Vamshi Krishna Tippavajhala

In Vivo Human Skin Penetration Study of Sunscreens by Confocal Raman Spectroscopy

This research work mainly deals with the application of confocal Raman spectroscopic technique to study in vivo human skin penetration of sunscreen products, as there are a lot of controversies associated with their skin penetration. Healthy human volunteers were tested for penetration of two commercial sunscreen products into their volar forearm skin for a period of 2xa0h. Measurements were taken before and after application of these sunscreen products. All the confocal Raman spectra were pre-processed and then subjected to multivariate two-dimensional principal component analysis and classical least squares analysis to determine the skin penetration of these sunscreens in comparison to the “sunscreen product spectrum” which was considered as the control. Score plots of principal component analysis of confocal Raman spectra indicated clear separation between the spectra before and after application of sunscreen products. Loading plots showed the maximum differences in the spectral region from 1590 to 1626xa0cm−1 where the characteristic peak of the pure sunscreen products was observed. Classical least squares analysis has shown a significant penetration to a depth of 10xa0μm in the volar forearm skin of healthy human volunteers for both these sunscreen products. The results confirm that the penetration of these tested sunscreen products was restricted to stratum corneum and also prove that confocal Raman spectroscopy is a simple, fast, nondestructive, and noninvasive semi-quantitative analytical technique for these studies.

In vivo study of dermal collagen of striae distensae by confocal Raman spectroscopy

This research work mainly deals with studying qualitatively the changes in the dermal collagen of two forms of striae distensae (SD) namely striae rubrae (SR) and striae albae (SA) when compared to normal skin (NS) using confocal Raman spectroscopy. The methodology includes an in vivo human skin study for the comparison of confocal Raman spectra of dermis region of SR, SA, and NS by supervised multivariate analysis using partial least squares discriminant analysis (PLS-DA) to determine qualitatively the changes in dermal collagen. These groups are further analyzed for the extent of hydration of dermal collagen by studying the changes in the water content bound to it. PLS-DA score plot showed good separation of the confocal Raman spectra of dermis region into SR, SA, and NS data groups. Further analysis using loading plot and S-plot indicated the participation of various components of dermal collagen in the separation of these groups. Bound water content analysis showed that the extent of hydration of collagen is more in SD when compared to NS. Based on the results obtained, this study confirms the active involvement of dermal collagen in the formation of SD. It also emphasizes the need to study quantitatively the role of these various biochemical changes in the dermal collagen responsible for the variance between SR, SA, and NS.

Statistical strategies to reveal potential vibrational markers for in vivo analysis by confocal Raman spectroscopy.

Abstract. The analysis of biological systems by spectroscopic techniques involves the evaluation of hundreds to thousands of variables. Hence, different statistical approaches are used to elucidate regions that discriminate classes of samples and to propose new vibrational markers for explaining various phenomena like disease monitoring, mechanisms of action of drugs, food, and so on. However, the technical statistics are not always widely discussed in applied sciences. In this context, this work presents a detailed discussion including the various steps necessary for proper statistical analysis. It includes univariate parametric and nonparametric tests, as well as multivariate unsupervised and supervised approaches. The main objective of this study is to promote proper understanding of the application of various statistical tools in these spectroscopic methods used for the analysis of biological samples. The discussion of these methods is performed on a set of in vivo confocal Raman spectra of human skin analysis that aims to identify skin aging markers. In the Appendix, a complete routine of data analysis is executed in a free software that can be used by the scientific community involved in these studies.

A Review on In Situ gel forming ophthalmic drug delivery systems

Nowadays ophthalmic route of administration of drugs is rapidly progressing and more studies are going on in formulating ophthalmic drug delivery systems. There are many conventional dosage forms available in the market like ointments, eye drops etc. The main drawback with these types of formulations is rapid drainage of the instilled dose due to the lacrimal fluid secretions and blinking of the eye lids. In order to minimize this drainage and to increase the ocular residence time and corneal contact time, in situ gel forming formulations are developed. In these systems sol to gel transformation takes place due to the environmental changes like pH, temperature, ionic strength. Some polymers like sodium alginate, HPMC are frequently used to initiate these processes. These formulations can be assessed for viscosity, clarity, gel strength, gelling capacity, gelling time, texture, isotonicity, sterility, ocular irritancy, anti-microbial efficacy, in vitro drug release, ex vivo release, in vivo absorption, in vivo retention and stability.

Hot-Melt Extrusion Technology in the Emerging Pharma Field

After the plastic industry, now in Pharmaceutical industry hot melt extrusion (HME) technology has emerged and has made its way for the easy development of the pharmaceutical products due to its severe advantages like free of solvents, faster processing technology, operation in simple and continuous process, and high degree of automation, are few among them over to the other conventional methods. Day by day the interest on HME technology has been increasing due to its promising approach towards the drug delivery systems. The gradual increase in the patents of HME technology will enlighten us the need of it in this field of medicines. This article mainly reviews the general design and construction of hot melt extruder along with the advantages, disadvantages and applications of the HME.

Comparative study of transdermal drug delivery systems of resveratrol: High efficiency of deformable liposomes

Trans-resveratrol (3, 5, 4 trihydroxystilbene, RSV) is a natural compound that shows antioxidant, cardioprotective, anti-inflammatory and anticancer properties. The transdermal, painless application of RSV is an attractive option to other administration routes owing to its several advantages like avoiding gastrointestinal problems and first pass metabolism. However, its therapeutic potential is limited by its low solubility and low stability in water and the reduced permeability of stratum corneum. To overcome these inconveniences the encapsulation of this compound in a drug delivery system is proposed here. In order to find the best carrier for transdermal application of RSV various liposomal nanoparticulate carriers like conventional liposomes (L-RSV), deformable liposomes (LD-RSV), ultradeformable liposomes (LUD-RSV) and ethosomes (Etho-RSV) were assayed. Transmission electron microscopic (TEM) and dynamic light scattering (DLS) studies were performed to analyze the surface morphology of these carriers. Structural characterization for these formulations was performed by confocal Raman spectroscopy. The spectroscopic results were analysed in conjunction with calorimetric data to identify the conformational changes and stability of formulations in the different nanoparticles induced by the presence of RSV. Comparison of the results obtained with the different carrier systems (L-RSV, LD-RSV, LUD-RSV and Etho-RSV) revealed that the best RSV carrier was LD-RSV. The increase in the fluidity of the bilayers in the region of the hydrophobic chains of the phospholipid by ethanol probably facilitates the accommodation of the RSV in the bilayer and contributes to the improved encapsulation of RSV without affecting the mobility of this carrier.

In Vivo Determination of Moisturizers Efficacy on Human Skin Hydration by Confocal Raman Spectroscopy

This research work deals with in vivo testing of the efficacy of commercial moisturizer products on the hydration of human skin, as there are various in vitro and ex vivo studies questioning their activity. Confocal Raman spectroscopy was used for this purpose of assessing the efficacy of moisturizers on skin hydration mainly owing to its simple, non-invasive, non-destructive, timesaving, and cost-effective nature. Water content and natural moisturizing factor (NMF) of stratum corneum were analyzed and compared using this method at high wavenumber (2500–4000xa0cm−1) and fingerprint (400–1800xa0cm−1) spectral regions, respectively, as these two parameters are correlated to skin hydration. Four commercial moisturizer products of different brands were tested on volar forearm region of healthy human female volunteers. This study was conducted for a period of 30xa0days with 0, 7, and 30xa0days as time points of analysis. The results of this study clearly indicate that not all the moisturizer products hydrate the skin to the expected levels, and this extent of skin hydration varies with duration of application of these products.

A review on the polymers for vegetarian soft gel capsule films

Soft capsules are a single piece, unit dosage forms containing hermetically sealed soft gelatin shell encapsulating a fill material which is mainly a solution, suspension or semisolid. Soft gel capsules are effective in the delivery of low dose drugs and easily degradable drugs due to the presence of a protective gelatin shell. However the use of gelatin as the shell material has certain demerits like it leads to the spread of bovine spongiform encephalopathy (BSE, Mad Cow disease) and is not preferred by people belonging to certain religious groups or those who have dietary restrictions. In this context, this review article details the various polymers obtained from vegetarian sources that can act as alternatives for the gelatin and succeed in dealing with the disadvantages of gelatin.