Background:
In this study, a liposomal gel based on a pH-gradient method was used to increase
the skin-layer retention of monocrotaline (MCT) for topical administration.
Methods:
Using the Box-Behnken design, different formulations were designed to form liposome suspensions
with optimal encapsulation efficiency (EE%) and stability factor (KE). In order to keep MCT
in liposomes and accumulate in skin slowly and selectively, MCT liposome suspensions were engineered
into gels.
Results:
A pH-gradient method was used to prepare liposome suspensions. The optimal formulation of
liposome suspensions (encapsulation efficiency: 83.10 ± 0.21%) was as follows: MCT 12 mg, soybean
phosphatidyl choline (sbPC) 200 mg, cholesterol (CH) 41 mg, vitamin E (VE) 5 mg, and citric acid
buffer solution (CBS) 4.0 10 mL (pH 7.0). The final formulation of liposomal gels consisted of 32 mL
liposome suspensions, 4.76 mL deionized water, 0.40 g Carbopol-940, 1.6 g glycerol, 0.04 g
methylparaben, and a suitable amount of triethanolamine for pH value adjustment. The results of in
vitro drug release showed that MCT in liposomal gels could be released in 12 h constantly in physiological
saline as a Ritger-Peppas model. Compared with plain MCT in gel form, liposomal MCT in gel had
higher skin retention in vitro.
Conclusion:
In this study, liposomal gels were formed for greater skin retention of MCT. It is potentially
beneficial for reducing toxicities of MCT by topical administration with liposomal gel.
Dissipation of the Proton Electrochemical Potential in Intact Chloroplasts (II. The pH Gradient Monitored by Cytochrome f Reduction Kinetics)
