Medicinal Chemistry I is a core subject that explores the design, synthesis, and biological activity of drugs. It bridges organic chemistry and pharmacology to enhance understanding of therapeutic agents.
Bioisosterism Definition: Bioisosterism are structurally similar chemical groups that mimic the biological activity of another. Importance in Drug Design: Improved Activity: Replacement of groups can enhance potency and reduce toxicity. Increased Stability: Bioisosteres improve metabolic stability. Reduced Side Effects: Modification helps improve drug safety. Examples: Sulfonamide (-SO₂NH₂) as a bioisostere of carboxyl (-COOH) in diuretics. Fluorine … Read more
Chelation Definition: Chelation is the formation of complexes between drugs and metal ions (e.g., Ca²⁺, Fe³⁺, Mg²⁺). Importance in Drug Action: Drug Absorption: Chelating with dietary minerals reduces absorption (e.g., tetracyclines + calcium). Toxicity Management: Chelating agents are used to remove heavy metals (e.g., lead, arsenic). Stability: It can enhance or reduce drug stability in … Read more
Protein Binding Definition: Protein Binding: Drugs bind to plasma proteins (e.g., albumin, globulins) in the bloodstream, affecting their distribution and activity. Importance in Drug Action: Free vs. Bound Drug: Only free drug is active; bound drug serves as a reservoir. Drug-Drug Interactions: Competition for binding sites can increase free drug concentration and toxicity. Duration of … Read more
Hydrogen Bonding Definition: Hydrogen bonding occurs when hydrogen (H) atoms interact with electronegative atoms (O, N, F). This contributes to a drug’s solubility and receptor binding. Importance in Drug Action: Water Solubility: More hydrogen bonds = better water solubility. Receptor Binding: Hydrogen bonds enhance drug-receptor interactions (enzyme active sites, DNA intercalation). Stability: Hydrogen bonds stabilize … Read more
Partition Coefficient Definition: The partition coefficient (P) is the ratio of a drug’s solubility in lipid (oil) vs. water. It is often expressed as log P, which quantifies lipophilicity. $P = \frac{\text{Concentration in lipid phase}}{\text{Concentration in aqueous phase}}$ High log P (>3): Lipophilic (fat-soluble) Low log P (<1): Hydrophilic (water-soluble) Optimal log P (~1-3): Good … Read more
Solubility Definition: Solubility is the ability of a drug to dissolve in a given solvent (e.g., water, lipids, organic solvents). Drugs must dissolve in biological fluids before they can be absorbed and exert their effect. Importance in Drug Action: Oral Bioavailability: Poorly soluble drugs have lower absorption and bioavailability. Drug Formulation: It determines the formulation … Read more
Ionization Definition: Ionization refers to the process by which a molecule gains or loses protons, leading to the formation of charged species (ions). The extent of ionization depends on the pKa of the compound and the pH of the surrounding environment. Importance in Biological Action: Drug Absorption: Non-ionized (neutral) drugs cross biological membranes (lipid bilayers) … Read more
Medicinal Chemistry History and Development has evolved over centuries, shaped by key discoveries, advancing methodologies, and a deeper understanding of biology and chemistry. Early Medicinal Chemistry History Ancient Times – Early medicinal practices in Egypt, China, and India relied on natural products and herbs for healing. Alchemy to Chemistry – Medieval alchemy laid the foundation … Read more
