No abstract

No abstract

Orally disintegrating systems have carved a niche amongst the oral drug delivery systems due to the highest component of compliance they enjoy in patients especially the geriatrics and pediatrics. In addition, patients suffering from dysphagia, motion sickness, repeated emesis and mental disorders prefer these medications because they cannot swallow large quantity of water. Further, drugs exhibiting satisfactory absorption from the oral mucosa or intended for immediate pharmacological action can be advantageously formulated in these dosage forms. However, the requirements of formulating these dosage forms with mechanical strength sufficient to with stand the rigors of handling and capable of disintegrating within a few seconds on contact with saliva are inextricable. Therefore, research in developing orally disintegrating systems has been aimed at investigating different excipients as well as techniques to meet these challenges. A variety of dosage forms like tablets, films, wafers, chewing gums, microparticles, nanoparticles etc. have been developed for enhancing the performance attributes in the orally disintegrating systems. Advancements in the technology arena for manufacturing these systems include the use of freeze drying, cotton candy, melt extrusion, sublimation, direct compression besides the classical wet granulation processes. Taste masking of active ingredients becomes essential in these systems because the drug is entirely released in the mouth. Fluid bed coating, agglomeration, pelletization and infusion methods have proven useful for this purpose. It is important to note that although, freeze dried and effervescent disintegrating systems rapidly disintegrate in contact with fluids, they do not generally exhibit the required mechanical strength. Similarly, the candy process cannot be used for thermolabile drugs. In the light of the paradoxical nature of the attributes desired in orally disintegrating systems (high mechanical strength and rapid disintegration), it becomes essential to study the innovations in this field and understand the intricacies of the different processes used for manufacturing these systems. This article attempts at discussing the patents relating to orally disintegrating systems with respect to the use of different formulation ingredients and technologies.

No abstract

Stratum corneum (SC) is comprised of lipids, protein and low molecular weight water-soluble components. Changes in these skin micro constituents can be understood by instrumental methods like differential scanning calorimetry (DSC) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The former provides information about changes in thermotropic behavior of SC lipids and proteins, whereas the latter provides data about alterations at molecular and conformational level. Most of the DSC thermograms of intact mammalian SC show two reversible and two irreversible transitions in the temperature range of 25-125 degrees C. The reversible endotherms are ascribed to lipid melting transitions, whereas the irreversible endotherms are ascribed to protein denaturation. Similarly, the FTIR spectral bands of SC occurring between 2920-2850 cm-1 and between 1650-1550 cm-1 have been suggested to arise from lipid and protein molecular vibrations, respectively. Treatment of skin with solvents or permeation enhancers alters the composition of lipids or their molecular arrangement in the skin microenvironment, which leads to changes in permeability of drug molecules. Furthermore, inhibition of lipid synthesis in epidermis with concomitant decrease in enthalpy of lipid endothermic transitions and reduction in height and area of asymmetric and symmetric C-H stretching peaks have been found to be directly correlated with enhanced permeation of drugs. In addition, method of skin preparation, type of skin, types of enhancer etc. also influence both the nature and intensity of responses recorded in spectrographs and thermograms. Therefore, the modification in spectrographs and thermograms of skin samples treated with various enhancers, vehicles etc. are expected to provide better insight into their mechanism of action on the skin. This review article shall critically evaluate the thermotropic and infrared spectroscopic data of SC/epidermis after various treatments.