Drug Pharmacokinetics and Pharmacodynamics


Pharmacokinetics (PK) and pharmacodynamics (PD) determine how effective and safe a drug is used in the body. The former involves processes that a drug undergoes in the body from the time of absorption to excretion. On the other hand, the latter includes the body’s biological reaction to a specific drug. PK and PD analysis of drugs are critical in predicting dose requirements and estimating the absorption and elimination rate (Balasundaram et al., 2017) This paper provides an in-depth discussion of a case study of an 80 years old African American man with a history of coronary artery disease with status post-CABG, HDL, diabetes mellitus type II, and anemia. Factors influencing the pharmacokinetics and pharmacodynamics of ciprofloxacin will be addressed, and a personalized plan of care will be discussed.

Case Scenario

The 80 years old African American male patient was nearly admitted with a history of coronary artery disease with status post-CABG, HDL, diabetes mellitus type II, and anemia. On the head-to-toe assessment, no abnormalities were noted. The patient supported himself with a walker when ambulating but showed high risks of falling. By that time, the patient was on pneumonia treatment using ciprofloxacin 500mg twice daily for seven days (Balasundaram et al., 2017). Drug process analysis is critical before prescribing medicines to the patient considering the factors that affect the pharmacokinetics and pharmacodynamics of the specific drugs.

Factors Influencing PD and PK

Age significantly affects the pharmacokinetics of ciprofloxacin, which in turn influences its pharmacodynamics. With an increase in age, the intestinal surface area and the splanchnic blood flow is reduced, which impacts the drug’s absorption. Older adults have minimized muscle mass and increased adipose tissue, a factor that slows the distribution of ciprofloxacin (Honore et al., 2017). Reduced flow of blood to the kidney and minimized glomerular filtrate rate distress the elimination of the ciprofloxacin. Adverse drug reactions are common in geriatrics because of the physiological changes in the body. Drug interactions are notable in the elderly due to the increased use of drugs with age (Drenth‐van Maanen et al., 2020). Older adults are prone to a variety of chronic conditions, such as diabetes and hypertension. This is an aspect of consideration during the prescription and dosage of medication.

Evidence from studies indicates that African Americans have reduced drug pharmacokinetics, especially on metabolism and drug elimination. The actual effect of gender on drug processes is unknown. Some investigations have indicated that gender does not affect drug interactions, contrary to what other investigations suggest (Drenth‐van Maanen et al., 2020). Due to the client’s age and ethnicity, ciprofloxacin is less likely to produce the desired effects on the patient. However, ciprofloxacin has been identified as the drug of choice in treating pneumonia in the elderly. Thus, it is better used as a second-line antibiotic to complement the antibiotic of choice.

Personalized Plan of Care

Physiological changes that occur with age significantly affect drug pharmacokinetics and pharmacodynamics. As a result, the patients are at risk of developing drug reactions and toxicities, thus requiring close monitoring (Honore et al., 2017). The healthcare provider is responsible for the assessment and planning of care for elderly patients taking drugs. The nurse will ensure strict compliance of the patient to the prescribed medication. Continuous assessments are vital for the early identification of undesired effects of the medications administered. Alternative medication will be prescribed in cases when the desired effect of the drug is not achieved. Thus, the nurses should monitor for duplicate prescriptions.


The main goal in the management of patients is to improve their health outcomes and quality of life. The best choice of medication ensures efficacy in treating any pathophysiology. Pharmacokinetics and pharmacodynamics inform the prescription of drugs to the body malfunction. Healthcare professionals should consider the rate of absorption and elimination of the drug to ensure its effectiveness. They also need to focus on coexisting conditions while managing the admitted condition.


Balasundaram, P., Veerappapillai, S., & Karuppasamy, R. (2017). Quinolones and fluoroquinolones to treat Salmonella typhimurium: A review of metabolism and pharmacokinetics. Current Drug Metabolism, 18(12), 1085−1094.

Drenth‐van Maanen, A. C., Wilting, I., & Jansen, P. A. F. (2020). Prescribing medicines to older people: How to consider the impact of ageing on human organ and body functions. British Journal of Clinical Pharmacology, 86(10), 1921−1930.

Honore, P. M., Jacobs, R., de Waele, E., & Spapen, H. D. (2017). Applying pharmacokinetic/pharmacodynamic principles for optimizing antimicrobial therapy during continuous renal replacement therapy. Anaesthesiology Intensive Therapy, 49(5), 412–418. Web.

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