Investigating the suitability of hibiscus sabdariffa calyx extract as colouring agent for paediatric syrups

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Effects of temperature, light and pH on formulated paediatric syrups: - Paracetamol, Chloroquine phosphate, Diphenhydramine and Paediatric cough linctus, using Hibiscus sabdariffa calyx extract as colouring agent, were investigated. Paediatric syrups formulated with amaranth as colouring agent, and used as a standard in the experiments, had comparable stabilities with Hibiscus sabdarffa at room temperature and at 370C Stabilities of the paediatric syrups on exposure to light showed that syrups. Chloroquine phosphate and Diphenhydramine were stable, whether coloured with amaranth or with Hibiscus sabdariffa calyx extract. Syrups Paracetamol and Paediatric Cough Linctus were unstable on exposure to light, hence the need to protect from light by use of amber bottles. pH stability for syrups coloured with Hibiscus sabdariffa extract was poor compared with those coloured with amaranth. Formulations buffered at pH 5.0 showed marked stability over the four month test period. Microbiological tests performed on Hibiscus sabdariffa calyx extract proved to have antimicrobial properties, but very little anti-fungal action. Methanolic extract of H. sabdariffa had better anti- microbial activity. The colour value of Hibiscus sabdariffa extract was determined and found to be within the BP range of not less than 0.25. The colour value for Hibicus sabdariffa being found to be 0.26, that of amaranth was 0.46. Hibiscus sabdariffa extract retained its colour value within BP standards for up to six months. The macroscopic, microscopic and physico-chemical properties of both test and standard colour agents were also investigated and found to have effects on colour stability. Colour extact from Hibiscus sabdamfa calyces was found to be a suitable colouring agent for the four paediatric syrups, at room temperature and at 37°C; and when stored in amber bottles, and buffered at pH 5.0
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Science in Pharmacy, (Pharmaceutics), 2008