Natural fibre-reinforced polymer composites are increasingly replacing commercial composite materials. The limitations of conventional composites materials are overcome by green composites, which are easily available, more eco-friendly and less toxic. In the current scenario, green composites are emerging in the field of material science that involves improving their physical, mechanical and thermal properties. The poor interfacial adhesion and surface incompatibility between natural fibre and biodegradable polymers lead to reduced physico-mechanical properties. In order to overcome this issue, physical and chemical modification methodologies of the natural fibre and polymer matrix are employed, among which the addition of coupling agents has a critical contribution. This paper compiles several recent research works in the utilization of coupling agents such as silane, maleic anhydride, isocyanate, triazine, etc., with the various combinations of natural fibres and polymers. In addition to this, the extents of influence of coupling agents on the characteristics of the natural fibre reinforced composite materials are also reported. This gives an overview for the future researchers to identify the gap in the field of green composite materials and novel coupling agents for different natural fibre/polymer matrix combination.
Objective: The present investigation was based on the design and evaluation of floating tablets of Pedalium murex and Tribulus terrestris fruit extracts as the medicinal source and the excipients that can enhance the bioactivity and prolong the gastric retention time.
Methods:The fruit extracts were prepared from the powdered dry fruits of Pedalium murex and Tribulus terrestris using Soxhelt apparatus for 8 h. direct compression technique was used for the formulation of polyherbal floating effervescence tablets which consists of different compositions of Hydroxy Propyl Methyl Cellulose (HPMC K4M, HPMC K15M), Micro Crystalline Cellulose (MCC) and Sodium bicarbonate (NaHCO3). The formulations were evaluated for thickness, hardness, friability, average weight variation, drug content, floating lag time, duration of floating and in vitro drug release. The data obtained from the in vitro dissolution studies were fitted in different models.Results: All the tablets were satisfactory during the preformulation studies while F11 polyherbal formulation showed the maximum floating time of 15 h, minimum floatation lag time of 35 s and drug release of 100.12%. The dissolution kinetic studies for the optimum formulation was found to follow Korsemeyer and Peppas model with R 2 value, rate constant KK and n as 0.9819, 1.0492 and 1.7385 respectively with a significance of P<0.05 and showed better results compared to that of film coated herbal tablets.
Conclusion:Thus this polyherbal floating effervescence tablets can be used not only as an effective drug release method for herbal drugs to enhance their bioactivity but also as a replacement for film coated herbal tablets.
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