Thesis

Analytical studies of the veterinary trypanocide isometamidium and related substances

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Awarding institution
  • University of Strathclyde
Date of award
  • 2010
Thesis identifier
  • T12604
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Abstract
  • Isometamidium (ISM) is a veterinary trypanocide, extensively used for chemotherapy and chemoprophylaxis against African animal trypanosomiasis in many prime areas of sub-Saharan Africia. Synthesis of ISM results in production of varying amounts of process-related impurities, with pharmacological activity primarily attributed to the principal component (ISM; M&B4180A). This thesis reports the development and validation of a selective, reproducible and precise assay for the separation and quantification of ISM and process-related by-products present in ISM formulations. A simple isocratic HPLC-UV assay has been developed and validated, which enables fast HPLC profiling of commercially available ISM products. The method has been successfully applied to a range of samples obtained from the open market in Africa, amongst which several counterfeit products were identified. Aiming at the determination of residual trypanocide in biological material of treated animals, the method was coupled with MS detection for increased sensitivity. A solid phase extraction (SPE) sample preparation procedure was developed and successfully optimised for the extraction of ISM and related substances from spiked plasma samples. The HPLC-MS assay however failed to provide good precision of the quantification at the very low concentrations of the analytes as present in biological samples from treated animals. Optimisation of the HPLC assay with respect to selectivity and efficiency in order to improve sensitivity was achieved in a comparative study of the effect of stationary phase chemistry and mobile phase selectivity on the HPLC separation. Computer-assisted method development resulted in an improved gradient method for highly sensitive determination of ISM and related substances. A semi-preparative HPLC method was developed for the specific isolation of ISM and related substances. Once isolated, the single compounds were characterised using MS, UV- and NMR-spectroscopy for the first time since their introduction on the market in 1958. This work will facilitate quality control of ISM products, and permit greater understanding of the pharmacokinetics of the drug in treated animals. It may ultimately lead to definition of further active compounds of the ISM formulation, and also perhaps new, therapeutically useful compounds with trypanocidal activity.
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Note
  • This thesis was previously held under moratorium from 4th October 2010 until 4th October 2011.
DOI
Date Created
  • 2010
Former identifier
  • 814653

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