Pharmaceutical Considerations of Microemulsion as a Drug Delivery System

Microemulsions were recognized after the work of Hoar and Schulman in 1943, which revealed the use of strong surface-active agent leading to spontaneous emulsification; however, it was in 1959 when Schulman first used the term “microemulsion” for such emulsion system. Microemulsions are optically transparent, thermodynamically stable colloidal systems, 10–100 nm diameters that form spontaneously upon mixing of oil, water, and emulsifier. After its discovery in 1943 to till date, more than 1200 publications have been reported and development of O/W type of microemulsions has been the priority for the researchers, mostly using non-ionic surfactants. Although microemulsions seem to be one of the most promising candidates in pharmaceuticals because of relative ease in the formulation and distinct characteristics when compared to other dispersion systems, its commercial success as a drug delivery system has been very little. Much of the time after its discovery has been exhausted in failure to understand correct formulation requisites or confusing it with other similar systems. In the face of increasing the number of publication year after year, its formulation has been generally based on trial-and-error. Efficient strategies for excipient selection and detailed understanding of microstructures contributing to its formulation is still required which may serve as the foundation for attaining greater success in this field. Keywords: Microemulsion, Surfactants. Spontaneous emulsification, Solubilization

DEVELOPMENT OF MICROEMULSION FORMULATION FOR ORAL DELIVERY OF ROSUVASTATIN CALCIUM

The purpose of conducting this study was to prepare an oral microemulsion formulation of Rosuvastatin calcium (RC) to improve its water solubility. Oil in water microemulsion was formulated using Oleic acid, Tween 80 and Polyethylene Glycol-400(PEG-400) as oil, surfactant and co-surfactant, respectively. The ideal proportion of surfactant: co-surfactant (Smix) was chosen by constructing pseudoternary diagrams. The microemulsion formulations which proved to be stable after thermodynamic stability testing were further evaluated for physical characteristics. Selected formulations were evaluated for droplet size, zeta potential, polydispersity index, viscosity and % drug content. The results were suggestive that optimized microemulsion formulation (F2) was thermodynamically stable and clear having a droplet size of 74.29 nm and zeta potential of -18.44.  In vitro dissolution study for optimized microemulsion was performed using a dialysis bag method and cumulative % drug release was determined. The result from the release study was indicative of improved solubility of Rosuvastatin calcium which may serve to boost up the oral bioavailability of drug.</jats:p

Cyanobacterial pigments as natural anti-hyperglycemic agents: An in vitro study

Traditional medicines for controlling postprandial hyperglycemia includes herbs and plant extracts as well as synthetic drugs like acarbose. Synthetic drug molecules frequently have side effects such as flatulence and diarrhea. Cyanobacterial pigments have excellent anti-oxidant and free radical scavenging properties. Thus, α-amylase and α-glucosidase inhibiting activities of purified pigments and crude extracts from three cyanobacterial species, Lyngbya, Microcoleus and Synechocystis sp., were investigated. Lyngbya extract had the highest total anti-oxidant activity (TAC) before digestion (48.26 ± 0.04 µg AAE ml-1) while purified lycopene had the highest TAC after digestion (154.16 ± 0.96 µg AAE ml-1). The Microcoleus extract had the highest ABTS scavenging activity before digestion (98.23 ± 0.25 %) while purified C-phycocyanin (C-PC) had the highest ABTS scavenging after digestion (99.69 ±0.04 %). None of the digested or undigested extracts performed better than acarbose in inhibiting α-amylase but the digested Microcoleus extract was able to inhibit its activity by ~35 %. The purified pigments gave inhibitory activities ranging from ~ 8 – 16 %. The Lyngbya extract had the highest inhibitory activity against α-glucosidase both before and after digestion (62.22 ± 0.02 and 97.82 ± 0.03 % respectively). Purified C-phycoerythrin (C-PE), C-PC, lycopene and myxoxanthophyll could inhibit α-glucosidase in a range of ~83 – 96 %. Considering the potent inhibitory activities of purified pigments against both α-amylase and α-glucosidase, cyanobacterial pigments could be used as food additives for their dual advantage of anti-oxidant and anti-hyperglycemic activities

Antioxidant, Anti-Nephrolithe Activities and in Vitro Digestibility Studies of Three Different Cyanobacterial Pigment Extracts

Phycobiliprotein-containing water and carotenoid-containing methanolic extracts of three different cyanobacteria, Pseudanabaena sp., Spirulina sp. and Lyngbya sp., were studied for their DPPH scavenging, iso-bolographic studies, and anti-nephrolithe activities. The best EC50 values for DPPH scavenging were in Lyngbya water (LW, 18.78 ± 1.57 mg·mg−1 DPPH) and Lyngbya methanol (LM, 59.56 ± 37.38 mg·mg−1 DPPH) extracts. Iso-bolographic analysis revealed most of the combinations of extracts were antagonistic to each other, although LM—Spirulina methanol (SM) 1:1 had the highest synergistic rate of 86.65%. In vitro digestion studies showed that DPPH scavenging activity was considerably decreased in all extracts except for Pseudanabaena methanol (PM) and LM after the simulated digestion. All of the extracts were effective in reducing the calcium oxalate crystal size by nearly 60%–65% compared to negative control, while PM and Spirulina water (SW) extracts could inhibit both nucleation and aggregation of calcium oxalate by nearly 60%–80%

Letrozole Versus Clomiphene Citrate for Superovulation in Intrauterine Insemination Cycles - Retrospective Comparative Study Conducted in the Department of Reproductive Medicine, Mahatma Gandhi Medical College &amp; Hospital, Jaipur

BACKGROUND Superovulation with intrauterine insemination (IUI) increases the probability of pregnancy by increasing number of oocytes and sperm density. The main oral agents used for superovulation are clomiphene citrate and letrozole. Clomiphene citrate a selective estrogen receptor modulator with predominant antiestrogenic action has adverse effects on endometrium and cervical mucous. Letrozole an aromatase inhibitor acts by reducing estrogen production by blocking androgen conversion to estrogen in ovary and peripheral tissues without affecting endometrium and cervical mucous. We wanted to compare the efficacy of letrozole v/s clomiphene citrate as first line ovulation induction drug in infertile patients undergoing IUI. METHODS Based on the inclusion and exclusion criteria, we included 160 patients in our study. They were divided into two groups of 80 each based on the drug given for ovulation induction. The drug was given for 5 days from D3 to D7 of menstrual cycle. IUI was done 38 - 40 hours after trigger and after confirmation of ovulation by sonography. RESULTS The mean age, body mass index (BMI), duration of infertility, type and cause of infertility in both groups were similar. Ovulation rate was 85 % in letrozole group and 71.25 % in clomiphene citrate group, which was statistically significant (P0.035). There was no statistically significant difference between endometrial thickness and total days till ovulation between two groups. Monofolliculogenesis and clinical pregnancy rate were statistically significantly higher in letrozole group. CONCLUSIONS Our study shows that letrozole has better pregnancy rate in comparison to clomiphene citrate (C. C.) in IUI cycles with less risk of anovulation, thin endometrium and multi follicular growth. KEY WORDS Clomiphene Citrate (C.C.), Letrozole (LTZ), Ovulation Induction (OI), Intrauterine Insemination (IUI)</jats:p