RESUMO
OBJECTIVES: We investigated changes of renal perfusion after topical and oral diclofenac administration in healthy volunteers using functional magnetic resonance imaging (MRI) with arterial spin labelling (ASL). METHODS: Twenty-four healthy human participants (21-51 years) underwent 1.5T MRI before and 1 h after a single oral dose of diclofenac (50 mg). Twelve of 24 participants underwent an additional MRI examination following 3-day topical diclofenac administration. For renal perfusion imaging, a flow-sensitive alternating inversion-recovery TrueFISP ASL sequence was applied. Plasma concentrations of diclofenac and serum concentrations of thromboxane were determined. KEY FINDINGS: After oral diclofenac application, large interindividual differences in plasma concentrations were observed (range <3-4604 nm). Topical diclofenac application did not result in relevant systemic diclofenac levels (range 5-75 nm). MRI showed a significant reduction of renal perfusion in individuals with diclofenac levels ≥225 nm (baseline: 347 ± 7 vs diclofenac: 323 ± 8 ml/min/100 g, P < 0.01); no significant differences were observed in participants with diclofenac levels <225 nm. Diclofenac levels correlated negatively with thromboxane B2 levels pointing towards target engagement. CONCLUSIONS: Single-dose diclofenac caused a decrease in renal perfusion in participants with diclofenac levels ≥225 nm. We demonstrated that even a single dose of diclofenac can impair renal perfusion, which could be detrimental in patients with underlying chronic kidney disease or acute kidney injury.