The objective of this study was to prepare the nanocrystals of curcumin didecanoate (CurDD) by wet ball milling and to investigate the comparative pharmacokinetics of oily nano- and micro-suspensions after intramuscular (i.m.) administration to rats. Upon optimizing the wet ball milling parameters, CurDD nanocrystals were produced with median particle size of ~500 nm and the freeze-dried nanocrystals were readily dispersed in peanut oil to form stable nanosuspensions. Although the nanosuspension appeared to exhibit slower clearance from the injection site after i.m. injection, compared to microsuspension (~5 μm), a significantly higher maximum plasma curcumin concentration (69.0 ng/ml) was observed for the former than that for the latter (18.5 ng/ml). In addition, the nanosuspension provided significant higher plasma curcumin concentrations and brain CurDD contents for at least 15 days than the microsuspension, except for the initial times. A single i.m. injection of nanosuspension appeared to achieve reversal effect on reserpine-induced hypothermia for at least 13 days. This study demonstrates that CurDD nanosuspension may act as a long-acting i.m. injectable for sustained delivery of curcumin, potentially applicable to elicit a long-lasting antidepressant effect.
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