Pharmacology Week 1&2 Notes PDF

Pharmacology it is the science dealing with the preparation, uses and especially the effects of drugs What is a drug? - Any chemical that can affect a physiologic process of a living organism - Those effects can be either therapeutic or "good/helpful" or they can be toxic "bad/harmful...

Pharmacology it is the science dealing with the preparation, uses and especially the effects of drugs What is a drug? - Any chemical that can affect a physiologic process of a living organism - Those effects can be either therapeutic or "good/helpful" or they can be toxic "bad/harmful" - The Ideal drug would be safe, selective and effective Wish list: - Reversability: - Predictability - No adverse effects - No interactions with other drugs - Cheap and simple Drug Names: You will find that drugs have different names for the same medication - They have their chemical name which is that big long equation with letters and hexagons and a bunch of stuff you don\'t necessarily need to know for this class. - Then they have their generic name which is the nonproprietary name that is not protected by any trademarks, ie. Aceteminophen is the generic name. Generic names are what we will learn drugs by this course and what will be on the NCLEX - The third drug name that exist is the trade name, or the commercial name of who is selling the specific drug, ie. Tylenol. Classifications: Drugs are grouped together into what are called drug classifications. The drugs are grouped together based on their structural properties or what they are used for. (beta- blockers or antibiotics) Pharm has 8 subspecialties in total. - For this class, we will dive into pharmaceutics, pharmacokinetics, pharmacodynamics, and pharmacotheraputics - Pharmaceutics is how different routes of medications influence the way a drug effects the body. You need to know the different forms medications can be dosed - Enteral routs are going to be your oral medications, rectal meds, sublingual or buccal (under the toungue/ inside the cheek) - Your parenteral route will include your injectable forms like IV medications, shots, etc. - Then Topical medications will be your creams, pastes, ointments, aerosols, etc. - STUDY TABLES 2.1 AND 2.2 as they give great information about speed of absorpstion in comparison to route as well as types of routes and what forms go within each route - Extended release medications are not to be crushed because this could cause the medications to be absorbed faster at higher concentration rates and lead to toxicity. What should you do if the patient is unable to take the medication in the extended-release oral dosage form given? Call your pharmacist! Make sure to study your clinical pearls in the chapters as well. It is important to know how the drug gets from the pill bottle to the point of effecting the patient. - Oral drug taken then it gets broken down in the GI tract then drug Molecules through GI Mucosa then the Drug is transported to site via blood/ lymph What is Pharmacokinetics: It is the movement of a drug through the body from entry to exit - What are the four principles or concepts that fall under pharmacokinetics? (ADME) - A: Absorption - D: Distribution - M: Metabolism - E: Excretion - What is Absorption? Movement of a drug from site of administration to the bloodstream for distribution - Absorption rate is going to be higher depending on the speed of the effect (how quickly the patient feels the effect of the drug) - Absorption amount is going to determine the intensity of effect the patient feels - What impacts drug absorption? - How fast the drug can dissolve - The quicker the drug dissolves the faster it makes it into the drug stream - The surface area where the drug is being absorbed - The larger the area the faster it will make it into the bloodstream - The quality of blood flow - The better the blood flow the faster the drug will make it into the bloodstream - The ability of the drug to cross cell membranes - The more easily a drug crosses a cell membrane the faster it will make it into the bloodstream - PH partitioning and drug ionization (pH 1.3 for stomach and 6 for intestine) - What is bioavailability? - The amount of a drug available after absorption has happened. - Explain first-pass effect (oral meds) - The drug has to pass through the liver before entering the blood stream - Alot of the drug is impacted by the first pass effect - Although usually occurs in the liver, can occur in the lungs, vasculature, the GI tract, and other metabolically active tissues - The first pass effect is why oral medications are much higher than IV medication doses (IV medications bypass metabolic structures and go straight into the blood stream) - What entaral (oral) dosing route has 100% Bio availability? Sublingual; because it bypasses the liver; highly vascularized area and drug goes straight into bloodstream. - Routes of Administration - Enteral - How drug is absorbed - Drug moves through the mucosa of the stomach and/ or small or large intestines into systemic circulation. It is then taken to the liver; it is metabolized, and the remaining active ingredients are sent through to the general circulation - Why might absorption be altered for those taking medication via the enteral route? - Loss of small bowel - Absence/ presence of food to activate those gastric enzymes - Gastrict surgery - Decreased blood flow to stomach/ intestines - Parenteral - Fastest route to which a drug can be absorbed - 100% Bioavailability; does not have the first-pass effect - What routes are only given by the physician/NP/Provider? - Intraarterial, intratrathecal, and intraarticular. - Explain injection sites: subcutaneous (under dermal layer), intradermal (under epidermal layer), intramuscular (into muscle) - Topical - Slow absorption times with prolonged duration - Does not go through first-pass effect with the exception of rectal meds - Distribution: the movement of a drug from the bloodstream to the target cells - Where do drugs cross membranes? - pores - Transport systems - Direct penetration - What does it take to have the most effective distribution? - Adequate blood flow to tissues - Ability of the drug to exit the vascular system - Ability of the drug to enter target cells - Challenges to Distribution: - Diabetic foot ulcer - Diabetic clients don\'t have good feeling in their feet so they could possibly step on something or get a cut and don\'t do regular foot care, they can get an infection - Giving the diabetic patient an antibiotic (Intravenously) because they don\'t have the vasculature to get the antibiotic to where the infection is - Abscesses - Dont have good blood supply because of the puss pocket - Have to be incised and drained then we can get the infection taken care of with the antibiotic - Tumors - Don\'t have a good blood supply to the core making it dificult to get chemo therapy to it and patients end up having to get surgery to make the tumor smaller so the chemo can take care of the tumor easier - Types of Capillary Beds - Most capillary beds loose - Drugs can pass between cells not through them - Capillaries in the CNS - Blood Brain Barrier (BBB) - Tight junctions (no gaps) - Drugs must pass through the cells instead of in between them - p-glycoprotein will pump blood back into the bloodstream vs brain - Only lipid soluble drugs with a transport system can cross the BBB - The purpose of the BBB protects us from toxins but also prevents some helpful medications from getting where needed - Newborns have immature BBB that allow drugs into the CNS - Placental Distribution - Does not prevent drugs from circulating to the baby/babies - Many drugs can pass through the placenta - Caution with any meds for pregnant women - Catagory X Drugs means DO NOT GIVE TO PREGNANT WOMEN!!! - Catagory X risk to baby clearly outweigh potential benefits - Metabolism: Chemical alteration of the drug "Bio transformation" - Most happens in the liver using p-450 - Different Results of Drug Metabolism - Faster excretion of drugs by kidneys (lipid to water solluble) - Inactivation of drugs - Bioactivation of "pro drugs" - Takes an inactive drug and makes it active pharmacologically - Toxicity can be increased or decreased - If it inactivates a drug one will have less risk for toxicity - If it activates a drug it might increase the risk for toxicity - Cytochrome P450 System - Microsomal enzyme system - Group of 12 closely related enzyme families - Metabolizes drugs and endogenous (things the human body makes by itself) compounds - Prodrug needs bioactivation - Excretion - Removal of the drugs from the body - Kidneys play a major role! - If a patient has kidney trouble or kidney failure that can increase risk of toxicity - Three main processes that the kidneys use to excrete drugs - Glomerular filtration - Drugs pass easily through capillary wall spaces and into urine in proximal tubule - Passive tubular removal - Drugs move from greater concentration to lower concentration - Active tubular secretion - Some drugs use active transport system to move from blood into urine - Other routes of Excretion - Not usually clinically significant foe most drugs, but some - Bile - Secretes into small intestines and exits in feces - Some drugs may reenter into the enterohepatic recirculation (portal vein) - Lungs - Example: anesthetics - Sweat and Saliva - Breastmilk - Because drugs can leave in breastmilk is another reason you should be careful of giving drugs to nursing mothers - Pharmacodynamics - Why does a nurse need to know pharmacodynamics? - It is the effects of a drug on the body - Understanding pharmacodynamics prepares you to: - Advocate effectively with other disciplines for medication changes - Make safe decisions about medications - Educate patients about their medications - Evaluate the safety of the medications your patient is receiving - Pharmacodynamic Terms: - Maximal efficacy: The biggest effect a drug can have on the body - Potent Drug: Produces effects at a relatively lower dosage - Two drugs may do similar things but one is more potent - Receptor binding: substances bind to unique receptors on cells, and it is most often reversable - Receptors are special proteins that other substances bind to - Affinity: The strength of the attraction of the molecule to the receptor - Receptor (either receives an agonist or antagonist) - Protein molecules - Receives specific chemical signals which cause or block a cellular or tissue response - Signals (agonist/antagonist) can come in the form of other molecules - Drugs - Hormones - Neurotransmitters - Agonist - Bind to receptors and cause the cellular process to become active - Antagonist - Bind to receptors and cause the cellular process to be "blocked" or inactive - Natural Agonist (Endorphins) vs Agonist drugs (Morphine) - Endorohins bind to opiod receptors and produce pain relief and euphoria - Morphine binds to opioid receptors - Similar enough to natural agonist to bond to the same receptors - Produces same or even stronger reaction of pain relief and euphoria - Adverse Drug Reactions (ADR) - Disulfiram like Reactions - They cause Severe flushing, anxiety, nausea, sweating, abdominal cramps, and possibly tachycardia and hypotension - Taking specific medications with alcohol can give a patient Disulfiram-like reactions - Medications that can cause disulfiram-like reaction when combined with alcohol: - Metronidazole: (antibiotic) - Bactrim (antibiotic) - Tinidazole (antiprotozoal) - Chloroprepamide, tolbutamide, glyburide (sulfonylureas) - Cardiovascular medications (isosorbide nitrate and nitroglycerine) - Allergic/Hypersensitivity Reactions - Early signs of allergic reaction: itching, rash, and hives - Hives and rashes can lead to anaphylaxis - Drugs that are most likely to do this are: - Antibiotics - Some ACE inhibitors - Angioedema - Swelling in the deep layers of the skin and other tissues. - Typically most concerned with swelling in organs that can block airways - Drug induced angioedema - Allergic reaction to medication can occur with new medications or later in course of treatment - Mainly ACE Inhibitors (treats high blood pressure) such as enalapril or lisinopril - Angiotensin-2 receptor blockers (ARBS) also treat hypertension such as losartan, valsartan, Olmesartan - Erosive Esophagitis Risk - What is Erosive Esophogitis? - Very painful and makes swallowing difficult. - Can even cause nausea, vomiting or indigestion - Want to educate patients not to take specific medications at night or lie down after taking these medications - Medications that can cause Erosive Esophagitis Risk: - Doxycycline (antibiotic) - Tetracycline (antibiotic) - Clindamycin (antibiotic) - Bisphosphonates (treats osteoporosis) - Bodys Response to Drug Dosage and Timing - Minimum efective concentration (MEC) - Lowest plasma dose that meets therapeutic objective - Therapeutic range - The "Sweet Spot" in between the MEC and the level of MTC - Minimum Toxic Concentration (MTC) - Plasma level where toxic effects start to occur - Drug Half-Life - Is the amount of time it takes for the amount of hte drug to decrease by 50% in the plasma - Can range from minutes to a week - If a drugs half-life is 4 hours, every 4 hours the level of the drug that is present in the body will decrease by 50% - Drugs with shorter half-life must be given more frequently than longer half-lives - Steady State - Is a plateau or a constant serum drug level - Requires multiple repeated dosage of medication - The amount of drug given is the amount of drug eliminated - Usually after the 4^th^ dose the steady state is achieved (with equal dosages given each time) - Drugs with shorter half-life means the steady state is reached quicker vs drugs with longer half life\'s - How to impact serum Drug levels - Constant IV infusions - Depot preparations - Release drugs slowly over extended period of time - Reduce interval between doses and individual doses of medication - Example: total daily dose remains the same: instead of 100mg everyday, give 50mg twice a day, or four times a day - Loading doses - Larger initial dose of medication then constant smaller doses - Shortens time to steady state for drugs with long half-lives - How long does it take for a Drug to Leave the Body? - After the medication is discontinued - For most drugs: The time is equal to approximately 4 half-lives for 94% of the drug to be eliliminated - Drugs with longer half-lives can remain in the body for a very long period of time - Pharmacology for pediatrics Patients (birth to 16 years) - The younger the patient the more immature the organs - Pediatric patients grouped by age: - Pre-natal: - premature infant: \ - 7 Medication Strategies for Elderly Patients - Be diligent to obtain a complete current mendication list incluting OTC's and herbal supplements - Collaborate with pharmacist to identify possible ADR's - Use Criteria to identify possible inappropriate meds for elderly. - Assess and accommodate age related pharmacokinetic and physical changes (hearing, vision, manual dexterity) - Assess ability to follow medication plan- including ability to acquire perscribed medications - Look for alternative options as appropriate - Utilize return demonstration in patient education - PEDIATRIC DOSES USE KILOGRAMS NOT POUNDS - MOST PEDIATRIC DOSES ARE IN mg/kg/day BUT SOME ARE mg/kg/dose - CREATININE CLEARANCE IS BETTER THAN CREATININE LEVEL IN GERIATRIC PATIENTS - Case Study - Scenario: A nurse is caring for 4 different patients with chest pain (angina), who are each being treated with nitroglycerin. - Patient A: - Takes 6.5 mg (extended-release) tablets PO 3 times daily - Patient B: - Takes transdermal patch that delivers 0.2 mg/hr - Patient C: - Takes 0.4 mg sublingually as needed for chest pain (angina) - Patient D: - (currently admitted to the hospital with severe heartfailure after myocardial infarction) Reciving 15 mcg/min intravenous infusion - Why were these specific routes chosen? - Patient needs - Which forms have an immediate action? - Sublingual - IV - Which patient will be affected most by the first pass effect? - PO - Transdermal patch - Why do PO and the transdermal patch be affected most by the first pass affect? - Because it has to pass through the liver or kidney and doesnt have the highest bioavailability meaning that the whole dose that is given does not get used - What would happen if Patient A chewed their nitro dose? - They would get a toxic dose because the drug is acting faster than intended/needed - What would happen if Patient C Chewed their dose of medication? - They would not get the medication - They won\'t get the full dose because it will be dispersed via the chewing. They also will not get the proper dose fast enough because the medication is dispersed thorough the mouth - What is Distribution - Transportation of a drug via the bloodstream to the site of action - How do drugs travel to the sites of action? - Free drug molecules are the only drug metabolites that are able to move outside of the vessels and to the action sites. They cannot be bound to any plasma proteins (which is albumin) because the proteins are too large to fit through the cell membranes for passage. FIG 2.4 - If a drug is unbound or "free" it is in an active state - If a drug is bound then it is in an unactive state - Why would the RN need to take caution in individuals who have low plasma proteins such as albumin? - Conditions that could cause this are extensive burns or malnourished states - What do you know about drug-drug interactions? - Some of them can me bad and you have to know what drugs cant work with other drugs - How could this affect the patient outcome? - Negatively - Explain blood brain barrier - What is it? - Semi-permeable border that only certain drugs pass through - Why is this important? - Protects the brain - What is metabolism: - Alteration of drug into one of these four states: an inactive metabolite, a more soluble compound, a more potent active metabolite, or a less active metabolite - What organ is most responsible for metabolism? - Liver - P-450 - What is it? - Enzyme that breaks down lipid soluble drugs - Responsible for the breakdown of the majority of medications - Excretion - What is excretion? - Elimination of drugs from the body - What is the primary organ system responsible? - Kidneys - Excretion process contains the glomerular filtration, active tubular reabsorption, and active sectretions - Explain the process of which the renal system uses to excrete a drug: - The kidneys filter the blood and the waste is excreted through urine - What is a half life - The time required for 50% of a drug to be eliminated from the body - Onset of Action - Time required for a drug to start to have a therapeutic response - Duration of action: - Length of time the drug concentration is sufficient without more doses - Peak level - Highest blood level - Trough level - Lowest blood level - Theraputic Drug Monitoring - Using the peak and trough levels to adequately and precisely verify drug exposure - FIG 2.6 - Pharmacodynamics: - What is pharmacodynamics? - Its the mechanisms of drug action in living tissues - Therapeutic effect= good - Mechanism of Action - How the drug interacts with the tissues at a cellular level - Interaction types - Receptor - When the drug molecule attaches to a reactive receptor site to accomplish the goal of the drug - TABLE 2.8 - Enzyme - When the drug molecule binds with the specific enzyme and either enhances or inhibits its function in the body (selective interaction) - Nonselective - Drugs that do not have specific interactions via receptor sites or enzymes but instead they target cell membrane to alter the metabolic processes of the cell (antibiotics or oncologics) - Pharmacotherapeutics - What is a contraindication - Any patient condition that makes the use of a specific drig (s) - Types of Therapy - Acute: drug therapy used in an acute care setting to treat disease or sustain life (pressors or volume expanders) - Maintenance: drug therapy to chronically control the disease but will not cure it (at home blood pressures or cholesterol meds) - Supplemental: gives the body what it is lacking to maintain function (insulin) - Palliative: makes the patient comfortable by treating symptoms of disease process (pain meds during cancer battle) - Supportive: used to keep optimal function of body while recovering (fluids to prevent dehydration, nausea, vomiting, and diarrhea - Prophylactic: prevents illness - Empirical: drugs used before confirmation of illness based on the probability of condition (UTI antibiotics) - Monitoring - Adverse effect: undesirable effect that is a direct response to one or more meds: predictable - Therapeutic Index: the ratio between toxicity of a drug and therapeutic effect (Small index= greater chance for toxicity) - Tolerance: a decreasing response to repeated doses of med - Dependence: physiologic/ psycologic need for a drug - Drug interactions: - TABLE 2.9 - Drug incompatibility: when 2 IV drugs are mixed and it results in either deterioration of one or both drugs or the creations of a physical precipitate - Always inspect IV bags for cloudiness or particulates before administration; contact the pharmacy and discard the IV bag - Adverse Drug Reaction: any reaction to a drug that is unexpected/ undesirable and occurs within the therapeutic range; not to be confused with adverse effects (which is a predictable response) - Medication errors: preventable situation where there is a compromise in the "Six Rights" of medication use; this is more common than adverse drug reactions - Allergic Reaction: when the immune system (immunoglobulins) sees the drug molecules as dangerous foreign bodies - Teratogenic effects: drugs that cause structural defects to babies in the womb - Carcinogenic effects: cancer- causing effects; called carcinogens - OVER THE COUTER MEDs - Safety with OTCs - Incorrect dosing/ timing - Appropriateness of using certain disease processes - Avoiding Seeking medical care which leads to severe critical illness - Patients think OTCs are harmless - Educating the patient about being careful when taking OTC's because there are quiet a few meds (cold and flu OTC's) that use the same ingredient or very similar ones - Educate teh patient that OTC's and herbal supplements are still meds and they need to let their healthcare provider know what they take. - HERBAL SUPPLEMENTS - FDA required info to be provided about the herb/ diet supp. But did not require approval for it to be sold on the market - Education - Herbs and drug interactions are a big education point for patients - Cranberry: decreases elimination of renally excreteddrugs - Garlic: Possible interference with decreased blood glucose therapy and warfarin - Ginko: Increased bleeding risk with anticoagulants and antiplatelets - Grapefruit: decreased metabolism of some drugs (primarily those that are metabolized via p-40) increases the intensity/ duration of caffeine effects - Kava: increases effects of barbiturates and ETOH; can cause liver toxicity - St. John's Wort: can lead to seratonin syndrome if taken with SSRIs has a list of drug classes that it may interact with - Make sure patients recive as much information about: - Safe use with herbal and OTC supplements - That herb/ dietary supplements are not FDA regulated - Just cause herbs or dietary supplaments may be a natural substance that does NOT mean they are safe during pregnancy - Patient-Centered Care Box pg 92 has great patient teachings to know and understand - What is our goal in Pharmacology? - Maximum benefit for the patients - Minimum harm to the patient - What is the nurses role in pharmacology? - Appropriate assessment before, during and after administering the drug - Evaluating the safety of the drug for this unique client - Minimizing and evaluating adverse effects - Educating the client and/or family