PCOL CHAP 1-4

• Pharmacology is the study of substances that interact with living systems through chemical processes, binding to regulatory molecules and activating or inhibiting normal body processes
• Medical Pharmacology is the science of substances used to prevent, diagnose, and treat disease
• Toxicology is the branch of pharmacology that deals with the undesirable effects of chemicals on living systems, from individual cells to humans to complex ecosystems
• Materia Medica is the science of drug preparation and the medical use of drugs, the precursor of pharmacology
• Two general principles:

  • All substances can be toxic under certain circumstances
  • Chemicals in botanicals (herbs and plant extracts) are similar to chemicals in manufactured drugs except for the proportion of impurities
• Pharmacogenomics and Pharmacogenetics study genetic variations that cause differences in drug response among individuals or populations
• Pharmacokinetics involves the absorption, distribution, metabolism, and excretion of a drug
• Pharmacodynamics involves the biochemical and physical effects of drugs and the mechanisms of drug actions
• Pharmacotherapeutics is the use of drugs to prevent and treat disease
• Each drug has at least three names:

  • Chemical Name: scientific name describing atomic and molecular structure
  • Generic Name (Nonproprietary name): abbreviation of the chemical name
  • Trade Name (Brand name/Proprietary name): selected by the drug company selling the product, protected by copyright
• Pharmacologic Class groups drugs that share similar characteristics, while Therapeutic Class groups drugs by therapeutic use
• Drugs can come from plants, animals, and minerals
• Old-Fashioned Medicines used various parts of plants for drug concoctions
• Power Plant components include Alkaloids, Glycosides, Gums, Resins, and Oils
• Animal-sourced drugs include hormones, oils, fats, enzymes, and vaccines
• Mineral Springs provide substances like Iron, Iodine, and Epsom salt
• Routes of Administration include buccal, sublingual, intradermal, intramuscular, oral, rectal, and others
• A Drug is any substance that brings about a change in biological function through its chemical actions
• Agonists are activators with affinity to the receptor and intrinsic activity, while Antagonists are inhibitors with affinity only
• Poisons are drugs with harmful effects, and Toxins are poisons of biologic origin
• Drugs can be solid, liquid, or gaseous, with varying sizes and reactivity
• Drug Shape depends on the chirality of the drug chemical structure
• New Drug Development involves phases like Phase I, II, III, and IV, with FDA approval based on satisfactory Phase III studies
• Pharmacodynamics focuses on the actions of drugs on the body, while Pharmacokinetics focuses on the actions of the body on the drug
• Absorption of Drugs involves mechanisms like Passive Diffusion, Facilitated Diffusion, Active Transport, Endocytosis, and Exocytosis
• Factors influencing drug absorption include pH, blood flow, surface area, contact time, and P-glycoprotein expression
• Bioavailability is the rate and extent to which an administered drug reaches the systemic circulation, influenced by various factors
• Factors influencing bioavailability:

  • First-pass hepatic metabolism: when a drug is absorbed from the GI tract, it enters the portal circulation before entering the systemic circulation
  • Solubility of the drug
  • Chemical instability
  • Nature of the drug formulation
• Bioequivalence:

  • Two drugs are bioequivalent if they show comparable bioavailability and similar times to achieve peak blood concentrations
• Therapeutic equivalence:

  • Two drugs are therapeutically equivalent if they are pharmaceutically equivalent with similar chemical and safety profiles
• Pharmaceutical equivalence:

  • Drugs have the same dosage form, contain the same active ingredient, and use the same route of administration
• Drug distribution:

  • The process by which a drug leaves the bloodstream and enters the interstitium (extracellular fluid) and the tissues
• Metabolism of drugs:

  • Three major routes of elimination: hepatic metabolism, biliary metabolism, urinary metabolism
  • Prodrug: an inactive precursor chemical that is converted to the active drug by biological processes inside the body
• Excretion:

  • Renal elimination of drugs through glomerular filtration, proximal tubular secretion, and distal tubular reabsorption
• Drug receptors and pharmacodynamics:

  • Pharmacodynamics describe the actions of a drug on the body and the influence of drug concentrations on the magnitude of the response
  • Receptor: the component of a cell or organism that interacts with a drug and initiates the chain of events leading to the drug's observed effects
• Macromolecular nature of drug receptors:

  • Orphan receptors: ligands are presently unknown and may be useful targets for the development of new drugs
  • Regulatory proteins: mediate the actions of endogenous chemical signals
  • Enzymes: identified as drug receptors and may be inhibited or activated by binding a drug
• Four subtypes of receptors:

  • Class 1: ionotropic receptors associated with ligand-gated ion channels
  • Class II: metabotropic 7 transmembrane-spanning G-protein-linked receptors
  • Class III: enzyme-linked receptors with tyrosine kinase activity
  • Class IV: intracellular receptors with effects lasting hours to days
• Relation between drug dose and clinical response:

  • Graded dose-response relations: pharmacologic potency and maximal efficacy
  • Potency: concentration or dose of a drug required to produce 50% of the drug's maximal effect
  • Efficacy: magnitude of response a drug causes when it interacts with a receptor
• Variation in drug responsiveness:

  • Idiosyncrasy: caused by genetic differences in drug metabolism or immunologic mechanisms
  • Hypersensitivity: allergic or immunologic responses to drugs
  • Tolerance: decreased responsiveness due to continued drug administration
• Classification of drugs:

  • Functional modifiers: alter normal physiological functions
  • Replenishers: supplement or replace endogenous substances that are lacking
  • Diagnostic agents: used for the diagnosis of certain conditions
  • Chemotherapeutic agents: drugs used to kill or inhibit the growth of cells or nucleic acids