Self-microemulsifying drug delivery systems
Self-microemulsifying drug delivery systems and microemulsions used to enhance the solubility of pharmaceutical ingredients comprising a polyoxyethylene sorbitan fatty acid ester emulsifier; a fatty acid ester co-emulsifier and an oil.
1. A self-microemulsifying drug delivery system consisting of:
(i) a polyoxyethylene sorbitan fatty acid ester emulsifier;
(ii) a co-emulsifier selected from glyceryl mono- or di-fatty acid esters of C 6 -C 18 fatty acids; and
(iii) an oil, selected from C 6 -C 12 fatty acid triglycerides;
wherein the polyoxyethylene sorbitan fatty acid ester emulsifier (i) and co-emulsifier (ii) are present in a ratio by weight of between 1:1 and 4:1 and
the emulsifier and co-emulsifier, (i)+(ii), and oil (iii) are present in a ratio by weight of between 4:1 and 10 000:1; and wherein said drug delivery system is stable on addition of any amount of water.
2. A self-microemulsifying drug delivery system according to claim 1 , wherein the emulsifier (i) is a polysorbate.
3. The self-microemulsifying drug delivery system of claim 2 , wherein the polysorbate is Polysorbate 80.
4. A self-microemulsifying drug delivery system according to claim 1 , wherein the ratios are selected from the group of ratios consisting of:
the polyoxyethylene sorbitan fatty acid ester emulsifier (i) and co-emulsifier (ii) are present in a ratio by weight of about 1:1, about 2:1, about 2.5:1, about 3:1, about 3.5:1 and about 4:1;
the ratio by weight of emulsifier and co-emulsifier, (i)+(ii), to oil (iii), is in the range selected from the group consisting of about 4:1 to 1000:1, about 4:1 to 100:1, and about 5:1 to 40:1; and
the ratio of coemulsifier (ii) to oil (iii) is selected from the group consisting of at least 1.5:1, at least 2:1, and at least 3:1.
5. A self-microemulsifying drug delivery system according to claim 1 , wherein the polyoxyethylene sorbitan fatty acid ester emulsifier (i) and co-emulsifier (ii) are present in a ratio by weight of between 2.5:1 and 3.5:1.
6. A self-microemulsifying drug delivery system according to claim 1 , wherein the co-emulsifier is selected from glyceryl mono- or di-fatty acid esters of C 6 -C 12 fatty acids.
7. The self-microemulsifying drug delivery system according to claim 6 , wherein the co-emulsifier is glyceryl caprylate.
8. A self-microemulsifying drug delivery system according to claim 1 , wherein the oil is a caprylic or a capric triglyceride oil.