Chemical classification of drugs MCQs With Answer is a focused study tool tailored for B.Pharm students to master drug classes by their core chemical structures, functional groups, heterocycles and structure-activity relationships. This concise introduction links important keywords — chemical classification of drugs, pharmacology, drug classes, functional groups, heterocycles, SAR and B.Pharm MCQs — to essential learning outcomes. The questions emphasize structural motifs (e.g., beta-lactams, benzimidazoles, phenanthrenes), implications for activity, prodrugs and stereochemistry, helping students connect chemistry with therapeutic use. Clear explanations strengthen exam readiness and practical understanding. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which ring system is common to both penicillins and cephalosporins?
- Indole ring
- Beta-lactam ring
- Pyridine ring
- Imidazole ring
Correct Answer: Beta-lactam ring
Q2. Which functional group defines sulfonamide antibacterial agents?
- Carboxyl group (-COOH)
- Sulfonamide group (-SO2NH2)
- Hydroxyl group (-OH)
- Thiol group (-SH)
Correct Answer: Sulfonamide group (-SO2NH2)
Q3. The benzimidazole nucleus is characteristic of which major drug class?
- Proton pump inhibitors
- Benzodiazepines
- Beta-blockers
- Macrolide antibiotics
Correct Answer: Proton pump inhibitors
Q4. The steroid nucleus consists of how many fused rings?
- Two fused rings
- Three fused rings
- Four fused rings
- Five fused rings
Correct Answer: Four fused rings
Q5. Amide-type local anesthetics are distinguished chemically by which linkage?
- Ether linkage (-O-)
- Amide linkage (-CONH-)
- Ester linkage (-COO-)
- Thioether linkage (-S-)
Correct Answer: Amide linkage (-CONH-)
Q6. Benzodiazepines are built from which fused ring system?
- Benzene fused to a seven-membered diazepine ring
- Benzene fused to a five-membered imidazole ring
- Naphthalene fused to pyrrole
- Pyridine fused to thiophene
Correct Answer: Benzene fused to a seven-membered diazepine ring
Q7. Fluoroquinolones share which core chemical scaffold?
- Quinolone nucleus
- Tetracyclic anthracyclin nucleus
- Macrolactone ring
- Aminoglycoside aminocyclitol
Correct Answer: Quinolone nucleus
Q8. Tetracyclines are characterized by what structural feature?
- A single aromatic ring
- Linear fused four-ring (naphthacene) nucleus
- Macrocyclic lactone ring
- Aminocyclitol core with sugars
Correct Answer: Linear fused four-ring (naphthacene) nucleus
Q9. Drugs like digoxin that have a steroidal aglycone attached to sugars belong to which chemical class?
- Aminoglycosides
- Macrolides
- Cardiac glycosides
- Glycopeptide antibiotics
Correct Answer: Cardiac glycosides
Q10. Which chemical moiety is central to the sulfonylurea class of antidiabetic drugs?
- Sulfonylurea moiety
- Carboxylic acid moiety
- Thiazolidinedione ring
- Biguanide structure
Correct Answer: Sulfonylurea moiety
Q11. The piperazine ring is a six-membered heterocycle containing how many nitrogen atoms?
- One nitrogen atom
- Two nitrogen atoms
- Three nitrogen atoms
- Four nitrogen atoms
Correct Answer: Two nitrogen atoms
Q12. Ibuprofen chemically belongs to which NSAID subclass?
- Salicylates
- Arylpropionic acids
- Acetic acid derivatives
- Fenamates
Correct Answer: Arylpropionic acids
Q13. The beta-lactam ring fused to a thiazolidine ring is the hallmark of which antibiotic class?
- Cephalosporins
- Penicillins
- Macrolides
- Glycopeptides
Correct Answer: Penicillins
Q14. Which functional group in captopril enhances ACE binding and confers potency?
- Carboxylate (-COO-)
- Thiol (-SH)
- Amide (-CONH-)
- Phenol (-OH)
Correct Answer: Thiol (-SH)
Q15. Classical opioids like morphine are derived from which polycyclic skeleton?
- Indole nucleus
- Phenanthrene nucleus
- Purine nucleus
- Pyrimidine nucleus
Correct Answer: Phenanthrene nucleus
Q16. Chloroquine is a member of which chemical antimalarial class?
- 4-aminoquinolines
- Quinones
- Artemisinins
- Biguanides
Correct Answer: 4-aminoquinolines
Q17. Tricyclic antidepressants are defined chemically by how many fused rings?
- One fused ring
- Two fused rings
- Three fused rings
- Four fused rings
Correct Answer: Three fused rings
Q18. Macrolide antibiotics are characterized by which major chemical feature?
- Beta-lactam ring
- Macrocyclic lactone ring
- Tetracyclic naphthacene core
- Aminocyclitol sugar core
Correct Answer: Macrocyclic lactone ring
Q19. Thiazide diuretics contain which distinctive heterocyclic nucleus?
- Benzothiadiazine nucleus
- Imidazoline nucleus
- Quinazoline nucleus
- Indoline nucleus
Correct Answer: Benzothiadiazine nucleus
Q20. Diclofenac is classified chemically as which subclass of NSAIDs?
- Arylpropionic acid derivative
- Acetic acid derivative
- Salicylate
- Oxicam
Correct Answer: Acetic acid derivative
Q21. Aminoglycoside antibiotics are built around which core structural feature?
- Aminocyclitol ring linked to amino sugars
- Macrocyclic lactone ring with sugars
- Tetracyclic naphthacene core
- Peptidic glycopeptide backbone
Correct Answer: Aminocyclitol ring linked to amino sugars
Q22. AZT (zidovudine) is best classified chemically as which type of antiviral?
- Neuraminidase inhibitor
- Nucleoside analogue reverse transcriptase inhibitor (NRTI)
- Protease inhibitor
- Integrase inhibitor
Correct Answer: Nucleoside analogue reverse transcriptase inhibitor (NRTI)
Q23. Prodrugs designed to improve lipophilicity commonly use which cleavable linkage?
- Ether bond
- Ester bond
- Amide bond
- Disulfide bond
Correct Answer: Ester bond
Q24. Pioglitazone belongs to which chemical class of antidiabetic agents?
- Biguanides
- Thiazolidinediones
- Sulfonylureas
- Alpha-glucosidase inhibitors
Correct Answer: Thiazolidinediones
Q25. Vancomycin is chemically classified as which type of antibiotic?
- Macrolide
- Glycopeptide
- Aminoglycoside
- Beta-lactam
Correct Answer: Glycopeptide
Q26. Many drugs are chiral; which of these is marketed as a single enantiomer (S-enantiomer)?
- Omeprazole
- Esomeprazole
- Lansoprazole
- Pantoprazole
Correct Answer: Esomeprazole
Q27. Phenothiazines used as antipsychotics are characterized by what central chemical framework?
- Monocyclic aromatic ring
- Tricyclic phenothiazine core with sulfur and nitrogen
- Bicyclic beta-lactam core
- Macrocyclic lactone ring
Correct Answer: Tricyclic phenothiazine core with sulfur and nitrogen
Q28. Cephalosporins differ from penicillins by having the beta-lactam fused to which ring?
- Thiazolidine ring
- Dihydrothiazine ring
- Pyrrolidine ring
- Imidazole ring
Correct Answer: Dihydrothiazine ring
Q29. Sulfonamide antibacterial agents exert their effect by mimicking which endogenous substrate?
- Adenosine triphosphate (ATP)
- Para-aminobenzoic acid (PABA)
- Folic acid
- Glucosamine
Correct Answer: Para-aminobenzoic acid (PABA)
Q30. Which functional group is commonly used in ACE inhibitors like enalaprilat for tight binding to zinc in the active site?
- Alcohol (-OH)
- Carboxylate (-COO-)
- Ether (-O-)
- Nitrate (-NO3)
Correct Answer: Carboxylate (-COO-)
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