<p>Diclofenac is completely absorbed from the GI tract but likely undergoes significant first pass metabolism with only 60% of the drug reaching systemic circulation unchanged <sup class="text-reference-group"><a class="reference-popover-link" data-content="Official drug label" href="#label-reference">Label</a>,<a class="reference-popover-link" data-content="Davies NM, Anderson KE: Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls. Clin Pharmacokinet. 1997 Sep;33(3):184-213. doi: 10.2165/00003088-199733030-00003. (PubMed ID 9314611)" href="#reference-A178633">7</a>,<a class="reference-popover-link" data-content="Todd PA, Sorkin EM: Diclofenac sodium. A reappraisal of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy. Drugs. 1988 Mar;35(3):244-85. doi: 10.2165/00003495-198835030-00004. (PubMed ID 3286213)" href="#reference-A180694">8</a></sup>. Many topical formulations are absorbed percutaneous and produce clinically significant plasma concentrations. Absorption is dose proportional over the range of 25-150 mg.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Davies NM, Anderson KE: Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls. Clin Pharmacokinet. 1997 Sep;33(3):184-213. doi: 10.2165/00003088-199733030-00003. (PubMed ID 9314611)" href="#reference-A178633">7</a></sup> Tmax varies between formulations with the oral solution reaching peak plasma concentrations in 10-40min, the enteric coated tablet in 1.5-2h, and the sustained- and extended-release formulations prolonging Tmax even further. Administration with food has no significant effects on AUC but does delay Tmax to 2.5-12h.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Davies NM, Anderson KE: Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls. Clin Pharmacokinet. 1997 Sep;33(3):184-213. doi: 10.2165/00003088-199733030-00003. (PubMed ID 9314611)" href="#reference-A178633">7</a>,<a class="reference-popover-link" data-content="Todd PA, Sorkin EM: Diclofenac sodium. A reappraisal of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy. Drugs. 1988 Mar;35(3):244-85. doi: 10.2165/00003495-198835030-00004. (PubMed ID 3286213)" href="#reference-A180694">8</a></sup> </p>