Jawaharlal Nehru Technological University Hyderabad B.Pharmacy III MEDICINAL CHEMISTRY-I Previous Question Paper (January/February - 2023 - R17)

Solubility is a critical physicochemical property that directly influences the bioavailability and pharmacological potency of a drug. For a drug to exert its biological effect, it must be sufficiently soluble in aqueous physiological fluids to reach the systemic circulation and cross biological membranes. While high aqueous solubility is essential for absorption, a drug must also possess sufficient lipophilicity to partition through lipid-rich cell membranes. Therefore, an optimal balance between solubility and lipophilicity, often described by the Lipinski's Rule of Five, is required to ensure effective transport to the site of action.

Isomerism is the phenomenon where two or more compounds possess the same molecular formula but differ in the arrangement of atoms in space or their structural connectivity, leading to distinct physical and chemical properties.

Bio-isosterism is a strategy used in medicinal chemistry to modify a lead compound by replacing a functional group with a bio-isostere—a group with similar physical or chemical properties that produce broadly similar biological effects. These replacements are employed to improve the pharmacological profile of a drug, such as increasing metabolic stability, enhancing potency, reducing toxicity, or altering solubility and pharmacokinetic properties.