3D printing of azithromycin loaded gummies for paediatric patients using a carrageenan-based thermoresponsive system

Azithromycin (AZT) is widely used in paediatric medicine, but its poor aqueous solubility and low oral bioavailability (∼37 %) limit its therapeutic effectiveness and required high dosages contribute to side effects that reduce treatment adherence. This study presents a formulation strategy that combines solubility enhancement with semisolid extrusion (SSE) 3D printing to produce personalised, chewable AZT-loaded gummies suitable for children. An oil-in-water (O/W) emulsion was developed using pumpkin seed oil, soy lecithin, and Labrasol® to improve AZT solubility. The emulsion was structured into a printable gel matrix using carrageenan and bentonite nanoclay, enabling extrusion at 62 °C and solidification at 15 °C without post-processing. Rheological analysis confirmed shear-thinning behaviour, high storage modulus, and 85.9 % thixotropic recovery, supporting smooth extrusion and shape retention. Moreover, the printed gummies met European Pharmacopoeia standards for weight and drug content uniformity and remained mechanically stable up to 90 days in packages sealed under vacuum. PXRD confirmed AZT was amorphously dispersed in the developed formulation, and antimicrobial assays showed retained efficacy against Escherichia coli and Staphylococcus aureus . This work demonstrates a reproducible and scalable method for paediatric antibiotic delivery that leverages SSE 3D printing, thus offering flexible dosing, improved solubility, and enhanced patient acceptability.