Irinotecan-Loaded Vaterite Microspheres for Drug Delivery: Drug Release and Dissolution Kinetics and Mechanism in an Aqueous Solution and Human Serum

The coprecipitation synthesis of calcium carbonate vaterite microspheres loaded with chemotherapeutic drug irinotecan is reported. High drug loading comparable to the best reported for other drugs in porous vaterite is achieved, and characterization confirms that the characteristic spherical morphology of vaterite is not disrupted by the presence of irinotecan. UV-vis spectroscopy demonstrates the release of the drug over time, and the latter, upon comparison with optical microscopy dissolution data, shows that drug release correlates with the time scale of dissolution of the vaterite host. To model application in a drug delivery context, the dissolution of unloaded vaterite and irinotecan-loaded vaterite in human serum and diluted human serum is investigated, revealing inhibition of dissolution by human serum that occurs in two distinct serum concentration-dependent ranges. Furthermore, irinotecan-loaded vaterite is tested in vitro on two human pancreatic cancer cell lines, MiaPaCa-2 and Capan-1, demonstrating a therapeutic effect in both cases.