PharmacologyTier 2Medical Sciences concept

NSAID cardiovascular risk and COX-2 selectivity

Core concept

The cardiovascular risk follows the imbalance between two prostanoids.

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COX-1 (platelet, constitutive)

COX-2 (endothelium, inducible)

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Selective COX-2 inhibition removes the antithrombotic prostacyclin while leaving platelet thromboxane intact
- -> net prothrombotic state, inc BP, Na retention
Naproxen carries the lowest cardiovascular risk of the commonly used NSAIDs
- Attributed to near-complete and sustained platelet COX-1 inhibition across the dosing interval (aspirin-like), offsetting the COX-2 effect
- The trade-off: naproxen has among the highest GI toxicity
Risk rises with dose and duration, and is present from the first weeks - not only with chronic use

Relative risk profile

Agent	COX-2 selectivity	CV risk	GI risk
Naproxen	Non-selective, sustained COX-1	Lowest	High
Ibuprofen	Non-selective	Intermediate (higher at >=1200-2400 mg/day)	Moderate
Diclofenac	Moderately COX-2 selective	High - comparable to coxibs	Moderate
Celecoxib	COX-2 selective	Moderate (PRECISION: non-inferior to ibuprofen and naproxen at moderate doses)	Lower
Etoricoxib	Highly COX-2 selective	High; inc BP	Lower
Indomethacin	Non-selective, potent	High	High

Ibuprofen (and naproxen) compete with aspirin for the platelet COX-1 channel -> blunt aspirin's irreversible cardioprotection
- -> take aspirin at least 30 min before, or 8 hours after, ibuprofen. Celecoxib and diclofenac do not interfere.

Other class effects driving harm

Renal: dec afferent arteriolar prostaglandin -> AKI, particularly in the "triple whammy" (NSAID + ACEi/ARB + diuretic)
Na and water retention -> inc BP (~3-5 mmHg), decompensation of heart failure
Hyperkalaemia (dec renin)
GI: ulceration and bleeding (COX-1-mediated loss of mucosal prostaglandin), small bowel enteropathy
Hepatotoxicity (diclofenac), aseptic meningitis (ibuprofen in SLE), aspirin-exacerbated respiratory disease
Topical NSAIDs achieve useful local concentrations with minimal systemic exposure - the safest option in the elderly

Prescribing rules

Lowest effective dose, shortest possible duration - the risk is dose- and duration-dependent
Avoid entirely in: established cardiovascular disease, heart failure, CKD (eGFR <30), cirrhosis with ascites, prior GI bleed, and in the 6 months after a myocardial infarction or bypass surgery
Contraindicated after coronary artery bypass grafting
If an NSAID is unavoidable with cardiovascular risk -> naproxen at the lowest dose, with a PPI
If GI risk dominates -> celecoxib + PPI
Check BP, renal function and potassium at baseline and within 1-2 weeks of starting in anyone at risk
Review the whole chart for the triple whammy, anticoagulants, SSRIs and corticosteroids
Third-trimester pregnancy: closure of the ductus arteriosus and oligohydramnios - avoid

Perspective

Absolute excess risk is small in a low-risk 40-year-old and substantial in an 80-year-old with heart failure - stratify, do not ban universally

Proton pump inhibitor adverse effects (the co-prescribed drug)
Drug-induced acute kidney injury; renal tubular drug secretion
Antiplatelet and anticoagulant mechanisms of action (aspirin-ibuprofen interaction)
Evidence-based pharmacotherapy in heart failure (NSAIDs among the drugs to avoid)
Uricosuric and urate-lowering effects of antihypertensive drugs; gout management
Aspirin-exacerbated respiratory disease and the leukotriene pathway
Age-related pharmacokinetic changes and deprescribing

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