Investigation of In vitro Release Kinetics of Carbamazepine from Eudragit® RS PO and RL PO Matrix Tablets

Purpose: The objective of this research work was to prepare and evaluate the effect of Eudragit RS PO and Eudragit RL PO polymers on the physical property and release characteristics of carbamazepine matrix tablets.Methods: Matrix tablets containing carbamazepine were prepared with Eudragit® RS PO alone as the rate-retarding polymer (coded batch series ‘A’) and also with a combination of Eudragit® RS PO and RL PO (coded batch series ‘B’). The tablets were characterized for hardness as well as for carbamazepine release. The release data were subjected to differentmodels in order to evaluate their release kinetics and mechanisms.Results: The hardness of batch series ‘A’ matrix tablet was >160 kg/cm2 while for batch series ‘B’, it was >170 kg/cm2. Carbamazepine tablets containing only Eudragit RS PO showed very slow release (less than 6% in 8 h) but when Eudragit RL PO was blended with Eudragit RS PO, the release rate improved significantly to 44% in 24 h (p < 0.05). Drug release mechanism was a complex mixture of diffusion and erosion.Conclusion: Carbamazepine matrix tablets of satisfactory hardness were produced. Furthermore, by blending Eudragit RS PO with Eudragit RL PO in the matrix, tablets of varying release characteristics can be prepared

Phytochemical Screening and In vitro Evaluation of Pharmacological Activities of Aphanamixis polystachya (Wall) Parker Fruit Extracts

Purpose: To investigate the crude n-hexane, ethyl acetate and methanol extracts of Aphanamixis polystachya fruit for their cytotoxic, antimicrobial, antioxidant and thrombolytic activities.Methods: The fruit extracts were screened for major phytochemical compounds using in vitro established procedures. Antimicrobial and cytotoxic studies of the fruit extracts were conducted using disc diffusion and brine shrimp lethality bioassay methods, respectively, while an in vitro thrombolytic model was used to assess the clot lysis effect of the extracts with streptokinase as positive control. Antioxidant activity was evaluated by free radical scavenging activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide assay as well as total phenolic content.Results: The fruit extracts were a rich source of phytochemicals and among the extracts n-hexane extract showed highest antimicrobial activity against Shigella dysenteriae (zone of inhibition: 9.7±0.2 mm) and Candida albicans (zone of inhibition: 8.8±0.3 mm) at a concentration of 1000ìg/disc, whereas at the same concentration methanol extract showed highest zone of inhibition, 10.1±0.4mm, against Staphylococcus aureus. Compared to potassium permanganate with a median lethal concentration(LC50) of 13.23 ìg/ml in the brine shrimp lethality assay, the LC50 of n-hexane, ethyl acetate and methanol extracts were 15.77, 17.51 and 141.37 ìg/ml, respectively. All the extracts showed significant clot lysis activity (p &lt; 0.001) with reference to negative control and % clot lysis of the extracts were approximately 13. Notable antioxidant activity of the methanol extract was observed unlike the other extracts.Conclusion: The results of the study demonstrated the potential cytotoxic, thrombolytic and antioxidant activities of the fruit extracts of A.  polystachya and therefore further studies on the isolation and identification of active principles are required.Keywords: Aphanamixis polystachya, Antimicrobial, Antioxidant, Cytotoxic, Thrombolytic, Phytochemical screenin