Pharmacology MCQS Set 3
51. Ad lib means;
A. Upto
B. As desired
C. Minimum
D. Less than desired
Correct Answer: (B) As desired
Explanation: The pharmaceutical abbreviation Ad lib (from the Latin ad libitum) means As desired or “at liberty,” often used for dosage frequency or the amount of feed or water offered.
52. The mechanism of transport of drug which work like active transport but the drug does not move against concentration gradient;
A. Pinocytosis
B. Passive diffusion
C. Facilitated diffusion
D. Endocytosis
Correct Answer: (C) Facilitated diffusion
Explanation: Facilitated diffusion is a carrier-mediated transport system (like active transport) but does not require energy and moves the drug only down its concentration gradient.
53. Hepatic and renal diseases;
A. Decrease the half life
B. Increase the half life
C. Do not affect the half life
D. All of the above
Correct Answer: (B) Increase the half life
Explanation: The liver (hepatic) and kidneys (renal) are the primary organs for drug metabolism and excretion, respectively. Damage to these organs impairs clearance, leading to a build-up of the drug and thus Increase the half life ($\text{t}1/2$).
54. If the gut motility is increased then;
A. Drug absorption is decreased
B. Drug absorption increased
C. Drug absorption is not affected
D. All of the above
Correct Answer: (A) Drug absorption is decreased
Explanation: If gut motility is increased (faster transit time), the drug has less time to interact with the absorptive surface of the intestine, leading to decreased residence time and consequently Drug absorption is decreased.
55. The rate of drug absorption is greatest in;
A. The small intestine
B. The large intestine
C. The stomach
D. Plasma
Correct Answer: (A) The small intestine
Explanation: The small intestine has the greatest rate of drug absorption due to its enormous surface area provided by folds, villi, and microvilli, despite the stomach having higher blood flow.
56. Drug distribution may depend on tissue perfusion;
A. Highly vascular organs a drug slowly
B. Highly vascular organ rapidly acquire a drug
C. Levels of drug in bone may rise quickly due to its high vascularity
D. None of the above
Correct Answer: (B) Highly vascular organ rapidly acquire a drug
Explanation: In the initial distribution phase, drugs are rapidly delivered to highly perfused (highly vascular) organs such as the heart, liver, kidney, and brain. Therefore, a Highly vascular organ rapidly acquire a drug.
57. Most drugs and metabolites are excreted by;
A. The kidneys
B. The bile
C. The lungs
D. The saliva
Correct Answer: (A) The kidneys
Explanation: Water-soluble, polar drugs and their metabolites (formed via biotransformation) are primarily eliminated from the body via filtration and secretion in The kidneys (renal excretion).
58. Pharmacodynamics considers;
A. The way in which the drug affects the body
B. The effect of drug in the body and mode of action
C. Drug metabolism
D. Drug excretion
Correct Answer: (B) The effect of drug in the body and mode of action
Explanation: Pharmacodynamics is the study of “what the drug does to the body,” encompassing The effect of drug in the body and mode of action.
59. A drug allergy occurs;
A. When too much drug has accumulated in the body
B. When body sees the drug as an antigen and an immune response is established against the drug
C. An unwanted but predictable response to a drug
D. An unwanted but unpredictable response to a drug
Correct Answer: (B) When body sees the drug as an antigen and an immune response is established against the drug
Explanation: A drug allergy is a specific adverse drug reaction where the body’s immune system mistakenly identifies the drug as a foreign invader (antigen) and mounts an immune, or hypersensitivity, response.
60. The drug receptor interaction is usually;
A. Irreversible
B. Reversible
C. Always irreversible
D. unchanged
Correct Answer: (B) Reversible
Explanation: For most drugs, the binding to the receptor is mediated by weak chemical bonds (ionic, hydrogen, van der Waals forces) and is therefore Reversible, allowing the drug to dissociate and terminate its action.
61. Cholinesterase enzyme is inhibited by;
A. Atropine
B. Organo phosphorus pesticide
C. Pilocarpine
D. Nicotine
Correct Answer: (B) Organo phosphorus pesticide
Explanation: The Cholinesterase enzyme (acetylcholinesterase) is responsible for breaking down acetylcholine. It is irreversibly inhibited by Organo phosphorus pesticides and certain nerve gases, leading to excessive cholinergic effects.
62. The osmotic diuretic produces diuresis;
A. By increasing osmolarity of tubule urine
B. By decreasing osmolarity of tubule urine
C. Increasing reabsorption of water
D. Decrease osmolarity of blood
Correct Answer: (A) By increasing osmolarity of tubule urine
Explanation: Osmotic diuretics are filtered at the glomerulus but poorly reabsorbed. They draw water into the renal tubules By increasing the osmolarity of tubule urine (lumen), preventing water reabsorption and increasing urine flow (diuresis).
63. The magnesium sulfate acts as a purgative because;
A. Magnesium and sulfate ions are rapidly absorbed
B. Magnesium and sulfate ions are poorly absorbed
C. Magnesium ion stimulate protect the mucosa
D. Magnesium ion inhibit peristalsis
Correct Answer: (B) Magnesium and sulfate ions are poorly absorbed
Explanation: Magnesium sulfate is an osmotic purgative. Because the high concentration of Magnesium and sulfate ions are poorly absorbed from the gut lumen, they retain water, increasing the volume and liquidity of the feces.
64. MAO inhibitors prevent;
A. The excretion of epinephrine
B. The metabolism of epinephrine
C. The distribution of epinephrine
D. The absorption of epinephrine
Correct Answer: (B) The metabolism of epinephrine
Explanation: MAO (Monoamine Oxidase) inhibitors block the MAO enzyme, which is responsible for the inactivation (metabolism) of monoamines like epinephrine (adrenaline), norepinephrine, and dopamine. Thus, they prevent The metabolism of epinephrine.
65. Acetazolamide produces diuresis;
A. By inhibiting carbonic anhydrase
B. By inhibiting cholinesterase
C. By inhibiting M.A.O.
D. By stimulating M.A.O
Correct Answer: (A) By inhibiting carbonic anhydrase
Explanation: Acetazolamide is a diuretic that works in the renal proximal tubule By inhibiting carbonic anhydrase. This blocks bicarbonate reabsorption, leading to mild diuresis.
66. Blood brain barrier can be crossed easily by;
A. Unionized and lipophilic drug
B. Ionized and hydrophilic drug
C. Highly ionized drug
D. Unionized and hydrophilic drug
Correct Answer: (A) Unionized and lipophilic drug
Explanation: The Blood-Brain Barrier (BBB) is composed of tightly joined endothelial cells. To cross the BBB via passive diffusion, a drug must be highly lipid-soluble (lipophilic) and in its non-charged (Unionized) form.
67. Renal function can be estimated by determining;
A. Renal clearance of potassium
B. Renal clearance of Na.
C. Renal clearance of creatinine
D. Plasma clearance of creatinine
Correct Answer: (C) Renal clearance of creatinine
Explanation: The glomerular filtration rate (GFR), a key measure of Renal function, is estimated using the Renal clearance of creatinine. Creatinine is a substance that is filtered freely by the glomerulus and is neither significantly reabsorbed nor secreted.
68. Zero order elimination is;
A. Dose independent
B. Dose dependent
C. Both A and B
D. None of the above
Correct Answer: (B) Dose dependent
Explanation: Zero order elimination occurs when the elimination mechanism (e.g., metabolism) is saturated. The rate of elimination is constant, but the time taken for the drug to clear is Dose dependent because the half-life increases with dose.
69. 1st order elimination is;
A. Dose independent
B. Dose dependent
C. Both A and B
D. None of the above
Correct Answer: (A) Dose independent
Explanation: 1st order elimination means that a constant percentage of the drug is eliminated per unit time. The half-life ($\text{t}1/2$) is constant and is therefore Dose independent.
70. Drugs mainly bind to protein in the body;
A. Albumin
B. Globulin
C. Hemoglobin
D. Starch
Correct Answer: (A) Albumin
Explanation: Acidic drugs and many neutral drugs mainly bind to plasma Albumin, the most abundant plasma protein. Basic drugs typically bind to alpha-1-acid glycoprotein.
71. H1-receptor of histamines are mainly associated with;
A. Blood vascular system
B. Blood vascular and respiratory system
C. Stomach
D. Heart
Correct Answer: (B) Blood vascular and respiratory system
Explanation: The H1-receptors are responsible for the effects traditionally associated with allergies and inflammation: vasodilation (in the Blood vascular system) and bronchoconstriction (in the respiratory system). H2 receptors are primarily in the stomach.
72. Pharmacognosy deals with;
A. Preparation of drug
B. Properties and identification of drugs
C. Doses of drugs
D. Weight and measures
Correct Answer: (B) Properties and identification of drugs
Explanation: Pharmacognosy is the study of drugs derived from natural sources, focusing on the botanical, chemical, and biological Properties and identification of drugs and raw materials.
73. Microsomal enzyme induction leads to;
A. Prolong the half life of drug
B. Shorten the half life of drug
C. No effect on the half life of a drug
D. None of the above
Correct Answer: (B) Shorten the half life of drug
Explanation: Microsomal enzyme induction increases the rate of drug metabolism by the liver. This speeds up the clearance of the drug from the body, leading to a Shorten the half life of drug.
74. Microsomal enzyme inhibitors;
A. Prolong the half life of a drug
B. Shorten the half life of a drug
C. None of A & B
D. No effect on the half life of a drug
Correct Answer: (A) Prolong the half life of a drug
Explanation: Microsomal enzyme inhibitors decrease the rate of drug metabolism by the liver. This slows down the clearance of the drug from the body, leading to a Prolong the half life of a drug and increasing the risk of toxicity.
75. Renal clearance of a drug refers;
A. The volume of blood cleared of drug per unit time
B. The volume of urine coming from kidney per unit time
C. The volume of drug cleared from the blood
D. The volume of drug cleared from the urine
Correct Answer: (A) The volume of blood cleared of drug per unit time
Explanation: Renal clearance is a hypothetical concept defined as The volume of blood (or plasma) cleared of drug per unit time (usually $\text{mL}/\text{min}$) by the kidney.