Polyglycolized saturated glyceride as a carrier and enhancer for drug penetration

In this study, the influence of the melting point and HLB (hydrophile-lipophile balance) value of Gelucire® -based formulations on the permeation of model drugs, including prostaglandin E₁ (PGE₁) and its alkyl esters, through the skin barrier was examined. Seven formulations consisting of three grades of Gelucire (44/14, 50/02, and 37/02) at different ratios with the addition of lauroglycol at a fixed ratio of 4: 1 to a total Gelucire amount were prepared with model drugs at a concentration of 0.1 mg/mg. For (PGE₁), the maximal flux at this concentration was about 35.95 nmole/cm² per h and occurred at the HLB value of 6.6; the melting point ranged from 49 to 54 °C. For the methyl ester of PGE₁, the maximal flux appeared to be 76.62 nmole/cm₂ per h and occurred at the HLB value of 5.3; the melting point ranged from 46 to 50 °C. For the ethyl ester of PGE₁, the maximal flux was around 33.45 nmole/cm² per h and occurred at the HLB value of 5.3; the melting point ranged from 46 to 50 °C. The maximal flux was 15.46 nmol/cm² per h for the isopropyl ester of PGE₁ and appeared at the HLB of 5.3; the melting point ranged from 46 to 50 °C. The maximal flux of the butyl ester of PGE₁ was around 13.67 nmol/cm² per h and occurred at the HLB value of 6.6; the melting point ranged from 41 to 48 °C. The promotion of penetration for PGE₁ and its alkyl esters seemed to be maximized with different Gelucire systems. Results also demonstrate that a higher melting point and a lower HLB value of Gelucire 50/02 resulted in a decreased permeation rate of PGE₁ alkyl esters. But the tendency for Gelucire 50/02 and 37/02 to promote the penetration of PGE₁ alkyl esters was similar, and the extent of the influence decreased with increased alkyl chain length. This is possibly explained by the fact that Gelucire 50/02 and 37/02 have the same HLB value. Similarly, the influence on drug flux of the HLB value of the Gelucire system was more profound than that of the melting point in this study.