Discussion: NURS 6521 Pharmacokinetics and Pharmacodynamics

March 6, 2022

Discussion: NURS 6521 Pharmacokinetics and Pharmacodynamics

Discussion: NURS 6521 Pharmacokinetics and Pharmacodynamics


A case study.

Recently a 62-year female patient was admitted for neurological deficits, typical of an acute infarction. Symptoms included right-sided facial numbness and slurred speech; both had subsided after 3-4 hours with no residual effects. Admitting vital signs; B/P 135 /80, HR 74, RR 16, afebrile. CXR clear, MRI revealed an acute left hemisphere stroke.

She is 177cm, weighs 74kg, and has a sedentary lifestyle (Gupta, A., Giambrone, A. E., et al., 2016). History includes post-menopausal depression and primary hypertension; she does not take drugs and has an occasional glass of wine. There is no history of heart disease in her family. Daily medications included Lexapro 20mg QD, Wellbutrin XL 300mg QD, and Lisinopril 20mg QD.

Over the following 48 hours, a comprehensive cardiac and neuro work-up ensued. ECHO >55%, clear carotids, EEG, and stress test were all without ischemia. Lab work was positive for slightly elevated Troponins that trended down during her stay, and additional values were negative for kidney and liver disease or elevated cholesterol.

Yet, the patients’ blood pressure continued to escalate – 200/100+; she was tachycardic and suffered from severe headaches, nausea, vomiting, and insomnia.

In addition to Lisinopril 20mg, Metoprolol, 50 mg QD was added, ASA 80mg, IV Hydralazine 20mg PRN every 3 -4 hours, IV Zofran 4mg q 4, PRN, IV Toradol, and Tylenol were given (Herman, L. L., & Bashir, K.,2021). Her blood pressure remained elevated, and a severe headache ensued. A stat brain MRI found no acute changes.

After 36 hours, IV Dilaudid 2 mg every 3 hours was ordered. This medication temporarily relieved her headache pain lowered her blood pressure, thus allowing her to sleep for short intervals. The patient remained in the hospital for an additional two days and continued with an elevated bp 160-180/ 8-90’s, tachycardia, and severe headache pain. After a 56 hour stay, the patient left. Discharge VS B/P 156/75, HR 88, and a moderate headache.

The “discharge” medication reconciliation was reviewed and updated; however, it revealed that this patient had not received her Lexapro or Wellbutrin during the hospital stay. Hence severe headaches, insomnia, nausea and vomiting, and elevated blood pressure are symptoms of Lexapro withdrawal (Potter, D. R., 2019).

Pharmacokinetics – absorption, distribution, metabolism, and excretion 

Lexapro/Escitalopram is an SSRI that increases serotonin levels in neuro synapses by preventing serotonin reuptake. It is a low protein binding drug that is metabolized in the liver and penetrates the tissues quickly. Rapidly absorbed, the medication peaks approximately 3–4 hours after administration. It can be taken once a day and has a significant half-life of 27–33 hours. A steady therapeutic level is reached within 7-10 days and may take up to six days to clear from the bloodstream. Approximately 90% of the total dose of Lexapro is metabolized through the liver; 8% of the total amount is eliminated in the urine unchanged, and 10% is eliminated in the urine as S-desmethylcitalopram, a metabolite of escitalopram. Lexapro is not affected by food; however, patients should avoid alcohol, as this may diminish the effects of the drug and exacerbate the symptoms (Potter, D. R., 2019).

Pharmacodynamics – affinity, efficacy, and potency

Lexapro is a serotonin reuptake inhibitor. This medication is broken down in the liver by 3 cytochrome P450 (CYP) and restores the balance of serotonin in the brain. Serotonin at the site of the neuro synapse dramatically affects mood, sleep, and other psychological behaviors. The low protein binding efficacy of Lexapro diminishes the possibility of negative interactions with highly protein-bound drugs (Ballinger, J., 2022). Lexapro can improve energy levels, increase focus and concentration, and improve feelings of guilt or worthlessness. It is also used to treat anxiety disorder by decreasing restlessness and irritability.

When treating depression, Lexapro (escitalopram) can improve energy levels, help maintain focus, and improve the lack of concentration, guilt, or worthlessness. Lexapro can also treat general anxiety disorder by easing symptoms of restlessness, irritability, and difficulty concentrating (Ballinger, J., 2022).

The recommended dose of Lexapro is 10 mg once daily with or without food. The effects of this drug are noted in 1 to 2 weeks and four weeks to feel the full benefits. Children nor pregnant nor breastfeeding women should avoid this medication. Abrupt discontinuance of Lexapro quickly throws the brain into a state of imbalance. Withdrawal symptoms are agonizing and debilitating and present within 24 to 48 hours post discontinuance. Symptoms include irritability, nausea and vomiting, nightmares, headache, paresthesia, agitation, aggression, hyper-insomnia, tachycardia, and labile blood pressure (Ballinger, J.,2022).

Unfortunately, this patients’ symptoms were related to Lexapro withdrawal, not cardiovascular disease. Her history of primary hypertension on low dose Lisinopril and negative testing for cardiac disease cleared her of genetic, ethnic, age, and behavioral issues. The new onset of labile hypertension, severe headache, and vomiting had no pathological basis (Potter, D. R., 2019). Antihypertensives, antiemetics, and pain medication had transient effects on her symptoms. Yet, this did not trigger anyone to investigate further.

Plan of Care

A comprehensive history is imperative to safe and effective care. An effective care plan should include reviewing and adherence to medications taken before admission. Any medicines that have an adverse effect when discontinued should be flagged for continuum. This patient received potentially lethal drugs for a disease she did not have. This misdiagnosis could have been disastrous. The ARNP is responsible for attentive patient care. A comprehensive history and an assessment of all patient data are fundamental to appropriate and advantageous care (Watkins, T., Whisman, L., & Booker, P., 2016).


Ballinger, J. (2022). Lexapro review.

Gupta, A., Giambrone, A. E., Gialdini, G., Finn, C., Delgado, D., Gutierrez, J., … &

Kamel, H. (2016). Silent brain infarction and risk of future stroke: a systematic review and meta-analysis. Stroke47(3), 719-725.

Herman, L. L., & Bashir, K. (2021). Hydrochlorothiazide. In StatPearls [Internet]. StatPearls Publishing.

Potter, D. R. (2019). Major depression disorder in adults: a review of antidepressants. Int. J. Caring Sci12, 1936.

Watkins, T., Whisman, L., & Booker, P. (2016). Nursing assessment of continuous vital sign surveillance to improve patient safety on the medical/surgical unit. Journal of clinical nursing25(1-2), 278-281.

Discussion: NURS 6521 Pharmacokinetics and Pharmacodynamics

NURS6521 Advanced Pharmacology

Week 1 Forum

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.

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Discussion: NURS 6521 Pharmacokinetics and Pharmacodynamics

Discussion: NURS 6521 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.

By Day 3 of Week 1

Post a description of the patient case from your experiences, observations, and/or clinical practice from the last 5 years. Then, describe factors that might have influenced pharmacokinetic and pharmacodynamic processes of the patient you identified. Finally, explain details of the personalized plan of care that you would develop based on influencing factors and patient history in your case. Be specific and provide examples.

By Day 6 of Week 1

Read a selection of your colleagues’ responses and respond to at least two of your colleagues on two different days by suggesting additional patient factors that might have interfered with the pharmacokinetic and pharmacodynamic processes of the patients they described. In addition, suggest how the personalized plan of care might change if the age of the patient were different and/or if the patient had a comorbid condition, such as renal failure, heart failure, or liver failure.

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