DESIGN AND EVALUATION OF INTRAGASTRIC BUOYANT TABLETS OF VENLAFAXINE HYDROCHLORIDE

Objective: The present study was undertaken to prolong the release of orally administered drug. The aim is to formulate, develop, and evaluate theintragastric buoyant tablets of venlafaxine hydrochloride, which releases the drug in a sustained manner over a period of 12 hrs. Different formulationswere formulated using the polymers Carbopol 934 P, xanthan gum, hydroxypropyl methylcellulose (HPMC K100M) with varying concentration ofdrug: Polymer ratio of 1:1, 1:1.5, 1:2, in which sodium bicarbonate acts as gas generating agent, and microcrystalline cellulose as a diluent.Methods: The tablets were prepared by direct compression and evaluated for tablet thickness, weight variation, tablet hardness, friability, in vitrobuoyancy test, in vitro drug release and Fourier transform infrared spectroscopy. Formulations were evaluated by floating time, floating lag time and in vitro drug release. Dissolution profiles were subjected for various kinetic treatments to analyze the release pattern of drug.Results: It was found that drug release depends on swelling, erosion, and diffusion, thus following the non-Fickian/anomalous type of diffusion.Formulation F8 was considered as an optimized formulation for gastro retentive floating tablet of venlafaxine hydrochloride. The optimizedformulation showed sustained drug release and remained buoyant on the surface of the medium for more than 12 hrs. As the concentration of HPMCK100M increases in the formulation the drug release rate was found to be decreased. The optimized formulation was subjected for the stability studiesand was found to be stable as no significant change was observed in various evaluated parameters of the formulation.Conclusion: It can be concluded that floating drug delivery system of venlafaxine hydrochloride can be successfully formulated as an approach toincrease gastric residence time, thereby improving its bioavailability. Â

Testing the optimal defence hypothesis for two indirect defences: extrafloral nectar and volatile organic compounds

Many plants respond to herbivory with an increased production of extrafloral nectar (EFN) and/or volatile organic compounds (VOCs) to attract predatory arthropods as an indirect defensive strategy. In this study, we tested whether these two indirect defences fit the optimal defence hypothesis (ODH), which predicts the within-plant allocation of anti-herbivore defences according to trade-offs between growth and defence. Using jasmonic acid-induced plants of Phaseolus lunatus and Ricinus communis, we tested whether the within-plant distribution pattern of these two indirect defences reflects the fitness value of the respective plant parts. Furthermore, we quantified photosynthetic rates and followed the within-plant transport of assimilates with 13C labelling experiments. EFN secretion and VOC emission were highest in younger leaves. Moreover, the photosynthetic rate increased with leaf age, and pulse-labelling experiments suggested transport of carbon to younger leaves. Our results demonstrate that the ODH can explain the within-plant allocation pattern of both indirect defences studied

Mouth cancer: presentation, detection and referral in primary dental care

Mouth cancer can present as a variety of abnormalities and visible changes affecting the oral mucosa, including ulceration, swelling and areas of erythema. The five-year survival from mouth cancer is poor at approximately 50%. Detection of the cancer while less than 2 cm in diameter with no metastasis greatly improves the outcome for the patient. Although many cancers in the mouth develop from what was previously an apparently normal mucosa, some arise in pre-existing conditions that are therefore regarded as potentially malignant. Regular assessment of the soft tissues within the mouth and the neck for the presence of abnormalities is an essential component of primary dental care. Any persistent and unexplained abnormality requires referral for definitive diagnosis and specialist management