Here are all 17 questions with their options and correct answers according to NCISM BAMS General Pharmacology: Q1. Therapeutic index is? A. LD100/ED100 B. ED100/LD100 ✅ C. LD50/ED50 D. ED50/LD50 --- Q2. Which of the following drugs have a narrow therapeutic index? ✅ A. Lithium B. Diazepam C. Penicillin D. Paracetamol --- Q3. Drugs are excreted from the body through A. Kidney B. Breast milk, saliva, sweat & bile C. Intestine ✅ D. All of the Above --- Q4. Efficacy of the drug is A. Median effect of a drug ✅ B. Maximum effect of the drug C. Threshold effect of drug D. No effect at all --- Q5. Absorption of drug into circulation is 100% when drug is administered through which route? A. Rectal B. Intramuscular C. Oral ✅ D. Intravenous --- Q6. Which type of drug can easily diffuse across the cell membrane? ✅ A. Lipophilic B. Protein bound C. Hydrophilic D. Ionized --- Q7. Bioavailability is defined as A. The fraction of the administered dose reaching the liver B. The fraction of the administered dose reaching the gut C. The fraction of the administered dose reaching the tissue ✅ D. The fraction of the administered dose reaching the systemic circulation --- Q8. A drug is safe when A. There is a narrow gap between therapeutic dose and toxic dose ✅ B. There is a wide gap between therapeutic dose and toxic dose C. There is no gap between therapeutic dose and toxic dose D. None of the above --- Q9. Blood-brain barrier is impermeable to which type of drug? A. Lipophilic B. Non-ionized ✅ C. Hydrophilic D. Hydrophobic --- Q10. The most common reaction among Type II metabolism is A. Sulfation B. Acetylation ✅ C. Glucuronidation D. Amino acid conjugation --- Q11. Site of drug action is A. Extracellular B. Cellular C. Intracellular ✅ D. All of the Above --- Q12. Following tablets are used as placebo A. Multivitamins B. Calcium ✅ C. Lactose D. Iron --- Q13. Pharmacodynamics include A. Drug distribution ✅ B. Effects of drug C. Drug side effects D. All of the above --- Q14. Antacids act A. Through receptors ✅ B. By chemical interaction C. By inhibiting enzymes D. By physical property --- Q15. Vaccines act by A. Antibody production B. Increase cell-mediated immunity C. Promote phagocytosis ✅ D. Both A & B --- Q16. Intrinsic activity of drug is A. Affinity B. Potency ✅ C. Efficacy D. Toxicity --- Q17. Antagonist drug has A. Efficacy ✅ B. Affinity C. Both of the above D. None of the above Answer Key 1. C 2. A 3. D 4. B 5. D 6. A 7. D 8. B 9. C 10. C 11. D 12. C 13. B 14. B 15. D 16. C 17. B
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NCISM BAMS General Pharmacology - All 17 Questions with Detailed Explanations
Q1. Therapeutic Index = LD50/ED50 ✅ C
The therapeutic index (TI) is defined as the ratio of the median lethal dose to the median effective dose:
TI = LD50 / ED50
- LD50 = dose that kills 50% of the test population
- ED50 = dose that produces the desired effect in 50% of the population
A high TI means the drug is safer (there is a large margin between the effective dose and the lethal dose). A low/narrow TI means the drug is dangerous because a small increase in dose can cause toxicity.
Why not LD100/ED100? Those extreme values are impractical - the dose-response curve never truly reaches 100% in a population, and measuring them requires far more animals. LD50/ED50 are statistically reproducible reference points.
"The ratio of the toxic dose and effective dose, TD50/ED50, is the therapeutic index." - Schwartz's Principles of Surgery, 11th Ed.
"The therapeutic index is a relative measure of the toxicity or safety of a drug and is defined as the ratio of the median toxic dose to the median effective dose." - Kaplan & Sadock's Synopsis of Psychiatry
Q2. Narrow Therapeutic Index Drug = Lithium ✅ A
A narrow therapeutic index (NTI) drug is one where the toxic dose is only slightly above the therapeutic dose, requiring close monitoring.
Classic NTI drugs to memorize:
| Drug | Why narrow TI |
|---|---|
| Lithium | Serum levels must be maintained 0.6-1.2 mEq/L; above 1.5 = toxicity |
| Digoxin | Very narrow margin between therapeutic and toxic |
| Warfarin | INR must be tightly controlled |
| Phenytoin | Zero-order kinetics; small dose change = large level change |
| Aminoglycosides | Ototoxicity and nephrotoxicity at high levels |
| Theophylline | Toxic at levels just above therapeutic |
The other options have wide TIs:
- Diazepam - benzodiazepines are remarkably safe alone; overdose rarely fatal without coingestants
- Penicillin - enormous safety margin; doses many times therapeutic are well tolerated
- Paracetamol - while hepatotoxic in overdose, a safe range is wide at therapeutic doses
"If the therapeutic index is low, as it is for lithium, careful monitoring of serum levels is essential." - Kaplan & Sadock's Comprehensive Textbook of Psychiatry
Q3. Drug Excretion Routes = All of the Above ✅ D
Drugs are eliminated from the body through multiple routes:
| Route | Examples |
|---|---|
| Kidney (urine) | Most drugs and their water-soluble metabolites - the PRIMARY route |
| Bile/Feces (intestine) | High molecular weight drugs, glucuronide conjugates (enterohepatic recirculation) |
| Breast milk | Lipophilic, low-protein-bound drugs (important in breastfeeding mothers) |
| Saliva | Some drugs appear in saliva (basis for saliva drug testing) |
| Sweat | Minor route; some heavy metals and drugs |
| Expired air (lungs) | Volatile anesthetics, alcohol |
The kidney is the most important excretory organ for most drugs, but the question acknowledges all routes - hence "All of the Above."
Q4. Efficacy = Maximum Effect of the Drug ✅ B
Two key pharmacodynamic terms to keep straight:
| Term | Definition | Relates to |
|---|---|---|
| Efficacy | The maximum response a drug can produce, no matter how high the dose | Ceiling effect on dose-response curve |
| Potency | The dose required to produce 50% of maximum effect (ED50) | Position of the curve on the x-axis |
A drug with high efficacy can produce a large maximum effect. A drug with high potency produces its effect at a lower dose.
Example: Morphine has higher efficacy than codeine (morphine can achieve stronger analgesia even at maximum doses). Fentanyl has higher potency than morphine (it works at much lower doses).
Q5. 100% Absorption = Intravenous (IV) ✅ D
Bioavailability by route:
| Route | Bioavailability |
|---|---|
| Intravenous (IV) | 100% by definition |
| Inhalation | ~80-100% (varies) |
| Sublingual | ~75% |
| Intramuscular (IM) | ~75% (variable) |
| Rectal | ~30-60% (some first-pass effect) |
| Oral | Variable, usually <100% due to first-pass hepatic metabolism |
IV is the only route where the drug is placed directly into systemic circulation, bypassing all absorptive barriers. This is why bioavailability = 1.0 (100%) for IV.
"For most intravenously administered drugs, the absolute bioavailability is close to unity and the rate is nearly instantaneous." - Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Ed.
Q6. Easily Diffuses Across Cell Membranes = Lipophilic ✅ A
Cell membranes are composed of a phospholipid bilayer - a hydrophobic (fatty) interior sandwiched between hydrophilic heads. Therefore:
- Lipophilic (fat-soluble) drugs: dissolve into the membrane easily, diffuse freely across - ✅
- Hydrophilic (water-soluble) drugs: cannot dissolve in lipid, cannot cross passively - ✗
- Ionized drugs: Carry an electrical charge, highly water-soluble, cannot cross lipid membranes - ✗
- Protein-bound drugs: Too large to pass through membranes in that state - ✗
This is the basis of the Henderson-Hasselbalch principle: the non-ionized (uncharged) form of a drug is the lipophilic form that crosses membranes. Weak acids are non-ionized in acidic environments; weak bases are non-ionized in basic environments.
Q7. Bioavailability = Fraction of Dose Reaching Systemic Circulation ✅ D
Bioavailability (F) is defined as the fraction (proportion) of an administered drug dose that reaches the systemic (general) circulation in unchanged (active) form.
"The extent of absorption of a drug into the systemic circulation may be incomplete. The bioavailability of a particular drug is the fraction (F) of the total drug dose that ultimately reaches the systemic circulation from the site of administration." - Goldman-Cecil Medicine
Why not the liver (option A) or gut (option B)? Those are intermediate stops on the way. First-pass metabolism in the gut wall and liver actually reduces bioavailability - drugs metabolized there never reach systemic circulation.
F = AUC (oral) / AUC (IV) - measured by comparing area under the concentration-time curve.
Q8. A Drug is Safe When = Wide Gap Between Therapeutic and Toxic Dose ✅ B
This is essentially a rewording of the therapeutic index concept:
- Wide gap = High therapeutic index = Safe drug (large margin for error)
- Narrow gap = Low therapeutic index = Dangerous drug (small dosing error can cause toxicity)
- No gap = Essentially no therapeutic window = Not usable clinically
This is why drugs like penicillin (wide gap) are very safe, while drugs like digoxin, lithium, and warfarin (narrow gap) require close monitoring of blood levels.
Q9. Blood-Brain Barrier Impermeable To = Hydrophilic Drugs ✅ C
The Blood-Brain Barrier (BBB) is formed by specialized tight junctions between brain capillary endothelial cells, plus astrocyte foot processes. It is functionally a lipid membrane.
"The blood-brain barrier prevents hydrophilic polar and large molecules in the blood from entering the brain." - Goldman-Cecil Medicine
Drugs that cross the BBB easily (lipophilic, non-ionized, small, low protein binding):
- Diazepam, thiopentone, halothane, general anesthetics
Drugs that cannot cross the BBB (hydrophilic, ionized, large):
- Aminoglycosides, dopamine (itself), atropine methobromide (vs atropine)
- Note: Morphine (relatively hydrophilic for an opioid) crosses less readily than fentanyl
"The blood-brain barrier capillary endothelial cells have very limited numbers of transmembrane hydrophilic channels." - Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Ed.
Q10. Most Common Phase II Reaction = Glucuronidation ✅ C
Phase II metabolism (conjugation reactions) involves attaching an endogenous molecule to a drug to make it more water-soluble for excretion.
| Phase II Reaction | Enzyme | Notes |
|---|---|---|
| Glucuronidation | UDP-glucuronosyltransferase (UGT) | Most common - occurs in liver, gut, kidney |
| Sulfation | Sulfotransferases | Common but saturates quickly |
| Acetylation | N-acetyltransferase | Polymorphic (fast/slow acetylators) |
| Amino acid conjugation | Various | Glycine, glutamine |
| Methylation | Methyltransferases | Less common |
| Glutathione conjugation | GST | Important in paracetamol toxicity |
Glucuronidation is the most abundant Phase II reaction because:
- UDP-glucuronic acid is abundantly available
- UGT enzymes are present in many tissues
- It handles a very wide variety of substrates (drugs, hormones, bilirubin)
Note: Neonates have immature UGT activity, which is why chloramphenicol causes "Grey Baby Syndrome" - they cannot glucuronidate it adequately.
Q11. Site of Drug Action = All of the Above ✅ D
Drug receptors and targets exist in all compartments of the cell:
| Location | Examples |
|---|---|
| Extracellular | Cell surface receptors (e.g., antibodies targeting extracellular antigens), antacids working in gut lumen |
| Cell surface/membrane | Ion channels, G-protein-coupled receptors (beta-blockers, opioids, muscarinic agonists) |
| Intracellular (cytoplasm) | Steroid hormone receptors (glucocorticoids), nitric oxide activating guanylyl cyclase |
| Intranuclear | Thyroid hormone receptors, retinoids, vitamin D receptors (act on DNA transcription) |
So the complete answer correctly includes all locations - extracellular, cellular (membrane), and intracellular.
Q12. Placebo Tablet = Lactose ✅ C
A placebo is an inert (pharmacologically inactive) substance used in clinical trials as a control, or sometimes therapeutically to exploit the placebo effect.
The ideal placebo tablet:
- Must be pharmacologically inert (no biological effect at the doses used)
- Must look identical to the active drug
- Must be safe in all patients
Lactose is an inert sugar used as a tablet filler/excipient - it has no pharmacological activity, making it the classic placebo tablet material.
Why not the others?
- Multivitamins: Biologically active - vitamins are drugs with metabolic effects
- Calcium: Pharmacologically active (affects bone, neuromuscular transmission, cardiac function)
- Iron: Pharmacologically active (treats iron deficiency anemia)
Q13. Pharmacodynamics Includes = Effects of Drug ✅ B
The two branches of pharmacology:
| Branch | Definition | Includes |
|---|---|---|
| Pharmacokinetics | What the body does to the drug | Absorption, Distribution, Metabolism, Excretion (ADME) |
| Pharmacodynamics | What the drug does to the body | Mechanism of action, receptor binding, effects, dose-response relationship |
So:
- Drug distribution = Pharmacokinetics (not pharmacodynamics)
- Effects of drug = Pharmacodynamics ✅
- "Drug side effects" alone is incomplete - it falls under pharmacodynamics but isn't the full definition
- "All of the above" is wrong because drug distribution is pharmacokinetics
Q14. Antacids Act = By Chemical Interaction ✅ B
Antacids (e.g., aluminium hydroxide, magnesium hydroxide, calcium carbonate, sodium bicarbonate) neutralize gastric hydrochloric acid by direct chemical reaction:
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O
This is a direct acid-base chemical neutralization reaction - not receptor mediated, not enzyme inhibition, and not a physical property (like osmotic laxatives or activated charcoal).
Compare with:
- Omeprazole (PPI): acts by inhibiting the H⁺/K⁺-ATPase enzyme (proton pump)
- Ranitidine/famotidine: act through receptors (H2 histamine receptor antagonists)
- Antacids: direct chemical interaction (neutralization)
Q15. Vaccines Act By = Both Antibody Production AND Cell-Mediated Immunity ✅ D
Vaccines stimulate adaptive immunity through both arms of the immune system:
Humoral (antibody-mediated) immunity:
- Antigens presented to B lymphocytes
- B cells differentiate into plasma cells
- Plasma cells produce specific antibodies (IgG, IgM, IgA)
- Memory B cells remain for future rapid response
Cell-mediated immunity:
- Antigens presented to T lymphocytes (via MHC class I and II)
- CD4+ helper T cells and CD8+ cytotoxic T cells activated
- Memory T cells persist long-term
- Especially important for intracellular pathogens (viruses, TB)
Promote phagocytosis (option C) is more of an indirect innate immune effect - it is not the primary mechanism by which vaccines work, hence option D (A & B) is correct, not "all of the above."
Q16. Intrinsic Activity = Efficacy ✅ C
Intrinsic activity (IA) is a pharmacodynamic property that describes the ability of a drug-receptor complex to produce a biological response. It ranges from 0 to 1.
| Drug Type | Affinity | Intrinsic Activity | Effect |
|---|---|---|---|
| Full Agonist | High | 1.0 (maximum) | Full response |
| Partial Agonist | High | 0.1-0.9 (partial) | Sub-maximal response |
| Antagonist | High | 0 | No response (blocks receptor) |
| Inverse Agonist | High | Negative | Opposite response |
Intrinsic activity = Efficacy because both describe the maximum response capability of the drug once it binds the receptor.
Affinity is different - it describes how strongly the drug binds to the receptor (measured by Kd or Ki), irrespective of whether it activates it.
Q17. Antagonist Drug Has = Affinity (but zero intrinsic activity) ✅ B
An antagonist is a drug that:
- Has affinity (binds to the receptor) - ✅ YES
- Has zero intrinsic activity/efficacy (does not activate the receptor) - ✗ NO
The antagonist occupies the receptor and blocks it from being activated by the agonist. Without binding (affinity), it couldn't block anything. Without intrinsic activity, it produces no effect on its own.
Types of antagonism:
- Competitive antagonist: Binds reversibly to the same site as the agonist (e.g., naloxone, atropine, propranolol)
- Non-competitive antagonist: Binds irreversibly or at a different site (e.g., phenoxybenzamine)
- Physiological antagonist: Opposes the agonist's effects by acting on a different receptor (e.g., adrenaline vs. histamine in anaphylaxis)
So antagonists have affinity but no efficacy - option B is correct.
Quick Memory Summary
| # | Key Concept | Answer |
|---|---|---|
| 1 | TI formula | LD50/ED50 |
| 2 | Narrow TI drug | Lithium |
| 3 | Excretion routes | All routes |
| 4 | Efficacy | Max drug effect |
| 5 | 100% bioavailability | IV route |
| 6 | Crosses membranes easily | Lipophilic |
| 7 | Bioavailability definition | Fraction reaching systemic circulation |
| 8 | Safe drug | Wide therapeutic-toxic gap |
| 9 | BBB impermeable to | Hydrophilic drugs |
| 10 | Most common Phase II | Glucuronidation |
| 11 | Site of drug action | All locations |
| 12 | Placebo tablet | Lactose |
| 13 | Pharmacodynamics | Effects of drug on body |
| 14 | Antacids mechanism | Chemical interaction (neutralization) |
| 15 | Vaccines mechanism | Antibody + cell-mediated immunity |
| 16 | Intrinsic activity | Efficacy |
| 17 | Antagonist property | Affinity only (no intrinsic activity) |
Sources: Goldman-Cecil Medicine, Goodman & Gilman's Pharmacological Basis of Therapeutics, Lippincott Illustrated Reviews in Pharmacology, Kaplan & Sadock's Synopsis of Psychiatry, Barash's Clinical Anesthesia, Schwartz's Principles of Surgery.
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