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Module 01 Notes/Key Info taken from Live Lecture -
Pharmacology for Professional Nursing
Giving medication to patient/educating If I am going to give a patient something to lower their BP, they are going to be at risk for hypotension. That BP med may work too well! Make sure that you know how to evaluate these patients after you administer meds and how to educate them (get out of the bed slowly, hold on to the wall, call me for help). Additional Rights of Administering Medication: In addition to Right: patient, medication, dose, route, time, documentation
- Expiration: some medications can be more potent and cause more harm if they are expired—or be ineffective - Documentation: If you did not document it did not happen - Education: Pt needs to know “What is this going to do to me?” “Are there any side effects I should be aware of?” - Assessment: BEFORE WE GIVE THE MEDICATION - Refuse: A part of the patient’s autonomy. Usually because of a lack of education. DO NOT bully the patient into taking the medication (yes, it happens) o The PATIENT HAS THE RIGHT TO REFUSE medication, but we are nurses HAVE THE RIGHT TO EDUCATE THEM. o If the patient still refuses post-education, then the nurse has to document it. “Patient educated on new reason behind medication. Still refused because of x, y, z.” o Communication in patient care, education is a very big deal. **Important to EVALUATE after you have given the medication. “I gave you medication for blood pressure, let’s make sure your blood pressure lowered.” “I gave you this medication, let me make sure it is giving you the desired effect.”
Medication Errors: CAUSES
- Wrong rights o Patient, med, dose, time, route - Miscommunication o Not going through and verifying medications before you are administering them - Look-alike, sound-alike medications - Nurse too busy, distracted, overworked o Can cause med errors **HOW TO PREVENT THEM
- Computerized order input o** You as the nurse do not have to try and interpret the doctor’s “chicken scratch” of a handwritten order “Is that a P or a Z?” What am I looking at? - NO ABBREVIATIONS (QD, QID, QOD) o QD – Just write the word “daily” o QID – Just write “everyday” o QOD – Just write “every other day” o “Unit” needs to be written out instead of writing down a “U” ▪ These words should be written out to prevent med errors!!! - Computerized med pass o Using an actual EMAR, scanning the patient’s armband, etc. **- No verbal phone orders/ unless emergency
- Dual verification on high alert drugs o** 2 licensed nurses need to verify** (Insulin, Heparin)
Absorption Distribution Metabolism/ Biotransformation Excretion/Elimination Via 4 Processes o This is how the drug acts in the body/how they produce their side effects o How they produce their ACTUAL effects? How are they working in the body? ENTERIC: of, relating to, or occurring in the intestines
- Medications that need to break down in the INTESTINES o Has a protective coating on it, so the stomach can not initiate breakdown If a drug is enteric coated, where do you suppose the drug disintegrates and is absorbed? - In the intestines! If a drug is enteric coated and meant to be absorbed in the small intestine, what would happen if you crushed it before taking it? - Absorption would begin the STOMACH & that is NOT where it needs to be absorbed. It would not work properly, it does not absorb correctly, and they can get an overdose of the medication; especially if the enteric coating is supposed to slowly reach it PHARMACOKINETIC phase: Important to know! - This is process of drug movement through the body to achieve drug action. o Sometimes referred to as “what the body does to the drug.” These 4 processes are the major determinants of the time course oPvherawrmhicahcokinetics drug responses take place Bioavailability = percentage of the drug that is absorbed into circulation
Swallowed drug
Digestive
System
Hepatic
Portal Vein
Liver
Rest of the
Body
o Bioavailability of the medication depends on how they get it o Are they getting it Oral, IV, SubQ, Intranasally, Intravaginally Intrarectally, Topical? First-Pass Effect: a process in which a drug administered PO is absorbed from the GI tract and transported via the portal vein to the liver, where it is metabolized. As a result, in some cases only a small proportion of the active drug reaches the systemic circulation and its intended target tissue. o First-pass effect can be bypassed by giving the drug via sublingual, buccal & intravenous routes. First pass effect (when you swallow)
- The body absorbing the drug
- Has to FIRST PASS THROUGH THE LIVER before it can affect targeted site Example: Intravenous (IV) o Injection straight into the systemic circulation is the most common parenteral route. It is the fastest and most certain & controlled way. It bypasses absorption barriers and first- pass metabolism/effect. It is used when a rapid effect is required, continuous administration and large volumes.
- Means that 80% of medication must go through FIRST PASS. - Tablet or capsules MUST dissolve. Drugs in liquid form are already liquid. MICROVILLI start ABSORPTION of the medication - With that being said, a patient with GI issues (Crohn’s, Celiac disease, etc.) has intestines that do not work the way they are supposed to - If their intestines are not working the way they are supposed to … then the medication WILL NOT WORK THE WAY IT IS SUPPOSED TO. - If anything is damaged in the intestines, it will impact absorption. - Patient has intestinal removal: they most likely WILL NOT get an enteric coated medication. - Damaged VILLI – LITTLE TO NO ABSORPTION o Think about it.. if it is intended to break down in the intestine, and they don’t have the intestine to do it.. then this patient will actually void out the whole tablet (because it won’t break down). It doesn’t have the ability to do what it’s supposed to. *****DUTY OF THE NURSE/DETECTIVE WORK: -** If you know your patient has had a bowel resection, ileostomy, ostomy.. then WHY do I have this order for an enteric coated medication for my patient. Something isn’t right here.. - You must always be able to back up what you are doing with a rationale! Why am I doing this?
ABSORPTION phase
- Drugs absorbed most easily by GI tract o Fat-soluble (lipid-soluble) ▪ o Nonionized (no electrical charge) Enteral: via the GI tract
- inside the GI tract (they have to swallow it) or it can be given through a suppository Parenteral: outside the GI tract; used to mean INJECTION (IV, IM, SQ, intrathecal, intraarterial)
- Parenteral injected into the veins and the muscles bypasses the GI tract and first pas effect
- Term I didn’t know: ** Intrathecal = route of administration for drugs via an injection into the spinal canal , or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF) & is useful in spinal anesthesia, chemotherapy, and pain management applications. “Topical” medications include: o Eye drops o Ear drops o Nasal sprays o Respiratory inhalants o Transdermal meds o Sublingual meds/buccal meds
o High fat foods increase absorption time ▪ High fat foods increase absorption time ▪ GI tract easily absorbs fat soluble foods If a patient is ingesting a medication & eating foods that are high in fat, there are other lipids that are fighting for those lipid bilayers to go ahead and cross into the circulatory system. o So, if you are eating HIGH-FAT FOOD, & you have a medication that is being absorbed via the lipid layer.. THE FATTY FOOD IS GOING TO MAKE IT TO THE FINISH LINE FIRST. ** IMPORTANT TO KNOW! High-fat foods increase absorption time because the body will choose to digest food before it gets to the medication!! o Exercise can increase drug absorption because of blood flow goes to the peripheral muscles instead of GI tract Exercise decreases absorption because blood is getting to the muscles and not the gut o You are working out. Your heart is racing. Your muscles are getting a lot more blood flow to the muscles so they can GROW. The muscles can heal, rip, and rebuild. ▪ The stomach is like “Meh.. I’m not hungry right now. Deal with it.” It does not need as much blood flow to the stomach.
- Why? The blood flow is being diverted from the stomach to provide blood to the muscles.
- So if the patient is taking a medication that it meant to absorb in the GI tract, exercise CAN affect it. DISTRIBUTION phase:
- The process by which the drug becomes available to the body fluids and body tissues from the bloodstream. - Influenced by: o Blood flow to tissues—BLOOD CAN AFFECT DISTRIBUTION o Drug’s ability to exit bloodstream o Drug’s ability to enter cells o Drug’s affinity to the tissue ▪ Affinity is the strength of attraction between the drug and receptor o Protein binding Influenced by tissue permeability. - Once in the bloodstream, the medication has to get to the organs it is particularly involved with/has to move around in the tissues that are highly perfused. - Once in the blood stream, it can get to get to the tissue it needs to (pH of the blood can also affect how meds are distributed) - A drug can bind to a receptor that can render the drug inactive. Only an unbound drug can attach to the receptors. o High Affinity = Binds EASILY o Low Affinity = Higher concentration of the drug needed to elicit a therapeutic response Distribution: Protein binding: IMPORTANT TO UNDERSTAND **** - As drugs circulate in the blood and plasma, some of them have a high affinity for binding to the plasma proteins (warfarin and furosemide) while others have low affinity (Lisinopril and metoprolol) o I want to bind to this certain protein, so I’m going to hang out in the body a little bit longer; we have a great bond.
o Not necessarily a “good thing” or a “bad thing” when it comes to protein binding” .. it is a natural response of the body. The body goes in and collects these free floating “things” they can bind to and activate OR deactivate (Oh you wait.. we will get into receptor sites shortly ) ▪ The protein that IS binding is holding some of the medication and the way that the drug manufacturers make the medication is if it is a higher affinity it will typically have a higher dose / whereas a lower affinity will have a lower dose that is required to do the same job Both high affinity and low affinity medications will cause a therapeutic response, but when they are competing for the same binding site, THAT’S when they build up. Example: 2 drugs with a high protein binding affinity
- One of them will WIN & BIND to the protein, while the other one will LOSE and potentially wind up causing a TOXICITY **Question: Should this be avoided?
- Having a patient on 2 higher affinity medications o** Better to avoid this, OR you can have them on 2 high affinity meds but SPACE THEM OUT. o This is when educating the patient on WHAT TIME they should take their medication(s) is important! If a patient has lower protein levels (they are malnourished, not receiving enough nutrition to help with healing) then they can have issues with the binding sites because there is not enough protein floating into the system for the medication to bind to. So they end up with a higher level of the medication floating around in the system than needs to be.
**Protein and albumin what does it tell us from a patient’s labs?? NUTRITION STATUS ** if malnourished they will have a greater potential for toxicity because they don’t have enough protein in their system to CORRECTLY BIND TO THE RECEPTORS Knowledge Check: Again, Remember that.. High affinity for protein binding More of the medication is binding to the protein so LESS of the medication is flowing the system Low affinity for protein binding Not a lot of the medication is binding to the protein so that means MORE medication free to float around in the system Blood Brain Barrier (BBB) KNOW THIS!!
- BBB affects the distribution of medications. - The tight cell junctions (capillaries) in the blood vessels in the brain protect the brain from foreign substances. o Blocks out about 98% percent of drugs on the market o Benzodiazepines can the cross through diffusion = faster onset Know this!!!! Important for Week 2 METABOLISM phase (AKA Biotransformation) “Medication actually doing its thing” - The chemical alteration of drug structure goes through and starts to change the makeup of the drug. - The liver changes lipid-soluble substances to water-soluble substances for renal excretion o The liver is metabolizing it or breaking it down. Breaking down a fat- soluble drug to a water-soluble drug so it can leave through URINE.
- If the patient has liver cirrhosis, liver disease, hepatotoxicity, etc. their waste system can NO LONGER DO ITS JOB - Think about this: A patient with liver issues will not get as much Tylenol as the person without liver issues. They are going to have a restriction on how much Tylenol they can have. - Daily cap for Tylenol is 4 g. A person with liver issues would probably have a daily cap of 2.5/2 g because their liver can’t process it so there is so there is more left in the system/is hepatotoxic and can cause MORE DEATH TO THE LIVER. We must pay attention to those things! - Is very important to know lab values and obtain lab results BEFORE you medicate.
- If anything happens to the liver, the BIOTRANSFORMATION PHASE CANNOT HAPPEN OR IS EXTREMELY IMPAIRED
- Decreased toxicity the liver is doing its job maybe even too well, but it’s doing its job FIRST PASS EFFECT/RAPID METABOLISM Also called “Hepatic First Pass”
- Many drugs are affected or altered by passing from the intestinal lumen into the portal vein and into the liver.
- Hepatic enzymes (CYP1, CYP2, CYP3) inactivate certain oral drugs rapidly, like Nitroglycerin, rendering them inactive completely, while others are inactivated at a slower rate.
- These enzymes are converting your lipid drug into water soluble.
- For this reason, Nitro and other drugs cannot be taken orally (if it were to go through first pass, it would be completely inactivated and no longer work) That is why you give Nitro topically or sublingually.
- Some medications that go through first pass will STAY IN THE SYSTEM LONGER.
- This is also the reason the same drug may be given at a different dose when given PO or IV. The enzymes convert the drug into to a water- soluble form and they linger around in the system before excretion. ***EXAMPLE: Morphine 10 mg of PO morphine = 1 mg of morphine IV
- The oral med has to go through first pass & be broken down, inactivating a majority of the drug
- When taken orally it will take about an hour to kick in but will stay in the system much longer because of first pass
- Morphine given intravenously will bypass first pass
- An oral dose of morphine can last for 6 hours while an IV dose of morphine can last for 2
- That’s why we give IV for breakthrough pain and PO for standard pain IV is effective and faster than PO especially when binding to pain receptor sites, but it doesn’t last as long. It doesn’t have a lingering effect like oral does.
- If you have a patient that is having breakthrough pain, you can usually give them IV and PO at the same time because by the time the oral med has kicked in the IV med will be worn off.
- The IV med is going to allow time for the oral med to start working
- Different for someone with kidney or liver cancer because of absorption rates BIOAVAILABILITY
- The drug was changed from fat-soluble to water-soluble in the liver by metabolism, and now its supposed to go where it gets filtered and excreted. - If the kidneys aren’t working to do that part, then all of that medication is just sitting there and building up. If there is renal impairment, what would you expect would have to be done with the drug dosing?
- They are going to get less. You can give you a smaller dose, and it will still act as if I gave you a big dose. HALF-LIFE The time is takes for the amount of drug to be reduced by half ** The time it takes for one half of the drug concentration to be eliminated from the body Example: Medication: 200mg with an 8 hr half-life
- Dose left in the system after first 8 hr is 100 mg
- Dose left in the system after 16 hr is 50 mg
- Dose left in the system after 24 hr is 25 mg
- Dose left in the system after 32 hour is 0 mg ** Dose keeps reducing by half every 8 hours! Example: Half-life of Ibuprofen is 1.8 to 2 hr Initial Dose 400 mg 800 mg 2 hrs later 200 mg 400 mg 2 hrs later 100 mg 200 mg 2 hrs later 50 mg 100 mg 2 hrs later 25 mg 50 mg 2 hrs later 12.5 mg 25 mg - Half-life can be affected by:
o The amount of drug administered o The amount of drug remaining from previous doses o Metabolism o Elimination **Note: Half-life of med will be affected in someone who has certain conditions (acute renal disease, acute renal failure, liver failure, etc.) **To maintain therapeutic effect, you still want a small amount of medication lingering in the system. Otherwise, it would be like starting over and over again. PHARMACODYNAMIC phase: “What the drug does to the body/how we can tell if the drug is doing its job” KNOW THIS! Onset, Peak, & Duration of Action
- Onset of the medication : time it takes for the smallest amount of dose to be effective in the body - Peak action: highest concentration that it can possibly be in the blood o Ex: Vancomycin 30 minutes you would draw a peak - Duration of action: the length of time the med is in the system performing it’s therapeutic effect o How long it’s been in the system and how its working Receptor Theory - Drugs (chemicals) act by binding to receptors to produce (agonist) or block (antagonist) a response - If a drug fits a receptor, a response will take place.. like a key fitting into a lock ▪ Causes the inside of the cells to ACTUALLY perform an action
