The preparation of Cistanche phenylethanoid glycosides liquid proliposomes: Optimized formulation, characterization and proliposome dripping pills in vitro and in vivo evaluation

Water-soluble Cistanche phenylethanoid glycosides (CPhGs) have poor permeability and low bioavailability. However, liposomes can improve the permeability of such drugs and their poor stability, and proliposomes have been used to overcome these problems. Based on this, Cistanche phenylethanoid glycoside liquid proliposomes (CPhGsP) and dripping(?) pills were prepared and optimized using response surface methodology. The properties of CPhGsP were evaluated in terms of their encapsulation efficiency, particle size, zeta potential, and morphology. The results obtained showed that the optimal formulation was drug/soybean phospholipid/poloxamer-188/sodium deoxycholate/propylene glycol 1:22.38:3.52:0.84:80 (w/w/w/w/v). This resulted in an encapsulation efficiency, particle size, and zeta potential of hydrated proliposomes with phosphate buffer solution (pH 7.4) of 51.97%, 671.7 nm, and − 25.49 mV, respectively. Stability testing of CPhGsP and CPhGs ordinary liposomes was carried out for 3 months at 4 ± 2 °C, 25 ± 2 °C, 40 ± 2 °C, 75 ± 5% RH. The results obtained showed that the stability of the proliposomes was better than that of ordinary liposomes at the same temperature, while a lower temperature of 4 °C is ideal for storage. Cistanche phenylethanoid glycoside liquid proliposomes dripping pills (CPhGsPD) are efficiently released in gastrointestinal solution as shown by in vitro release experiments and the structure of the liposomes does not destroy the proliposome dripping pills by hydration. In vivo experiments showed that the areas under the plasma level-time curves and peak concentrations of CPhGsPD and hydrated proliposomes were higher than those of CPhGs. Moreover, with CPhGsPD, the pharmacokinetic parameters were similar to those with hydrated proliposomes. These results showed that CPhGsPD offer a good way to improve the oral delivery of CPhGs.