Safety monitoring experience of single-low dose primaquine co-administered with artemether-lumefantrine among providers and patients in routine healthcare practice: a qualitative study in Eastern Tanzania.

BACKGROUND: Primaquine is a gametocytocidal drug recommended by the World Health Organization (WHO) in a single-low dose combined with artemisinin-based combination therapy (ACT) for the treatment and prevention of Plasmodium falciparum malaria transmission. Safety monitoring concerns and the lack of a universal validated and approved primaquine pharmacovigilance tool is a challenge for a national rollout in many countries. This study aimed to explore the acceptance, reliability and perceived effectiveness of the primaquine roll out monitoring pharmacovigilance tool (PROMPT). METHODS: This study was conducted in three dispensaries in the Coastal region of Eastern Tanzania. The study held six in-depth interviews with healthcare providers and six participatory focus group discussions with malaria patients (3) and parents/guardians of sick children (3). Participants were purposively sampled. Thematic analysis was conducted with the aid of NVivo qualitative analysis software. RESULTS: The respondents' general acceptance and perceived effectiveness of the single-low dose primaquine and PROMPT was good. Screening procedure for treatment eligibility and explaining to patients about the possible adverse events was considered very useful for safety reasons. Crushing and dissolving of primaquine tablet to get the appropriate dose, particularly in children, was reported by all providers to be challenging. Transport costs and poor access to the health facility were the main reasons for a patient failing to return to the clinic for a scheduled follow-up visit. Treatment was perceived to be safe by both providers and patients and reported no case of a severe adverse event. Some providers were concerned with the haemoglobin drop observed on day 7. CONCLUSION: Single-low dose primaquine was perceived to be safe and acceptable among providers and patients. PROMPT demonstrated to be a reliable and user-friendly tool among providers. Further validation of the tool by involving the National Malaria Control Programme is pivotal to addressing key challenges and facilitating primaquine adoption in the national policy.

Development of a capillary electrophoresis method for the enantioselective estimation of primaquine in pharmaceutical formulations.

A capillary electrophoresis (CE) method has been developed that allows the separation and estimation of primaquine enantiomers using hydroxypropyl-gamma-cyclodextrin (HP-gamma -CD) as a chiral selector. The influence of chemical and instrumental parameters on the separation, such as type and concentration of CD, buffer concentration, buffer pH, applied voltage, capillary temperature, and injection time, were investigated. Good separation of the racemic mixture of primaquine was achieved using a fused-silica capillary (52.5 cm effective length x 50 microm id) and a background electrolyte composed of tris-phosphate buffer solution (50 mM, pH 2.5) containing 15 mM HP-gamma-CD as a chiral selector. The recommended applied voltage, capillary temperature, and injection time were 15 kV, 25 degrees C, and 6 s, respectively. Within-day and interday reproducibility of peak area and migration time gave relative standard deviation values ranging from 1.05-3.30%. Good recoveries (range of 96.8-104.9%) were obtained from the determination of placebos that were spiked with 0.25-1.00 mg/L primaquine. The proposed CE method was successfully applied to the assay of primaquine diphosphate in pharmaceutical formulations (tablets).

[In vitro dissolution profile of primaquine tablets available for malaria treatment in Brazil]. / Perfil de dissolução in vitro de comprimidos de primaquina disponíveis para tratamento de malária no Brasil.

The clinical inefficacy of many medications has served to highlight the need for deeper studies on the formulation components, processes used and physicochemical characteristics of drugs. The objective of this study was to evaluate the in vitro release of primaquine phosphate from tablets available in Brazil for treating malaria, and the development of new formulations for conventional release. Although the primaquine phosphate tablets studied had been approved according to the criteria proposed by the United States Pharmacopoeia (2006) for the dissolution test, they did not present adequate dissolution performance characteristics, in that there was drug retention during the release process. The results indicate the existence of problems in the primaquine phosphate tablets analyzed, and it may suggest that this is one of the factors responsible for the appearance of parasite resistance.

Can primaquine therapy for vivax malaria be improved?

The incidence and range of endemic malaria caused by Plasmodium vivax has expanded during the past 30 years. This parasite forms hypnozoites in the liver, creating a persistent reservoir of infection. Primaquine (PQ), introduced 50 years ago, is the only drug available to eliminate hypnozoites. However, lengthy treatment courses and follow-up periods are not conducive to assessing the effectiveness of this drug in preventing relapses. Resistance to standard therapy could be widespread. Studies are urgently needed to gauge this problem and to determine the safety, tolerability and efficacy of shorter courses and higher doses of PQ.

Quality of antimalarial drugs and antibiotics in Papua New Guinea: a survey of the health facility supply chain.

BACKGROUND: Poor-quality life-saving medicines are a major public health threat, particularly in settings with a weak regulatory environment. Insufficient amounts of active pharmaceutical ingredients (API) endanger patient safety and may contribute to the development of drug resistance. In the case of malaria, concerns relate to implications for the efficacy of artemisinin-based combination therapies (ACT). In Papua New Guinea (PNG), Plasmodium falciparum and P. vivax are both endemic and health facilities are the main source of treatment. ACT has been introduced as first-line treatment but other drugs, such as primaquine for the treatment of P. vivax hypnozoites, are widely available. This study investigated the quality of antimalarial drugs and selected antibiotics at all levels of the health facility supply chain in PNG. METHODS AND FINDINGS: Medicines were obtained from randomly sampled health facilities and selected warehouses and hospitals across PNG and analysed for API content using validated high performance liquid chromatography (HPLC). Of 360 tablet/capsule samples from 60 providers, 9.7% (95% CI 6.9, 13.3) contained less, and 0.6% more, API than pharmacopoeial reference ranges, including 29/37 (78.4%) primaquine, 3/70 (4.3%) amodiaquine, and one sample each of quinine, artemether, sulphadoxine-pyrimethamine and amoxicillin. According to the package label, 86.5% of poor-quality samples originated from India. Poor-quality medicines were found in 48.3% of providers at all levels of the supply chain. Drug quality was unrelated to storage conditions. CONCLUSIONS: This study documents the presence of poor-quality medicines, particularly primaquine, throughout PNG. Primaquine is the only available transmission-blocking antimalarial, likely to become important to prevent the spread of artemisinin-resistant P. falciparum and eliminating P. vivax hypnozoites. The availability of poor-quality medicines reflects the lack of adequate quality control and regulatory mechanisms. Measures to stop the availability of poor-quality medicines should include limiting procurement to WHO prequalified products and implementing routine quality testing.

Quality of essential drugs in tropical countries: evaluation of antimalarial drugs in the Brazilian Health System.

INTRODUCTION: The emergence of drug resistance is one of the main problems concerning malaria treatment. The use of counterfeit and/or substandard antimalarial drugs can contribute to the development of parasite resistance. Thus, the aim of this study was to evaluate the quality of antimalarial drugs distributed in Brazil. METHODS: Samples containing chloroquine phosphate, mefloquine hydrochloride, primaquine phosphate, and quinine sulfate tablets were delivered to the Rio de Janeiro central storeroom (CENADI), state storerooms (SS), and Basic Health Units (BHUs) in the north region of Brazil - a total of 10 sample sets. After 5 months of storage, the samples were collected, and in vitro quality control analyses according to official and published methods were performed. RESULTS: Inadequate drug storage conditions were found in two SS and in all BHUs evaluated. There were no quality deviations found in the chloroquine samples. The quinine samples exhibited weight variation above the allowed limits. The primaquine samples were found to have packaging deficiency. The release of mefloquine in samples from some regions showed a statistically significant difference when compared with the CENADI samples. CONCLUSIONS: It is important to periodically evaluate the quality and storage conditions of essential drugs. The quality deviations found with the primaquine and quinine samples are not related to storage conditions and must be addressed urgently. The decreased mefloquine release from tablets is related to formulation problems or influenced by inadequate storage conditions, prompting further investigation. Even with the mentioned problems, the samples would probably not contribute to resistant parasite selection.

Quality of essential drugs in tropical countries: evaluation of antimalarial drugs in the Brazilian Health System / Qualidade de medicamentos essenciais em países tropicais: avaliação de medicamentos antimaláricos no Sistema de Saúde do Brasil

INTRODUCTION: The emergence of drug resistance is one of the main problems concerning malaria treatment. The use of counterfeit and/or substandard antimalarial drugs can contribute to the development of parasite resistance. Thus, the aim of this study was to evaluate the quality of antimalarial drugs distributed in Brazil. METHODS: Samples containing chloroquine phosphate, mefloquine hydrochloride, primaquine phosphate, and quinine sulfate tablets were delivered to the Rio de Janeiro central storeroom (CENADI), state storerooms (SS), and Basic Health Units (BHUs) in the north region of Brazil - a total of 10 sample sets. After 5 months of storage, the samples were collected, and in vitro quality control analyses according to official and published methods were performed. RESULTS: Inadequate drug storage conditions were found in two SS and in all BHUs evaluated. There were no quality deviations found in the chloroquine samples. The quinine samples exhibited weight variation above the allowed limits. The primaquine samples were found to have packaging deficiency. The release of mefloquine in samples from some regions showed a statistically significant difference when compared with the CENADI samples. CONCLUSIONS: It is important to periodically evaluate the quality and storage conditions of essential drugs. The quality deviations found with the primaquine and quinine samples are not related to storage conditions and must be addressed urgently. The decreased mefloquine release from tablets is related to formulation problems or influenced by inadequate storage conditions, prompting further investigation. Even with the mentioned problems, the samples would probably not contribute to resistant parasite selection.

INTRODUÇÃO: O aparecimento de resistência aos medicamentos é um dos maiores problemas do tratamento da malária. O uso de medicamentos falsos e/ou de má qualidade pode contribuir para o desenvolvimento de resistência no parasita. Este estudo tem por objetivo avaliar a qualidade dos medicamentos antimaláricos distribuídos no Brasil. MÉTODOS: Amostras contendo comprimidos de difosfato de cloroquina, cloridrato de mefloquina, difosfato de primaquina e sulfato de quinina foram enviadas ao almoxarifado central na Cidade do Rio de Janeiro (CENADI), almoxarifados estaduais (SS) e Unidades Básicas de Saúde (UBS) nos estados da região norte do Brasil, totalizando dez amostras. Após cinco meses de armazenamento, as amostras foram coletadas e analisadas segundo métodos oficiais e da literatura. RESULTADOS: Foram encontradas condições inadequadas de armazenamento de medicamentos em duas SS e em todas as UBS avaliadas. Não foram encontrados problemas de qualidade com as amostras de cloroquina. As amostras de quinina apresentaram variação de peso acima dos limites permitidos. Amostras de primaquina foram encontradas com problemas na embalagem. A cedência de mefloquina de comprimidos, em algumas regiões, apresentou diferença estatisticamente significativa quando comparada com a amostra do CENADI. CONCLUSÕES: É importante avaliar, periodicamente, a qualidade e as condições de armazenamento de medicamentos essenciais. Desvios de qualidade encontrados com as amostras de primaquina e quinina não estão relacionados às condições de armazenamento e devem ser corrigidos urgentemente. O decréscimo na cedência de mefloquina dos comprimidos está relacionado com a formulação ou foi influenciada por condições de armazenamento inadequadas, necessitando de uma investigação posterior. Apesar dos problemas mencionados, as amostras provavelmente não contribuiriam para a seleção de parasitas resistentes.

Perfil de dissolução in vitro de comprimidos de primaquina disponíveis para tratamento de malária no Brasil / In vitro dissolution profile of primaquine tablets available for malaria treatment in Brazil

A ineficácia clínica de muitos medicamentos tem servido de alerta para estudos mais profundos sobre os componentes da formulação, processos empregados e características físico-químicas dos fármacos. O objetivo deste trabalho foi avaliar a liberação in vitro de comprimidos de fosfato de primaquina disponíveis no Brasil para tratamento da malária, e o desenvolvimento de novas formulações de liberação convencional. Embora os comprimidos de fosfato de primaquina estudados tenham sido aprovados pelos critérios propostos pela Farmacopéia Americana (2006) para o teste de dissolução, não apresentaram desempenho adequado para o perfil de dissolução, mostrando retenção do fármaco durante a liberação. Os resultados indicam a existência de problemas nos comprimidos de fosfato de primaquina analisados, podendo sugerir como um dos fatores responsáveis pelo aparecimento de resistência dos parasitas.

The clinical inefficacy of many medications has served to highlight the need for deeper studies on the formulation components, processes used and physicochemical characteristics of drugs. The objective of this study was to evaluate the in vitro release of primaquine phosphate from tablets available in Brazil for treating malaria, and the development of new formulations for conventional release. Although the primaquine phosphate tablets studied had been approved according to the criteria proposed by the United States Pharmacopoeia (2006) for the dissolution test, they did not present adequate dissolution performance characteristics, in that there was drug retention during the release process. The results indicate the existence of problems in the primaquine phosphate tablets analyzed, and it may suggest that this is one of the factors responsible for the appearance of parasite resistance.