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

Abstract

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. Hydrogels are an emerging drug delivery strategy which can release drugs at a controlled rate and overcome many of the problems with traditional delivery techniques. This controlled delivery is vital for prolonged delivery of drugs which can be hazardous when applied in higher doses such as butorphanol. However, many modern hydrogels lack the stability for prolonged drug release or present other problems including prohibitive cost and bio-incompatibility. In order to solve these problems and improve the delivery system, hydrogels were developed using nanocellulose derivatives coupled with traditional hydrogel materials. These systems allowed slow sustained release of butorphanol in broiler chickens species with limited observed side effects due to the biocompatible nature of the hydrogels. The hydrogels provided an analgesic effect for up to 26.5 hours which was a longer time than the 4 hours produced by the subcutaneously injected commercially available butorphanol.