Pharmacological Principles Notes PDF

Pharmacological Principles CHAPTER 2 1 Pharmacology Drug ◦Any chemical that affects the physiological processes of a living organism Pharmacology ◦Broadest term for the study or science of drugs...

Pharmacological Principles CHAPTER 2 1 Pharmacology Drug ◦Any chemical that affects the physiological processes of a living organism Pharmacology ◦Broadest term for the study or science of drugs 2 Drug Names Chemical name ◦ Describes the drug’s chemical composition and molecular structure Generic name (nonproprietary, official name) ◦ Name given to a drug approved by Health Canada Trade name (proprietary name) ® ◦ The drug has a registered trademark; use of the name is restricted by the drug’s patent owner (usually the manufacturer). 3  Chemical, Generic, and Trade Names and Chemical Structure of Ibuprofen 4  Drug Classification ◦Drugs are grouped together based on their similar properties ◦Drugs can be classified by their structure ◦Drugs can be classified by their therapeutic use 5  Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacolog Pharmacogenomics ical (pharmacogenetics) Principles Pharmacotherapeutics Pharmacognosy Pharmacoeconomics Toxicology 6 Pharmaceut ics The study of how various drug forms influence the way in which the drug affects the body Different properties influenced by injection, tablet, capsule, extended release, intravenous Dosage forms determine the rate of dissolution and absorption 7 A client is prescribed ibuprofen 200 mg PO every 4 hours as needed (PRN) for pain. The pharmacy sends up enteric-coated tablets, but the patient refuses the tablets, stating that she cannot swallow pills. What will the nurse do? A. Crush the tablets and mix them with applesauce or pudding. B. Call the pharmacy and ask for the liquid form of the medication. C. Call the pharmacy and ask for the intravenous (IV) form of the medication. D. Encourage the patient to try to swallow the Practice Question tablets. 8 Pharmacolo gy: 3 Phases 9 Pharmacokinetics The study of what the body does to the drug From the time drug is put into the body until the parent drug and metabolites have left the body ◦ Absorption ◦ Distribution ◦ Metabolism ◦ Excretion 10  Movement of a drug from the site of administration into the bloodstream ◦Bioavailability: extent of Absorptio drug absorption or n “portion of dose that reaches systemic circulation….available to act on body cells” ◦First Pass Effect 11  First-Pass Effect Medications absorbed through digestive system are transported to the liver via the hepatic-portal vein The liver inactivates a portion of the medication before releasing it back into systemic circulation This ↓ bioavailability of the medication ↑ FPE=drug calculated to compensate* 12  Factors Affecting the Rate of Absorption Route of Administration Dosage Formulation Solubility pH GI motility (rapid vs impaired) Status of Absorptive Surfaces Blood Flow (IM) Presence of food/fluids ingested with drug 13 Route of Administration 14 Enteral Route The drug is absorbed into the systemic circulation through the mucosa of the stomach, small intestine, or large intestine ◦Oral (PO) ◦Sublingual ◦Buccal ◦Rectal (can also be topical) 15 Parenteral Route Intravenous ◦ fastest due to direct delivery into the blood circulation Intramuscular Subcutaneous Intradermal Intra-arterial Intrathecal Intra-articular 16 Topical Route Skin (including transdermal patches) Eyes Ears Nose Lungs (inhalation) Rectum Vagina 17 Dissolution of Oral Medications Solid medications must be dissolved in fluid in order for absorption to occur Additives/Coatings Enteric-Coated Time-Released 18 Time-Released Products CR Controlled/Continuous release CRT Controlled release tablet LA Long acting SR Sustained release/Slow release TR Time release TD Time delay SA Sustained-action ER/XL/XR Extended release MR Modified-released Factors Affecting Enteral Absorption Gastric Contents Acidity Motility Blood Flow Absorptive Surfaces 1st Pass Effect 20 The nurse is giving a medication that has a high first- pass effect. The health care provider has changed the route from IV to PO. The nurse expects the oral dose to be A. Higher because of the first-pass effect. B. Lower because of the first-pass effect. C. The same as the IV dose. D. Unchanged. Practice Question 21 Promoting Absorption of Oral Meds 1 2 3 4 Take meds Take meds at Shake Follow the with full least 1/2 hr. suspension instruction before bed glass of fowlers s well s H2O position ideal 22 Absorption of Parenterals pH must be similar to blood Not too concentrated/corrosive IV instantaneous & complete 100% IM rapid to long-acting Subcut similar to IM 23 Factors Affecting IM/Subcutaneous Absorption Fat content of tissue Solubility of medication Blood flow Proper administration 24 A patient reports severe pain and has orders for morphine sulphate. The nurse knows that the route that would give the slowest pain relief would be which route? A. IV B. Intramuscular C. Subcutaneous D. PO Practice Question 25 Topicals Local Effect: when a drug acts only superficially on the surface area and is not absorbed and distributed through the blood stream Systemic Effect: when the drug enters the blood/lymph stream and is distributed through body tissues 26 Transdermal Advantages? Used systemically Constant amount of drug/unit of time for specified time period (24/72 h) Examples: fentanyl nitro nicotine estrogen 27 The nurse is preparing to administer a transdermal patch to a patient and finds that the patient already has a medication patch on the right upper chest. What will the nurse do? A. Remove the old medication patch and notify the health care provider. B. Apply the new patch without removing the old one. C. Remove the old patch and apply the new patch in the same spot. D. Remove the old patch and apply the new patch to a different, clean area. Practice Question 28  ◦Transport of a drug by the bloodstream to the drug’s site of action Distributi ◦Drugs distributed first to areas with extensive blood on supply ◦Heart, liver, kidneys and brain 29 Drug Transport in the Body 30 Protein-binding In order for drugs to reach tissue outside of blood, they cannot be bound to plasma proteins If they DO bind, too large to pass through capillary walls into tissue Unbound drug is active (able to reach target site) Bound drug is inactive 31 Albumin: Primary Protein 3 conditions that cause ↓ albumin levels burns malnourishment (−) N balance 32 Drug-Drug Interactions When 2 drugs are highly protein bound, drugs will compete to bind with the primary plasma proteins May lead to an unpredictable drug response When the presence of 1 drug ↓ or ↑ the action of another drug administered concurrently 33 Volume of Distribution Describes the areas where drugs may be distributed: blood total body water fat other tissues/organs 34  Water vs Fat Soluble Drugs WATER FAT Small volume of Large volume of distribution and ↑ distribution and ↓ blood blood concentrations. concentration → drug Chemically repelled by stays in blood water in blood and attracted to ↓ water and 35 What happens when a drug is Related to absorption to water tissue? soluble Related to onset of action? and protein bound? 36 What happens when drug is fat Related to distribution? soluble and has poor protein binding? 37  ◦Also referred to as biotransformation ◦Biochemical alteration of a drug into any of the following: Metaboli ◦an inactive metabolite sm ◦a more soluble compound ◦a more potent metabolite (as in the conversion of an inactive prodrug to its active form) ◦a less active metabolite 38 Metabolism Cont’d ◦Cytochrome P-450 enzymes (or simply P-450 enzymes), also known as microsomal enzymes ◦ Lipophilic (“fat loving”) ◦Hydrophilic (“water loving”) ◦Substrates ◦Enzyme inhibitors ◦Enzyme inducers 39 Sites of Metabolism Liver Skeletal muscle Kidneys Lungs Plasma Intestinal mucosa 40 Altering Rate of Metabolism Delaying drug metabolism results in: Accumulation of drugs Prolonged action of the drugs Stimulating drug metabolism causes: Diminished therapeutic effects 41  Elimination of drugs from the body Primary organ responsible is kidney Excretion Liver and bowel also play a role Renal excretion Biliary excretion 42 Renal Drug Excreti on 43  Factors Altering Excretion Renal Function – example very young and old  Pregnancy- ’s renal blood flow Renal Disease Dehydration Gallbladder Disease - if drug is excreted in bile 44 Half-Life ◦ Time required for half (50%) of a given drug to be removed from the body ◦ Steady state ◦ Onset of action ◦ Peak effect ◦ Duration of action ◦ Influences the frequency of dose administration 45 Relevance of Half-Lives Longer half lives = longer to reach steady state = levels take more days to be effective Eg. ASA 1-3 h half life = q 3-4h Other meds 10 hour half life= once a day 46  Therapeutic Monitoring Onset: The time it takes for the drug to elicit its therapeutic response Peak: The time it takes for a drug to reach its maximum therapeutic response Duration: The time a drug concentration is sufficient to elicit a therapeutic response Trough level: lowest blood level of a drug Toxicity: occurs if the peak blood level of the drug is too high 47 Therapeutic Effects 48 Pharmacodyna mics The study of what the drug does to the body ◦The mechanism of drug actions in living tissues ◦Therapeutic effect ◦The goal of drug therapy ◦Mechanism of action ◦Receptor interactions ◦Enzyme interactions 49 Potential Drug Effects 50  Pharmacotherape utics The clinical use of drugs to prevent and treat diseases Desired therapeutic outcomes is patient-specific, established in collaboration with the patient. Outcome goals need to be realistic. 51 Types of Therapy ◦ Acute ◦ Maintenance ◦ Supplement al (or replacement ) ◦ Palliative ◦ Supportive ◦ Prophylactic ◦ Empirical 52  Monitoring ◦ Therapeutic action ◦ Beneficial effects ◦ Adverse effects ◦ Predictable adverse drug reactions ◦ Toxic effects ◦ Therapeutic index ◦ Drug concentration ◦ Patient condition 53 Potential for Abuse Tolerance: decreasing response to repeated drug doses Dependence: physiological or psychological need for a drug Physical dependence: ◦ physiological need for a drug to avoid physical withdrawal symptoms Psychological dependence (addiction): ◦ obsessive desire for a drug 54 Additional Considerations ____________________________________________________________________________________________ o Drug interactions o Medication error o Additive effects o Adverse drug o Synergistic effects withdrawal event o Antagonistic o Adverse drug effects reaction o Incompatibility o Allergic reaction o Adverse drug event o Idiosyncratic reaction o Other drug effects 55 Ten Rights of Medication Administration ◦ Right drug for Right Medication ◦ Right dose ◦ Right time ◦ Right route ◦ Right patient ◦ Right reason ◦ Right documentation ◦ Right evaluation for right assessment ◦ Right patient education ◦ Right to refuse 56