NURS 6521 Pharmacokinetics and Pharmacodynamics

NURS 6521 Pharmacokinetics and Pharmacodynamics

Sample Answer for NURS 6521 Pharmacokinetics and Pharmacodynamics Included After Question

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.  

RESOURCES 

 

Be sure to review the Learning Resources before completing this activity.
Click the weekly resources link to access the resources.  

WEEKLY RESOURCES 

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 Reply button to complete your initial post. Remember, once you click on Post Reply, you cannot delete or edit your own posts and you cannot post anonymously. Please check your post carefully before clicking on Post Reply!  

A Sample Answer For the Assignment: NURS 6521 Pharmacokinetics and Pharmacodynamics

Title: NURS 6521 Pharmacokinetics and Pharmacodynamics

I had a recent clinical experience where a patient of mine was sensitive to medications. She had recently had high blood pressure in the 200’s and acute kidney failure. She was given IV hydralazine and labetalol in the emergency room. She had a reaction to the medication and her heart rate dropped into the 20’s and she became unresponsive. The emergency room staff performed chest compressions and administered to the patient, and she was transferred to the ICU.

A case study writes about adverse effects of hydralazine and notes “Hydralazine was chosen for its antihypertensive effect and 2 mg were administered intravenously (IV). Within a brief period of time (30-45 sec) the patient developed a profound bradycardia from 52-10 beats/min occasioned by premature ventricular contractions (PVCs)” (Wehner & Romanauskas, 1981). A different case study notes a similar adverse effect of labetalol, “She was thought to have an anaphylactoid reaction and was treated intravenously with fluids, diphenhydramine (50 mg), and methylprednisolone (250 mg), without initial improvement. While urinating in the bedpan, she developed bradycardia and hypotension, with a pulse of 30/min and a blood pressure of 60/40. Trendelenburg’s position and 2 L of normal saline were needed to restore her blood pressure to normal, although her bradycardia resolved spontaneously” (Ferree, 1986).

This patient had orders to receive hydralazine IV to maintain a blood pressure of 140/80 so that she could have a kidney biopsy. “Most patients who undergo renal biopsy have hypertension, but hypertension is almost never considered a single or leading indication for biopsy” (Stompór & Perkowska-Ptasińska, 2020).

I diluted the hydralazine and pushed it over 10 minutes minimum and monitored the patient closely. I checked her blood pressure 15-30 minutes after administration and monitored her heart rate. She did not have any adverse reaction to the hydralazine when I administered it. I instructed the patient to use her call light button if she had any strange reactions or felt odd. I kept the physician updated on the patient’s blood pressure and heart rate throughout the night. The patient was able to transfer to a medical-surgical floor for a lower level of care.

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References

FERREE, C. E. (1986). Apparent Anaphylaxis from Labetalol. Annals of Internal Medicine104(5), 729–730. https://doi-org.ezp.waldenulibrary.org/10.1059/0003-4819-104-5-729_2

Links to an external site.

Stompór, T., & Perkowska-Ptasińska, A. (2020). Hypertensive kidney disease: a true epidemic or rare disease? Polish Archives of Internal Medicine130(2), 130–139. https://doi-org.ezp.waldenulibrary.org/10.20452/pamw.15150

Links to an external site.

Wehner RJ, & Romanauskas VS. (1981). An adverse reaction with hydralazine: a case study. AANA Journal49(3), 274–276

The patient was in her mid-40’s. Her renal function was impaired. BUN and creatine levels were high. She had no

NURS 6521 Pharmacokinetics and Pharmacodynamics
NURS 6521 Pharmacokinetics and Pharmacodynamics

medical history but had presented to the ED after a routine visit with her PCP because her blood pressure was high, and her kidney markers were abnormally high. A research study states that hydralazine can cause reflex bradycardia, which is a paradoxical response that is not well understood (Sánchez-Salvatori, & Vidrio, 2003). Another possibility is that with the patient’s impaired renal function, that her kidneys were not able to metabolize the drug properly, causing the half life of hydralazine to be increased. I was able to find a case study which states, “Following a single 50 mg dose of hydralazine (Apresoline) in 13 patients with impaired renal function, a decrease in glomerular filtration rate (GFR) was correlated with an increase in serum half-life (T1/2) of the drug (r=-0.69; p less than 0.01)” (Talseth, p.1, 1976).

 

References

 

Sánchez-Salvatori, M. A., & Vidrio, H. (2003). Reflex bradycardia induced by hydralazine in sino-aortic deafferented conscious rats. Autonomic & Autacoid Pharmacology23(1), 63–71. https://doi.org/10.1046/j.1474-8673.2003.00278.x

Hey Anastasia thanks for sharing informative post, as we are aware Pharmacokinetic process includes four main steps such as absorption, distribution, metabolism, and excretion that explain movement of drug throughout the body. Applying detailed knowledge of these four steps to drug therapy will be beneficial in achieving maximum effects of drugs and minimize harm .IV hydralazine is usually used in the hospitalized patient with hypertensive emergency. The pattern of drug absorption such as rate and extent of absorption is unique and the route by which the drug is administered significantly affects both the onset and intensity of effects (Rosenthal and Burchum, 2021, p 13). However as mentioned in the scenario patient was given IV hydralazine hence the absorption phase is bypassed and absorption happens instantaneous with rapid onset, and precise control over drug levels can be maintained. It is very critical to dilute the IV hydralazine with 10cc of sodium chloride prior to its administration and should be injected slowly over 2 minutes to avoid precipitous decrease in arterial pressure with a critical reduction in cerebral and utero-placental perfusion. This process or administration of 5-10 mg of IV hydralazine can be repeated every 20-30 minutes until the desired effect is achieved however the blood pressure and heart rate of patient should be monitored entire time. Hypotensive effects occur 5-30 minutes after an IV dose. The antihypertensive effects of an IV dose last 2-6 hours on average, although the effects of a parenteral dose can last up to 12 hours; the affinity of hydralazine for arterial walls may partially explain the prolonged effect. The patient here in the scenario is admitted with hypertension and acute kidney failure so it is also critical to consider pharmacokinetic parameters such as drug excretion as the majority of the drug excretion occurs via kidneys and in the case of acute renal failure both the duration and intensity of drug responses may increase. Hence it is important to check on creatinine clearance levels and adjust the dose based on its function.

References

hydralazine hydrochloride – Drug Summary. PDR.net. (n.d.). Retrieved December 2, 2022, from https://www.pdr.net/drug-summary/Hydralazine-Hydrochloride-Tablets-hydralazine-hydrochloride-738

Hydralazine 20mg Powder for Concentrate for Solution for Injection/Infusion. ADVANZ PHARMA. (2022, August 8). Retrieved from https://www.medicines.org.uk/emc/product/6710/smpc#gref

 

Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (2nd ed.) St. Louis, MO: Elsevier.

As a preoperative nursenurses administer versed and fentanyl on a daily basis as directed by the anesthesiologist’s orders. While other

drugs are given, this is primarily an orthopedic facility and these are the most commonly given pre-op drugs, especially for sedation for

nerve blocks.  Patients’ ages range from small children to elderly and medical history varies vastly among each patient. To establish

desired effect, but avoid causing harmful side effects, the appropriate dosage must be given. For patients with an intravenous (IV) access,

these drugs have instantaneous absorption with rapid onset (Rosenthal & Burchum, 2021). Dependent upon the patient’s age, frequency

of use of analgesics, and size the anesthesiologist decides on the dosage to be given prior to initiation of a nerve block. Generally

speaking, most patients reach the desired pleasant state resulting in minimal discomfort during the short procedure. However, there are

two instances that come to mind and that is the patients that, for different reasons, have very high tolerance to some medications and

then those who are “light weights” as we tend to refer to them. However, older patients typically require smaller dosages of versed and

fentanyl. Sometimes the versed is even omitted and a lesser amount of fentanyl is given to avoid over sedation and confusion. Drug

sensitivity varies across the lifespan, but infants and elderly patients have increased sensitivity to drugs (Rosenthal & Burchum, 2021).

Usually, the anesthesiologists are great at judging what dosage is appropriate for each patient, but sometimes the tiny, elderly patients

can be easily over sedated. When this happens, mental status is altered and oxygen saturation, respiratory, and heart rate may drop.

Although fentanyl has an onset of less than sixty seconds, ninety minute half-life, and thirty to sixty minute duration of action with peak

affect at two to five minutes; older adults metabolize drugs more slowly (Rosenthal & Burchum, 2021). In older adults, absorption rate is

altered because of delayed gastrointestinal transit time. Drug distribution is affected as a result of less lean body mass and water within

the body. Other considerations for older adults are reduction in hepatic blood flow as well as renal elimination of drugs. Normally

fentanyl is redistributed to sites such as fat and muscle, pretty much exclusively metabolized by the liver with a small percentage

excreted by the kidneys (Peng & Sandler, 1999).  Due to the body’s pharmacokinetic and pharmacodynamics changes with aging, opioids

dosage should be reduced by 25-50% as compared to that given to a younger patient (Chau, et al., 2008). In addition to low flow nasal

cannula and pulse oximetry during the procedure, robinul can be given to decrease bradycardic affects for these patients (Gallanosa &

Quick, 2019). Each patient should be personally evaluated for medical history, medication reconciliation done, medications taken that

day noted, and weight noted prior to administering these drugs.

References

Chau, D. L., Walker, V., Pai, L., & Cho, L. M. (2008). Opiates and elderly: use and side effects. Clinical interventions in aging, 3(2), 273–

278. https://doi.org/10.2147/cia.s1847

Links to an external site.

Gallanosa, A., & Quick, J. (2019). Glycopyrrolate. Nih.gov; StatPearls Publishing.

https://www.ncbi.nlm.nih.gov/books/NBK526035/

Links to an external site.

Peng, P. W. H., & Sandler, A. N. (1999). A Review of the Use of Fentanyl Analgesia in the Management of Acute Pain in Adults.

Anesthesiology, 90(2), 576–599. https://doi.org/10.1097/00000542-199902000-00034

Links to an external site.

Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants

(2nd ed.) St. Louis, MO: Elsevier.