Development of a potential carrageenan-based hard capsule as the alternative of conventional capsules by implementing the oligomerization reaction

Abstract

Carrageenan-based (CRG) hard capsules have a slower disintegration rate compared to that of gelatin capsules. Therefore, there is an urgent need to optimize the performance of this material using the oligomerization process. The preparation was conducted by oligomerizing CRG, cross-linking it with maltodextrin (MD), and plasticizing it with sorbitol (SOR). Based on our research, we found that the capsule prepared with the code CRG(O)-MD/SOR had an ash content of 11.80% and a water content of 17.20 ± 1.20 %. No microbes or yeast were found in the capsule, and only negligible amounts of heavy metal traces were present. Scanning electron microscopy (SEM) morphology analysis of the capsule surface showed that no pores were observed, even at a magnification of 10,000 times. This result was supported by the BET-BJH analysis, which showed that the pores had an average diameter of 49.26 Ǻ. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the Tg of the prepared capsules was at 51.4 °C. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the presence of citric acid as the oligomerization agent had changed the chain composition of the carrageenan. Acute toxicity analysis showed that the capsule was safe even at a dose of 3,000 mg/bw. The Young's modulus of CRG(O)-MD/SOR was determined to be 1.500 ± 0.52 MPa. In vitro disintegration testing of CRG(O)-MD/SOR showed that the capsule required 20.01 ± 1.13 mins, 23.13 ± 1.14 mins, and more than 120 mins to disintegrate at pH 1.2, 4.5, and 6.8, respectively. Release kinetics analyses showed that the drugs paracetamol (PCT) and salicylamide (SCA) followed the zeroth-order model at pH 1.2 and 4.5, while they were best described by the Peppas-Sahlin model at pH 6.8. Finally, the maximum swelling degree of the CRG(O)-MD/SOR hard capsule was determined to be 708.88%, which was reached in 15.22 mins. This capsule has the potential to be used as an alternative to conventional hard capsules on a broader scale. Furthermore, this work supports Sustainable Development Goals (SDGs) point 3, good health and well-being, by providing a capsule made from biomaterial.