G01

Pharmaceutical Chemistry & Allied Subjects

Pharmaceutical analysis, inorganic & organic chemistry, biochemistry, medicinal chemistry

30.4%

of the paper

≈ 152 marks

by weightage

of 5 heads

2153

questions

with explanations

cite a source

reference material

Weightage follows the locked NBEMS GPAT blueprint (docs/12-GPAT-TAXONOMY.md), not an estimate. Question counts are read from the live bank when this page is built.

Subtopics in this bank

Acids, Bases, Buffers, Isotonicity and Physiological ElectrolytesAliphatic Reaction Mechanisms: Alkanes, Alkenes, Conjugated Dienes, Alkyl Halides and Alcohols (SN1/SN2, E1/E2, Addition)Anti-infective Chemotherapeutics: Antimalarial, Antitubercular, Antiviral, Antifungal, Antiprotozoal, Anthelmintic and SulphonamidesAntibiotics: β-Lactams, Aminoglycosides, Tetracyclines and Macrolides (Chemistry, SAR, Degradation)Antihistaminic Agents, Gastric Proton Pump Inhibitors and Antineoplastic AgentsAromatic Chemistry: Benzene, Phenols, Aromatic Amines and Aromatic AcidsAtomic and Scattering Techniques: Flame Photometry, Atomic Absorption Spectroscopy and NepheloturbidimetryBiomolecules, Bioenergetics and EnzymologyCarbonyl Compounds, Carboxylic Acids and Aliphatic Amines: Named Condensations, Acidity and BasicityCardiovascular Agents and Diuretics (Anti-anginals, Antihypertensives, Antiarrhythmics, Antihyperlipidemics, Anticoagulants)Classification, IUPAC Nomenclature and Structural Isomerism of Organic CompoundsDrug Design: QSAR, Prodrugs, Pharmacophore Modelling/Docking and Combinatorial ChemistryElectrochemical Methods of Analysis: Conductometry, Potentiometry and PolarographyFats and Oils: Reactions, Rancidity and Analytical ConstantsFundamentals of Pharmaceutical Analysis: Standards, Concentration and ErrorsHeterocyclic Compounds: Synthesis, Aromaticity, Reactivity and Medicinal UsesImpurities in Pharmaceutical Substances and Pharmacopoeial Limit TestsInorganic Pharmaceuticals by Therapeutic Class (GI Agents, Antimicrobials, Dental Products, Haematinics, Antidotes, Astringents)Instrumental and Specialised Chromatography: GC, HPLC, Ion Exchange, Gel and AffinityIntermediary Metabolism and Biological Oxidation: Carbohydrate, Lipid and Amino Acid Pathways with Associated DisordersMedicinal Chemistry of Autonomic Nervous System Drugs (Adrenergic and Cholinergic Agents, SAR)Medicinal Chemistry of CNS Drugs: Sedative-Hypnotics, Antipsychotics, Anticonvulsants, Anaesthetics, Analgesics and Anti-inflammatory AgentsMolecular Spectroscopy: UV-Visible, Fluorimetry and IR (Theory, Instrumentation, Applications)Named Reactions of Synthetic Importance (Reductions, Oxidations, Rearrangements)Nucleic Acid Metabolism and Genetic Information TransferPhysicochemical Properties in Relation to Biological Action and Drug MetabolismPlanar and Column Chromatography and Electrophoresis (Column, TLC, Paper)Polynuclear Hydrocarbons and Cycloalkane Strain TheoriesQuality assurance systems: cGMP, TQM, ICH, QbD, ISO, GLP, documentation and validationRadiopharmaceuticalsStereochemistry: Optical, Geometrical and Conformational IsomerismSteroids and Endocrine Drugs, Antidiabetic Agents and Local AnaestheticsTitrimetric Analysis: Acid–Base, Non-Aqueous, Precipitation, Complexometric, Gravimetric and Redox

Sample questions, with the reasoning

Every question in the bank is explained like this — including why each wrong option is wrong.

(R)-(−)-Adrenaline is far more potent at adrenergic receptors than its (S)-(+)-enantiomer, and the (S)-(+)-enantiomer is approximately equipotent with the corresponding β-deoxy (deshydroxy) analogue. According to the Easson–Stedman hypothesis, this pattern is explained by the fact that:

A)the (S)-(+)-enantiomer is selectively and rapidly destroyed by catechol-O-methyltransferase, so less of it reaches the receptor.
B)the (R)-enantiomer alone can engage all three complementary binding points of the receptor, whereas the (S)-enantiomer and the β-deoxy analogue can engage only two of them and are therefore roughly equipotent with each other.✓
C)only the (R)-enantiomer possesses the catechol hydroxyl groups needed for receptor activation.
D)the (S)-enantiomer binds the receptor with equal affinity but behaves as a competitive antagonist.

Why B is correct

Easson and Stedman proposed a three-point attachment model: the aromatic (catechol) ring, the protonated amine and the benzylic β-hydroxyl each contact a complementary receptor site. Only one configuration at the carbinol carbon allows all three contacts simultaneously, so the (R)-(−) form is the eutomer. Its antipode presents the β-hydroxyl to the wrong side and can therefore make only two productive contacts — exactly as many as a molecule from which the hydroxyl has been removed, which is why the two are approximately equipotent. This equipotency is the diagnostic prediction that distinguishes the hypothesis from a simple 'wrong-shape' argument.

AI fact-checked

100 mL of an ophthalmic solution is to contain 1.0 g of a drug whose sodium chloride equivalent (E value) is 0.20. Taking an isotonic solution to be equivalent to 0.9% w/v NaCl, the mass of sodium chloride that must be added to render the whole solution isotonic is:

A)0.70 g✓
B)0.90 g
C)0.20 g
D)1.10 g

Why A is correct

NaCl needed for 100 mL isotonic = 0.9 g. The drug contributes 1.0 g × 0.20 = 0.20 g of NaCl-equivalent tonicity. NaCl to be added = 0.9 − 0.20 = 0.70 g.

AI fact-checked

2-Bromo-2-methylbutane is treated with a small, unhindered base (sodium ethoxide in ethanol), and elimination follows the Saytzeff rule. Which alkene is the major product?

A)2-Methylbut-2-ene✓
B)2-Methylbut-1-ene
C)3-Methylbut-1-ene
D)Pent-2-ene

Why A is correct

Removing a β-hydrogen from the CH₂ group gives the more highly substituted (trisubstituted) alkene 2-methylbut-2-ene. With a small base, the thermodynamically more stable Saytzeff product predominates.

AI fact-checked

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