Self-microemulsifying drug delivery system

A self-microemulsifying drug delivery system (SMEDDS) is a drug delivery system that uses a microemulsion achieved by chemical rather than mechanical means. That is, by an intrinsic property of the drug formulation, rather than by special mixing and handling. It employs the familiar ouzo effect displayed by anethole in many anise-flavored liquors. Microemulsions have significant potential for use in drug delivery, and SMEDDS (including so-called "U-type" microemulsions) are the best of these systems identified to date.[1] SMEDDS are of particular value in increasing the absorption of lipophilic drugs taken by mouth.

SMEDDS in research or development include formulations of the drugs anethole trithione,[2] oridonin,[3][4][5] curcumin,[6] vinpocetine,[7][8] tacrolimus,[9][10][11] berberine hydrochloride,[12] nobiletin,[13] piroxicam,[14][15] anti-malaria drugs beta-Artemether[16] and halofantrine,[17][18] anti-HIV drug UC 781,[19][20] nimodipine,[21][22] exemestane,[23] anti-cancer drugs 9-nitrocamptothecin (9-NC)[24] paclitaxel,[25][26] and seocalcitol,[27][28] alprostadil (intraurethral use),[29] probucol,[18][30] itraconazole,[31] fenofibrate,[32] acyclovir,[33] simvastatin,[34][35] xibornol,[36] silymarin,[37][38] alpha-asarone,[39] enilconazole,[19] puerarin (an isoflavone found in Pueraria lobata),[40][41][42][43] atorvastatin,[44][45][46] heparin,[47] carvedilol,[48] ketoconazole,[49] gentamicin,[50] labrasol,[51] flurbiprofen,[52] celecoxib,[53] danazol,[54] cyclosporine,[55] and idebenone.[56]

SMEDDS offer numerous advantages: spontaneous formation, ease of manufacture, thermodynamic stability, and improved solubilization of bioactive materials.[1] Improved solubility contributes to faster release rates and greater bioavailability. For many drugs taken by mouth, faster release rates improve the drug acceptance by consumers. Greater bioavailability means that less drug need be used; this may lower cost, and does lower the stomach irritation and toxicity of drugs taken by mouth.

For oral use, SMEDDS may be formulated as liquids or solids, the solids packaged in capsules or tablets. Limited studies comparing these report that in terms of bioavailability liquid SMEDDS are superior to solid SMEDDS,[21] which are superior to conventional tablets.[42][47][21] Liquid SMEDDS have also shown value in injectable (IV and urethral) formulations and in a topical (oral) spray.[36]

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