Lipids and Surfactants: The Inside Story of Lipid-Based Drug Delivery Systems.

In the bioavailability enhancement of poorly aqueous soluble drugs, self-emulsifying/microemulsifying drug delivery systems (SEDDS/SMEDDS) are isotropic mixtures of oils, surfactants, solvents, and cosolvents/surfactants that have gained immense popularity because of their self-emulsification ability. This characteristic relies on some critical parameters such as surfactant concentration, oil-to-surfactant ratio, polarity of the emulsion, droplet size and charge, which are acquired from an amalgamation of appropriate excipients. The fabrication of this combination is of utmost importance for formulation scientists. Hence, to explore the potential of such a delivery system, standardized guidelines for excipients must be developed to address bioavailability issues. In the present review, we summarize the approaches to selecting the most suitable lipid(s)-based drug delivery system, including characterization, especially for oral delivery, of both physicochemical and biopharmaceutical aspects and properties of assorted excipients as well as the related patent reports.

Granulated colloidal silicon dioxide-based self-microemulsifying tablets, as a versatile approach in enhancement of solubility and therapeutic potential of anti-diabetic agent: formulation design and in vitro/in vivo evaluation.

The current research work was executed with an aim to explore and promote the potential of self-microemusifying drug delivery systems (SMEDDS) in the form of tablets, in order to enhance solubility and oral bioavailability of poorly aqueous soluble drug Repaglinide (RPG). RPG-loaded liquid SMEDDS were developed consisting Labrafil M 1944CS, Kolliphor EL and Propylene glycol, which were then characterized on various parameters. After characterization and optimization, liquid SMEDDS were converted into solid form by adsorbing on Aeroperl® 300 pharma and polyplasdoneTM XL. Further, selection of suitable excipients was done and mixed with prepared solidified SMEDDS powder followed by the preparation of self-microemulsifying tablets (SMET's) wet granulation-compression method. SMET's were subjected to differential scanning calorimetry (DSC) and particle X-ray diffraction (RXRD) studies, results of which indicated transformation of crystalline structure of RPG because of dispersion of RPG at molecular level in liquid SMEDDS. This was further assured by micrographs obtained from scanning electron microscope. SMET's shown more than 85% (30 min) of in vitro drug release in contrast to conventional marketed tablets (13.2%) and pure RPG drug (3.2%). Results of in vivo studies furnished that SMET's had shown marked decrease in the blood glucose level and prolonged duration of action (up to 8 h) in comparison with conventional marketed tablets and pure RPG drug. In conclusion, SMET's serves as a promising tool for successful oral delivery of poorly aqueous soluble drug(s) such as RPG.

In-vitro and in-vivo evaluation of repaglinide loaded floating microspheres prepared from different viscosity grades of HPMC polymer.

During the study repaglinide encapsulated floating microspheres were formulated and characterized for enhancing residence time of drug in git and thereby increasing its bioavailability. Floating microspheres of ethylcellulose (EC) and hydroxypropyl methyl cellulose (HPMC) (5 and 100 cps) were prepared by emulsion solvent diffusion technique. During process optimization various parameters were studied such as: drug: polymer ratio, polymer ratio, concentration of emulsifier and stirring speed. Selected optimized formulations were studied for SEM, entrapment, floating behavior, drug release and kinetics. In-vivo floating ability (X-ray) study and in-vivo antidiabetic activity were performed on alloxan induced diabetic rats. Microspheres prepared with different viscosity grade HPMC were spherical shaped with smooth surface. Size of microspheres was in the range of 181.1-248 µm. Good entrapment and buoyancy were observed for 12 h. X-ray image showed that optimized formulation remained buoyant for more than 6 h. Optimized formulation treated group shows significant (p < 0.01) reduction in blood glucose level as compared to pure drug treated group. Repaglinide loaded floating microspheres expected to give new choice for safe, economical and increased bioavailable formulation for effective management of NIDDM.

Antidiabetic potential of polysaccharides from the white oyster culinary-medicinal mushroom Pleurotus florida (higher Basidiomycetes).

This study was designed to examine the antihyperglycemic potential of the polysaccharide fraction of Pleurotus florida. Hyperglycemia was induced by streptozotocin (50 mg/kg intraperitoneal). Single- and multiple-dose studies were performed to assess the antihyperglycemic potential of the P. florida polysaccharides (PFPs). Organisation for Economic Co-operation and Development guideline 423 was followed to study the acute toxicity of PFP. PFP was found to be nontoxic up to 4000 mg/kg. In this investigation, 200- and 400-mg/kg doses of PFP were used. Blood glucose, serum cholesterol, triglycerides, urine glucose and ketones, and glycosylated hemoglobin were estimated, and biological markers were determined. Treatment with PFP (200 and 400 mg/kg) significantly lowered glucose concentrations compared to the control group. Serum cholesterol, triglycerides, and urine glucose and ketones in animals treated with PFP also decreased. There was a significant decrease in the concentrations of malondialdehyde and nitric oxide, whereas concentrations of superoxide dismutase, catalase, and reduced glutathione were restored. Therefore, these results suggest that PFPs may ameliorate hyperglycemia and hypercholesteremia associated with diabetes. Thus PFPs could be used as adjunct therapy along with first-line therapy in type 2 diabetes mellitus.

Pharmacognostical standardization and antidiabetic activity of Syzygium cumini (Linn.) barks (Myrtaceae) on streptozotocin-induced diabetic rats.

BACKGROUND: The objectives of the present study were phytochemical and pharmacological screening of bark of Syzygium cumini on streptozotocin (STZ)-induced diabetic Wistar albino rats. METHODS: Dose selection was made on the basis of acute oral toxicity study (300-5,000 mg/kg b.w.) as per OECD guidelines. Rats were made diabetic by a single dose of STZ at 50 mg/kg b.w. intraperitoneally. The effect of Syzygium cumini extracts (500 mg/kg) on postprandial blood glucose level was determined in fasted diabetic and normal rats. Blood glucose levels were measured at 0, 30, and 90 min after the glucose administration in the OGTT study. The bark extracts were administered orally at the dose of 500 mg/kg for 21 days in the chronic study. Glibenclamide (2.5 mg/kg) was used as a standard drug for activity comparison. Statistical analyses were performed using one-way ANOVA followed by Bonferroni's multiple comparison tests. RESULTS: The phytochemical screening showed positive results for triterpenes/steroids, glycosides, carbohydrates, alkaloids, flavonoids, saponins, tannins and amino acids. Administration of Syzygium cumini extracts 30 min before oral glucose loading significantly suppressed (p<0.001) the rise in postprandial blood glucose levels in treated rats compared to control rats but less significant than glibenclamide. Daily, continuous oral treatment of STZ-induced diabetic with various extract of Syzygium cumini for 3 weeks resulted in significant reductions in fasting blood glucose levels compared with diabetic controls. The ethanol and aqueous extracts were most active. CONCLUSIONS: This study brings out the evidence regarding phytochemistry and pharmacological activities of Syzygium cumini.