Background: Diclofenac is an effective, opiate-sparing analgesic for acute pain in children, which is commonly used in pediatric surgical units. Recently, a Cochrane review concluded the major knowledge gap in diclofenac use is dosing information. A pharmacokinetic meta-analysis has been undertaken with the aim of recommending a dose for children aged 1-12 years. Methods: Studies containing diclofenac pharmacokinetic data were identified during a Cochrane systematic review, and authors were asked to provide raw data. A pooled population analysis was undertaken in NONMEM to define the pharmacokinetics of intravenous, oral, and rectal diclofenac in children. Simulations were performed to recommend a dose yielding an equivalent area under diclofenac concentration-time curve (AUC) to a 50-mg dispersible tablet in adults. Results: Data from 111 children aged 1-14 years consisting of 375 samples following intravenous, oral suspension, and suppositories were used. Adult dispersible tablet and suspension data were added to provide a reference AUC and support the absorption modeling, respectively. A three-compartment model described disposition, a dual-absorption compartment model was used for suspension and dispersible tablet data, and single-absorption compartment model for suppositories. The estimate of clearance was 16.5 l·h-1·70 kg-1 and bioavailabilities were 0.36, 0.63, and 0.35 for suspension, suppository, and dispersible tablets, respectively. Conclusions: Single doses of 0.3 mg·kg-1 for intravenous, 0.5 mg·kg-1 for suppositories, and 1 mg·kg-1 for oral diclofenac in children aged 1-12 years are recommended as they yield a similar AUC to 50 mg in adults.

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Keywords Cochrane Library, NONMEM, area under the curve, article, child, diclofenac, dispersible tablet, drug bioavailability, drug clearance, human, major clinical study, pharmacokinetics, postoperative pain, priority journal, single drug dose
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Journal Paediatric Anaesthesia
Standing, J.F, Tibboel, D, Korpela, R, & Olkkola, K.T. (2011). Diclofenac pharmacokinetic meta-analysis and dose recommendations for surgical pain in children aged 1-12 years. Paediatric Anaesthesia, 21(3), 316–324. doi:10.1111/j.1460-9592.2010.03509.x