A self-microemulsifying drug delivery system (SMEDDS) is a drug delivery

Drug delivery

Drug delivery is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals. Drug delivery technologies modify drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy and safety, as well...

 system that uses a microemulsion

Microemulsion

Microemulsions are clear, thermodynamically stable, isotropic liquid mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. The aqueous phase may contain salt and/or other ingredients, and the "oil" may actually be a complex mixture of different hydrocarbons and olefins...

 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

Ouzo effect

The ouzo effect is a phenomenon observed when water is added to ouzo and other anise-flavored liqueurs and spirits, such as pastis, raki, arak and absinthe, forming a milky oil-in-water microemulsion...

 displayed by anethole

Anethole

Anethole is a phenylpropene, a type of aromatic compound that occurs widely in nature, in essential oils...

 in many anise

Anise

Anise , Pimpinella anisum, also called aniseed, is a flowering plant in the family Apiaceae native to the eastern Mediterranean region and Southwest Asia. Its flavor resembles that of liquorice, fennel, and tarragon.- Biology :...

-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. 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

Anethole trithione

Anethole trithione, anetholtrithione, or anetholtrithion is a drug used in the treatment of dry mouth. It is listed in the U.S...

, oridonin, curcumin

Curcumin

Curcumin is the principal curcuminoid of the popular Indian spice turmeric, which is a member of the ginger family . The other two curcuminoids are desmethoxycurcumin and bis-desmethoxycurcumin. The curcuminoids are natural phenols and are responsible for the yellow color of turmeric...

, vinpocetine

Vinpocetine

Vinpocetine is a semisynthetic derivative alkaloid of vincamine , an extract from the periwinkle plant....

, tacrolimus

Tacrolimus

Tacrolimus is an immunosuppressive drug that is mainly used after allogeneic organ transplant to reduce the activity of the patient's immune system and so lower the risk of organ rejection...

, berberine

Berberine

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis Berberine is a quaternary...

 hydrochloride

Hydrochloride

In chemistry, hydrochlorides are salts resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base . This is also known as muriate, derived from hydrochloric acid's other name: muriatic acid....

, nobiletin

Nobiletin

Nobiletin is a chemical compound. It is an O-methylated flavone, a flavonoid isolated from citrus peels like in tangerine.-External links:* , phytochemicals.info...

, piroxicam

Piroxicam

Piroxicam is a non-steroidal anti-inflammatory drug of the oxicam class used to relieve the symptoms of rheumatoid and osteoarthritis, primary dysmenorrhoea, postoperative pain; and act as an analgesic, especially where there is an inflammatory component...

, anti-malaria

Malaria

Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

 drugs beta-Artemether and halofantrine

Halofantrine

Halofantrine is a drug used to treat malaria. Halofantrine's structure contains a substituted phenanthrene, and is related to the antimalarial drugs quinine and lumefantrine. Marketed as Halfan, halofantrine is never used to prevent malaria and its mode of action is unknown...

, anti-HIV

HIV

Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 drug UC 781, nimodipine

Nimodipine

Nimodipine is a dihydropyridine calcium channel blocker originally developed for the treatment of high blood pressure...

, exemestane

Exemestane

Exemestane is a drug used to treat breast cancer. It is a member of the class of drugs known as aromatase inhibitors. Some breast cancers require estrogen to grow. Those cancers have estrogen receptors , and are called ER-positive. They may also be called estrogen-responsive,...

, anti-cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

 drugs 9-nitrocamptothecin (9-NC) paclitaxel

Paclitaxel

Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. It was discovered in a U.S. National Cancer Institute program at the Research Triangle Institute in 1967 when Monroe E. Wall and Mansukh C. Wani isolated it from the bark of the Pacific yew tree, Taxus brevifolia and named it taxol...

, and seocalcitol, alprostadil

Alprostadil

Prostaglandin E1 , known pharmaceutically as alprostadil, is a prostaglandin. It is a drug used in the treatment of erectile dysfunction and has vasodilatory properties.-Sexual dysfunction:...

 (intraurethral

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

 use), probucol

Probucol

Probucol is an anti-hyperlipidemic drug initially developed in the treatment of coronary artery disease.However, clinical trials were stopped after it was found that may lower HDL in patients with a previous history of heart disease....

, itraconazole

Itraconazole

Itraconazole , invented in 1984, is a triazole antifungal agent that is prescribed to patients with fungal infections. The drug may be given orally or intravenously.-Medical uses:...

, fenofibrate

Fenofibrate

Fenofibrate is a drug of the fibrate class. Fenofibrate was developed by Groupe Fournier SA, before it was acquired in 2005 by Solvay Pharmaceutical, a business unit owned by the Belgian corporation, Solvay S.A. In 2009 Solvay Pharmaceutical was acquired by Abbott Laboratories. It is mainly used to...

, acyclovir, simvastatin

Simvastatin

Simvastatin is a hypolipidemic drug used to control elevated cholesterol, or hypercholesterolemia. Simvastatin is a member of the statin class of pharmaceuticals, is a synthetic derivate of a fermentation product of Aspergillus terreus.-Medical uses:The primary uses of simvastatin is for the...

, xibornol

Xibornol

Xibornol is an antibiotic.It is primarily administered to the throat.Xibornol is a lipophilic drug mainly used in Italy and Spain in spray dosage forms for the local treatment of infection and inflammation of the throat...

, silymarin, alpha-asarone

Asarone

Asarone, which includes alpha and beta types, is an ether found in certain plants such as acorus and asarum. As a volatile fragrance oil, it is used in killing plant fungal pests and bacteria...

, enilconazole

Enilconazole

Enilconazole is a fungicide widely used in agriculture, particularly in the growing of citrus fruits...

, puerarin

Puerarin

Puerarin is one of several known isoflavones. Puerarin is found in a number of plants and herbs like the root of Pueraria notably of the kudzu plant.Puerarin is the 8-C-glucoside of daidzein....

 (an isoflavone

Isoflavone

Isoflavones comprise a class of organic compounds, often naturally occurring, related to the isoflavonoids. Many act as phytoestrogens in mammals...

 found in Pueraria lobata), atorvastatin

Atorvastatin

Atorvastatin , sold by Pfizer under the trade name Lipitor, is a member of the drug class known as statins, used for lowering blood cholesterol. It also stabilizes plaque and prevents strokes through anti-inflammatory and other mechanisms...

, heparin

Heparin

Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...

, carvedilol

Carvedilol

Carvedilol is a non-selective beta blocker/alpha-1 blocker indicated in the treatment of mild to moderate congestive heart failure . It is marketed under various trade names including Carvil , Coreg , Dilatrend , Eucardic , and Carloc as a generic drug ., and as a...

, ketoconazole

Ketoconazole

Ketoconazole is a synthetic antifungal drug used to prevent and treat fungal skin infections, especially in immunocompromised patients such as those with AIDS or those on chemotherapy. Ketoconazole is sold commercially as an anti-dandruff shampoo, topical cream, and oral tablet.Ketoconazole is...

, gentamicin

Gentamicin

Gentamicin is an aminoglycoside antibiotic, used to treat many types of bacterial infections, particularly those caused by Gram-negative organisms. However, gentamicin is not used for Neisseria gonorrhoeae, Neisseria meningitidis or Legionella pneumophila...

, labrasol, flurbiprofen

Flurbiprofen

Flurbiprofen is a member of the phenylalkanoic acid derivative family of non-steroidal anti-inflammatory drugs used to treat the inflammation and pain of arthritis...

, celecoxib

Celecoxib

Celecoxib INN is a sulfa non-steroidal anti-inflammatory drug and selective COX-2 inhibitor used in the treatment of osteoarthritis, rheumatoid arthritis, acute pain, painful menstruation and menstrual symptoms, and to reduce numbers of colon and rectum polyps in patients with familial...

, danazol

Danazol

Danazol is a derivative of the synthetic steroid ethisterone, a modified testosterone. Also known as 17alpha-ethinyl testosterone. Before becoming available as a generic drug, Danazol was marketed as Danocrine in the United States. It was approved by the U.S. Food and Drug Administration as the...

, cyclosporine, and idebenone

Idebenone

Idebenone is an experimental drug, initially developed by Takeda Pharmaceutical Company for the treatment of Alzheimer's disease and other cognitive defects. This has been met with limited success. The Swiss company Santhera Pharmaceuticals has started to investigate it for the treatment of...

.

Self-microemulsifying drug delivery system (SMEDDS) offer numerous advantages: spontaneous formation, ease of manufacture, thermodynamic stability, and improved solubilization of bioactive materials. 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, which are superior to conventional tablets. Liquid SMEDDS have also shown value in injectable (IV and urethral) formulations and in a topical (oral) spray.