Q.1 What does pharmacokinetics primarily study?
Drug absorption and elimination
Drug mechanism of action
Drug receptor binding
Drug classification
Explanation - Pharmacokinetics is the study of how the body absorbs, distributes, metabolizes, and eliminates drugs.
Correct answer is: Drug absorption and elimination
Q.2 Which pharmacokinetic phase involves the movement of a drug from the bloodstream to tissues?
Absorption
Distribution
Metabolism
Excretion
Explanation - Distribution describes how drugs move from the blood into tissues and organs.
Correct answer is: Distribution
Q.3 Which organ is primarily responsible for drug metabolism?
Kidney
Liver
Lung
Spleen
Explanation - The liver is the main site of drug metabolism, particularly via the cytochrome P450 system.
Correct answer is: Liver
Q.4 The term 'bioavailability' refers to:
The solubility of the drug
The fraction of drug reaching systemic circulation
The rate of drug distribution
The extent of drug binding to plasma proteins
Explanation - Bioavailability is the proportion of a drug that enters systemic circulation unchanged after administration.
Correct answer is: The fraction of drug reaching systemic circulation
Q.5 Which route of drug administration has 100% bioavailability?
Oral
Intravenous
Subcutaneous
Inhalation
Explanation - Intravenous administration delivers the drug directly into the bloodstream, ensuring 100% bioavailability.
Correct answer is: Intravenous
Q.6 What does 'first-pass effect' mean?
Drug excretion by the kidney
Drug metabolism before reaching systemic circulation
Drug protein binding in plasma
Drug inactivation at the receptor site
Explanation - The first-pass effect occurs when drugs are metabolized in the liver before reaching systemic circulation.
Correct answer is: Drug metabolism before reaching systemic circulation
Q.7 Which of the following is an example of zero-order kinetics?
Phenytoin
Alcohol
Aspirin at low dose
Most antibiotics
Explanation - Alcohol follows zero-order kinetics because it is metabolized at a constant rate regardless of concentration.
Correct answer is: Alcohol
Q.8 Which factor most influences drug absorption from the gastrointestinal tract?
Lipid solubility
Protein binding
Renal clearance
Plasma pH
Explanation - Drugs with higher lipid solubility cross cell membranes more easily, enhancing absorption.
Correct answer is: Lipid solubility
Q.9 The half-life (t½) of a drug represents:
The time required for half the drug to be eliminated
The time for the drug to act
The duration of the drug’s effect
The time taken to reach steady state
Explanation - Half-life is the time needed for the plasma concentration of a drug to reduce by 50%.
Correct answer is: The time required for half the drug to be eliminated
Q.10 What type of kinetics do most drugs follow?
Zero-order
First-order
Second-order
Mixed-order
Explanation - Most drugs follow first-order kinetics, where the rate of elimination is proportional to drug concentration.
Correct answer is: First-order
Q.11 Which plasma protein is most important for drug binding?
Albumin
Globulin
Fibrinogen
Transferrin
Explanation - Albumin is the main plasma protein responsible for binding acidic and neutral drugs.
Correct answer is: Albumin
Q.12 If a drug has high first-pass metabolism, which route avoids this effect?
Oral
Rectal (lower rectum)
Intramuscular
Sublingual
Explanation - Sublingual administration bypasses the liver and avoids first-pass metabolism.
Correct answer is: Sublingual
Q.13 Which pharmacokinetic parameter determines the dosing frequency?
Half-life
Bioavailability
Volume of distribution
Clearance
Explanation - The half-life determines how long the drug stays in the body and guides dosing intervals.
Correct answer is: Half-life
Q.14 Clearance of a drug refers to:
Rate of absorption
Rate of metabolism and excretion
Drug plasma concentration
Extent of protein binding
Explanation - Clearance is the volume of plasma cleared of a drug per unit time.
Correct answer is: Rate of metabolism and excretion
Q.15 Steady-state concentration is achieved after approximately how many half-lives?
1
2
4-5
10
Explanation - Steady state is reached after about 4-5 half-lives of continuous dosing.
Correct answer is: 4-5
Q.16 Volume of distribution (Vd) represents:
Drug dose/plasma concentration
Rate of clearance
Half-life × clearance
Bioavailability × dose
Explanation - Vd is calculated as the amount of drug in the body divided by plasma drug concentration.
Correct answer is: Drug dose/plasma concentration
Q.17 Which route has the slowest absorption rate?
Intravenous
Intramuscular
Subcutaneous
Oral
Explanation - Oral administration is slower due to absorption barriers and first-pass metabolism.
Correct answer is: Oral
Q.18 Drugs that are weak bases are better absorbed in:
Stomach (low pH)
Small intestine (higher pH)
Liver
Kidneys
Explanation - Weak bases are more unionized and absorbed in the alkaline environment of the intestine.
Correct answer is: Small intestine (higher pH)
Q.19 The term 'prodrug' refers to:
Drug given in active form
Drug requiring metabolic activation
Drug that bypasses absorption
Drug excreted unchanged
Explanation - A prodrug is inactive until metabolized into its active form in the body.
Correct answer is: Drug requiring metabolic activation
Q.20 Which factor does NOT affect drug distribution?
Blood flow
Protein binding
Solubility
Tablet color
Explanation - Drug distribution depends on physiological factors, not on physical appearance like color.
Correct answer is: Tablet color
Q.21 Which transport process requires energy for drug absorption?
Passive diffusion
Facilitated diffusion
Active transport
Osmosis
Explanation - Active transport involves carrier proteins and ATP to move drugs against a gradient.
Correct answer is: Active transport
Q.22 Which parameter best reflects the efficiency of drug elimination?
Volume of distribution
Clearance
Half-life
Bioavailability
Explanation - Clearance measures the body's efficiency in removing the drug from plasma.
Correct answer is: Clearance
Q.23 Which organ is the primary site of drug excretion?
Liver
Kidney
Intestine
Skin
Explanation - Most drugs and their metabolites are excreted through the kidneys in urine.
Correct answer is: Kidney
Q.24 The time taken to reach maximum drug concentration after administration is called:
t½
Cmax
Tmax
Clearance
Explanation - Tmax is the time required to reach peak plasma concentration after drug administration.
Correct answer is: Tmax
Q.25 Which of the following decreases drug clearance?
Liver disease
Increased renal blood flow
Enzyme induction
Good hydration
Explanation - Liver disease reduces metabolism and thus lowers drug clearance.
Correct answer is: Liver disease