Extraction of Nicotine from Tobacco Leaves and Development of Fast Dissolving Nicotine Extract Film.

Nicotine (NCT), administered in the form of a fast dissolving oral delivery system, can be a potential alternative to nicotine replacement therapy. NCT was extracted by maceration and acid-base extraction methods from Burley tobacco leaves with different stalk positions and extraction yield and NCT content were further determined. The extract with the highest nicotine content was selected for incorporation into a fast dissolving film formulation. The optimized film was evaluated for its physical and mechanical properties, in vitro disintegration, and drug release profile. The results demonstrated that the extract from the upper part of tobacco leaves using the acid-base extraction method had the highest amount of NCT. NCT fast dissolving film consisting of this extract as the active ingredient and HPMC E15 as a film polymer resulted in a homogeneous translucent film with a light brown color. The addition of NCT significantly affected the film properties in terms of weight, disintegration time, tensile strength, percentage elongation at break, and Young's modulus values. The drug release of NCT fast dissolving film showed a rapid initial release of 80% within three minutes, and its kinetics followed the Higuchi matrix model. The results suggest that these NCT films can be employed in the development of NCT fast dissolving films for clinical use.

Stability and Influence of Storage Conditions on Nanofibrous Film Containing Tooth Whitening Agent.

Carbamide peroxide (CP), a tooth whitening agent, is chemically unstable. The present study explores stability enhancement of CP by loading in a nanofibrous film (CP-F) composed of polyvinyl alcohol/polyvinylpyrrolidone/silica mixture, using an electrospinning technique. Kept at a temperature range of 60-80 °C for 6 h, CP in CP-F showed significantly higher stability than that in a polymer solution and in water, respectively. Degradation of CP in CP-F could be described by the first order kinetics with the predicted half-life by the Arrhenius equation of approximately 6.52 years. Physicochemical properties of CP-F after long-term storage for 12 months at different temperatures and relative humidity (RH) were investigated using scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. It was found that high temperature and high humidity (45 °C/75% RH) could enhance water absorption and destruction of the nanofibrous structure of CP-F. Interestingly, kept at 25 °C/30% RH, the nanofibrous structure of CP-F was not damaged, and exhibited no water absorption. Moreover, the remaining CP, the mechanical properties, and the adhesive properties of CP-F were not significantly changed in this storage condition. It is concluded that the developed CP-F and a suitable storage condition can significantly improve CP stability.

Development of Controlled-Release Carbamide Peroxide Loaded Nanoemulgel for Tooth Bleaching: In Vitro and Ex Vivo Studies.

Burst release of carbamide peroxide (CP) from traditional hydrogels causes severe inflammation to periodontal tissues. The present study explores the development of a novel CP nanoemulgel (CP-NG), an oil-in-water nanoemulsion-based gel in which CP was loaded with a view to controlling CP release. CP solid dispersions were prepared, using white soft paraffin or polyvinylpyrrolidone-white soft paraffin mixture as a carrier, prior to formulating nanoemulsions. It was found that carrier type and the ratio of CP to carrier affected drug crystallinity. Nanoemulsions formulated from the optimized CP solid dispersions were used to prepare CP-NG. It was found that the ratio of drug to carrier in CP solid dispersions affected the particle size and zeta potential of the nanoemulsions as well as drug release behavior and tooth bleaching efficacy of CP-NG. Drug release from CP-NG followed a first-order kinetic reaction and the release mechanism was an anomalous transport. Drug release rate decreased with an increase in solid dispersion carriers. CP-NG obtained from the solid dispersion with a 1:1 ratio of CP to the polymer mixture is suitable for sustaining drug release with high tooth bleaching efficacy and without reduction of enamel microhardness. The developed CP-NG is a promising potential tooth bleaching formulation.

Enhancing Stability and Tooth Bleaching Activity of Carbamide Peroxide by Electrospun Nanofibrous Film.

Carbamide peroxide (CP) possesses a strong tooth bleaching activity, however, its clinical application is limited because of its instability in aqueous formulations. This study explores the improvement of CP stability and bleaching activity by loading CP in electrospun nanofibrous film (ENF). Polyvinylalcohol, polyvinylpyrrolidone, and silica were used as components for core-based nanofibers of ENF. Electrospinning feed aqueous solutions (EFASs) were developed for preparing CP loaded ENF (CP-ENF). Stability of CP in EFASs is significantly higher than in pure water. The highest stability of CP is found in PPS-CP3, composed of 0.5% CP, 5.5% polyvinylalcohol, 3% polyvinylpyrrolidone, and 1% silica. The results from X-ray diffraction indicate that CP is dispersed as a non-crystalline form in CP-ENFs. CP and the compositions of EFASs play a major role on characteristics and bleaching efficiency of CP-ENFs. Drug release of CP-ENFs is the first order kinetics. CP-ENF obtained from PPS-CP3 shows the highest drug entrapment efficiency, high adhesion, and suitable sustained release. Drug release mechanism is along with anomalous transport according to Korsmeyer-Peppas model. In an ex vivo study using human teeth, it shows the highest bleaching efficiency among the others. Therefore, CP-ENF obtained from PPS-CP3 is a promising ENF for clinical use.

Preparation and characterization of rice gels containing tooth bleaching agent.

In the present study, the modified white rice of Jasmine (JM) and Saohai (SH) were used to prepare the rice gels. Carbamide peroxide (CP) containing rice gels (CP rice gels) of JM (CP-JM) and SH (CP-SH) were prepared. The rice gels and CP rice gels show homogenous texture. Rice variety influences the characteristics and properties of the rice gels. Amylose content of JM was lower than SH. Rheological behavior of JM and CP-JM was pseudoplastic without thixotropy whereas that of SH and CP-SH was pseudoplastic with thixotropy. CP-SH showed higher adhesive property and viscosity than CP-JM whereas CP-JM showed faster in vitro drug release than CP-SH. For ex vivo efficacy evaluation, 55 normal human teeth were subjected to the CP rice gels. Samples were applied on tooth surface according to the dental bleaching techniques. For at-home bleaching technique, the CP rice gels with 10% and 20% CP were used with bleaching time of 8h and 4h, respectively. For in-office bleaching technique, the CP rice gels with 35% CP was used with bleaching time of 1 h. The developed CP rice gels showed significantly higher efficacy than the positive and negative controls. For at-home bleaching technique, CP-SH was the most effective gels whereas for in-office bleaching technique, CP-JM was the most effective gels.

Effect of rice variety and modification on antioxidant and anti-inflammatory activities.

The effects of variety and modification of rice on its antioxidant and anti-inflammatory activities were investigated. White rice varieties; Jasmine (JM) and Saohai (SH), and pigmented rice varieties; Doisket (DS) and Homnil (HN) were used. The modified rice samples were obtained from chemical modification using etherification reaction. The activities of the modified rice samples were compared with the ethanol extracts of the raw rice at the same rice concentration. Antioxidant activity was measured by the free radical scavenging activity tests and ferric reducing power assay. Results indicated that the ethanol extracts of raw rice had higher antioxidant activity than the modified rice. Among the raw rice tested, the pigmented rice showed higher antioxidant activity than white rice. Trolox equivalent antioxidant capacity values from free radical scavenging activity test were revealed that 50% ethanol extracts of HN and DS possessed the highest antioxidant activity. Ferric reducing power assay showed that 50% ethanol extracts of DS had the highest antioxidant activity. The anti-inflammatory activity was evaluated in vitro using a lipopolysaccharide-stimulated RAW264.7 macrophage cell model with enzyme-linked immunosorbent assay. Absolute ethanol extracts of HN reduced interleukin-6 secretion whereas that of DS suppressed interleukin-6 and tumor necrosis factor -α secretion. These results indicate that variety of rice, chemical modification, and extracting solvent were the factors that play an important role on antioxidant and anti-inflammatory activity. This study supports the potential use of the pigmented rice, especially DS, as a promising choice of a natural source because of its antioxidant and anti-inflammatory activities.

Tooth whitening efficacy of pigmented rice gels containing carbamide peroxide.

Carbamide peroxide (CP) is commonly used as a tooth whitening agent. However, efficacy of CP can be enhanced if it is in the suitable delivery system. In the present study, CP loaded in pigmented rice gels were developed and investigated for their physicochemical properties and tooth whitening efficacy. The modified pigmented rice of two varieties, Homnil (HN) and Doisket (DS) were prepared and used as a gelling agent. The outer appearance of the obtained rice gels containing 10% CP (CP-HN and CP-DS, respectively) were transparent and homogeneous texture. The pH of both rice gel bases was neutral but became slightly acidic after incorporating with CP. The adhesive property of HN gel was significantly higher than DS gels. In vitro drug release profile exhibited that the release of CP from CP-DS was significantly higher than CP-HN and the commercial gel (CP-CG), respectively. In vitro tooth whitening efficacy in 45 normal teeth revealed that the tooth whitening efficacy of the gels was time dependent. At the end of the treatment, CP-HN showed significantly higher tooth whitening efficacy than CP-DS and CP-CG, respectively. It is concluded that the physicochemical properties, particularly the adhesive and dissolution properties, play an important role in the tooth whitening efficacy of the CP gels.

Effect of rice variety on the physicochemical properties of the modified rice powders and their derived mucoadhesive gels.

In the present study; the glutinous Niaw Sanpatong (NSP) and Niaw Koko-6 (NKK), and the non-glutinous Jasmine (JM) and Saohai (SH) were chemically modified. The difference of these rice varieties on the physicochemical characteristics of the modified rice powders and the properties of the derived gels were evaluated. X-ray diffractometer was used for crystalline structure investigation of the rice powders and gels. A parallel plate rheometer was used to measure the rheological property of the gels. It was found that the non-glutinous varieties produced gels with higher mucoadhesive properties than the glutinous rice. Rheological behavior of JM and SH gels was pseudoplastic without yield value whereas that of NSP and NKK gels was plastic with the yield values of 1077.4 ± 185.9 and 536.1 ± 45.8 millipascals-second (mPas), respectively. These different properties are considered to be due to the amylose content in different rice variety. The results suggest that the non-glutinous rice varieties with high amylose content are the most suitable for preparing gels as local delivery systems via the mucosal membrane.

Preparation and characterization of lidocaine rice gel for oral application.

The objective of the present study was to prepare buccal anesthetic gels using rice as gelling agent. Rice grains of four rice varieties, Jasmine (JM), Saohai (SH), Homnil (HN), and Doisket (DS) were chemically modified. Buccal rice gels, containing lidocaine hydrochloride as local anesthetic drug were formulated using the respective modified rice varieties. The gels were evaluated for outer appearance, pH, color, gel strength, foaming property, adhesion, in vitro drug release and in vivo efficacy. It was found that the developed rice gels possessed good texture. Rice varieties showed influence on gel strength, color, turbidity, adhesive property, release property, and anesthetic efficacy. JM gel showed the lowest turbidity with light transmission of 86.76 ± 1.18% whereas SH gel showed the highest gel strength of 208.78 ± 10.42 g/cm(2). Lidocaine hydrochloride can cause a decrease in pH and adhesive property but an increase in turbidity of the gels. In vitro drug release profile within 60 min of lidocaine SH gel and lidocaine HN gel showed that lidocaine could be better released from SH gel. Evaluation of in vivo anesthetic efficacy in 100 normal volunteers indicates that both lidocaine rice gels have high efficacy but different levels. Lidocaine SH gel possesses faster onset of duration and longer duration of action than lidocaine HN gel.