DQ: Pharmacokinetics and Pharmacodynamics
NURS 6521 Discussion Pharmacokinetics and Pharmacodynamics
DQ: Pharmacokinetics and Pharmacodynamics
Working in an intermediate care unit, I get to see patients from all races with different healthcare needs and conditions. One obvious thing observed from the so many patients that come into the facility is the prevalence of diabetes, hypertension and chronic obstructive pulmonary disease (COPD) in patients ages 20 years and above. Though the diseases are common, the types of medications used in treating them may differ in dose, brand, and pricing. When prescribing medications for an individual patient, the physician considers the effects of the drugs and the mechanism of their action on that particular patient.
Let us consider a 75-year-old male patient who is admitted for uncontrolled Diabetes. The patient has a past medical history of Diabetes type II and takes metformin to control his glucose but had not been able to afford the refills for his medication. On admission the patient presented with a blood glucose of 288 mg/dl and was ordered Lispro on a low dose sliding scale with blood glucose monitoring before meals and at bedtime. The patient was assigned to a young nurse who had recently just started working on the unit.
DQ Pharmacokinetics and Pharmacodynamics
Just before the lunch trays came in, the nurse went to review the patients’ blood glucose levels the nurse tech had checked. Without paying much attention, the nurse drew up 8 units of lispro insulin and administered it to the patient for what she thought was a blood sugar of 288mg/dl. After about 20 minutes the nurse discovered that the patient was sweating a lot and had an increased heart rate with slight shivers. The young nurse called the attention of an older nurse and explained all the care she had provided to the patient prior to discovering his current state. The two nurses reviewed the documentation on the computer and saw that the patients’ last blood glucose check was 98mg/dl and not 288mg/dl as the young nurse had thought it was. The older nurse immediately got a glucometer and checked the patients’ blood glucose which was now 52mg/dl, and also discovered that the patient had not eaten anything. The older nurse immediately followed the establishment’s protocol and administered 1 gram of glucagon to the patient, checked his blood glucose which had gone up slightly and then administered another gram, checked his blood glucose again, and then provided the patient with a small cup of orange juice and a cracker.
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As nurse practitioners, it is important to know and understand the pharmacokinetics and pharmacodynamic processes. Pharmacokinetics is the process of a drug being absorbed, distributed, metabolized, and excreted from the body (Rosenthal and Burchum, 2021). Pharmacodynamics is the relationship between drug concentration at the site of action and the resulting effects which include the time and severity of therapeutic and adverse effects (DiPiro, 2008).
Lispro Insulin is a rapid-acting insulin that has a short duration of action which is used to improve blood glucose management in patients with diabetes (Rosenthal and Burchum, 2021). It is more effective than the normal human insulin in improving and helping to maintain blood glucose control (Campbell et al., 1996). Factors that might influence the pharmacokinetics and pharmacodynamics of insulin are the size of the dose, the injected volume and the insulin concentration, vigorously rubbing the site of the injection, increase in temperature which increases absorption rate, site of the injection (absorption is faster when administered in the abdomen), and exercising of extremity within an hour of injection can speed up absorption (Donner and Sarkar, 2019). The patient received a large dose of insulin for an inaccurate blood glucose reading and presented with a hypoglycemic reaction due to the large amount of insulin that was administered.
A personalized care plan for the patient based on influencing factors and the patients history would be to set goals for the patient that include effective treatments to normalize and manage blood glucose levels, decrease the risk for hypoglycemic or hyperglycemic events using insulin medication, diet, and exercise, informing and educating the patient on the importance of compliance with medication regimen and importance of monitoring blood glucose, providing the patient with prescription savings or discount cards like Good Rx, and providing the patient with location to local community clinics that help with providing low-cost prescription medications.
Ensuring that the patient is properly educated and provided with the necessary resources to provide for his medication will promote his participation in self-care and ensure his compliance with monitoring and maintaining manageable blood glucose levels.
References:
Campbell, R. K., Campbell, L. K., & White, J. R. (1996, November). Insulin lispro: its role in the treatment of diabetes mellitus. The Annals of pharmacotherapy. https://pubmed.ncbi.nlm.nih.gov/8913409/.
Donner, T., & Sarkar, S. (2019). Insulin – Pharmacology, Therapeutic Regimens, and Principles of Intensive Insulin Therapy. Endotext [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK278938/.
DiPiro, J. T. (2008). Pharmacotherapy: A pathophysiologic approach. McGraw-Hill Medical.
Rosenthal, L. D., & Burchum, J. R. (2021). Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (2nd ed.) Elsevier.
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.