Development of ALZET® osmotic pump compatible solvent compositions to solubilize poorly soluble compounds for preclinical studies.

Hydrophilic, non-aqueous solvents are frequently used to solubilize poorly water soluble compounds for use in ALZET® osmotic pumps used during the discovery and preclinical stages. Though these solvents exhibit the potential to solubilize several poorly soluble compounds, the solubilized compounds are prone to crystallization up on contact with aqueous fluids in vitro and in vivo. Crystallization of a compound can potentially cause pain at the release site, erratic blood levels, and uneven or delayed pharmacokinetic profiles. In this study, we discussed the development of ALZET® pump compatible hydrophilic, non-aqueous vehicles that solubilized two poorly soluble model compounds (ELND006 and ELN 481594) and prevented their crystallization from solutions in vitro and in vivo. The selected formulations were filled into the pumps at three concentrations for each model compound and investigated for their compatibility with the pumps and the subcutaneous tissue of mice where the pump was inserted. The results showed that the formulations were stable physically with no crystallization and chemically with no degradation and were compatible with the pump and animal tissue. The plasma concentration of ELND006 decreased with time at each dose. The extent of the time-dependent decrease in ELND006 plasma levels increased as the amount of dose delivered increased. This time and dose dependent decrease in ELND006 plasma concentrations was attributed to the known auto-induction of hepatic enzymes by the compound. In contrast, the plasma concentration of ELN 481594 increased significantly at higher dose, likely due to accumulation of the compound.