K N Singh

Development of self-microemulsifying drug delivery system and solid-self-microemulsifying drug delivery system of telmisartan

Objective: Self-microemulsifying drug delivery system (SMEDDS) and solid-SMEDDS of telmisartan was aimed at overcoming the problems of poor solubility and bioavailability. Methodology: The formulation strategy included selection of oil phase based on saturated solubility studies and surfactant and co-surfactant screening on the basis of their emulsification ability. Ternary phase diagrams were constructed to identify the self-emulsifying region using a dilution method. The prepared formulations of SMEDDS were evaluated for their drug content, loading efficiency, morphology, globule size determination. Solid-SMEDDS were prepared by adsorption technique using microcrystalline cellulose (1% w/w) and were evaluated for micromeritic properties, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction. Results: The formulation containing telmisartan (20 mg), castor oil (30% w/w), tween 20 (55% w/w), propylene glycol (15% w/w) was concluded to be optimized. The optimized SMEDDS and solid-SMEDDS exhibited 100% in vitro drug release up to 120 min, which was significantly higher (P < 0.05, t-test) than that of the pure drug. Solid-SMEDDS may be considered as a better solid dosage form as solidified formulations are more ideal than liquid ones in terms of its stability. Conclusion: These results suggest the potential use of SMEDDS and solid-SMEDDS to improve the dissolution and hence oral bioavailability of poorly water-soluble drugs like telmisartan through oral route.

Regeneration Pattern of Tree Species in Forested Landscapes of Himachal Pradesh, Western Himalayan Region, India

The present work was conducted to assess the regeneration pattern of dominant tree species in the forested landscapes of Himachal Pradesh, India. The study was conducted in four agro-climatic zones viz., zone I, zone II, zone III and zone IV, of the state at 58 locations during 2002–2007. Stratified random quadrat sampling was employed to estimate regeneration pattern of tree species by classifying them into seedling, sapling and adult stages. The analysis of data was carried out using MS excel while it was spatially represented in Geographic Information System environment. The regeneration pattern was divided in to four classes namely good, fair, poor and no regeneration. A total of 23 forest landscape elements (LSEs) dominated by 18 tree species were observed at the surveyed localities. These tree species are representative of the western Himalayan ecosystem. The number of seedlings, saplings and adults ranged from 0 to 2,700/ha, 0 to 1,500/ha, and 20 to 1,470/ha, respectively in different LSEs. Picea smithiana was observed to posses highest number of seedlings (2,700/ha) and saplings (1,500/ha) in zone IV and zone III, respectively. Cedrus deodara, on the other hand, had the maximum number of adults (1,470/ha) in its pure patch in Shimla in zone III. The results showed that amongst the four agro-climatic zones, the zone I in general had a trend of poor to no regeneration while other zones generally had fair regeneration. Zone I and zone II had poor, fair and no regeneration pattern. The trees in zone III and zone IV had good regeneration pattern in addition to poor, fair and no regeneration. Based on the results of present study, it is suggested that efficient measures are needed to conserve and to increase the tree regeneration growth in zone I of the state, whereas special efforts should be made to maintain the luxuriant forest status in rest of the agro-climatic zones of Himachal Pradesh.