NUR 557 Module 9 Final Project Example

Final Project: Seven Medicines and Slowing Kidneys, a Prescribing Rationale for an 81-Year-Old Who Fell

[Student Name]

Southern New Hampshire University

NUR 557: Advanced Pathophysiology and Pharmacology Across the Lifespan

Final Project

[Instructor Name]

[Date]

The organization, setting and figures below are a composite written as a model document. No real employer, client, colleague or patient is described.

Final Project: Seven Medicines and Slowing Kidneys, a Prescribing Rationale for an 81-Year-Old Who Fell

Older adults with reduced kidney function are where pathophysiology and pharmacology meet most dangerously. Drugs that are safe at one level of kidney function accumulate at another, and the symptoms of accumulation, dizziness, confusion and falls, are easily blamed on age. This final project reviews every medicine taken by a composite 81-year-old woman after a fall. It argues that most of her new symptoms can be explained by drugs that are cleared by the kidneys or act on the brain, that estimating her kidney function correctly is the first step to fixing them, and that the safest plan removes two medicines, lowers three doses and keeps the ones that protect her heart and kidneys.

The Case

The patient is an 81-year-old widow who lives with her daughter. Over two months she has felt dizzy on standing, had two episodes of confusion in the evening and fell in the bathroom at night, bruising her hip. She has type 2 diabetes, hypertension, painful diabetic neuropathy, an overactive bladder and occasional heartburn. She weighs 58 kg. Laboratory results show a creatinine of 1.4 mg/dL with a reported eGFR of 36, potassium 5.0 mmol/L and A1C 6.6%. Table 1 lists her medicines.

Table 1

Current Medicines and Their Elimination

Note. Composite patient.

Why Her Kidneys Matter for Every Drug

Kidney function declines with age, and her diabetes and hypertension have added chronic kidney disease. Drugs excreted unchanged by the kidneys accumulate as filtration falls, raising their levels and prolonging their effects. Aging also lowers muscle mass, so serum creatinine underestimates the decline: a creatinine of 1.4 appears only slightly high on paper, but she has little muscle to produce it (Mangoni & Jackson, 2004). The aging brain is also more sensitive to drugs that act on it, especially those with anticholinergic or sedating effects, so the same level produces more confusion and imbalance than in a younger adult.

Estimating Her Kidney Function Two Ways

Her reported eGFR of 36 mL/min/1.73 m² comes from an equation standardized to average body size. The Cockcroft-Gault equation, which many drug labels use, estimates creatinine clearance from age, weight, sex and creatinine (Cockcroft & Gault, 1976): for her, 59 (140 less her age) times 58 kg times 0.85 for female sex gives about 2,909, and dividing by 100.8 (72 times her creatinine) yields roughly 29 mL/min. The difference is not an error. She is small and old, and Cockcroft-Gault gives more weight to both, so it returns a lower value. Current kidney guidance supports using validated estimates for drug dosing and adding cystatin C when creatinine-based estimates may be misleading, as in people with low muscle mass (Stevens et al., 2024). For drugs with narrow margins, the more conservative estimate, around 29 mL/min, is the safer basis until a cystatin C-based estimate is available.

Drug-by-Drug Review

Gabapentin is the most likely cause of her dizziness, confusion and fall. It is eliminated unchanged by the kidneys, so at a clearance near 29 mL/min her current 900 mg daily produces levels far higher than intended; labeling limits the daily dose considerably at this level of kidney function. The dose should be reduced substantially, for example to 100 mg twice daily, and adjusted to pain and side effects (Rosenthal & Burchum, 2021).

Oxybutynin is strongly anticholinergic, and older adults taking drugs with strong anticholinergic effects face more confusion, constipation and falls, which is why the Beers panel lists them for avoidance; it may be contributing to her evening confusion (American Geriatrics Society Beers Criteria Update Expert Panel, 2023). It should be stopped, with bladder training, timed voiding and a review of alternatives. Ibuprofen should also stop: nonsteroidal anti-inflammatory drugs reduce prostaglandin-dependent kidney blood flow, especially alongside an ACE inhibitor, and are on the Beers list for people with reduced kidney function. Topical diclofenac or acetaminophen can manage her knee pain.

Famotidine is cleared mainly by the kidneys, and the Beers Criteria call for dose reduction when clearance is reduced because of the risk of confusion; at her level, 20 mg once daily or less is appropriate, and whether she needs it at all is worth reviewing. Metformin should be reduced: with an eGFR between 30 and 44, current standards advise lowering the dose, commonly to no more than 1,000 mg daily, and stopping below 30 (American Diabetes Association Professional Practice Committee, 2025). With an A1C of 6.6%, lower intensity is also appropriate for her age.

Lisinopril and atorvastatin stay. Lisinopril protects her kidneys, though her potassium of 5.0 mmol/L needs watching, particularly as ibuprofen stops and kidney function is rechecked. Atorvastatin is cleared by the liver and needs no adjustment.

Monitoring Built From the Physiology

The monitoring plan follows from the changes. Kidney function and potassium are rechecked in two to four weeks, since stopping ibuprofen may improve filtration and the ACE inhibitor affects potassium, and then at intervals appropriate to her stage of kidney disease (Stevens et al., 2024). A cystatin C level refines the kidney estimate. Standing and sitting blood pressures are checked, since dizziness on standing may also reflect her blood pressure regimen. Her daughter is asked to note any evening confusion, falls or return of neuropathic pain after the gabapentin reduction. Glucose checks confirm that the lower metformin dose keeps her near an appropriate target, and her bladder symptoms are reviewed after oxybutynin stops.

Making the Changes Stick

Five changes at once can confuse anyone, so the plan staggers them: ibuprofen and oxybutynin stop now, gabapentin is reduced now because it is the most likely culprit, and famotidine and metformin are adjusted at the next visit. A single updated medicine list, with the reason for each drug in plain words, goes to her and her daughter, and the pharmacy is asked to package her medicines by time of day. She is told that some pain or bladder symptoms may return briefly and what to do if they do, which makes it less likely she will restart the stopped drugs on her own.

Conclusion

This patient's dizziness, confusion and fall are best explained by drugs that accumulate as her kidneys slow and by drugs that affect an aging brain. Estimating her kidney function carefully, and recognizing that her creatinine understates the decline, reveals that gabapentin, famotidine and metformin are dosed for a younger person, while ibuprofen and oxybutynin do more harm than good. Reducing three doses, stopping two drugs and keeping the two that protect her heart and kidneys, then monitoring what the physiology predicts, is the integration of pathophysiology and pharmacology this course set out to teach.

References

American Diabetes Association Professional Practice Committee. (2025). 9. Pharmacologic approaches to glycemic treatment: Standards of care in diabetes 2025. Diabetes Care, 48(Suppl. 1), S181-S206. https://doi.org/10.2337/dc25-S009

American Geriatrics Society Beers Criteria Update Expert Panel. (2023). American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society, 71(7), 2052-2081. https://doi.org/10.1111/jgs.18372

Cockcroft, D. W., & Gault, M. H. (1976). Prediction of creatinine clearance from serum creatinine. Nephron, 16(1), 31-41. https://doi.org/10.1159/000180580

Mangoni, A. A., & Jackson, S. H. D. (2004). Age-related changes in pharmacokinetics and pharmacodynamics: Basic principles and practical applications. British Journal of Clinical Pharmacology, 57(1), 6-14. https://doi.org/10.1046/j.1365-2125.2003.02007.x

Rosenthal, L. D., & Burchum, J. R. (2021). Lehne's pharmacotherapeutics for advanced practice nurses and physician associates (2nd ed.). Elsevier.

Stevens, P. E., Ahmed, S. B., Carrero, J. J., Foster, B., Francis, A., Hall, R. K., Herrington, W. G., Hill, G., Inker, L. A., Kazancıoğlu, R., Lamb, E., Lin, P., Madero, M., McIntyre, N., Morrow, K., Roberts, G., Sabanayagam, D., Schaeffner, E., Shlipak, M., . . . Levin, A. (2024). KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney International, 105(4S), S117-S314. https://doi.org/10.1016/j.kint.2023.10.018