Pharmacokinetics and Pharmacodynamics

Pharmacokinetics and Pharmacodynamics

Recently, I experienced a case of Mr. Y, a patient who had presented to the hospital with his left lower limb being swollen, warm, and red. He also reported feeling pain on the limb. On investigation, it was found that he was suffering from deep vein thrombosis. The physician prescribed warfarin and heparin to manage his condition. Heparin was given for only 5 days and discontinued as the patient now continued with oral warfarin therapy. As he took the oral warfarin tablets, his internationalized normal ratio (INR) was determined after every three days. The INR was within the normal range when it was first measured, and it was reported that it would be determined 2 more times, and Mr. Y would be ready for discharge if it remained within the normal range. However, on determination for the second time, the patient’s INR was very low, and his condition had worsened. It was later found that the patient had been taking in more green leafy vegetables, which are known to contain vitamin K.

In Mr. Y’s case, the change in diet was the main reason why his condition worsened. He had been taking in more green leafy vegetables at the hospital, which affected the efficacy of warfarin. Green leafy vegetables such as kale, spinach, and turnip greens contain vitamin K (Siltari & Vapaatalo, 2018). Vitamin K at high doses reduces the efficacy of warfarin which predisposes a patient to blood clotting (Tadesse et al., 2018). Therefore, it would be important to manage Mr. Y’s condition with clear dietary guidelines.

Part of the personalized plan of care for Mr. Y would entail advising him to reduce the intake of foods containing vitamin K. Since green leafy vegetables such as spinach, kale, and turnip greens contain a lot of vitamin K, he should be advised to reduce the intake of the foods. This is because a reduced intake of green leafy vegetables reduces the effect of vitamin K on warfarin therapy (Liyew et al., 2017). However, he should also ensure his intake of the foods is regular such that he only takes once per week. This would reduce the impact of vitamin K on warfarin therapy.

References

Liyew, Z., Tadesse, A., Bekele, N., & Tsegaye, T. (2017). Evaluation of anticoagulation outcome among patients taking warfarin : A Single-center experience, northwest Ethiopia. Research Square, 20–25. https://doi.org/https://doi.org/10.21203/rs.3.rs-138820/v1

Siltari, A., & Vapaatalo, H. (2018). Vascular calcification, vitamin k and warfarin therapy – Possible or plausible connection? Basic and Clinical Pharmacology and Toxicology, 122(1), 19–24. https://doi.org/10.1111/bcpt.12834

Tadesse, T. A., Alebachew, M., & Woldu, A. (2018). Prevalence of warfarin drug interaction and warfarin education practice in outpatient setups of university teaching hospital: A retrospective chart review and an observational study. Journal of Basic and Clinical Pharmacy, 9(2), 262–266. https://www.jbclinpharm.org/articles/prevalence-of-warfarin-drug-interaction-and-warfarin-educationpractice-in-outpatient-setups-of-university-teaching-hospi.pdf

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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.

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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.