STABILITAS DAN TRANSPOR MELEWATI MEMBRAN IMPREGNASI ISOPROPIL MIRISTAT SEDIAAN MIKROEMULSI ASKORBIL PALMITAT

Bambang Hernawan Nugroho, Prof. Dr. Suwaldi, M.Sc., Apt

2013 | Tesis | S2 Ilmu Farmasi

Vitamin C memiliki beberapa turunan, antara lain berupa askorbil palmitat yang memiliki kepolaran yang rendah, salah satu kendala dalam membuat sediaan vitamin C topikal adalah rendahnya stabilitas dan penetrasi ke dalam kulit. Mikroemulsi memiliki keunggulan antara lain mempunyai kestabilan yang baik, serta dapat meningkatkan penetrasi obat ke dalam kulit. Penelitian ini bertujuan mengetahui kestabilan mikroemulsi askorbil palmitat dan kemampuan askorbil palmitat dalam mikroemulsi melewati membran impregnasi isopropil miristat. Mikroemulsi askorbil palmitat dibuat dengan tehnik low energy, dilakukan verifikasi metode analisa dan uji stabilitas fisik meliputi visikositas, sifat alir, pemisahan fase dan homogenitasnya. Uji stabilitas kimia dilakukan dengan prosedur uji hidrolisis (0,1 N HCl, air dan 0,1 N NaOH) dan oksidasi (H2O2 3%). Penetapan kadar askorbil palmitat pada kondisi penyimpanan suhu 25°C dan 40°C dengan metode HPLC. Uji pelepasan dan transpor askorbil palmitat menggunakan sel difusi tipe Franz dengan media reseptor metanol dan dapar fosfat (pH 6.5) (50%:50%) Hasil stabilitas fisik dari mikroemulsi mengalami perubahan warna dan homogenitas. Stabilitas kimia menunjukan askorbil palmitat mengalami degradasi secara hidrolisis dan dilanjutkan dengan degradasi secara oksidasi. Bedasarkan parameter t1/2 dan t90 askorbil palmitat dalam mikroemulsi memiliki nilai lebih tinggi dibandingkan dalam dapar fosfat pH 5,4. Askorbil palmitat mampu melewati membran impregnasi, koefisien difusi dan koefisien permeabilitas memiliki nilai yang lebih rendah dibandingkan dengan tanpa impregnasi.

Ascorbyl palmitate is a derivative of ascorbic acid which has a more lipophilic than ascorbic acid. Ascorbic acid as a hydrophilic compound, in topical formulation has low penetration through the skin. Ascorbyl palmitate has better penetration through the skin than that of ascorbic acid. Problem of ascorbic acid and its derivatives have a low stability in topical formulation. Microemulsion may increase stability of drugs and have better penetration through the skin. The objective of this research was to evaluate stability and penetration of ascorbyl palmitate in microemulsion through the isopropyl miristate impregnated membrane. Ascorbyl palmitate microemulsion was made by low energy process. Verification of analytical method was done. Physical stability of microemulsion was examined for viscosity, phase separation and homogeneity. Stress testing was also performed to the drug for hydrolisis (0.1 N HCl, water and 0.1 N NaOH) and oxidation (3% H2O2). A degradation of ascorbyl palmitate in a microemulsion that stored at temperature of 25°C and of 40°C was examined by using HPLC method. The release and transport of ascorbyl palmitate in a microemulsion was carried out using Franz cell diffusion type with methanol and phosphate buffer (pH 6.5) (50%:50%) as receptor media. Ascorbyl palmitate microemulsion changed in colour, viscosity and pH values during storage at temperature of 25°C and of 40°C. The stability of microemulsion, ascorbyl palmitate underwent degradation by route of hydrolysis at first and then followed by oxidation. Based on t1/2 and t90, chemical stability of ascorbyl palmitate increased in microemulsion formulation, better than in phosphate buffer (pH 5.4). Ascorbyl palmitate in microemulsion could diffuse through impregnated membrane, the diffusion coefficient and permeability had values which were lower than in non impregnated membrane.

Kata Kunci : askorbil palmitat, mikroemulsi, stabilitas, difusi