Combined use of crystalline sodium salt and polymeric precipitation inhibitors to improve pharmacokinetic profile of ibuprofen through supersaturation.

ABSTRACT

To maximize the pharmacological effect of a pain reliever such as ibuprofen, early onset of action is critical. Unfortunately, the acidic nature of ibuprofen minimizes the amount of drug that can be solubilized under gastric conditions and would be available for immediate absorption upon entry into the intestine. Although the sodium salt of ibuprofen has higher solubility, rapid conversion from the salt to the poorly soluble free acid phase occurs under gastric conditions. Therefore, the combination of the highly soluble sodium salt form of ibuprofen with polymers was evaluated as an approach to prolong supersaturation of ibuprofen during the disproportionation of the salt. Binary combinations of ibuprofen sodium with polymers resulted in the identification of several formulations that demonstrated high degrees and extended durations of supersaturation during in vitro dissolution experiments. These formulations included HPMC, polyvinyl pyrrolidone-vinyl acetate copolymer (PVP-VA64), methylcellulose (MC), and hydroxypropyl cellulose (HPC). The in vitro supersaturation observed with these ibuprofen-polymer formulations translated to an increase in Cmax and an earlier Tmax for the PVP-VA64, MC, and HPC formulations relative to ibuprofen only controls when administered orally to rats under fasted conditions. Based on these observations, combining ibuprofen sodium with polymers such as PVP-VA64, MC, or HPC is a viable formulation approach to prolong supersaturation in the stomach and enable an optimized pharmacokinetic profile in vivo where rapid onset of action is desired.