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.
Drug Metabolism Principles Definition Drug Metabolism Principles: Drug metabolism is the biochemical modification of pharmaceutical substances in the body, primarily carried out by liver enzymes. It occurs in two main phases: Phase I Metabolism Overview: Phase I reactions modify drug molecules via oxidation, reduction, or hydrolysis, often introducing or exposing functional groups (-OH, -NH₂, -SH). Common … Read more
Drug metabolism is the chemical transformation of pharmaceuticals, primarily in the liver, converting lipophilic compounds into water-soluble metabolites for easier excretion. Key Goals of Drug Metabolism Detoxification: Converts toxic compounds into less harmful forms. Excretion: Enhances drug elimination via urine or bile. Regulation of Drug Activity: Activates prodrugs or inactivates drugs, influencing their effect. Enzymatic … Read more
Optical and Geometrical Definition Optical and Geometrical Isomerism: Stereoisomerism is a form of isomerism in which compounds have the same molecular formula and sequence of bonded atoms (constitution) but differ in the spatial arrangement of atoms or groups. It includes geometrical isomerism, which arises from restricted rotation around double bonds or ring structures leading to … Read more
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
