Transcript File
Principles of Drug Action and Interaction Jane Bordner, RN, BSN Nursing Instructor HACC N100 Spring 2015 Drug Names • Chemical name/Scientific name – Exact chemical make up of drug Drug Names • Generic – Name as designated by US Adopted Names Council of Federal Government (FDA) – Based on chemical compound of drug – Not capitalized – Example = ibuprofen Drug Names • Trade – Brand name given to drug by pharmacological company that developed and patented drug – Patent by US patent office and approved by FDA – Always capitalized – Example = Motrin and Advil Sources of New Drug Information • • • • • Nursing Drug Reference Books Physician’s Desk Reference (PDR) Package inserts National Formulary On-line resource: – http://www.nlm.nih.gov/medlineplus/dr uginformation.html – http://www.drugguide.com/ddo/ub Drug Categories • • • • Prescription Nonprescription (OTC) Controlled substances Herbal and dietary suppliments Controlled Substance Act • 5 Schedules or levels of drugs – Classification related to potential for abuse and severity of dependence – Schedule 1 has highest potential for abuse – Schedule 5 lowest Herbal and Dietary Suppliments • 80% of world’s population relies on herbs • Not without adverse effects • Can be toxic especially in combination with another medication Legal Regulations and Standards R/T Medication Adm. • The Controlled Substance Act designates categories or schedules, that classify controlled drugs according to their potential for abuse. • Department of State and State Board of Nursing delineates the scope of practice for nurses in each state. State Board of Nursing • Board that is charged with regulating nursing practice • Very fluid • Scope of practice may be different in each state Practical Nurse and Medication Administration • May administer PO, IM and SQ • May perform intradermal skin testing • May administer premixed IV drugs • May monitor IV fluids Practical Nurse and Medication Administration • MAY NOT administer certain IV medications – Antineoplastic agents – Blood and blood products – Total Parenteral Nutrition – IV push medications – Titrated medications Drug Classifications • Drugs classified by – Body system – Therapeutic use – Clinical indication – Physiologic or chemical action Phases of Pharmacology • Pharmaceutic • Pharmacokinetic • Pharmacodynamic I. Pharmaceutic Phase • • • • • • Dissolution of drug How drug becomes soluble Drug must be soluble to be absorbed Dependent on dosage form Occurs in GI tract Enteric coated/time-release meds II. Pharmacokinetic • Movement of drug through body – Includes: • Absorption • Distribution • Metabolism • Excretion • http://www.merck.com/mmhe/sec02/ch011/ ch011a.html Absorption • Drug made available for use in body • How drug is transferred from site of entry into body fluids – Route of administration – Solubility of drug – Blood flow in tissue Absorption • Active transport • Passive transport • Pinocytosis • http://www.wwnorton.com/college/biology/d iscoverbio4/animations/main.aspx?chno=ch0 6a01 Pinocytosis Variables Affecting Rate of Absorption • Route of administration • Solubility of drug • First-pass effect • Surface area • • • • Rate of blood flow pH GI motility Drug interactions Route of Administration • Enteral • Parenteral • Percutaneous Solubility of Drug • Dissolve in water or fat • Blood brain barrier General body cells Brain Cells First Pass Effect • Liver changes drugs before they pass into general circulation • PO dose vs. IV dose Surface Area • Related to site of administration • How much medication is available to site of absorption? • Oral medications = mucosal lining of small intestine Blood Flow • Absorption depends on blood flow – blood flow = absorption – blood flow = absorption Other Variables • pH – pH of gastric contents – pH of blood • GI motility – Enteral route only – Fat content of food • Drug interactions Distribution • How drug is carried from site of absorption to site of action • Drug storage Factors That Influence Distribution • Blood flow • Drug Solubility • Protein binding – Plasma carrier proteins – Storage tissue proteins – Receptor proteins • Inactive drug • Active drug Plasma Carrier Proteins Storage Tissue Proteins Receptor Proteins Receptor Protein Storage Tissue Protein Plasma Carrier Protein Metabolism/Biotranformation • Process by which body changes drugs • Metabolites • Liver is primary site for most drugs Excretion • Metabolites and/or active drug is removed from body • Primary routes of excretion Half-life • Time required for 50% of a drug to be eliminated from body • Determine dosage regimen of drug Half-Life # 4 hour intervals 0 Time in hours Dosage in mg. 0 1 4 2 8 3 12 4 16 Half-Life # 6 hour intervals 0 Time in hours 1 6 2 12 3 18 4 24 0 Dosage in mg. Half-Life Onset, Peak, and Duration • ONSET – Drug is sufficiently absorbed to reach effective level • PEAK – Maximum blood level for dose • DURATION – Length of time drug concentration is sufficient to produce a therapeutic response Peak Duration Onset III. Pharmacodynamic Phase • Mechanism by which drug produces biochemical or physiological changes • Drug action and effect on body tissues • Occurs with Pharmacokinetics Drug Action • Interaction at cellular level between a drug and cellular components • Therapeutic action – Target sites • Secondary actions Alteration in Cellular Function • Receptor-mediated • Mimic or block regular cell function • Number of receptors influences drug effect Receptor-Mediated Alteration in Cellular Environment • Drug changes cellular environment – Physically and Chemically • • • • • • Osmotic pressure Drug – Enzyme Antimetabolites Absorption/Chelating Agents pH Changes in Cell Membranes Drug Effect • Response resulting from a drug action • Example: Insulin – Drug Action = Transport of glucose across the cell membrane – Drug Effect = Lowering of blood glucose level Factors Influencing Drug Response • • • • • • Age Weight Gender/Genetics Disease/Illness Route of Administration Psychological Factors Infants and Children • Immature organ systems – Liver and kidneys • Smaller doses • Some drug too toxic