Module 2: Pharmacological Principles PDF

**Module 2 : Pharmacological Principles** **Pharmacology** - **Pharmaceutics:** The study of how various drug forms influence the way in which the drug affects the body. This includes the dissolution of solid dosage forms and their absorption. - **Pharmacokinetics:** The study of what...

**Module 2 : Pharmacological Principles** **Pharmacology** - **Pharmaceutics:** The study of how various drug forms influence the way in which the drug affects the body. This includes the dissolution of solid dosage forms and their absorption. - **Pharmacokinetics:** The study of what the body does to a drug from the time it enters the body until the parent drug and metabolites have left the body. This includes: - **Absorption:** The movement of a drug from the site of administration into the bloodstream. Different dosage forms affect the rate of dissolution and the onset of action. - **Dosage Forms:** - **Enteral:** Absorbed into systemic circulation through the mucosa of the stomach and small/large intestines. - Oral - Sublingual - Buccal - Enteric-Coated - **Parenteral:** Bypasses the gastrointestinal tract. Includes intravenous, intramuscular, subcutaneous, intradermal, intra-arterial, intrathecal, and intra-articular routes. - **Topical:** Skin, eyes, ears, nose, lungs (inhalation), rectum, vagina. Includes transdermal patches. - **Bioavailability**: The amount of drug available for absorption after reaching the liver. - The first-pass effect reduces the bioavailability of oral drugs. - Intravenous drugs are 100% bioavailable. - **Distribution:** The transport of a drug by the bloodstream to its site of action. - Drugs are first distributed to areas with a rich blood supply: heart, liver, kidneys, and brain. - Drugs bind to plasma proteins, primarily albumin. Only unbound (free) drug is active. - **Factors affecting distribution:** - **Plasma membranes:** Drugs must cross numerous membranes to reach target cells. - **Protein binding:** Bound drug is inactive; only unbound (free) drug is active. - **Physiological processes:** Enzymes, phagocytes, and the immune system can affect drug distribution. - **Metabolism:** The biochemical alteration of a drug, primarily in the liver. - Also called biotransformation. - Involves cytochrome P450 enzymes. - Converts drugs into metabolites: inactive, more soluble, more potent, or less active forms. - **Excretion:** The elimination of drugs from the body, primarily through the kidneys. - Liver and bowel also contribute. - Drugs may be excreted in their original form or as metabolites. - **Pharmacodynamics:** How the drug affects the body. This includes: - **Mechanism of Action:** Drugs can interact with receptors, enzymes, or through nonselective interactions. - Drugs cannot make cells or tissues perform functions outside their natural physiology. - **Receptor Interactions**: Drugs bind to receptors on the surface or inside of cells. - Drugs with a high affinity for a receptor are more likely to bind to it. - **Agonists** elicit a physiological response; **antagonists** block a physiological response. - **Enzyme Interactions**: Drugs can inhibit or enhance enzyme activity. - **Therapeutic Index**: The ratio of a drug\'s toxic level to the level that provides therapeutic benefits. - A low therapeutic index means the difference between a therapeutic dose and a toxic dose is small, requiring close monitoring. - **Onset of Action:** The time required for a drug to elicit a therapeutic response. - **Peak Level:** The highest blood level of a drug. - **Trough Level:** The lowest blood level of a drug. - **Duration of Action:** The length of time the drug concentration is sufficient to elicit a therapeutic response. - **Toxicity:** Occurs if the peak blood level is too high. - **Pharmacotherapeutics**: The clinical use of drugs to prevent and treat diseases. This includes: - **Types of therapy:** Acute, maintenance, supplemental, palliative, supportive, prophylactic, and empirical. - **Pharmacogenomics:** The study of how genetics affects the body\'s response to drugs. - Goal: Individualize drug therapy based on a patient\'s genetic makeup. - Considers genetic polymorphisms, which are differences in alleles that can affect drug metabolism. - **Patient-Focused Considerations** - **Pediatrics:** - Neonates, children, and older adults have special considerations due to variations in pharmacokinetics. - **Children:** Immature organ function impacts absorption, distribution, metabolism, and excretion of drugs. - **Older adults:** Age-related organ decline leads to increased sensitivity to drugs and potential for adverse effects. - **Drug Interactions:** The alteration of one drug\'s action by another, which can lead to additive, synergistic, or antagonistic effects. - **Tolerance and Dependence:** - **Tolerance:** A decreasing response to repeated drug doses. - **Dependence:** A physiological or psychological need for a drug. - **Physical dependence:** Physiological need to avoid physical withdrawal symptoms. - **Psychological dependence (addiction):** Obsessive desire for a drug.