Project – Formulation and Stability Evaluation of Artemether-Lumefantrine Suspensions Produced by Selected Pharmaceutical Companies in Nigeria

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Malaria remains one of the most serious public health challenges globally, particularly in sub-Saharan Africa where the burden of infection and mortality is highest. According to the World Health Organization (2024), an estimated 263 million malaria cases and 597,000 malaria-related deaths occurred worldwide in 2023, with Africa accounting for over 94% of all cases and deaths. Nigeria continues to bear the highest malaria burden globally, contributing approximately 27% of global malaria cases and 31% of malaria deaths (World Health Organization [WHO], 2024). The disease disproportionately affects children under five years of age and pregnant women, resulting in significant socioeconomic consequences including reduced productivity, increased healthcare expenditure, and poor educational outcomes (Aregawi et al., 2017).

The emergence and spread of resistance to conventional antimalarial drugs such as chloroquine and sulfadoxine-pyrimethamine necessitated the adoption of Artemisinin-based Combination Therapies (ACTs) as the first-line treatment for uncomplicated malaria (White, 2008). Among the various ACTs currently available, Artemether-Lumefantrine (AL) is one of the most commonly prescribed combinations because of its high efficacy, favorable safety profile, and ability to rapidly clear malaria parasites (Ashley et al., 2014). Artemether provides rapid parasite reduction while lumefantrine, a longer-acting partner drug, eliminates residual parasites and reduces the risk of recrudescence (Nosten & White, 2007).

Artemether-Lumefantrine is available in several dosage forms, including conventional tablets, dispersible tablets, and oral suspensions. Oral suspensions are particularly valuable in pediatric populations because they facilitate administration among children who cannot easily swallow solid dosage forms (Aulton & Taylor, 2018). The use of liquid formulations improves patient adherence and dosage flexibility, thereby enhancing therapeutic outcomes. However, suspension dosage forms are inherently less stable than solid dosage forms because the active pharmaceutical ingredients are dispersed rather than dissolved, making them susceptible to sedimentation, caking, crystal growth, microbial contamination, hydrolysis, and oxidation (Allen, 2022).

Pharmaceutical stability is a critical quality attribute that determines whether a product retains its identity, strength, quality, purity, and therapeutic effectiveness throughout its shelf life (United States Pharmacopeia, 2024). Stability studies are therefore essential during product development and post-marketing surveillance because they provide information regarding storage conditions, packaging requirements, and expiry dates (Blessy et al., 2014). According to the International Council for Harmonisation (ICH, 2023), stability testing helps predict the behavior of pharmaceutical products under various environmental conditions and ensures that medicines remain safe and effective throughout distribution and use.

Nigeria’s tropical climate presents unique challenges to pharmaceutical stability. High ambient temperatures, elevated relative humidity, inadequate storage facilities, and interruptions in electricity supply can accelerate degradation processes and compromise medicine quality (Yadav et al., 2015). These challenges are particularly significant for liquid dosage forms such as suspensions because physical and chemical changes occur more rapidly than in tablets and capsules (Aulton & Taylor, 2018). Exposure to excessive heat and moisture may lead to reduced drug potency, changes in viscosity, altered pH, increased sedimentation, and microbial proliferation, all of which can adversely affect therapeutic efficacy (Allen, 2022).

The Nigerian pharmaceutical industry has experienced considerable growth over the last two decades, with increasing emphasis on local manufacturing to improve medicine accessibility and reduce dependence on imported products (Onwujekwe et al., 2019). One of the major pharmaceutical production hubs in the country is the Aba Pharmaceutical Manufacturing Cluster located in Abia State. The cluster comprises several indigenous pharmaceutical companies engaged in the production of essential medicines, including antimalarial formulations, antibiotics, analgesics, and pediatric preparations. The growth of pharmaceutical manufacturing activities in Aba has contributed significantly to employment generation, industrial development, and medicine availability within Nigeria (Federal Ministry of Health, 2021).

Despite these achievements, concerns remain regarding the quality, stability, and regulatory compliance of some locally manufactured pharmaceutical products. Previous studies have reported variability in the quality of antimalarial medicines circulating in African countries, including Nigeria (Bate et al., 2009; Nayyar et al., 2012). Substandard medicines may contain inadequate amounts of active ingredients or exhibit poor stability characteristics that compromise therapeutic effectiveness. Such deficiencies can contribute to treatment failure, increased morbidity, mortality, and the emergence of antimalarial drug resistance (Ashley et al., 2014).

Furthermore, the importance of evaluating the stability of Artemether-Lumefantrine suspension formulations has become increasingly evident following regulatory concerns regarding the stability of reconstituted antimalarial suspensions. The discontinuation of certain multi-dose Artemether-Lumefantrine oral suspension products by NAFDAC due to stability concerns highlights the need for continuous monitoring of formulation performance under local environmental conditions (NAFDAC, 2025). Therefore, evaluating the formulation characteristics and stability profiles of Artemether-Lumefantrine suspensions produced within the Aba Pharmaceutical Manufacturing Cluster is essential to ensuring product quality, therapeutic effectiveness, and patient safety.

1.2 Statement of the Problem

The effectiveness of malaria treatment depends largely on the quality, safety, and stability of antimalarial medicines administered to patients. Although Artemether-Lumefantrine remains the first-line treatment for uncomplicated malaria in Nigeria and many malaria-endemic countries, concerns persist regarding the stability of liquid suspension formulations, particularly under tropical environmental conditions (WHO, 2024).

Suspension dosage forms are generally more susceptible to instability than solid dosage forms because of their dispersed particulate nature. During storage, suspensions may undergo sedimentation, caking, crystal growth, viscosity changes, pH alterations, microbial contamination, and degradation of active pharmaceutical ingredients (Allen, 2022). These changes can result in reduced potency, non-uniform dosing, poor patient compliance, and ultimately therapeutic failure (Aulton & Taylor, 2018).

Nigeria’s climatic conditions, characterized by high temperatures and relative humidity, further increase the likelihood of pharmaceutical instability (Yadav et al., 2015). In many cases, medicines are transported and stored under conditions that do not fully comply with recommended standards, thereby increasing the risk of quality deterioration before they reach patients (Nayyar et al., 2012). Such deterioration is particularly concerning for antimalarial medicines because subtherapeutic drug concentrations may promote parasite resistance and compromise malaria control efforts (Ashley et al., 2014).

Although pharmaceutical manufacturing activities have expanded considerably within the Aba Pharmaceutical Manufacturing Cluster, limited empirical data exist regarding the formulation quality and stability characteristics of Artemether-Lumefantrine suspensions produced by these companies. Most available studies in Nigeria have focused on tablet dosage forms, leaving a significant knowledge gap regarding suspension formulations that are widely used among pediatric patients (Onwujekwe et al., 2019).

Additionally, the recent regulatory action taken by NAFDAC regarding the discontinuation of certain Artemether-Lumefantrine oral suspension products due to stability concerns raises questions about the quality and long-term performance of similar formulations produced by local manufacturers (NAFDAC, 2025). Without adequate scientific evaluation, healthcare providers, regulators, and patients may have limited information regarding the ability of these products to maintain their quality throughout storage and use.

Therefore, the problem addressed by this study is the insufficient information regarding the formulation quality and stability characteristics of Artemether-Lumefantrine suspensions produced by selected pharmaceutical companies in the Aba Pharmaceutical Manufacturing Cluster. This knowledge gap necessitates a comprehensive evaluation to ensure compliance with pharmaceutical standards, improve product quality, and support effective malaria treatment in Nigeria.

1.3 Aim of the Study

The aim of this study is to evaluate the formulation and stability characteristics of Artemether-Lumefantrine suspensions produced by selected pharmaceutical companies in the Aba Pharmaceutical Manufacturing Cluster.

1.4 Objectives of the Study

The specific objectives are to:

1. Evaluate the physicochemical properties of selected Artemether-Lumefantrine suspensions produced in Aba.
2. Determine the stability profiles of the formulations under specified storage conditions.
3. Assess changes in active ingredient content during storage.
4. Evaluate sedimentation characteristics and redispersibility of the suspensions.
5. Determine the compliance of the formulations with established pharmacopeial standards.

1.5 Research Questions

1. What are the physicochemical properties of Artemether-Lumefantrine suspensions produced by selected pharmaceutical companies in Aba?
2. How stable are the formulations under recommended storage conditions?
3. Does the concentration of active ingredients change significantly during storage?
4. What are the sedimentation and redispersibility characteristics of the formulations?
5. Do the formulations comply with pharmacopeial quality requirements?

1.6 Research Hypothesis

Null Hypothesis (H₀)

There is no significant difference in the stability characteristics of Artemether-Lumefantrine suspensions produced by selected pharmaceutical companies in the Aba Pharmaceutical Manufacturing Cluster.

1.7 Significance of the Study

The findings of this study will be beneficial to:

• Pharmaceutical manufacturers in improving formulation quality and product stability.
• NAFDAC and other regulatory agencies in strengthening quality assurance activities.
• Healthcare professionals in making informed decisions regarding antimalarial therapy.
• Researchers by providing empirical data for future studies on pharmaceutical stability.
• Patients through improved access to effective and safe antimalarial medicines.

1.8 Scope of the Study

This study focuses on the formulation and stability evaluation of Artemether-Lumefantrine suspensions produced by selected pharmaceutical companies within the Aba Pharmaceutical Manufacturing Cluster, Abia State, Nigeria. The study will assess physicochemical properties, active ingredient stability, sedimentation behavior, redispersibility, and compliance with pharmacopeial specifications under specified storage conditions.

1.9 Operational Definition of Terms

Artemether-Lumefantrine Suspension: A liquid antimalarial dosage form containing artemether and lumefantrine dispersed in a suitable vehicle.

Formulation: The process and composition involved in preparing a pharmaceutical dosage form.

Stability: The ability of a pharmaceutical product to maintain its quality, safety, and efficacy throughout its shelf life.

Physicochemical Properties: Physical and chemical characteristics of a pharmaceutical product, including pH, viscosity, sedimentation volume, and drug content.

Pharmaceutical Manufacturing Cluster: A geographical concentration of pharmaceutical industries involved in medicine production, such as the Aba Pharmaceutical Manufacturing Cluster.

Shelf Life: The period during which a pharmaceutical product remains suitable for use under specified storage conditions.

Project – Formulation and Stability Evaluation of Artemether-Lumefantrine Suspensions Produced by Selected Pharmaceutical Companies in Nigeria