d Excretion the kidneys 2 Pharmacodynamics a Receptors activation b Drug Receptor Interactions Basic Principles of Pharmacology Study Guide 1 Pharmacokinetics a Absorption Definition The process by which a drug enters the bloodstream from the site of administration Factors influencing absorption Route of administration drug formulation blood flow to the site and drug properties b Distribution Definition The transport of a drug throughout the body to its target site of action Factors influencing distribution Blood flow drug solubility protein binding and tissue permeability c Metabolism Biotransformation Definition The enzymatic alteration of a drug into metabolites often in the liver Enzymes involved Cytochrome P450 system Consequences Metabolism can lead to activation or inactivation of drugs Definition The removal of drugs or their metabolites from the body primarily through Other routes of excretion Bile feces lungs Definition Specific sites on cells where drugs bind to produce their effects Agonists vs Antagonists Agonists activate receptors while antagonists block receptor Affinity and Efficacy Affinity is the strength of the drug receptor binding and efficacy is the ability of the drug to produce a response c Dose Response Relationships Dose Response Curve Graphical representation of the relationship between drug dose and its effect ED50 and LD50 Effective dose for 50 of the population and lethal dose for 50 respectively d Therapeutic Index Definition The ratio of the median lethal dose LD50 to the median effective dose High vs Low Therapeutic Index High TI indicates a wide margin of safety low TI ED50 requires careful monitoring e Drug Interactions Pharmacokinetic Interactions Changes in drug absorption distribution metabolism or excretion Pharmacodynamic Interactions Combined effects on the same receptor 3 Drug Classification a Based on Therapeutic Use Example Analgesics pain relievers antibiotics antihypertensives b Based on Chemical Structure Example Beta blockers ACE inhibitors statins c Based on Mechanism of Action Example Beta 2 adrenergic agonists ACE inhibitors serotonin reuptake inhibitors 4 Pharmacotherapy Principles a Individual Variation b Placebo Effect Factors affecting response Age gender genetics comorbidities and organ function Definition A psychological and physiological response to an inactive substance Importance in Clinical Trials Used as a control to assess the true effect of a drug c Adverse Drug Reactions ADR Types Side effects allergic reactions idiosyncratic reactions toxic reactions Monitoring and Reporting Importance of identifying and reporting ADRs d Patient Education and Compliance Importance Enhances treatment outcomes and reduces the risk of adverse effects Factors influencing compliance Understanding motivation and convenience 5 Drug Development and Approval Process a Preclinical Testing Animal studies Assess safety toxicity and efficacy b Clinical Trials Phase I II III IV trials Progressively larger studies to evaluate safety and effectiveness Regulatory Approval Obtaining approval from health regulatory agencies