The development and implementation of a protocol for the characterisation of poor-quality antimalarials (COPA)

Abstract

This thesis describes the development and implementation of a protocol to characterise poor-quality antimalarials (COPA). The research focused on artemisinin-derived combination therapies (ACTs) of co-formulated artemether (ATM) and lumefantrine (LUM). These antimalarials are the most commonly procured ACTs used to combat a malaria infection. Therefore, the protocol to identify poor-quality treatments is highly relevant and applicable. Chapter 1 provides an introduction into the paradigm of poor-quality antimalarials at the onset of the research project. A systematic literature review is presented1, which quantitatively assesses relevant field surveys investigating the quality of antimalarials to determine why there is still a lack a consensus on characterising medicines as falsified, substandard, and degraded. While many field surveys did possess the analytical capability, there was a lack in accurate characterisation. The chapter addresses the importance of characterising the outcomes, specifically, how the characterisation can inform effective countermeasures and positive outcomes. The aims and overview of the COPA research are included at the conclusion of the chapter. Chapter 2 describes the attempted application of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the detection of ATM, LUM and their potential degradant products, including how in-source fragmentation and in-system precipitation were encountered and dealt with. Guided by the outcomes of the Chapter 1 literature review, the experimental design subsequently focussed on the use of high-performance liquid chromatography (HPLC) with photodiode array (PDA) detection. The results suggest that the validated HPLC method can quantitatively measure the quality of the antimalarial by assessing active pharmaceutical ingredients (API) contents and detect their possible degradation products. The validated method was utilised to assess degradation observed in harsh degradation studies. Furthermore, the method by which to quantitatively assess the degradation products was proposed. Chapter 3 investigates the degradation of the ATM/LUM co-formulated tablets using laboratory-based stability tests. The currently accepted standard for an accelerated stability test was compared against a novel application of a cyclic stability test. The cyclic stability test recreates the day/night fluctuation of temperature and relative humidity that medicines would be exposed to in an uncontrolled environment in the target country of the field survey, e.g. transport and storage in a non-airconditioned supply chain. These stability tests represent a situation of controlled and monitored conditions. The antimalarials were then analysed using physical measurements and the HPLC-PDA method validated in Chapter 2 for API content and degradation profiles, in addition to disintegration testing. The results suggest that medicines that are exposed to the cyclic fluctuation degrade quicker than when stored in static accelerated conditions even when the average temperature and humidity conditions are comparable. The degradation of the samples in the laboratory resulted in the observation of three degradant products. All samples passed the disintegration testing based on the British Pharmacopeia guidelines. Chapter 4 presents atypical stability tests, in which antimalarials were stored in a shipping container in Darwin, Northern Territory, and outside in Perth, Western Australia. The two locations represent two different climate zones with different temperature and humidity conditions. These stability tests represent a situation of uncontrolled but monitored conditions. After storage for six months, the antimalarials were then analysed using physical measurements and the HPLC-PDA method validated in Chapter 2 for API content and degradant profiles, in addition to disintegration testing. The results were like those of Chapter 3, in which medicines experience increased degradation when exposed to real-world cyclic conditions greater than the recommended storage conditions. The samples stored in Darwin experienced higher levels of degradation, with conditions that were similar to the the cyclic conditions of Chapter 3. All samples passed the disintegration testing based on the British Pharmacopeia guidelines. Chapter 5 describes the implementation of the COPA protocol in a field survey of five administrative districts of Uganda, Africa. The field survey was an overt stratified random sampling method directed at collecting co-formulated ATM/LUM treatments and distributing written surveys regarding pharmacy practices of the visited points of distribution (PODs). The surveys identified that while most PODs do not have an effective form of climate regulation (i.e. an air-conditioning system), the medicines are generally stored for short period before sale (< 3 months). The collected medicines were then analysed using the HPLC-PDA method validated in Chapter 2. The results support the observations of the written survey, as only one location was found to possess a degraded medicine when the degradation profile was assessed. Furthermore, based on the packaging analysis of the collected samples another POD was found to have distributed a falsified medicine. All samples passed the disintegration testing based on the British Pharmacopeia guidelines. Chapter 6 revisits the analysis technique of LC-MS, utilising an instrument with greater sensitivity that is capable of high-resolution mass spectrometry (HRMS) to confirm the presence of the two API and identify the three degradant products observed. Accurate mass information for the two API, ATM and LUM, was obtained and two of the three degradant products were identified as diketo-aldehyde, an ATM-related degradant, and desbenzylketo, a LUM-related degradant. The identity confirms the use of the two degradant products as indicators for degradation. However, the successful HRMS application still requires further development before HRMS can be replace of photo diode array detection Chapter 7 summarises the research output, detailing the successful development and implementation of the COPA protocol. The real-world applicability of novel cyclic stability testing (Chapter 3) is addressed, detailing how the results are reflective of those observed after storing antimalarials in Darwin (Chapter 4). With the proven successes of the COPA protocol in earlier chapters, Chapter 7 addresses the public health implications of the COPA protocol, and how it can be used to inform effective countermeasures, moving forward. Furthermore, the direction of future recommended research is also included. The recommendations include increasing engagement with pharmaceutical companies for field surveys and identifies improved analytical capabilities that would enhance the outcomes of the COPA protocol.

Date of Award	2019
Original language	English
Supervisor	Tamsin KELLY (Supervisor), Gabrielle Cooper (Supervisor), Mark NAUNTON (Supervisor), Jackson THOMAS (Supervisor) & James Robertson (Supervisor)