PHARMACOLOGY MCQ AND NPC EXAM DAILY SERIES 23

 NPC EXAM DAILY SERIES

[GENERAL PHARMACOLOGY QUESTIONS]

PHARMACOLOGY MCQ AND NPC EXAM DAILY SERIES

1. All of the following are general

mechanisms of drug permeation except:

(a) Aqueous diffusion

(b) Aqueous hydrolysis

(c) Lipid diffusion

(d) Pinocytosis or endocytosis

2. If the plasma concentration of a drug

declines with “first-order kinetics”, this

means that: 

(a) There is only one metabolic path for drug disposition

(b) The half-life is the same regardless of the plasma concentration

(c) The drug is largely metabolized in the liver after oral administration and has low bioavailability elimination

(d) The rate of climination is proportionate to the rate of administration at all times

3. Regarding termination of drug action: 

(a) Drug must be exerted from the body to terminate their action

(b) Metabolism of drugs always increases their water solubility

(c) Metabolism of drugs always abolishes their pharmacologic activity

(d) Hepatic metabolism and renal excretion are the two most important mechanisms involved

4. Distribution of drugs to specific tissues

(a) Is independent of blood flow to the organ

(b) Is independent of the solubility of the drug in that tissue

(c) Depends on the unbound drug concentration gradient between blood and tissue

(d) Is increased for drugs that are strongly bound to plasma proteins

5. A physical process by which a weak acid becomes less water-soluble and more lipid-soluble at low pH is

(a) Distribution 

(b) Elimination

(c) First-pass effect

(d) Protonation

6. Dose-response curves are used for drug evaluation in the animal laboratory and in the clinic, Quantal dose-response curves are often

(a) Used for determining the therapeutic index of a drug

(b) Used for determining the maximal efficacy of a drug

(c) Invalid in the presence of inhibitors of the drug being studied

(d) Obtained from the study of intact subject but not from isolated tissue preparations

7. The following are excreted faster in basic urine

(a) Weak acids 

(b) Strong acids

(c) Weak Bases 

(d) None of the above

8. Which of the following statements about spare receptors is most correct ?

(a) Spare receptors, in the absence of drug, are sequestered in the cytoplasm

(b) Spare receptors will be detected if the intracellular effect of drug-receptor interaction lasts longer than the drug-receptor interaction itself

(c) Spare receptors influence the maximal efficacy of the drug-receptor system

(d) Spare receptors activate the effector

machinery of the cell without the need for a drug

9. Which of the following  terms best

describes an antagonist that interacts

directly with the agonist and not at all or only incidentally, with the receptor ?

(a) Pharmacological antagonist

(b) Partial agonist

(c) Physiological antagonist

(d) Chemical antagonist

10. Which of the following  terms best

describes a drug that blocks the action of epinephrine at its receptors by occupying those receptors without activating them ?

(a) Pharmacological antagonist

(b) Partial agonist

(c) Physiological antagonist

(d) Chemical antagonist                               

11. Which of the following provides information about the variation in sensitivity of the drug within the population studied ?

(a) Maximal efficacy

(b) Therapeutic index

(c) Drug potency

(d) Quantal dose-response curve

12. Which of the following most accurately describes the transmembrane signaling process involved in steroid hormone action ?

(a) Action on a membrane spanning tyrosine kinase

(b) Activation of a G protein which activates or inhibits adenyl cyclase

(c) Diffusion into the cytoplasm and binding to an intracellular receptor

(d) Diffusion of “STAT” molecules across the membrane

13. Which of the following is a phase II drug metabolizing reaction ?

(a) Acetylation 

(b) Deamination

(c) Hydrolysis 

(d) Oxidation

14. Which of the following drugs may inhibit the hepatic microsomal P450 responsible for warfarin metabolism:

(a) Cimetidine 

(b) Ethanol

(c) Phenobarbital 

(d) Procainamide

15. With regard to clinical trials of new drugs, which of the following is most correct ?

(a) Phase I involves the study of a small number of normal volunteers by highly trained clinical pharmacologists

(b) Phase II involves the use of the new drug in a large number of patients (100-5000) who have the disease to be treated

(c) Phase III involves the determination of the drug’s therapeutic index by the cautious induction of toxicity

1. What are the general mechanisms of drug permeation?

Drug permeation occurs through aqueous diffusion, lipid diffusion, and pinocytosis (endocytosis). Aqueous hydrolysis is not a mechanism of permeation.

2. What does "first-order kinetics" mean in drug elimination?

In first-order kinetics, the half-life remains constant, meaning that a fixed percentage of the drug is eliminated per unit of time, regardless of concentration.

3. How is drug action terminated in the body?

Termination of drug action primarily occurs through hepatic metabolism and renal excretion, although metabolism does not always inactivate a drug.

4. What factors affect the distribution of drugs in the body?

Drug distribution depends on blood flow to tissues, the solubility of the drug, and the unbound drug concentration gradient between blood and tissue.

5. How does pH affect drug solubility?

At low pH, a weak acid becomes less water-soluble and more lipid-soluble due to protonation, making it easier to cross cell membranes.

6. What is the purpose of quantal dose-response curves?

Quantal dose-response curves are used to determine the therapeutic index of a drug and assess variations in drug sensitivity across a population.

7. Which types of drugs are excreted faster in basic urine?

Weak acids are excreted faster in basic (alkaline) urine due to increased ionization, reducing their reabsorption in the renal tubules.

8. What are "spare receptors" in pharmacology?

Spare receptors are extra receptors that allow a maximal drug response even when not all receptors are occupied, often due to a long-lasting intracellular effect.

9. What is a chemical antagonist?

A chemical antagonist interacts directly with an agonist, neutralizing it without involving receptors (e.g., chelating agents that bind heavy metals).

10. What is a pharmacological antagonist?

A pharmacological antagonist blocks a receptor without activating it, such as beta-blockers that prevent epinephrine from binding to beta-adrenergic receptors.

11. What provides information about variations in drug sensitivity in a population?

The quantal dose-response curve shows how drug responses vary within a population, helping determine safety margins.

12. How do steroid hormones signal inside cells?

Steroid hormones diffuse into the cytoplasm and bind to intracellular receptors, which then interact with DNA to regulate gene expression.

13. What is a Phase II drug metabolism reaction?

Acetylation is a Phase II reaction where drugs are conjugated with acetyl groups, making them more water-soluble for excretion.

14. Which drug inhibits the hepatic microsomal P450 enzyme system?

Cimetidine inhibits P450 enzymes, potentially increasing the plasma concentration of drugs like warfarin.

15. What happens in the different phases of clinical drug trials?

Phase I: Small group of healthy volunteers to assess safety.
Phase II: Patients with the disease (100-5000) to test efficacy and side effects.
Phase III: Large-scale trials to confirm effectiveness and monitor adverse effects before FDA approval.