A highly absorbing substrate based on functionalized calcium carbonate for personalized dosing of clonidine by drop-on dispensing.

As precision medicine advances, the need for customizable drug delivery systems has become increasingly important. In this study, we developed porous tablets as substrates for drop-on dispensing of drug-containing ink in personalized doses. We evaluated this approach with clonidine hydrochloride, a hydrophilic drug prescribed in low doses for pediatric patients with hypertension. Porous tablets were compacted from functionalized calcium carbonate (FCC), a filler with a mesoporous structure that can absorb water-based ink without loss of tablet integrity. To improve the compactibility of FCC, the powder was dry granulated and mixed with two different binders: either microcrystalline cellulose (MCC) or ethylcellulose (EC). This was done in various ratios either intragranularly or extragranularly. Tablets (6 mm diameter × 1.6-1.7 mm thickness) with 9.5% (w/w) MCC as intragranular or with 5.0% (w/w) EC as extragranular binder could be loaded with 30 µl clonidine-containing ink. Dissolution experiments in acidic medium (pH 2.0 at 37 °C), mimicking the conditions of the stomach, showed release of clonidine with almost complete dissolution of the drug after 1-2 h. Our findings demonstrate the potential of FCC porous tablets as substrates for drop-on dispensing in the context of personalized dosing of medicines.