Question
A 65-year-old lady presented with pain in both knees more on the left side. The pain is worsened by walking or standing for some time. X-Ray of knee shows narrowing of joint space, mild effusion and osteophytic projections. A diagnosis of Osteoarthritis of knee is made. She gave past history of ischemic heart disease a year back which was treated by angioplasty and a stent was placed. (
- (a) Classify Non-steroidal Anti-Inflammatory Drugs (NSAIDs). ( 4 mark(s)
- (b) Which NSAID will be suitable for reliving knee pain. Justify. ( 2 mark(s)
- (c) Which NSAID is to be avoided. Why. ( 2 mark(s)
- (d) Describe the mechanism of action, uses and adverse effects of Aspirin. 7 mark(s)
Answer
a) Classification of NSAIDs
| Class | Examples |
|---|---|
| Non-selective COX inhibitors | Ibuprofen, Naproxen, Diclofenac |
| Preferential COX-2 inhibitors | Nimesulide, Meloxicam |
| Selective COX-2 inhibitors | Celecoxib, Etoricoxib |
| Salicylates | Aspirin |
b) NSAID suitable for this patient, with justification Naproxen — among non-selective NSAIDs, naproxen has the most favourable cardiovascular safety profile in large comparative trials, making it the preferred choice in a patient with a recent coronary stent and established ischemic heart disease, where minimizing added thrombotic risk is a priority alongside pain relief.
c) NSAID to avoid, and why Selective COX-2 inhibitors (e.g. Celecoxib, and also Diclofenac among non-selective agents) should be avoided — COX-2 inhibition suppresses vascular endothelial prostacyclin (an antiplatelet, vasodilator mediator) without the offsetting COX-1/thromboxane suppression that non-selective NSAIDs provide, shifting the hemostatic balance toward thrombosis — a specifically dangerous property in a patient with a recent stent and established coronary disease.
d) Aspirin — mechanism, uses, adverse effects Mechanism: irreversibly acetylates and inhibits cyclooxygenase (COX-1 and COX-2), blocking prostaglandin and thromboxane A2 synthesis. At low doses, predominantly and durably suppresses platelet thromboxane A2 (antiplatelet effect, since platelets cannot resynthesize COX); at higher doses, gives analgesic, antipyretic, and anti-inflammatory effects.
Uses: analgesia, antipyresis, anti-inflammatory use (high dose), antiplatelet prophylaxis (low dose) — particularly relevant to this patient, who would already be on low-dose aspirin post-stenting as part of dual antiplatelet therapy.
Adverse effects: GI irritation/peptic ulceration, increased bleeding risk, hypersensitivity/bronchospasm in aspirin-sensitive asthmatics, Reye’s syndrome (children with viral illness), salicylism/toxicity in overdose.