Dual Loading of Primaquine and Chloroquine into Liposome

Primaquine (PQ) has long been recognized as the only effective drug in the treatment of hepatic stage malaria. However, severe toxicity limits its therapeutical application. Combining PQ with chloroquine (CQ) has been reported as enhancing the former's efficacy, while simultaneously reducing its toxicity. In this study, the optimal conditions for encapsulating PQ-CQ in liposome, including incubation time, temperature and drug to lipid ratio, were identified. Furthermore, the effect of the loading combination of these two drugs on liposomal characteristics and the drug released from liposome was evaluated. Liposome is composed of HSPC, cholesterol and DSPE-mPEG₂₀₀₀ at a molar ratio of 55:40:5 and the drugs were loaded by means of the transmembrane pH gradient method. The particle size, ζ-potential and drug encapsulation efficiency were subsequently evaluated. The results showed that all liposome was produced with a similar particle size and ζ-potential. PQ and CQ could be optimally loaded into liposome by incubating the mixtures at 60°C for 20 minutes at a respective drug to lipid ratio of 1:3 for PQ and CQ. However, compared to single drug loading, dual-loading of PQ+CQ into liposome resulted in lower drug encapsulation and slower drug release. In conclusion, PQ and CQ can be jointly loaded into liposome with differing profiles of encapsulation and drug release.