?
A. Steady-state plasma concentration of a drug may be achieved faster than four half-live by the administration of an initial loading-dose (LD).
B. By convention, the LD is four times the usual dose.
C. When administering a LD caution must be exercised because too high a dose may cause adverse effects.
D. After the administration of an initial LD, the dose recommended to maintain optimal therapeutic levels is defined as the maintenance dose (MD) of the drug.
