Pharmacokinetics and Pharmacodynamics
Pharmacokinetics and pharmacodynamics are an essential part of understanding drug efficacy. Meanwhile, pharmacokinetics deals with the study of the effect of a drug on the body through absorption, distribution, metabolism and excretion. pharmacodynamics addresses how the drug affects the body. The objective of pharmacokinetics is to improve medication efficacy and decrease drug toxicity while benefiting from the therapeutic results. Due to the correlation of the concentration of the drug in the body and the effect of the medication on the body, prescribers are called upon to monitor the usefulness of the medication. This has therefore, make pharmacokinetics and pharmacodynamics very important in medicine (Arcangelo, Peterson, Wilbur, & Reinhold, 2017). In order to understand the effect of drug pharmacokinetics and pharmacodynamics in patients this discussion focuses on explaining how this disease influences the effect of drugs on the body.
Patient is 16year old morbidly obese Native American female with a history of uncontrolled diabetes type II and depression. She came with her mom to the pediatric clinic because she was presented with lower abdominal pain for one week. In the evaluation process, the urine laboratory showed high levels of protein in the urine. Patient was admitted to the pediatric unit for treatment.
Plan of care
If the patient’s condition is observed, diabetes is a major contributing factor to her problem. In addition, the fact that she is in renal failure, which makes the treatment problematic, needs the doctor to consider the doses of medication. Following the pharmacokinetic and pharmacodynamic function, diabetes must be closely monitored. The pharmacokinetics of drugs are affected by the body’s ability to absorb, distribute, metabolize and eliminate the drug from the system. Diabetes is also a condition that damages the body’s ability to carry out its normal functions. The prescription of medications for this patient has a lot to do with her diabetic disease process that may be the cause of kidney disease. Prescribers will have to carefully consider the effect of the disease on the drugs reaching their therapeutic level, as well as the elimination process. The half-life of drugs will be an essential tool for prescribing.
Factors impacting pharmacokinetics
Effect of absorption : increase in extracellular glucose affects membrane permeability and drug bioavailability.
Effect of distribution : The binding and affinity of albumin is impaired, due to the presence of high levels of glucose that glycate along with hemoglobin. The presence of free fatty acids also decreases the binding capacity of albumin.
Effect of metabolism : Most drugs are metabolized in the liver, but in the diabetic Mellitus condition, there is a decrease in CYP 3A4.
Effect on excretion : an increased rate of glomerular infiltration is observed in patients with diabetes mellitus. Microvascular and macrovascular changes are observed in patients with uncontrolled diabetes.
Pharmacodynamics
These medications, such as metformin, decrease hepatic glucose production, decrease intestinal glucose production, and increase peripheral glucose production and utilization.
Regular examinations for cardiovascular disease, liver function tests, evaluation of the kidneys should be carried out by the patient.
To conclude, the fact that diabetes patients turn to take more medication than nondiabetic patient, understanding the pharmacokinetics and pharmacodynamics of their medication will help providers prescribe safe medication to their patient (Dostalek, Akhlaghi, & Puzanovova, 2012).
Reference
Amir Houshang, M. V. (2015). Effect of diabetes mellitus on the metabolism of drugs and toxins. Journal of Clinical Toxicology, 05(02). doi:10.4172/2161-0495.1000233
Arcangelo, V. P., Peterson, A. M., Wilbur, V., & Reinhold, J. A. (2017). Pharmacotherapeutics for advanced practice: A practical approach (4th ed.). Ambler, PA: Lippincott Williams & Wilkins.
Dostalek, M., Akhlaghi, F., & Puzanovova, M. (2012). Effect of diabetes mellitus on pharmacokinetic and pharmacodynamic properties of drugs. Clinical Pharmacokinetics, 51(8), 481-499. doi:10.2165/11631900-000000000-00000
Elbarbry, F., & Tran, M. (2016). Influence of diabetes mellitus on pharmacokinetics of drugs. MOJ Bioequivalence & Bioavailability, 2(1). doi:10.15406/mojbb.2016.02.00016
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.
