Pharmacology MCQS Set 2
26. Posology deals with;
A. Weighing and measuring of drug
B. Dose and dosage
C. Metabolism of drugs
D. Development of drug
Correct Answer: (B) Dose and dosage
Explanation: Posology is the branch of pharmacology that studies drug dose and dosage; it is concerned with the amount of medication required to produce a therapeutic effect.
27. Ice burge theory explains the mode of action of;
A. Local anesthetics
B. All general anesthetics
C. Volatile general anesthetics
D. a and b
Correct Answer: (A) Local anesthetics
Explanation: The Iceberg theory (or pH-partition hypothesis) is used to explain how the non-ionized form of a Local Anesthetic penetrates the nerve sheath and enters the axon, where it becomes ionized to block the sodium channels.
28. Penicillin gives their bactericidal action due to;
A. Inhibition of protein synthesis
B. Inhibition of nucleic acid synthesis
C. Inhibition of cell wall synthesis
D. Inhibition of cell membrane synthesis
Correct Answer: (C) Inhibition of cell wall synthesis
Explanation: Penicillins (and cephalosporins) are beta-lactam antibiotics that exert their bactericidal action by interfering with the synthesis of peptidoglycans, leading to the Inhibition of cell wall synthesis.
29. Sulfonamide give their bacteriostatic action due to;
A. Protein synthesis inhibition
B. Competing antimetabolite
C. Cell wall synthesis inhibition
D. nucleic acid synthesis inhibition
Correct Answer: (B) Competing antimetabolite
Explanation: Sulfonamides are structural analogs of PABA. They exert their bacteriostatic action by acting as a Competing antimetabolite to inhibit the enzyme dihydropteroate synthase, disrupting folic acid synthesis in bacteria.
30. Tachyphylaxis develops;
A. Over days
B. Over weeks
C. Within minutes
D. Over Years
Correct Answer: (C) Within minutes
Explanation: Tachyphylaxis is a phenomenon where the body develops a rapid, acute decrease in response to a drug after its initial administration, sometimes occurring Within minutes or hours (acute tolerance).
31. Tolerance to drug may develop due to;
A. Increase rate of metabolism of drug
B. Decrease rate of metabolism of drug
C. Decrease in the excretion of drug
D. Impaired excretion of drug
Correct Answer: (A) Increase rate of metabolism of drug
Explanation: Pharmacokinetic tolerance can develop when a drug induces its own hepatic microsomal enzymes (e.g., CYP450). This leads to an Increase rate of metabolism of the drug, lowering its plasma concentration and reducing its effect.
32. Tachyphylaxis may develop due to;
A. Increase rate of metabolism of drug
B. Exhaustion of mediators
C. Decrease rate of metabolism of drug
D. All of the above
Correct Answer: (B) Exhaustion of mediators
Explanation: A common mechanism for Tachyphylaxis is the rapid depletion or Exhaustion of chemical mediators (e.g., norepinephrine stores) that the drug relies upon for its indirect action.
33. Acetylcholine is a chemical mediator at;
A. Sympathetic nervous system
B. Parasympathetic nervous system
C. None of the above
D. All of the above
Correct Answer: (D) All of the above
Explanation: Acetylcholine is the primary neurotransmitter for the entire Parasympathetic nervous system, the pre-ganglionic neurons of the Sympathetic nervous system, and the somatic nervous system (neuromuscular junction). Therefore, it is involved in All of the above options (A and B).
34. Prontosil is reduced to ___________ in the body;
A. Aryl amine
B. Acetate
C. Sulfanilamide
D. Sulfamethazone
Correct Answer: (C) Sulfanilamide
Explanation: Prontosil is a prodrug. It is inactive itself but is reduced in the body (by azo reductases) to the active antibacterial compound, Sulfanilamide.
35. Acetate and choline are metabolite of;
A. Nor epinephrine
B. Neostigmine
C. Acetylcholine
D. Epinephrine
Correct Answer: (C) Acetylcholine
Explanation: Acetylcholine is rapidly metabolized and terminated in the synapse by the enzyme acetylcholinesterase, which hydrolyzes it into its two inactive components: Acetate and choline.
36. Chloral hydrate is converted into ______ by the liver which is an active metabolite;
A. Butanol
B. Trichloroethanol
C. Trichloroacetic acid
D. All of the above
Correct Answer: (B) Trichloroethanol
Explanation: The hypnotic drug Chloral hydrate is metabolized by the liver into the active compound Trichloroethanol, which is responsible for most of its sedative effects.
37. Glucuronide conjugation is missing in;
A. Cat
B. Dog
C. Pig
D. Horse
Correct Answer: (A) Cat
Explanation: The Cat (feline species) exhibits a genetic deficiency in the enzyme Uridine Diphosphate (UDP)-glucuronosyltransferase, making Glucuronide conjugation low or deficient. This significantly impairs the metabolism of many drugs and toxins.
38. Sulfate conjugation is of low level in;
A. Cat
B. Pig
C. Dog
D. Horse
Correct Answer: (B) Pig
Explanation: The Pig has a notable deficiency in the enzyme required for Sulfate conjugation, one of the key Phase II metabolic reactions.
39. Sulfonamide are metabolized in the body by the reaction;
A. Oxidation
B. Reduction
C. Acetylation
D. All of the above
Correct Answer: (C) Acetylation
Explanation: The primary Phase II metabolic reaction for Sulfonamides is Acetylation, catalyzed by N-acetyltransferase. This process can sometimes lead to metabolites that are less soluble and may precipitate in the renal tubules (crystalluria).
40. Drug allergy refers to those situations in which unusual response is due to;
A. Over dose
B. Wrong rout of administration
C. Antigen-antibody reaction
D. Hypersensitivity
Correct Answer: (C) Antigen-antibody reaction
Explanation: A Drug allergy is specifically an adverse immune response mediated by the body’s immune system, which recognizes the drug (or a metabolite) as a foreign substance (antigen) and mounts an Antigen-antibody reaction (Type I – IV hypersensitivity).
41. Histamine is stored in the following cell in the body;
A. Epithelial cells
B. Eosinophils
C. Mast cells and basophils
D. Plasma cells
Correct Answer: (C) Mast cells and basophils
Explanation: Histamine is synthesized and stored primarily in the granules of Mast cells and basophils throughout the body’s tissues and blood.
42. Idiosyncrasy is attributable to;
A. Immunological basis
B. Genetic abnormality
C. Over dose of a drug
D. Resistance to drug
Correct Answer: (B) Genetic abnormality
Explanation: Idiosyncrasy is an abnormal, often peculiar, drug response that is qualitatively different from the typical pharmacological effect, usually occurring at therapeutic doses. It is typically attributed to an underlying Genetic abnormality (pharmacogenetics) affecting drug metabolism or receptor function.
43. Biotransformation facilitates the excretion of drugs by changing them into;
A. More ionized and less lipid soluble
B. Less ionized and more lipid soluble
C. More ionized and more lipid soluble
D. less ionized and less lipid soluble
Correct Answer: (A) More ionized and less lipid soluble
Explanation: To be readily excreted by the kidney, a drug must be less easily reabsorbed from the renal tubules. This is achieved by converting the drug into a compound that is More ionized and less lipid soluble (more polar).
44. Basic nitrogenous substances available in plants are exploited for their pharmacological actions are known as;
A. Tannins
B. Glucoside
C. Alkaloids
D. Saponins
Correct Answer: (C) Alkaloids
Explanation: Alkaloids are a large group of naturally occurring organic compounds found in plants that contain at least one nitrogen atom in a heterocyclic ring. They are often basic in nature and possess pronounced pharmacological activities (e.g., morphine, atropine, cocaine).
45. Styptics are used to prevent;
A. Minor hemorrhages
B. Clotting of blood
C. Perfuse hemorrhages
D. Major hemorrhages
Correct Answer: (A) Minor hemorrhages
Explanation: Styptics (or hemostatics) are topical agents that cause local vasoconstriction or promote coagulation when applied to small cuts or wounds, used to prevent Minor hemorrhages (bleeding).
46. Oxidative reactions are called;
A. Synthetic reaction
B. Non synthetic reaction
C. Conjugation reaction
D. Acetylation reaction
Correct Answer: (B) Non synthetic reaction
Explanation: Oxidative reactions are classified as Phase I reactions in drug metabolism. Phase I reactions (Oxidation, Reduction, Hydrolysis) are collectively referred to as Non synthetic reactions, as they do not involve the addition of a molecule (conjugation).
47. When a drug potentiates or complements the action of other drug the phenomenon is called;
A. Antagonism
B. Drug interaction
C. Synergism
D. Summation
Correct Answer: (C) Synergism
Explanation: Synergism occurs when the combined effect of two drugs is greater than the sum of their individual effects ($\text{1} + \text{1} > \text{2}$). This means one drug potentiates or complements the action of the other.
48. The substances added to a dosage form in addition to active ingredients are called;
A. Inert
B. Excipient
C. Recipient
D. Polar
Correct Answer: (B) Excipient
Explanation: Excipients (or additives) are pharmacologically inactive substances that are intentionally added to a dosage form along with the active drug (active ingredient) to aid in its preparation, stability, and administration.
49. Hard solid preparation applied to skin under a cloth are leather covering are known as;
A. Emulsions
B. Lotions
C. Plasters
D. Cream
Correct Answer: (C) Plasters
Explanation: Plasters are solid or semi-solid preparations that are spread upon a backing material (cloth, plastic, or leather) and intended for external application to the skin.
50. The drug preparations which are used by licking are;
A. Aerosole
B. Dragee
C. Linctures
D. Lotions
Correct Answer: (C) Linctures
Explanation: Linctures are viscous, liquid oral preparations, often cough syrups, intended to be swallowed slowly and used by the patient (or animal) licking them to coat the pharyngeal mucosa.