Pharmacokinetics and Safety of a Diclofenac Sodium 75 mg/1 mL Solution (Akis(®)/Dicloin(®)) Administered as a Single Intravenous Bolus Injection in Healthy Men and Women

BACKGROUND: A 1-mL aqueous solution for parenteral injection containing diclofenac sodium and hydroxypropyl-β-cyclodextrin, presently on the market for intramuscular and subcutaneous administration (Akis(®)/Dicloin(®)), was further developed for intravenous (i.v.) bolus administration. OBJECTIVES: The study objective was to compare the tolerability and diclofenac pharmacokinetics after a single i.v. bolus of the investigational solution to those of other parenteral diclofenac products. METHODS: The study comprised three parts: (i) Part 1: an exploratory dose-escalation study to evaluate the tolerability of 25 mg/1 mL, 50 mg/1 mL and 75 mg/1 mL diclofenac sodium formulations administered as a single 5-s i.v. bolus; (ii) Part 2: an exploratory, randomised, crossover study to evaluate the pharmacokinetics of diclofenac following 5-, 15-, and 30-s i.v. bolus injections of diclofenac sodium 75 mg/1 mL; (iii) Part 3: a randomised crossover study to compare the pharmacokinetics of diclofenac following a 5-s i.v. bolus of the 75 mg/1 mL solution to the pharmacokinetics of diclofenac following a 30-min i.v. infusion or intramuscular administration of a 75 mg/3 mL reference formulation. RESULTS: The extent of exposure to diclofenac sodium afforded by the 5-s i.v. bolus of 75 mg/1 mL was equivalent to that provided by the 30-min i.v. infusion of 75 mg/3 mL, since the 90% confidence interval of the geometric mean ratio (GMR) of the area under the curve (AUC) from time 0 to the last plasma concentration time t (AUC(0-t)) was within the limits 80.00–125.00%, as was the 90% confidence interval of the GMR of the AUC from time 0 extrapolated to infinity (AUC(0-∞)). The maximum observed plasma concentration (C(max)) was approximately 2.7-fold higher and was achieved earlier (0.05 vs. 0.50 h) with the 1 mL than with the 3 mL formulation, and was similar to data published for a 75 mg/2 mL formulation given as a 15-s i.v. bolus. CONCLUSIONS: Diclofenac sodium 75 mg/1 mL solution administered as a 5-s i.v. bolus was well tolerated. The pharmacokinetic profile, which showed a faster onset and a higher concentration peak than seen for other products and administration routes, suggests a superior analgesic effect.