Study Of Pingyangmycin In Situ Gel For Treatment Of Haemangioma

Sclerotherapy was frequently used for complicated haemangioma, and Pingyangmycin （PYM） was the most promising sclerosing agent. However, according to the reports, the cure rate of PYM to cavernous hemangioma, the most epidemic vascular malformation, was not satisfying. A new drug delivery system, Pingyangmycin in situ gel, was designed in this study to get better curative effect of haemangioma and vascular malformation.The refining process of zein, the main matrix of Pingyangmycin in situ gel, was decided according to orthogonal experiment. The result of SDS-PAGE showed that the refined zein contained two compositions, and their molecular weight were 19 kDa and 22 kDa, respectively. The decolorized zein was produced with optimized decolorizing process.Factors which could influence the in vitro embolizing effect of Pingyangmycin in situ gel were studied, and the proper concentration of zein was 240.0 mg·mL^-1. The maximum caliber of the draining blood vessel for treated haemangioma and vascular malformation was 2 mm., and moreover the most effective embolizing site was around the orifice of the draining blood vessel. A certain amount of sucrose acetate isobutyrate or PEG 6000 would not influence obviously the embolizing effect.Rheology study of in situ gel showed that G′, G″,ηincreased andδdecreased sharply when it contacted with normal sodium. These phenomena indicated that in situ gel solution contacting with NS changed into gel. SAIB could increaseδof PYM in situ gel, modulate its phase transition and improve the embolizing effect and delayed release.In vitro release study revealed that release area, in situ get amount, shake rate and temperature would affect drug release; PEG 6000 would quicken drug release, and proper amount of SAIB would significantly cut down the initial burst of PYM from the in situ gels; the increase of drug loaded would result in faster release, higher initial burst, shorter release period and higher accumulated release of PYM; trypsin would enhance drug release.Small Angle X-ray Scattering （SAXS） was applied to study the three diamensions structure of zein in glycerol formal. Its Rg and Rc were 4.15±0.04 nm and 1.78±0.03 nm, respectively. It was ratiocinated that zein existed in glycerol formal as a pentamer with 3D of 13.0 nm×5.4 nm×3.0 nm. According to the result of light microscope, SEM and atomic force microscope （AFM）, the mechanism of gel formation and drug release for PYM in situ gel was further discussed. In vitro PYM plasma protein binding fractions in rabbit and canis familiaris blood were evaluated with microdialysis sampling technique. And the blood concentration of PYM in rabbits was studied with traditional blood sampling and microdialysis sampling simultaneously. The in vivo PYM plasma protein binding fraction in rabbits was 31.96＋7.51%, which was similar with the in vitro one. The drug release of PYM in situ gel in the animal model of venous malformation was investigated in conscious rabbits. Compared with the PYM solution, the in situ gel could sustain the release of PYM and prolong its local retention. In vivo releases of the in situ gels of PYM-Zein and PYM-Zein-SAIB were up to 3 days and 4days, respectively. SAIB could significantly cut down the initial burst of PYM and prolong drug release.The result of inhibitory effect of PYM and PYM in stiu gel on ECV304 cell presented that the inhibitory effect had time and concentration dependent. IC₅₀ for 24h, 48h and 72h were 16.05±1.21, 1.99±0.56 and 0.29±0.18μg·mL^-1, respectively. PYM in situ gel could sustain the release of PYM. Molecular biological study found that inhibition of PYM on ECV304 cell was achieved by two ways, apoptosis and necrosis.Pharmacodynamics of PYM in situ gel was studied with rabbit ear venous system. The results showed that PYM-Zcin-SAIB in situ gel could cmbolizc rabbit car venous and sclerize it. Its inflammatory reaction was slighter than PYM-Zcin in situ gel. Its therapeutic effect was better than PYM solution, blank in situ gel and PYM-Zein in situ gel. These results suggested considerable potential for use of PYG-loadcd injectable Zcin-SAIB-based in situ gels for sclcrotherapy of venous malformations.