The pharmacokinetics and pharmacodynamics of dexamethasone following epidural SP-102 or intravenous dexamethasone sodium phosphate injection in subjects with lumbosacral radicular pain

Objectives: To evaluate the pharmacokinetics, pharmacodynamics (PD), safety, and tolerability of epidural SP-102 (10 mg dexamethasone sodium phosphate injectable gel) compared to an intravenous injection of 10 mg dexamethasone sodium phosphate, USP (IV USP). Materials and methods: Subjects with lumbosacral radiculopathy received a single dose of epidural SP-102, followed by a single dose of IV USP 4 weeks later. Dexamethasone plasma levels, cortisol levels, white blood cells (WBC), and blood glucose levels were assessed. Results: Twelve subjects entered and completed the study. The mean total dexamethasone exposure (AUClast and AUCinf) following SP-102 by epidural injection was equivalent to the total exposure following IV USP. A lower mean plasma Cmax (~ 50% lower) was observed following epidural administration compared to IV injection. PD parameters were similar between treatments. Adverse events (AEs) were mild, with no serious AEs or study discontinuations due to AEs. Conclusion: In this small study, epidural SP-102 injection was well tolerated, was not associated with greater systemic dexamethasone exposure than IV USP, and both treatments had similar PD effects on cortisol suppression, blood glucose, and WBC levels.