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.
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.
Sample Discussion: Pharmacokinetics and Pharmacodynamics
Scenario
P.K, a 23-year-old Caucasian American female, presented to the emergency clinic with severe stomach pain and vaginal bleeding. She has a history of bipolar illness and is obese. Although she did not seem pregnant at the time of admittance, there was speculation that she was. Sadly, she was unable to recall her LMP. She was found to be pregnant after a pregnancy test, and she was sent for an ultrasound to determine the size of the fetus.
Further testing was performed, such as a cervical exam to determine the rate of contraction and the best timing for delivery. The contractions ranged from 5 to 7 minutes apart. When the patient’s history was taken, it was noted that she had a history of substance abuse, with her favorite drug being Desoxyn, which she had used one hour before her admittance to the emergency room. After some time in the emergency room, her contractions became closer, ranging from three to five minutes apart. Her pain level was 10/10, and she was admitted to the labor and delivery unit for ongoing care.
Pharmacokinetic Process
When taken orally, Desoxyn is quickly absorbed into the bloodstream. This absorption peaks in blood plasma and lasts for about 6 hours after administration. Desoxyn can cross the blood-brain barrier more rapidly than other stimulants. The kidney eliminates Desoxyn, with speed substantially controlled by urinary pH; when administered orally, roughly 55 percent of the dosage is excreted into the urine unchanged, whereas, with IV-dose, only around 45 percent is excreted in the urine unchanged (Markowitz & Patrick, 2017). Besides, the plasma half-life of Desoxyn is 5 to 30 hours. When this drug is injected into the body of pregnant women, the likelihood of preeclampsia, preterm rupture of membranes, and preterm deliveries escalate. And once the baby is born, Desoxyn side effects such as lethargy, heart and brain abnormalities may still present.
Pharmacodynamic Process
Desoxyn is a full agonist of trace amine-associated receptor 1, a G protein-coupled receptor that modulates catecholamine systems in the brain. The trace amine-associated receptor is triggered cAMP generation, and either entirely blocks or reverses the dopamine, norepinephrine, and serotonin transporters’ transport routes. The binding of Desoxyn to trace amine-associated receptor activates the transporter phosphorylation via protein kinase A and protein kinase C signaling, eventually culminating in the internalization of monoamine transporters (Prakashet al., 2017). Desoxyn has also been shown to elevate intracellular calcium, which is linked to DAT phosphorylation via a Ca2+/calmodulin-dependent protein kinas-dependent signaling pathway, resulting in dopamine efflux.
Personalized Plan of Care
When a patient with a history of substance abuse arrives in the labor and delivery room, the very first line of therapy is to discover whatever illegal substance they are currently using. It is vital to consider this since pain control is the most challenging task for these people owing to their high tolerance for illicit medications. It is also essential to guarantee that there are orders for volume expanders are if the patient has suffered extreme fluid loss as a result of Abruption. The NICU and social programs must be included in the care plan prepared with the OB care provider (Fallettaet al., 2018).
References
Falletta, L., Hamilton, K., Fischbein, R., Aultman, J., Kinney, B., & Kenne, D. (2018). Perceptions of child protective services among pregnant or recently pregnant, opioid-using women in substance abuse treatment. Child abuse & neglect, 79, 125-135.
Markowitz, J. S., & Patrick, K. S. (2017). The clinical pharmacokinetics of amphetamines utilized in the treatment of attention-deficit/hyperactivity disorder. Journal of child and adolescent psychopharmacology, 27(8), 678-689. https://www.liebertpub.com/doi/abs/10.1089/cap.2017.0071
Prakash, M. D., Tangalakis, K., Antonipillai, J., Stojanovska, L., Nurgali, K., & Apostolopoulos, V. (2017). Methamphetamine: effects on the brain, gut and immune system. Pharmacological research, 120, 60-67. https://www.sciencedirect.com/science/article/abs/pii/S1043661816312002
Learning Resources
Required Readings
Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (2nd ed.) St. Louis, MO: Elsevier.
• Chapter 1, “Prescriptive Authority” (pp. 1–3)
• Chapter 2, “Rational Drug Selection and Prescription Writing” (pp. 4–7)
• Chapter 3, “Promoting Positive Outcomes of Drug Therapy” (pp. 8–12)
• Chapter 4, “Pharmacokinetics, Pharmacodynamics, and Drug Interactions” (pp. 13–33)
• Chapter 5, “Adverse Drug Reactions and Medication Errors” (pp. 34–42)
• Chapter 6, “Individual Variation in Drug Response” (pp. 43–45)
American Geriatrics Society 2019 Beers Criteria Update Expert Panel. (2019). American Geriatrics Society 2019 updated AGS Beers criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society, 67(4), 674–694. doi:10.1111/jgs.15767
American Geriatrics Society 2019 updated AGS Beers criteria for potentially inappropriate medication use in older adults by American Geriatrics Society, in Journal of the American Geriatrics Society, Vol. 67/Issue 4. Copyright 2019 by Blackwell Publishing. Reprinted by permission of Blackwell Publishing via the Copyright Clearance Center.
This article is an update to the Beers Criteria, which includes lists of potentially inappropriate medications to be avoided in older adults as well as newly added criteria that lists select drugs that should be avoided or have their dose adjusted based on the individual’s kidney function and select drug-drug interactions documented to be associated with harms in older adults.
Drug Enforcement Administration. (n.d.-a). Code of federal regulations. Retrieved February 1, 2019, from https://www.deadiversion.usdoj.gov/21cfr/cfr/1300/1300_01.htm
This website outlines the code of federal regulations for prescription drugs.
Drug Enforcement Administration. (n.d.-b). Mid-level practitioners authorization by state. Retrieved May 13, 2019, from http://www.deadiversion.usdoj.gov/drugreg/practioners/index.html
This website outlines the schedules for controlled substances, including prescriptive authority for each schedule.
Drug Enforcement Administration. (2006). Practitioner’s manual. Retrieved from http://www.legalsideofpain.com/uploads/pract_manual090506.pdf
This manual is a resource for practitioners who prescribe, dispense, and administer controlled substances. It provides information on general requirements, security issues, recordkeeping, prescription requirements, and addiction treatment programs.
Drug Enforcement Administration. (n.d.-c). Registration. Retrieved February 1, 2019, from https://www.deadiversion.usdoj.gov/drugreg/index.html
This website details key aspects of drug registration.
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.). American Nurses Association.
This resource introduces the code of ethics for nurses and highlights critical aspects for ethical guideline development, interpretation, and application in practice.
Institute for Safe Medication Practices. (2017). List of error-prone abbreviations, symbols, and dose designations. Retrieved from https://www.ismp.org/recommendations/error-prone-abbreviations-list
This website provides a list of prescription-writing abbreviations that might lead to misinterpretation, as well as suggestions for preventing resulting errors.
Ladd, E., & Hoyt, A. (2016). Shedding light on nurse practitioner prescribing. The Journal for Nurse Practitioners, 12(3), 166–173. doi:10.1016/j.nurpra.2015.09.17
This article provides NPs with information regarding state-based laws for NP prescribing.
Sabatino, J. A., Pruchnicki, M. C., Sevin, A. M., Barker, E., Green, C. G., & Porter, K. (2017). Improving prescribing practices: A pharmacist‐led educational intervention for nurse practitioner students. Journal of the American Association of Nurse Practitioners, 29(5), 248–254. doi:10.1002/2327-6924.12446
The authors of this article assess the impact of a pharmacist‐led educational intervention on family nurse practitioner (FNP) students’ prescribing skills, perception of preparedness to prescribe, and perception of a pharmacist as a collaborator.