Introduction to Pharmacology PDF

Introduction to pharmacological principles MARYAM SAWALHA 1 2 3 4 5 6 7 8  Sources of Drugs 1- Animals : * Insulin Cow and pig pancreas tissue Use to replace human chemicals not produced caused by disea...

Introduction to pharmacological principles MARYAM SAWALHA 1 2 3 4 5 6 7 8  Sources of Drugs 1- Animals : * Insulin Cow and pig pancreas tissue Use to replace human chemicals not produced caused by disease/genetic problem *Thyroid drugs & growth hormones animal thyroid/hypothalamus tissues 9 2- Plants Digitalis ( cardiac disorders) Foxglove leavescontain digitalis (digitalis purpura) (digoxin) Opiates (for sedation) Opium poppy: Dried juice from seeds yields morphine, a natural opiate. 10 Marijuana Has no legal/accepted medical use (delta-9- tetrahydrocannabinol ) found in marijuana that prevent nausea & vomiting in cancer patient but with less effect than the leaf is smoked 11  3- Minerals / Inorganic Elements with therapeutic effects in human body : Aluminum Antacids gastric acidity Fluoride Prevention of dental cavities Iron Treatment of IDA Gold Rheumatoid arthritis 12  4- Synthetic products : Artificially produced or duplicated substances using different compounds used to be found in plants/animals/environment Benefits: 1. Drugs from the sources are produce to eliminate side effects 2. Increase potency of the drug Example : Aspirin , Paracetamol 13 4- Synthetic Microbes Genetic engineering (altering DNA) Permits the production of human insulin by altering E.coli 14 15 16 17 18 19 20 21 22 A branch of pharmacology that deals with the undesirable effects of chemicals on living systems. 23 The “Five Rights” of medication administration : Right drug Right dose Right time Right route Right patient 24 25 An unintended action of a drug. Results from a lack of specificity of drug action. All drugs are capable of producing adverse effects 26  Food & Drug Administration (FDA) The federal agency responsible for the safety and efficacy of all drugs in the US. It is also responsible for food and cosmetics also. 27 28 29 30 31 32 33  Pharmacologic Principles: Drug Names Chemical name The drug’s chemical composition and molecular structure Generic name (nonproprietary name) Name given by the United States Adopted Name Council Trade name (proprietary name) The drug has a registered trademark; use of the name restricted by the drug’s owner (usually the manufacturer 34  Chemical name (+/-)-2-(p-isobutylphenyl) propionic acid Generic name Ibuprofen Trade name Motrin 35  Grouping of drugs: Pharmacologic class (or family): – drugs that share similar characteristics – Example: beta-adrenergic blockers are an example of a pharmacologic class. Therapeutic class: – groups drugs by therapeutic use – Example: Antihypertensives 36  Routes of Drug Administration MARYAM SAWALHA 37  Routes of Drug Administration The route of administration (ROA) that is chosen may have a profound effect upon the speed and efficiency with which the drug acts 38  The possible routes of drug entry into the body may be divided into two classes: Enteral Parenteral 39  Enteral Routes Drug placed directly in the GI tract: Sublingual: placed under the tongue Oral: swallowing (p.o.) Rectum: Absorption through the rectum 40  Oral Advantages Convenient - can be self- administered, pain free, easy to take Absorption - takes place along the whole length of the GI tract Cheap - compared to most other 41 parenteral routes Oral Disadvantages : Sometimes inefficient - only part of the drug may be absorbed First-pass effect - drugs absorbed orally are initially transported to the liver via the portal vein Irritation to gastric mucosa - nausea and vomiting 42 Oral Disadvantages cont. Destruction of drugs by gastric acid and digestive juices Effect too slow for emergencies Unpleasant taste of some drugs Unable to use in unconscious patient 43  First-pass Effect The first-pass effect the term used for the hepatic metabolism of a pharmacological agent when it is absorbed from the gut and delivered to the liver via the portal circulation. The greater the first-pass effect the less the agent will reach the systemic circulation when the agent is administered orally 44 First-pass Effect 45  Sublingual/Buccal Some drugs are taken as smaller tablets which are held in the mouth or under the tongue. Advantages : rapid absorption drug stability avoid first-pass effect 46  Sublingual/Buccal Disadvantages inconvenient small doses unpleasant taste of some drugs 47  Rectal Advantages o Unconscious patients and children o If patient is nauseous or vomiting o Good for drugs affecting the bowel such as laxatives o Easy to terminate exposure Disadvantages: Absorption may be variable Irritating drugs contraindicated 48  Parenteral Routes Intravascular (IV, IA)- placing a drug directly into the blood stream Intramuscular (IM) - drug injected into skeletal muscle Subcutaneous - Absorption of drugs from the subcutaneous tissues Inhalation - Absorption through the lungs 49 Parenteral Routes 50  Intravascular Absorption phase is bypassed (100% bioavailability) 1. precise, accurate and almost immediate onset of action, 2. large quantities can be given, fairly pain free 3. greater risk of adverse effects a. high concentration attained rapidly b. risk of embolism 51  Intramuscular 1. Very rapid absorption of drugs in aqueous solution 2.Repository and slow release preparations: Depot Effect 3.Pain at injection sites for certain drugs 52  Subcutaneous 1.Slow and constant absorption 2.Absorption is limited by blood flow, affected if circulatory problems exist 3.Concurrent administration of vasoconstrictor will slow absorption 53 Inhalation 1.Gaseous and volatile agents and aerosols 2.Rapid onset of action due to rapid access to circulation a. Large surface area b.Thin membranes separates alveoli from circulation c. High blood flow 54 Topical Mucosal membranes (nasal, vaginal, etc.) Skin a. Dermal - rubbing in of oil or ointment (local action) b. Transdermal - absorption through skin (systemic action) i. Stable blood levels ii. No first pass metabolism iii. Drug must be potent or 55  Time-release preparations Oral - controlled-release, timed- release, sustained-release designed to produce slow,uniform absorption for 8 hours or longer better compliance, maintain effect over night 56  Time-release preparations Depot or reservoir preparations - parental administration (except IV), may be prolonged by using insoluble salts or suspensions in non- aqueous vehicles. 57  Important Info The ROA is determined by the physical characteristics of the drug, the speed which the drug is absorbed and/ or released, as well as the need to bypass hepatic metabolism and achieve high conc. at particular sites 58  No single method of drug administration is ideal for all drugs in all circumstances 59 Drug movement through the body 60  Drug Movement 1. Aqueous diffusion 2. Passive diffusion 3. Active transport 4. Endocytosis 61  Aqueous Diffusion Movement through body water Occurs 1- between aqueous body compartments 2- through pores between cells Driven by concentration difference on each side of the membrane 62  Endocytosis Also called pinocytosis Drug binds to special component of membrane Membrane folds over drug Membrane-surrounded drug released into the cell Many peptides are transported this way For example Vitamin A, D, E, and K 63  Active Transport Requires a carrier molecule and a form of energy. The process can be saturated Transport can proceed against a concentration gradient Used by endogenous substances ordinarily Example : polar drugs (ie, with low lipid solubility; eg, many antibiotic ) 64  Facilitated Transport A drug carrier is required but no energy is necessary. e.g. vitamin B12 transport Saturable if not enough carrier No transport against a concentration gradient, downhill but faster 65  Passive Diffusion Most drugs cross membranes by passive diffusion Drug concentration on one side of the membrane is higher than that on the other side 66 Drug movement through the body 67