Intro to pcol

• Pharmacology is the study of how a drug affects a biological system.
• A drug is any chemical substance used in the diagnosis, treatment, and prevention of disease.
• Drug substances are administered as different dosage forms such as capsules, tablets, syrups, elixirs, and solutions.
• Drugs are delivered through different routes of administration in order to enter the body.
• Oral Ingestion is the most convenient route and can be used for both solid and liquid dosage forms.
• A drug is ingested and passes through the GIT for absorption.
• The rate of absorption is greater in the intestine than in the stomach, primarily because of less mucous layer and larger surface area of the intestine.
• Gastric emptying, which takes about 4 hours, is important for intestinal absorption of a drug. Gastric emptying is directly proportional to the rate of absorption of a drug.
• Absorption most likely takes place in the small intestines.
• Sublingual Administration involves placing a drug underneath the tongue, where it dissolves and is absorbed through sublingual veins directly into the systemic circulation.
• Venous drainage from the mouth is to the superior vena cava which brings the drug into the systemic circulation.
• Sublingual administration - This route bypasses the hepatic circulation and protects soluble drugs from first-pass metabolism.
• Ion trapping is when a drug remains in a specific compartment because it is non-diffusible.
• Endocytosis is the process by which a substance is bound at a cell surface receptor, engulfed by the membrane, and then carried into the cell by pinching off a newly formed vesicle inside the membrane.
• Bioavailability (F) is the relative amount (in percentage) of drug from an administered dosage form which enters the systemic circulation and the rate at which the drug appears in the blood stream.
• Active transport is when a drug uses specific membrane proteins called “pumps” to move across a cell membrane against the concentration gradient (low to high) with expenditure of energy.
• Bioequivalence is when the rates and extent of F of the active ingredient in two drug products are not significantly different under suitable test.
• Facilitated transport is when a drug uses specific membrane proteins called “carriers” to move across a cell membrane along the concentration gradient (high to low) without expenditure of energy.
• Transdermal Absorption involves delivering a drug via a transdermal patch or as a solution for transdermal spray.
• Lipinski’s Rule of Five is a common rule followed to determine the oral bioavailability of drugs.
• Exocytosis is the expulsion of a material that is membrane-encapsulated inside the cell and going out of the cell.
• Cell membranes are semi-permeable and bulk flow of water can carry drug substances.
• The Henderson-Hasselbalch Equation represents the relation of pH, pKa, and the drug’s degree of ionization.
• TRANSDERMAL ABSORPTION - Drug absorption via this route is dependent on the surface area of application and lipid solubility of the drug.
• Factors that increase transdermal absorption include inflamed, abraded, burned, or denuded skin, high-lipid solubility, use of oily vehicle for the drug, and rubbing of the preparation into the skin.
• Hydration of the skin with an occlusive dressing can enhance transdermal absorption.
• A receptor is a regulatory molecule to which a drug binds, serving as the target of the drug. These molecules are found in the cell membrane, cytoplasm, or in the nucleus.
• Most drugs follow linear kinetics, also known as concentration-independent kinetics.
• Receptors can be in the active (Ra) or inactive (Ri) forms.
• Elimination is observed to follow either of the two patterns: Linear Kinetics or First-order Kinetics.
• In First-order Kinetics, the elimination rate is proportional to the concentration in the body at the time.
• Pharmacodynamics is the area of pharmacology that is concerned with how the drug affects the body.
• Half-life is independent of dose in First-order Kinetics.
• Ligand-Regulated Transmembrane Enzyme (Tyrosine Kinase) are common for insulin and various growth factor.
• Drug-Receptor binding is formed in several ways: Covalent Bond, Electrostatic Bond, and Hydrophobic Bond.
• Drugs are any substance that brings about a change in biologic function.
• True half-life or elimination constant does not exist in Non-linear Kinetics.
• Several drugs follow Non-linear Kinetics, including theophylline, aspirin, phenytoin, and ethanol.
• Abnormal clearance is expected in patients with major kidney, liver, or heart impairment.
• In Non-linear Kinetics, also known as Zero-order Kinetics, a constant amount of the drug concentration is removed per unit time.