Stomach-sparing is not kidney-sparing, which is what the author of this MN553 Unit 6 seminar reflection learned when a defended celecoxib choice met a class effect selectivity does not escape. Searches like "mn 553 unit 6 assignment example", "mn553 unit 6 sample" and "mn553 unit 6 example" land here.
Selective for the Stomach, Not for the Kidney: A Seminar Reflection on Celecoxib in a 69-Year-Old Taking Lisinopril
[Student Name]
Purdue University Global
MN553: Advanced Pharmacology
Unit 6 Seminar Reflection
[Instructor Name]
[Date]
The case discussed is a composite prepared for teaching. No real patient is described.
The Defense as I Gave It
The seminar case was a composite 69-year-old retired upholsterer with osteoarthritis of the right knee that limits his walking, a duodenal ulcer treated eight years ago, and hypertension controlled on lisinopril 20 mg daily. Acetaminophen had not given him enough relief. When the facilitator asked each of us to choose an oral agent and defend it, I chose celecoxib, and I defended it with confidence.
My argument went like this. Celecoxib is selective for cyclooxygenase-2, the isoform induced at sites of inflammation, and it spares cyclooxygenase-1, which maintains the protective prostaglandins of the gastric and duodenal mucosa. Because of that selectivity, serious gastrointestinal events are less frequent than with nonselective NSAIDs. His ulcer history made the stomach the organ I most wanted to protect. I finished by saying that celecoxib was "the safe choice for him." I am reporting that argument at full strength because it was not a weak argument about the stomach; it was an incomplete argument about the patient.
One Question From the Room
A classmate who works in a nephrology clinic asked, "What does celecoxib do in his kidney? Doesn't the kidney use COX-2 too?" I did not have an answer ready. I said I thought COX-2 selectivity was about the gut, and the facilitator asked me to hold the question and look it up before our next session. The question exposed that I had chosen the drug by the one organ I was thinking about, not by the patient in front of me.
Prostaglandins Holding Filtration Steady
What I found changed my view. The kidney expresses both cyclooxygenase isoforms, and COX-2 is constitutively present in the macula densa, the thick ascending limb and the renal medulla. Locally made prostaglandins, mainly PGE2 and prostacyclin, keep the afferent arteriole open. In a healthy, well-hydrated person this contribution is small. It becomes important when the kidney is under pressure: in volume depletion, in heart failure, in older adults, and when angiotensin II is blocked. In those settings, afferent dilation by prostaglandins is one of the main things holding glomerular filtration steady (Brunton & Knollmann, 2023).
This man is taking lisinopril, which reduces angiotensin II and so relaxes the efferent arteriole. If an NSAID then removes the prostaglandins that dilate the afferent arteriole, both ends of the glomerular circulation are working against filtration at the same time. Adding a diuretic would complete the combination sometimes called the triple whammy. Celecoxib, as a COX-2 inhibitor, does not escape this. Its selectivity moves gastrointestinal risk, but its renal and blood pressure effects are close to those of the whole NSAID class, including sodium retention, a rise in blood pressure and a risk of acute kidney injury in someone like him.
I also went back to the cardiovascular question, which I had not raised at all. The PRECISION trial randomized more than 24,000 patients with arthritis and increased cardiovascular risk to celecoxib, naproxen or ibuprofen and found celecoxib at moderate doses noninferior to the other two for cardiovascular safety, with fewer serious gastrointestinal events than either (Nissen et al., 2016). That result keeps me from overcorrecting. Celecoxib is not uniquely dangerous to the heart, but the trial does not make it safe for the kidney either.
A Plan Rebuilt Around the Knee
My revised plan starts with the joint rather than with a systemic drug. For a single knee, topical diclofenac is recommended and produces much lower blood levels than oral NSAIDs, which reduces both the gastrointestinal and the renal exposure (Kolasinski et al., 2020). Exercise and weight management, which I had skipped entirely in seminar, belong in the plan too. If an oral agent were still needed, I would check his kidney function and blood pressure first, choose the lowest effective dose for the shortest time, add a proton pump inhibitor because of his ulcer history, and recheck creatinine and blood pressure within a few weeks. I would not simply swap celecoxib for another oral NSAID, since that would change the name of the drug without changing the reasoning.
The Question Still Open
One question I cannot yet answer is how much renal risk remains with topical diclofenac in a man on an ACE inhibitor whose kidney function is already reduced. Systemic exposure is low, but it is not zero, and I have not found data specific to that combination. I plan to bring that question to our next session rather than claim more certainty than the evidence gives me.
References
Brunton, L. L., & Knollmann, B. C. (Eds.). (2023). Goodman and Gilman's the pharmacological basis of therapeutics (14th ed.). McGraw Hill.
Kolasinski, S. L., Neogi, T., Hochberg, M. C., Oatis, C., Guyatt, G., Block, J., Callahan, L., Copenhaver, C., Dodge, C., Felson, D., Gellar, K., Harvey, W. F., Hawker, G., Herzig, E., Kwoh, C. K., Nelson, A. E., Samuels, J., Scanzello, C., White, D., ... Reston, J. (2020). 2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee. Arthritis Care and Research, 72(2), 149-162. https://doi.org/10.1002/acr.24131
Nissen, S. E., Yeomans, N. D., Solomon, D. H., Lüscher, T. F., Libby, P., Husni, M. E., Graham, D. Y., Borer, J. S., Wisniewski, L. M., Wolski, K. E., Wang, Q., Menon, V., Ruschitzka, F., Gaffney, M., Beckerman, B., Berger, M. F., Bao, W., & Lincoff, A. M. (2016). Cardiovascular safety of celecoxib, naproxen, or ibuprofen for arthritis. New England Journal of Medicine, 375(26), 2519-2529. https://doi.org/10.1056/NEJMoa1611593
How this MN553 Unit 6 example is structured
The moment the defense failed is the hinge of the reflection, and seminar grading usually looks there. The original argument is reported at full strength rather than weakened in hindsight, so the change of mind is visible as a change and not as a revised memory. The challenge from the room appears word for word, with credit. Between the challenge and the new position sits the pharmacology the author went back to: afferent arteriole tone maintained by prostaglandins when renin and angiotensin are active, and the specific danger of combining any NSAID with an ACE inhibitor in an older adult. The revised plan is short and conditional, favoring topical diclofenac for a single knee, with an oral agent only after kidney function and blood pressure are checked. A final paragraph names one question the author still cannot answer.
Get an MN553 Unit 6 example written to your instructions
Describe the drug choice your MN553 group argued over in the Unit 6 seminar and the moment your own view shifted, then attach the case and the reflection rubric. A first reflection costs nothing and arrives in 24-48h, built around that shift, the pharmacology behind it and the question the session left open. The paper above is an original model document written by our desk, not a submitted student paper and not an official Purdue University Global document.
MN553 Unit 6 questions, answered
Does the reflection still work if the author's position held?
A view that survived a real challenge is still material for reflection, provided the challenge is shown in full. The strongest objection from the session goes in, along with the reason it failed to overturn the choice and the kind of evidence that would have. Claiming nobody pushed back usually turns the piece into a summary, which these rubrics rarely reward.
How much pharmacology belongs in a reflection?
Enough to show why the reasoning moved. In this sample the kidney physiology takes one paragraph, because that paragraph is the reason the author changed position. A reflection is not a mechanism paper, so detail irrelevant to the change can be left out, but the key mechanism should be stated precisely rather than gestured at.
Can the seminar reflection come from the written alternative?
Yes. Most sections run a written alternative alongside the live session, and it tends to ask for the same things: a position, a challenge and a response. The sample's structure works either way; for the written version, the challenge often comes from the assigned reading or a posted case rather than a classmate's question.