Principles of Pharmacokinetics and Pharmacodynamics
Advanced practice nurses have the responsibility of understanding pharmacokinetics and pharmacodynamics of the medications they prescribe to their patients. Pharmacokinetics refer to the way drugs move throughout the body by means of absorption, distribution, metabolism, and excretion. Pharmacodynamics refer to the ways drugs physiologically impact the body as evident by drug responses, interpatient variability, dose-response relationships, drug receptor interactions and a drug’s therapeutic index. Pharmacokinetics and pharmacodynamics collectively impact the therapeutic response a drug has on a patient (Rosenthal and Burchum, 2021).
Professional Experience
My experience as a hospice nurse over the last 2 years has enlightened me on the challenges in managing symptoms of patients at the end of life. Opioids such as Morphine, Fentanyl, and Dilaudid are effective in reliving symptoms of pain and dyspnea that patients often experience in their last days of life due to terminal diagnoses such as cancer or end stage COPD. Although, opioids are very effective in reliving these symptoms not all opioids possess the same pharmacokinetics and pharmacodynamics (Franken et al., 2016)
For example, an internal medicine physician referred his patient to me who was a 65-year-old female with metastatic ovarian cancer. The patient was described to me as being cachectic, weak with severe protein calorie malnutrition, hypernatremia, and an acute kidney injury. The physician told me the patient was interested in enrolling in hospice. When I entered the patient’s hospital room for my initial visit it was apparent to me the patient was exhibiting myoclonus as evident by the involuntary muscle jerking of the arms she was experiencing while lying in bed along with nonverbal signs of pain. Upon chart review my attention was raised to the fact the patient had an elevated creatinine level and was recently started on IV Morphine Sulfate for symptom management of pain.
Factors that Influenced the Patient
When morphine sulfate is given intravenously it is absorbed in the blood. Then, it is distributed and metabolized by the kidneys where it is then eliminated (Rosenthal and Burchun, 2021). Since the patient’s renal function was impaired due to metastatic disease the body’s inability to metabolize and excrete morphine caused myoclonus. The complications of the patient’s metastatic disease including cachexia, severe protein calorie malnutrition, hypernatremia, and acute kidney injury may also contribute to the pharmacodynamics of morphine sulfate and its individual variation effect on the patient. Interestingly, Rosenthal and Burchum, 2021, share that some opioids are more effective in women versus men, therefore, women may require lower doses of opioids to reach pain relief (Rosenthal and Burchum, 2021, p 159).
Personalized Care Plan
As the hospice nurse I was responsible for collaborating with the hospice physician to develop personalized hospice plan of care. I paged the hospice physician to the bedside and reviewed the patient’s medical history, other medications prescribed as well as informing the physician of my assessment of the patient. The decisions was then made by the hospice physician to transition the patient from IV Morphine Sulfate to IV Fentanyl. The British journal of clinical pharmacology warns patients being transitioned off one opioid and on to another must be closely monitored because there is risk the patient maybe be either over medicated or under medicated (Kuip et al., 2017). In this case the patient’s myoclonus resolved after 24 hours of discontinuation of Morphine Sulfate and patient was able to verbally report adequate pain relief with the use of Fentanyl.
Resources
Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice
nurses and physician assistants (2nd ed.) St. Louis, MO: Elsevier.
Franken, L.G., De Winter, B.C.M., Van Esch, H.J., Van Zuylen, L., Baar, F. P. M., Tibboel, D.,
Mathôt, R.A.A., Van Gelder, T., and Koch, B.C.P. (2016). Pharmacokinetic considerations and recommendations in palliative care, with focus on morphine, midazolam and haloperidol. Expert Opinion on Drug Metabolism & Toxicology, 12(6), 669-680. https://doi.org/10.1080/17425255.2016.1179281
Kuip, E. J. M., Zandvliet, M. L., Koolen, S. L. W., Mathijssen, R. H. J., and van der Rijt, C. C.
D. (2017) A review of factors explaining variability in fentanyl pharmacokinetics; focus on implications for cancer patients. British Journal of Clinical Pharmacology, 83, 294– 313. https://doi: 10.1111/bcp.13129.
response
Your work as a hospice nurse truly utilizes your ability to advocate for your patient. Your experience assessing this patient and formulating interventions demonstrates your autonomy and advocacy for patient care. Your advocacy for patient care is described in provision 3 in the code of ethics by utilizing your knowledge and skill (Fowler, 2015). As you assessed the patient for her disease process you also assessed potential adverse drug reactions. Reactions can occur for many reasons and the nurse must evaluate patients effectively to avoid or minimize harm (Rosenthal and Burchum, 2021).
References
Fowler, M.D.M., & American Nurses Association. (2015). Guide to the Code of Ethics for Nurses with Interpretive Statements: Development, Interpretation, and
Application (2nd ed.). Silver Spring, Maryland: American Nurses Association.
Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice
nurses and physician assistants (2nd ed.) St. Louis, MO: Elsevier.
post 2
Pharmacokinetics and pharmacodynamics are important when managing the health of patients. Pharmacokinetics is defined as the study of drug movement throughout the body (Rosenthal and Burchum, 2021). It consists of four processes including absorption, distribution, metabolism, and excretion. These processes can have an effect on the therapeutic management of drug therapy in patients. Pharmacodynamics is the study of biochemical and physiologic effects on the body and the molecular mechanisms by which these effects are produced (Rosenthal and Burchum, 2021). The results of these effects are based on the time and intensity of the therapeutic effects, as well as the occurrence of adverse drug reactions. There are several factors that can influence the pharmacokinetics and pharmacodynamic processes, including age, gender, ethnicity, behavior, genetics, and disease processes. It is important for the health care provider to have an understanding of pharmacokinetics and pharmacodynamics and its influence on drug therapy in order to develop an effective the plan of care for patients.
One previously worked as a home care nurse and took care of K.S. in her home. K.S. is a 70-year-old, African American female who was recently discharged from the hospital after undergoing a tricuspid valve repair. K.S. medical history includes right-sided heart failure, hypertension, hepatitis C, and ascites of the liver. K.S. was diagnosed post-surgery with chronic kidney disease, hypotension, and atrial fibrillation. K.S. discharge instructions were to include continuing taking previous medications prescribed along with midodrine and warfarin. K.S. was unsure of why she was taking certain medications, if and when her blood pressure should be checked, blood pressure parameters when taking midodrine and other prescribed hypertensive medications, the daily of dosage of warfarin and when laboratory testing needed to be completed to check PT/INR. K.S. observed to be frail in statue and was ordered Ensure three times per day.
Age along with pathophysiologic changes related to disease are huge factors that can affect pharmacokinetics and pharmacodynamic processes. According to Rodrigues, Herdeiro, Figueiras, Coutinho, and Roque (2020), ageing is a process that inevitable resulting in a decline in functioning and increased susceptibility to certain diseases, requiring the use of an increased amount of medication. Ageing can affect the distribution, metabolism, and excretion in the process of pharmacokinetics. Changes in body mass and protein synthesis can affect distribution of a drug and nutritional status can affect the rate of metabolism of a drug in an ageing patient (Rodrigues et. al, 2020). Most drugs are eliminated through kidneys. In the ageing patient, there is a decline in renal function related to a decrease in the glomerular filtration rate and renal blood flow, which makes it difficult for drugs to be excreted through the kidneys. This, in turn, puts the patient at risk for adverse drug reactions. According to Ponticelli, Sala, and Glassock (2015), older patients who have kidney disease are most at risk for adverse drug reactions. The process of pharmacodynamics affected by ageing can cause drug sensitivity and impaired homeostasis.
The patient K.S. has several medical conditions, resulting in a numerous amount of prescribed medications. She is frail in statue and has a lean body mass, which can affect the distribution of the medications prescribed. She, also, has poor nutritional status, which can affect the metabolism of the medications prescribed. She has been recently diagnosed with chronic kidney disease, which can affect elimination of the medications prescribed. She is prescribed warfarin, in which the response can be increased due to drug sensitivity leading to an adverse event. Also, due to impaired homeostasis, blood pressure regulation could be affected.
In developing a personalized plan of care for patient K.S., one has to take into consideration the patient’s age and medical history. One would review the drug therapy with the patient and discontinue any medications that are not necessary, have drug interactions, or put the patient at risk for an adverse drug reaction. One would ensure that current laboratory testing has been completed and review the laboratory results with the patient. Based on these results, one would consider medications that are safer for the patient and has the lowest effective dose possible. One would provide education to the patient on disease processes, purpose of medications prescribed, checking blood pressure and parameters to follow. One would stress the adherence to medication regimen and the importance of laboratory testing.
References
Ponticelli, C., Sala, G., and Glassock, R. (2015). Drug management in the elderly adult with
chronic kidney disease: a review for the primary care physician. Mayo Clinic Proc., 90
(5). Doi.org/10.1016/j.mayocp.2015.01.016.
Rodrigues, D., Herdeiro, M., Coutinho, P., and Roque, F. (2020). Elderly and polypharmacy:
physiological and cognitive changes. Frailty in the Elderly.
Doi:10.5772/intecopen.92122.
Rosenthal, L.D. and Burchum, J.R. (2021). Lehne’s pharmacotherapeutics for advanced practice
nurses and physician assistants (2nd ed.). St. Louis, MO: Elsevier.
response
Hello,
Great discussion post, I really enjoyed reading your discussion. I’ve worked in a hospital for five years and one of the main reason for readmission is patients not taking medications, due to not understanding why they are taking them, not to mention over taking medications that cause a whole new list of issues. Medications like midodrine and coumadin are very sensitive medications that need to be closely monitored. For a patient taking midodrine, the patient needs to understand that this medication is very influential peripheral acting aplpha-1 agonist that is mostly used for patients with hypotension (Wong, Wong, Robertson, Burns, Roberts and Isbister, 2017). The mechanism of action of Midodrine is to make an increase in peripheral venous resistance and then to decline venous capacity, with the goal being to increase laying and standing blood pressure ( Wong, Wong, Robertson, Burns, Roberts and Isbister, 2017). With midodrine the patient needs to educate on heart rate to make sure they don’t become bradycardic; the patient needs to be educated on how to check pulse and blood pressure before medication administration and there needs to be an order for parameters for the patient, for when the patient should and should not take the medication ( Wong, Wong, Robertson, Burns, Roberts and Isbister, 2017).
With coumadin the patient needs to have their INR checked frequently to make sure it’s within a therapeutic range, and to also make sure the patients’ blood is not too thin. Anticoagulation drugs have a risk for bleeding due to their complexity (Bajorek,2011). For this patient you stated in this scenario she was on several other medications as well, and when patients are on several medications, the risk of them being misused is even higher (Bajorek,2011). When a patient is unable to take medications as prescribed, there current health care issues aren’t being treated, which is why a lot of times they end up being readmitted with the same problem they were previously in the hospital for. Kymes, Sullivan, Jackson & Raj (2020), note that a patient not being able to comply with their medications is a very huge public health problem, that affects a lot of comorbidities that a person has. I agree with your plan of care and discontinuing any medications that aren’t necessary, as more medications add to more adverse reactions that could happen and to monitor blood pressure and pulse before administration of midodrine. The patient also needs to be following the orders for her coumadin and to have her INR checked as frequent as the physician wants. The patient can have her INR checked at home with a home health nurse. I would also suggest this patient to keep a log of her blood pressure and pulse to show her provider, so they can adjust as needed to keep her as safe as possible
References:
Bajorek B. (2011). A review of the safety of anticoagulants in older people using the medicines management pathway: weighing the benefits against the risks. Therapeutic advances in drug safety, 2(2), 45–58. https://doi.org/10.1177/2042098611400495
Kymes, S. M., Sullivan, C., Jackson, K., & Raj, S. R. (2020). Real-world droxidopa or midodrine treatment persistence in patients with neurogenic orthostatic hypotension or orthostatic hypotension. Autonomic Neuroscience: Basic and Clinical, 225. https://doi-org.ezp.waldenulibrary.org/10.1016/j.autneu.2020.102659
Wong, L. Y., Wong, A., Robertson, T., Burns, K., Roberts, M., & Isbister, G. K. (2017). Severe Hypertension and Bradycardia Secondary to Midodrine Overdose. Journal of Medical Toxicology: Official Journal of the American College of Medical Toxicology, 13(1), 88–90. https://doi-org.ezp.waldenulibrary.org/10.1007/s13181-016-0574-4
Discussion: Pharmacokinetics and Pharmacodynamics
As an advanced practice nurse assisting physicians in the diagnosis and treatment of disorders, it is important to not only understand the impact of disorders on the body, but also the impact of drug treatments on the body. The relationships between drugs and the body can be described by pharmacokinetics and pharmacodynamics.
Pharmacokinetics describes what the body does to the drug through absorption, distribution, metabolism, and excretion, whereas pharmacodynamics describes what the drug does to the body.
Photo Credit: Getty Images/Ingram Publishing
When selecting drugs and determining dosages for patients, it is essential to consider individual patient factors that might impact the patient’s pharmacokinetic and pharmacodynamic processes. These patient factors include genetics, gender, ethnicity, age, behavior (i.e., diet, nutrition, smoking, alcohol, illicit drug abuse), and/or pathophysiological changes due to disease.
For this Discussion, you reflect on a case from your past clinical experiences and consider how a patient’s pharmacokinetic and pharmacodynamic processes may alter his or her response to a drug.
To Prepare
- Review the Resources for this module and consider the principles of pharmacokinetics and pharmacodynamics.
- Reflect on your experiences, observations, and/or clinical practices from the last 5 years and think about how pharmacokinetic and pharmacodynamic factors altered his or her anticipated response to a drug.
- Consider factors that might have influenced the patient’s pharmacokinetic and pharmacodynamic processes, such as genetics (including pharmacogenetics), gender, ethnicity, age, behavior, and/or possible pathophysiological changes due to disease.
- Think about a personalized plan of care based on these influencing factors and patient history in your case study.
By Day 3 of Week 1
Post a description of the patient case from your experiences, observations, and/or clinical practice from the last 5 years. Then, describe factors that might have influenced pharmacokinetic and pharmacodynamic processes of the patient you identified. Finally, explain details of the personalized plan of care that you would develop based on influencing factors and patient history in your case. Be specific and provide examples.
By Day 6 of Week 1
Read a selection of your colleagues’ responses and respond to at least two of your colleagues on two different days by suggesting additional patient factors that might have interfered with the pharmacokinetic and pharmacodynamic processes of the patients they described. In addition, suggest how the personalized plan of care might change if the age of the patient were different and/or if the patient had a comorbid condition, such as renal failure, heart failure, or liver failure.
Note: For this Discussion, you are required to complete your initial post before you will be able to view and respond to your colleagues’ postings. Begin by clicking on the “Post to Discussion Question” link, and then select “Create Thread” to complete your initial post. Remember, once you click on Submit, you cannot delete or edit your own posts, and you cannot post anonymously. Please check your post carefully before clicking on Submit!
| Excellent | Good | Fair | Poor | |
|---|---|---|---|---|
| Main Posting |
45 (45%) – 50 (50%)
Answers all parts of the discussion question(s) expectations with reflective critical analysis and synthesis of knowledge gained from the course readings for the module and current credible sources.
Supported by at least three current, credible sources. Written clearly and concisely with no grammatical or spelling errors and fully adheres to current APA manual writing rules and style. |
40 (40%) – 44 (44%)
Responds to the discussion question(s) and is reflective with critical analysis and synthesis of knowledge gained from the course readings for the module.
At least 75% of post has exceptional depth and breadth. Supported by at least three credible sources. Written clearly and concisely with one or no grammatical or spelling errors and fully adheres to current APA manual writing rules and style. |
35 (35%) – 39 (39%)
Responds to some of the discussion question(s).
One or two criteria are not addressed or are superficially addressed. Is somewhat lacking reflection and critical analysis and synthesis. Somewhat represents knowledge gained from the course readings for the module. Post is cited with two credible sources. Written somewhat concisely; may contain more than two spelling or grammatical errors. Contains some APA formatting errors. |
0 (0%) – 34 (34%)
Does not respond to the discussion question(s) adequately.
Lacks depth or superficially addresses criteria. Lacks reflection and critical analysis and synthesis. Does not represent knowledge gained from the course readings for the module. Contains only one or no credible sources. Not written clearly or concisely. Contains more than two spelling or grammatical errors. Does not adhere to current APA manual writing rules and style. |
| Main Post: Timeliness |
10 (10%) – 10 (10%)
Posts main post by day 3
|
0 (0%) – 0 (0%)
|
0 (0%) – 0 (0%)
|
0 (0%) – 0 (0%)
Does not post by day 3
|
| First Response |
17 (17%) – 18 (18%)
Response exhibits synthesis, critical thinking, and application to practice settings.
Responds fully to questions posed by faculty. Provides clear, concise opinions and ideas that are supported by at least two scholarly sources. Demonstrates synthesis and understanding of learning objectives. Communication is professional and respectful to colleagues. . Responses to faculty questions are fully answered, if posed. Response is effectively written in standard, edited English. |
15 (15%) – 16 (16%)
Response exhibits synthesis, critical thinking, and application to practice settings.
Responds fully to questions posed by faculty. Provides clear, concise opinions and ideas that are supported by at least two scholarly sources. Demonstrates synthesis and understanding of learning objectives. Communication is professional and respectful to colleagues. . Responses to faculty questions are fully answered, if posed. Response is effectively written in standard, edited English. |
13 (13%) – 14 (14%)
Response is on topic and may have some depth.
Responses posted in the discussion may lack effective professional communication. Responses to faculty questions are somewhat answered, if posed. Response may lack clear, concise opinions and ideas, and a few or no credible sources are cited. |
0 (0%) – 12 (12%)
Response may not be on topic and lacks depth.
Responses posted in the discussion lack effective professional communication. Responses to faculty questions are missing. No credible sources are cited. |
| Second Response |
16 (16%) – 17 (17%)
Response exhibits synthesis, critical thinking, and application to practice settings.
Responds fully to questions posed by faculty. Provides clear, concise opinions and ideas that are supported by at least two scholarly sources. Demonstrates synthesis and understanding of learning objectives. Communication is professional and respectful to colleagues. . Responses to faculty questions are fully answered, if posed. Response is effectively written in standard, edited English. |
14 (14%) – 15 (15%)
Response exhibits critical thinking and application to practice settings.
Communication is professional and respectful to colleagues. Responses to faculty questions are answered, if posed. Provides clear, concise opinions and ideas that are supported by two or more credible sources. Response is effectively written in standard, edited English. |
12 (12%) – 13 (13%)
Response is on topic and may have some depth.
Responses posted in the discussion may lack effective professional communication. Responses to faculty questions are somewhat answered, if posed. . Response may lack clear, concise opinions and ideas, and a few or no credible sources are cited. |
0 (0%) – 11 (11%)
Response may not be on topic and lacks depth.
Responses posted in the discussion lack effective professional communication. Responses to faculty questions are missing. No credible sources are cited. |
| Participation |
5 (5%) – 5 (5%)
Meets requirements for participation by posting on three different days.
|
0 (0%) – 0 (0%)
|
0 (0%) – 0 (0%)
|
0 (0%) – 0 (0%)
Does not meet requirements for participation by posting on 3 different days
|
| Total Points: 100 |
|---|
responses
Diabetes management can be complex and therefore needs interdisciplinary and collaborative care. Effective management requires that patients with diabetes focus on self-management support measures, improved patient engagement, teamwork, and population management. Glycemic control and management extend beyond just glycemic control measures which may include blood pressure control, cholesterol levels control, early screening dietary modification, lifestyle changes, and cessation of smoking. Uncontrolled diabetes can lead to retinopathy, nephropathy, cardiomyopathy, peripheral neuropathy, and many other medical complications (Lu, Xu, Zhao, & Han, 2016). Diabetes impacts drug pharmacodynamics and pharmacokinetics, however uncontrolled diabetes can have a significant negative impact because it can trigger multi organ failure and some cases lead to diabetic ketoacidosis which can lead to death. When dosing or administering medication to diabetics we must keep into consideration of various factors which include how these medications interact with their glycemic control regimen, how the medication will impact their blood sugar levels, and overall.
Reference
Lu, Y., Xu, J., Zhao, W., & Han, H. R. (2016). Measuring Self-Care in Persons with Type 2
Diabetes: A Systematic Review. Evaluation & the health professions, 39(2), 131–184. https://doi.org/10.1177/0163278715588927
There is currently a 14-year-old Type I DM in the school building that I work in. There are times when he comes to school with numbers well above 400+. My fear for this child is that he will be one of those individuals who end up with kidney failure. The explanation provided your paper on how drugs are metabolized in the diabetic body touched on the importance of adequate patient education, compliance, and follow-ups. It is essential to have a level of understanding of how the body functions when a patient has kidney failure. Understanding the pharmacodynamic and pharmacokinetics in the correlation to the pathophysiology of treating those with renal failure is essential when creating a management or treatment plan.
Reading your paper, the relationship between the two mechanisms of actions works together as a cause and effect. In the article, Principles of Drug Response and Alterations in Kidney Disease, the level of a drug’s concentration works in conjunction with its effects in the body (Keller & Hann, 2018). It precisely explains the kinetics and dynamics of a drug’s movement through the body system. It is this cause and effect approach that allows a drug to work in the body to produce an action. In regards to the effects of a drug’s movement in patients with kidney failure, Keller and Hann’s article also inferred that pharmacokinetics is usually considered over pharmacodynamics when prescribing medications for the treatment of those with kidney disease (2018). However, pharmacodynamics is rarely considered drug metabolism in those with kidney disease. Nevertheless, when both mechanisms are reported, drug dosing can be modified per patient for better efficacy.
Reference:
Keller, F., & Hann, A. (2020). Clinical Pharmacodynamics Principles of Drug Response and Alterations in Kidney Disease.
Clinical Journal of the American Society of Nephrology, 15(8), 1073–1074. https://doi.org/doi.org/10.1016/j.pedn.2017.05.001 0882-5963/