Cyclodextrin grafted calcium carbonate vaterite particles: efficient system for tailored release of hydrophobic anticancer or hormone drugs

Porous CaCO 3 microparticles have been used earlier for sustained drug release of hydrophilic drugs but have certain drawbacks for use with hydrophobic drugs. Hence, to overcome these drawbacks, a novel composite of CaCO 3 along with cyclodextrin (CD-CaCO 3 ) for the delivery of hydrophobic drugs was developed. Cyclodextrins (CDs), when incorporated within CaCO 3 , increased the porosity and surface area of microparticles thereby enhancing the encapsulation efficiency of hydrophobic drugs (5-Fluorouracil or Na- l -thyroxine) by forming inclusion complexes with cyclodextrin. Thermogravimetric and FTIR studies confirmed the interaction between the cyclodextrin and CaCO 3 microparticles. Raman spectra confirmed the peak of vaterite crystals before and after loading of hydrophobic drugs within the composite. In vitro release studies when performed at pH 4.8 (5-Fu) and pH 1.2 (Na- l -thy) showed release at low pH as CaCO 3 is soluble at acidic pH unlike slower release at basic pH. Release kinetics followed a Higuchi kinetic model at pH 4.8 (5-Fu) and pH 1.2 (Na- l -thy) respectively. The porous cyclodextrin-CaCO 3 microparticles are acting as the intelligent hydrophobic drug carriers, where the loaded drug is stable at blood pH but released at acidic pH (cancer cells) due to recrystallization of CaCO 3 particles.