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Subject: search.filters.subject.Controlled release

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    An investigation into nanocellulose based hydrogels for analgesic treatment of avian species : thesis presented in partial fulfilment of the requirements for the degree of Master of Science, Chemistry, Massey University, Palmerston North, New Zealand
    (Massey University, 2018) Allan, David Bruce
    Drug delivery techniques are an integral component in modern medical practices. Numerous drugs have been designed to exploit drug delivery systems, primarily oral administration, as it is preferred by the public for treatment of animals and humans. Butorphanol is a commonly used opioid analgesic drug for pain relief in avian species. The pharmacokinetic reports on butorphanol suggest that it is metabolised and cleared from an avian body at a much faster rate when compared to mammals. A single intravenous injection of butorphanol at 2 mg/kg provides analgesia for only 2 hours. When given at higher doses, butorphanol starts to produce side effects such as hyperventilation, cardiac insufficiency, coma and death. Therefore, there is a need to develop a slow release drug delivery system for butorphanol which can prolong the duration of analgesia without the side effects.
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    Ionically cross-linked alginate hydrogels as drug delivery systems for analgesics in broiler chickens : thesis presented in partial fulfilment of the requirement for the degree of Masters of Science in Chemistry at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2017) Booty, Samuel James
    Treating birds with analgesic drugs requires continuous injections of near lethal concentrations to maintain the therapeutic dose in the blood plasma. This is due to birds having higher metabolic rates than mammals. Therefore, there is a need to develop drug delivery systems that can control and slow down the release of analgesics in birds. This study was designed to analyse the sustained release of the model analgesics, sodium salicylate and sodium aspirin, from ionically cross-linked alginate hydrogels, in in vitro and in vivo experiments using broiler chickens as the model bird. Analgesic loaded hydrogels separated into two layers, unlike the homogeneous blank hydrogels. This was labelled as the separation effect. Swelling studies indicated the absence of the insoluble cross-linked alginate material in the hydrogels where the separation effect occurred, with most of the hydrogels dissolving back into the medium. The highest equilibrium swelling percentage achieved in the loaded hydrogels was 68 %. In comparison, the highest equilibrium swelling percentage in the blank hydrogels was 622 %. In vitro drug release profiles showed that the hydrogels released up to 100% of the sodium salicylate within 3.33 hours. In contrast, the hydrogels containing sodium aspirin released only 35 % of the encapsulated drug. Hydrogels containing a drug concentration of 150 mg/mL were injected into the model birds at a dose rate of 150 mg/Kg. No chicken reacted negatively to the hydrogel injection. In vivo results indicate sustained release of the model analgesic from the hydrogels compared to the release from the aqueous solutions of the drug. The effective concentration for an analgesic effect of sodium salicylate was maintained by the group injected with an aqueous solution of sodium salicylate 18 hours after the injection. The groups injected with the hydrogel with the maximum calcium chloride content saw the largest sustained release, with the plasma concentration of sodium salicylate remaining over the effective concentration for up to 36 hours after the injection. Keywords: Sodium salicylate, sodium aspirin, hydrogel, analgesia, sustained release, broiler chicken.