Pharmaceutical Sciences (Pharmaceutics, Medicinal Chemistry, Pharmacognosy)
Pharmaceutics
Understand dosage form design: solutions, suspensions, emulsions, tablets, capsules, and modified-release systems. Know factors affecting bioavailability (dissolution rate, particle size, polymorphism, first-pass metabolism) and the difference between bioequivalence and pharmaceutical equivalence. Be familiar with sterility, pyrogens and stability concepts, and the role of excipients (binders, disintegrants, preservatives, antioxidants).
Medicinal chemistry
Focus on structure–activity relationships: functional groups that drive receptor binding and solubility (ionisable groups, hydrogen bonding, lipophilicity). Understand how prodrug design improves absorption or masks taste, and how stereochemistry (enantiomers) affects activity.
Pharmacognosy
Know major plant-derived drugs and their active constituents - for example, digoxin (cardiac glycosides), morphine (alkaloids), artemisinin (sesquiterpene lactone), and quinine (alkaloid). Recognise the difference between crude drugs, extracts and isolated compounds.
Traps in questions
- Treating bioequivalence as identical to chemical equivalence - it concerns rate and extent of absorption.
- Ignoring polymorphism, which can change dissolution and bioavailability.
- Confusing an alkaloid with a glycoside or terpene class.
Rule of thumb
For bioavailability questions, remember the rate and extent phrase, and that slow dissolution is the most common formulation-related cause of poor absorption.
Worked example
Two tablets contain identical active ingredient but one is poorly bioavailable. The most likely formulation cause is slow dissolution due to crystal form or binder choice - not a difference in chemical identity.