Introduction to Pharmacology

• Pharmacokinetics is the study of how drugs are absorbed, distributed, metabolized, and excreted by the body.
• Pharmacology deals with the interactions that exist between drugs administered with the living system or body.
• Pharmacology ensures the effective and safe use of medicines.
• 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.
• Drugs are administered as different dosage forms such as capsules, tablets, syrups, elixirs, and solutions.
• Drugs are delivered through different routes of administration 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.
• Cell membranes are semi-permeable and bulk flow of water can carry drug substances.
• 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.
• Lipinski’s Rule of Five is a common rule followed to determine the oral bioavailability of drugs.
• pH is the negative log of the H+ ion concentration.
• Ion trapping is when a drug remains in a specific compartment because it is non-diffusible.
• 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.
• pKa is the pH of the medium at which 50% of the drug is ionized and 50% is non-ionized.
• 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.
• Exocytosis is the expulsion of a material that is membrane-encapsulated inside the cell and going out of the cell.
• 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.
• The Henderson-Hasselbalch Equation represents the relation of pH, pKa, and the drug’s degree of ionization.
• 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.
• Bioequivalence is when the rates and extent of F of the active ingredient in two drug products are not significantly different under suitable test.
• Gastric emptying, which takes about 4 hours, is important for intestinal absorption of a drug.
• Absorption most likely takes place in the small intestines.
• Cellular transport refers to the movement of substances across the cell membrane.
• Liberation is the process where the drug is released from the site of action.
• Absorption is the process of uptake of the compound from the site of administration into the systemic circulation.
• Absorption is more favored when the drug is in the non-ionized and more lipophilic form.
• Unwanted site of action is where the drug binds but does not exert its pharmacologic effect.
• Therapeutic site of action is where the drug binds and exerts its pharmacologic effect.
• The central compartment is where the free drug and protein-bound drug metabolites are located.
• Metabolism is the process wherein the parent drug and its metabolites leave the body.
• Distribution is the stage when a drug moves from the site of entry to the other organs or areas of the body.
• Passive transport or diffusion is when a drug penetrates by diffusion and moves along the concentration gradient (high to low) by virtue of its solubility in the lipid bilayer.
• Factors affecting drug absorption include lipid solubility, molecular size/weight of the drug, and degree of drug ionization.
• Tissue reservoirs are areas in the body where the drug accumulates.
• Pharmacokinetics is the domain of pharmacology that looks into the process that are involved in the handling of the drug as it enters and leaves the body.
• Absorption is the movement of a drug from its site of administration into the central compartment and the extent to which it occurs.
• Excretion is the stage when the body transforms the drug into metabolites.
• The plasma membrane is made of phospholipid bilayer with an outer phosphate head that is hydrophilic and an inner lipid tail that is hydrophobic.