NURS 6521 Week 2 Assignment - The Pharmacokinetic and Pharmacodynamic Processes

Introduction Presented in the case study was a 74yo male African American seeing his primary care provider (PCP) because he woke up feeling like his heart was not beating right and feeling like it was going too slowly. The patient also complained of nausea, vomiting, and dizziness earlier in the day. Some medication changes were made six weeks prior; he started on Diltiazem CD, and his Metoprolol was lowered from 75mg to 50 mg twice daily to help lower his blood pressure. Some of his objective vital signs included a blood pressure of 110/50 and a heart rate of 38, and his PCP recommended he go to the hospital. This paper aims to explore age as a factor that may influence the pharmacokinetic and pharmacodynamic processes, how changes in these processes may impact the patient’s recommended drug therapy, and how I might improve the patient’s drug therapy plan. Age Might Influence the Pharmacokinetic and Pharmacodynamic Processes Aging is exemplified by a continual change in the physiological and functionality of the human body, declining its homeostatic mechanisms (Simic, P., Guarente, Leonard P. and Rogers, Kara., 2022). These changes alter drugs’ pharmacokinetics (PK) and pharmacodynamics (PD), resulting in possibly less desirable outcomes and efficacy. The body and its physiological system changes occur naturally over time. Chronic disease, morbidity, and comorbidity are more commonly seen in the elderly (Comorbidities in Older Adults, 2022). With chronic diseases being more prevalent in the elderly, the likelihood of being prescribed more than one drug at a time increases, impacting the pharmacological effects of drugs. A reduction in vessel expansion occurs, and the vessels remain more constricted as we age. From the time a person goes from age 20 to 80 years old, 90% of the vessel’s elastic abilities are gone increasing systolic pressure and reducing blood flow through the body (World Journal of Pharmaceutical and Medical Research, 2017). Since there is a decrease in blood flow, it will take longer for the blood to circulate, perfuse, and alter the pharmacokinetics of medications filtration, absorption, and metabolism mechanisms. 3 The blood flow to and through the liver and kidneys decreases significantly with age (Physiopedia, 2023). The size of the liver also shrinks. Changes to the body and the liver slow down the rate medicine is metabolized and excreted from the body slows also. With medicines taking longer to metabolize and excrete, the risk of overdosing increases, and the effects of medication can have a heightened effect or stay in the body longer (World Journal of Pharmaceutical and Medical Research, 2017). Liver and kidney diseases can also exacerbate these effects making metabolizing and excreting drugs more challenging. Additionally, older adults tend not to weigh as much and have decreased amounts of water in the body with higher amounts of fat (World Journal of Pharmaceutical and Medical Research, 2017). Fat- soluble medications may stay in the body longer, such as anticholinergics and antianxiety medications like Amitriptyline and Diazepam (World Journal of Pharmaceutical and Medical Research, 2017). Elderly patients may also have increased adverse effects and sensitivities to medications pharmacodynamics due to the rise in chronic diseases, comorbidities, and decreased body composition (World Journal of Pharmaceutical and Medical Research, 2017). The therapeutic ranges are much more narrow than that of a younger person. Aging slows cell receptors, signaling, and physiological substrates (Brenes-Salazar et al., 2015). Another example of drug sensitivity in the elderly is Morphine, a painkiller in the central nervous system. Improving Patient’s Drug Therapy Plan Moving forward with the patient’s new drug therapy plan is essential to getting the patient’s lab values back within normal ranges and improving the patient’s symptoms. The patient is experiencing nausea, vomiting, and dizziness, all signs of Digoxin toxicity or an increase in its side effects (Cummings E. & Swoboda H., 2022). With the patient’s Dig level of 2.78, and 87% of patients experiencing toxicity when it reaches 2.5, it may be toxicity (Laboratory Corporation of America, 2021). When combined with Digoxin, Diltiazem slows down the excretion of Digoxin, holding it in the body longer (K. Davis, 2017). I