Dose-dependency of the cardiovascular risks of non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat pain and inflammatory conditions such as arthritis. However, both arthritis and many NSAIDs increase cardiovascular (CV) risks. The dose-dependency of the elevated CV risks of NSAIDs has not been well-studied. We tested the hypothesis that low but still effective doses of these drugs are void of CV side effects. As the model drug, we chose diclofenac because of its known high CV toxicity, as markers of CV risks, we assessed concentrations of cytochrome P450-mediated metabolites of arachidonic acid (ArA), and we used adjuvant arthritis as an experimental model of arthritis. Following 7 daily doses (2.5-15 mg/kg), the effective dosage range of diclofenac was identified (> 5 mg/kg/day). While 7 consecutive days of low therapeutic doses did not alter the CYP-mediated ArA metabolism, the highest dose of 15 mg/kg/day caused imbalances in ArA metabolic profiles toward cardiotoxicity by increasing the ratio of cardiotoxic 20-hydroxyeicosatetraenoic acid over cardioprotective epoxyeicosatrienoic acids. This is suggestive of dose-dependency of NSAID cardiotoxicity, and that low therapeutic doses may be void of CV side effects. Human studies are needed to examine the safety of low but effective doses of NSAIDs.