A Phase 1, multiple-dose, single-center, randomized, open-label, 2-period, 2-treatment crossover systemic bioavailability study of diclofenac comparing XXX g (XXX mL) of AMZ001 (Diclofenac sodium gel XXX %) applied once daily (XXXXXXXXX) versus XXX g of Voltaren Emulgel 1.16% Gel (Diclofenac diethylamine gel 1.16%) applied 4 times daily (4 times 4 g on each knee) in healthy subjects