https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:56774 Wed 26 Oct 2022 10:32:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:56775 Wed 26 Oct 2022 10:14:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:56776 Wed 21 Sep 2022 19:37:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:50038 Wed 20 Apr 2022 08:42:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45283 Wed 16 Mar 2022 15:50:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28087 Wed 15 Mar 2023 09:37:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45420 Tue 25 Apr 2023 08:55:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:69914 Tue 21 Nov 2023 20:30:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:69913 Tue 21 Nov 2023 20:15:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:49973 Tue 19 Jul 2022 07:43:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27444 Tue 13 Jun 2023 11:29:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20633 Tue 10 Aug 2021 12:31:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28697 Thu 20 Apr 2023 10:03:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3766 Thu 13 May 2021 15:43:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3857 Thu 13 May 2021 13:27:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3733 Thu 13 May 2021 12:37:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3872 Thu 13 May 2021 12:09:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3769 Thu 13 May 2021 10:28:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3760 Thu 13 May 2021 09:28:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3784 Thu 13 May 2021 09:24:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26599 0.999 were obtained for each assessment of linearity and FTC, TNF and EFV are linear in the range 0.4-40 μg/ml, 0.6-60 μg/ml and 1.2-120 μg/ml. The equation of the best-fit least squares regression lines for FTC, TNF and EFV were y = 0.0191x+0.0007, y = 0.0163x+0.0116 and y = 0.01x+0.016, respectively. The method is accurate as the y-intercept was < 2% of the detector response for all ARV, and the method is precise in terms of intra- and inter-assay precision as all % RSD < 2%. The stability-indicating nature of the method was demonstrated under acidic, alkaline and oxidative stress in addition to UV exposure and elevated temperatures, and the individual chromatograms were overlaid using Empower® 3 Software to establish whether there was interference with the peaks of interest. The forced degradation studies demonstrated the selectivity of the method for the ARV compounds. The method was applied to assay and in vitro dissolution studies of commercially available tablets. The amount of each active ingredient released from Atripla® was determined and compared to the amount of each drug released from Aspen Efavirenz® and Truvada® (a combination of FTC and TNF). The percent FTC released from Atripla® and Truvada® was similar based on the acceptance criteria for immediate-release BCS class 1 compounds. Statistical analysis was undertaken to compare the dissolution profiles of FTC, TNF and EFV. The percent of these compounds released in these studies indicate that bioequivalence testing would be required to declare these products interchangeable. The validated RP-HPLC and in vitro dissolution test method are suitable for routine quality control testing of solid oral dosage forms containing EFV, FTC and TNF, and as the dissolution method can discriminate between different formulations of the same molecule, these tools can also be used for analysis during formulation development studies. The method is not suitable for the analysis of the ARV plasma due to lack of sensitivity and an inability to quantitate the compounds at the required concentration levels. The use of HPLC with mass spectroscopy for quantitation would enhance the sensitivity of the method and may eliminate the quantitation of the molecules in the presence of interference that was observed when using UV detection. Fixed dose combination tablets are convenient for patient therapy and it is likely that in the future more molecules will be formulated into such dosage forms. However formulations such as these can pose significant difficulties when developing and using analytical methods for the quantitation of all compounds in the dosage form at the same time, in particular when the compounds have vastly different physico-chemical properties that impact the quality of a separation and therefore the analysis. Therefore when embarking on the development of FDC product cognisance of the difficulties of developing single methods for the analyses is required and approaches to overcome these difficulties should be considered.]]> Thu 13 May 2021 08:54:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3807 Thu 13 May 2021 08:45:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3845 Thu 13 May 2021 08:22:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3820 Thu 13 May 2021 08:21:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3776 Thu 13 May 2021 08:08:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3818 Thu 13 May 2021 08:08:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3728 Thu 13 May 2021 07:31:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3843 Thu 13 May 2021 07:24:56 SAST ]]> 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https://vital.seals.ac.za/vital/access/manager/Repository/vital:28421 85 % isoniazid released at 24 h, implying that the majority of encapsulated isoniazid would be available for absorption. The manufacturing process resulted in the production of hard spherical particles and particle size analysis revealed that the microspheres ranged between 415.76 ± 76.93 μm and 903.35 ± 197.10 μm in diameter. The microspheres exhibited excellent flow properties attributed to the spherical nature of particles. Carr‟s index (CI) was 4.934 ± 0.775 % and the Hausner ratio (HR) was 1.148 ± 0.033 indicating good packability of the microspheres that would help in achieving weight and content uniformity of capsule dosage units. The manufacturing process however produced a low % yield suggesting that scale up difficulties may be encountered. However the high encapsulation efficiency observed may counter the challenges associated with the low yield. The DSC thermograms and FT Raman spectra of 1:1 mixtures of isoniazid, excipients and the microspheres did not reveal any potential detrimental interactions. Microporous floating sustained release microspheres for the delivery of rifampicin in the stomach have been successfully manufactured using emulsification and a diffusion/evaporation process. A novel approach using solvent mixture of acetone and dichloromethane that has not been reported for the manufacture of rifampicin microspheres was successfully used and resulted in the formation of a stable emulsion and the manufacture of rifampicin-loaded microspheres with uniform characteristics. In addition the manufacturing process was shorter than most other reported methods. A Box-Behnken experimental design was successfully used to study the influence of ethylcellulose, Eudragit® RLPO and d-glucose content on the floating properties, encapsulation efficiency and % yield of microspheres. The optimised formulation did not yield desired floating characteristics as the % buoyancy was low and floating lag times were high. The optimised formulation was modified by addition of NaHCO3 to increase the % buoyancy and reduce the floating lag time. Rifampicin release from the microspheres of the modified batch was 87.10 % at 12 h and the microspheres exhibited a % buoyancy of 87.66 ± 1.28 % (n = 6) and floating lag time of 15 ± 3.2 (n = 6) seconds. The microspheres remained buoyant for up to 12 h and an encapsulation efficiency of 88.26 ± 1.25 % was achieved. SEM images of microspheres following exposure to dissolution fluid revealed that the microspheres had numerous pores on their surface. The mean particle size distribution ranged between 423.19 ± 121.86 μm to 620.07 ± 102.67 μm. The microspheres exhibited similar flow characteristics to isoniazid microspheres with a CI of 1.422 ± 0.074 %, and HR of 1.034 ± 0.002. The excellent flow characteristics indicate that filling of the microspheres into hard gelatin capsules was unlikely to pose a challenge in respect of producing a product with uniform content. Rifampicin-excipient compatibility studies did not reveal any potential or significant interactions suggesting that the excipients used for the manufacture of the microspheres were compatible, although long term stability studies would be required to ascertain this is, indeed the case. The microporous floating sustained release microspheres manufactured in these studies has the potential to increase the bioavailability of rifampicin as they may be retained in the stomach where the solubility of rifampicin is high and from which absorption is best achieved. The degradation of rifampicin after 12 h dissolution testing in pH 1.2 0.1 M HCl in the presence of isoniazid gastric-resistant sustained release microspheres was only 4.44%. These results indicate that the degradation of rifampicin in the presence of isoniazid in acidic media can be overcome by encapsulation of both active pharmaceutical ingredients in a manner that ensure release in different segments of the gastrointestinal tract. The use of sustained release microporous gastroretentive rifampicin microspheres in combination with sustained release isoniazid gastric-resistant microspheres revealed that accelerated degradation of rifampicin in the presence of isoniazid is reduced significantly when using this approach and a FDC of rifampicin and isoniazid microspheres has the potential to improve the bioavailability of rifampicin thereby enhancing therapeutic outcomes. In vivo studies would be required to confirm the potential benefits of using this approach to deliver rifampicin in combination with isoniazid.]]> Mon 13 Mar 2023 11:57:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:56777 Fri 30 Sep 2022 10:25:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35677 Fri 08 Dec 2023 06:04:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27447 Fri 06 Aug 2021 10:31:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3726 Fri 06 Aug 2021 10:17:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42109 80%. The formulation composition identified was subsequently used for the optimization of the manufacturing parameters viz. sonication time and amplitude, using a Central Composite Design (CCD) . The LC and EE, in vitro CLA release, cytotoxicity, osmolarity, pH, degree of crystallinity and lipid modification, elemental analysis and surface morphology of the optimized batch was investigated and mon itored to ensure that CLA - loaded NLC, of the desirable quality, had been produced. On the day of manufacture the mean PS and PDI of the optimized CLA - loaded NLC formulation adjusted to physiological osmolarity (250 – 450 mOsm/kg) was 461.9 ± 40.16 nm and 0. 523 ± 0.104, respectively. The ZP for the optimized NLC generated on the day of manufacture using HPLC grade water as the dispersion medium was - 20.5 ± 4.82 mV. The pH and osmolarity of the optimized CLA - loaded NLC formulation was 7.76 ± 0.01 and 316 ± iii 2 m Osm/Kg, respectively and the EE was 88.62 ± 0.23 %. The optimized NLC exhibited a decreased crystallinity in comparison to the bulk lipid materials. DSC, WAXS and FT - IR revealed that CLA was molecularly dispersed in the nanocarriers. The optimized CLA - load ed NLC exhibited muco - adhesive properties, when tested under stationary conditions using laser doppler anemometry (LDA). The optimized formulation also exhibited sustained release of CLA over 24 hours during in vitro release testing and CLA release was bes t described using the Baker - Lonsdale model . The cumulative % CLA released over 24 hours was 56.13 ± 0.23% and mass balance analysis revealed 41.38 ± 0.02% CLA had been retained in the NLC. In vitro cytotoxicity testing revealed that the optimized CLA - NLC w ere less cytotoxic to HeLa cells when compared to CLA alone and further confirmed that the lipids and excipients used in these studies were of GRAS status . Stability studies revealed that the EE reduced over 28 days by 14.42% and 5.14% when stored at 4 °C and 22 °C , respectively. In addition, the particle size increased from the nm to μm range for samples stored at 22 °C. The findings are a good starting point but require further optimization to ensure prolongation of stability. In addition , the technology requires additional developmental studies and a powder for reconstitution for use as a single - dose considered as single dose packaging may be a solution to the compromised formulation stability observed in these studies. The CLA - NLC produced in these stu dies exhibit sound product attributes which serve as a useful foundation for the novel delivery of antibiotics to the eye. The results suggest that the optimized NLC have the potential to enhance precorneal retention and increase ocular availability of CLA , which in turn may be useful to reduce the required dose and dosing frequency when administering CLA as a reconstituted solution to treat susceptible organisms that infect ocular tissues.]]> Fri 06 Aug 2021 09:14:42 SAST ]]>