Atovaquone-proguanil for prophylaxis and treatment of malaria

Proguanil Suppresses Breast Tumor Growth In Vitro and In Vivo by Inducing Apoptosis via Mitochondrial Dysfunction

Breast cancer, ranking as the second leading cause of female cancer-related deaths in the U.S., demands the exploration of innovative treatments. Repurposing FDA-approved drugs emerges as an expedited and cost-effective strategy. Our study centered on proguanil, an antimalarial drug, reveals notable anti-proliferative effects on diverse breast cancer cell lines, including those derived from patients. Proguanil-induced apoptosis was associated with a substantial increase in reactive oxygen species (ROS) production, leading to reduced mitochondrial membrane potential, respiration, and ATP production. Proguanil treatment upregulated apoptotic markers (Bax, p-H2AX, cleaved-caspase 3, 9, cleaved PARP) and downregulated anti-apoptotic proteins (bcl-2, survivin) in breast cancer cell lines. In female Balb/c mice implanted with 4T1 breast tumors, daily oral administration of 20 mg/kg proguanil suppressed tumor enlargement by 55%. Western blot analyses of proguanil-treated tumors supported the in vitro findings, demonstrating increased levels of p-H2AX, Bax, c-PARP, and c-caspase3 as compared to controls. Our results collectively highlight proguanil's anticancer efficacy in vitro and in vivo in breast cancer, prompting further consideration for clinical investigations.

An update on prevention of malaria in travelers

Malaria, a parasitic disease caused by protozoa belonging to the genus Plasmodium, continues to represent a formidable public health challenge. Despite being a preventable disease, cases reported among travelers have continued to increase in recent decades. Protection of travelers against malaria, a potentially life-threatening disease, is of paramount importance, and it is therefore necessary for healthcare professionals to be up to date with the most recent recommendations. The present review provides an update of the existent measures for malaria prevention among travelers.

Drug interactions with antimalarial medications in older travelers: a clinical guide

Increasingly older adults are traveling to international destinations with malaria as a present risk. Surveillance systems indicate that older adults are more likely to suffer severe complications from malaria. The role of health care providers in selecting an appropriate medication for chemoprophylaxis or treatment of malaria in adults becomes more difficult as older adults undergo physiologic changes that alter the pharmacokinetic and pharmacodynamic nature of medications potentially causing increased drug interactions, adverse events and altered drug action. A comprehensive literature search from 1970 to present, with a focus on the past 10 years, was conducted on drug interactions, pharmacokinetic and pharmacodynamic effects on antimalarials in adults. It was determined that due to pharmacodynamic and pharmacokinetic changes in older adults, especially renal and cardiovascular, special attention should be given to this population of travelers in order to minimize the likelihood of adverse events or altered drug efficacy. Antimalarial drug-disease interactions in older adults can occur more often due to QT prolongation, exacerbation of hypoglycemia, decreased renal elimination and decreased hepatic metabolism. Older antimalarials have well-documented drug-drug interactions. Tafenoquine, a new antimalarial, requires glucose-6-phosphate dehydrogenase screening like primaquine and monitoring of new potential drug interaction with MATE1 and OCT2 substrates. While drug-drug interactions in older travelers may occur more often as a result of polypharmacy, data did not indicate adverse reactions or decreased drug efficacy is greater compared with younger adults. Overall, with the exception of recently approved tafenoquine, much is known about antimalarial drug and disease interactions, but new drugs are always being approved, requiring travel health providers to understand the pharmacokinetics and pharmacodynamics of antimalarial drugs to predict the impact on safety and efficacy in travelers. This guide provides travel health providers with valuable insights on potential outcomes associated with drug interactions in adults and recommended monitoring or drug regimen modification.

Injectable anti-malarials revisited: discovery and development of new agents to protect against malaria

Over the last 15 years, the majority of malaria drug discovery and development efforts have focused on new molecules and regimens to treat patients with uncomplicated or severe disease. In addition, a number of new molecular scaffolds have been discovered which block the replication of the parasite in the liver, offering the possibility of new tools for oral prophylaxis or chemoprotection, potentially with once-weekly dosing. However, an intervention which requires less frequent administration than this would be a key tool for the control and elimination of malaria. Recent progress in HIV drug discovery has shown that small molecules can be formulated for injections as native molecules or pro-drugs which provide protection for at least 2 months. Advances in antibody engineering offer an alternative approach whereby a single injection could potentially provide protection for several months. Building on earlier profiles for uncomplicated and severe malaria, a target product profile is proposed here for an injectable medicine providing long-term protection from this disease. As with all of such profiles, factors such as efficacy, cost, safety and tolerability are key, but with the changing disease landscape in Africa, new clinical and regulatory approaches are required to develop prophylactic/chemoprotective medicines. An overall framework for these approaches is suggested here.

Efficacy and safety of atovaquone-proguanil in treating imported malaria in Japan: the second report from the research group

Malaria remains an important health risk among travelers to tropical/subtropical regions. However, in Japan, only 2 antimalarials are licensed for clinical use - oral quinine and mefloquine. The Research Group on Chemotherapy of Tropical Diseases introduced atovaquone-proguanil in 1999, and reported on its excellent antimalarial efficacy and safety for treating non-immune patients with uncomplicated Plasmodium falciparum malaria (20 adult and 3 pediatric cases) in 2006. In the present study, additional cases of malaria were analyzed to confirm the efficacy and safety of this antimalarial drug. Fourteen adult and 2 pediatric cases of P. falciparum malaria and 13 adult cases and 1 pediatric case of P. vivax/ovale malaria were successfully treated with atovaquone-proguanil, including 3 P. falciparum cases in which the antecedent treatment failed. Two patients with P. vivax malaria were treated twice due to primaquine treatment failure as opposed to atovaquone-proguanil treatment failure. Except for 1 patient with P. falciparum malaria who developed a moderate liver function disturbance, no significant adverse effects were observed. Despite the intrinsic limitations of this study, which was not a formal clinical trial, the data showed that atovaquone-proguanil was an effective and well-tolerated therapeutic option; licensure of this drug in Japan could greatly contribute to individually appropriate treatment options.

Clinical development of new prophylactic antimalarial drugs after the 5th Amendment to the Declaration of Helsinki

Malaria is of continuing concern in nonimmune traveling populations. Traditionally, antimalarial drugs have been developed as agents for dual indications (treatment and prophylaxis). However, since 2000, when the 5th Amendment to the Declaration of Helsinki (DH2000) was adopted, development of new malaria prophylaxis drugs in this manner has ceased. As a consequence, there may not be any new drugs licensed for this indication in the foreseeable future. Major pharmaceutical companies have interpreted DH2000 to mean that the traditional development paradigm may be considered unethical because of doubt over the likelihood of benefit to endemic populations participating in clinical studies, the use of placebo, and the sustainability of post-trial access to study medications. In this article, we explore the basis of these concerns and suggest that the traditional development paradigm remains ethical under certain circumstances. We also consider alternative approaches that may be more attractive to sponsors as they either do not use placebo, or utilize populations in endemic countries who may unambiguously benefit. These approaches represent the way forward in the future, but are at present unproven in clinical practice, and face numerous regulatory, logistical and technical challenges. Consequently, in the short term, we argue that the traditional clinical development paradigm remains the most feasible approach and is ethical and consistent with the spirit of DH2000 under the appropriate circumstances.

An update on malaria prevention, diagnosis and treatment for the returning traveller

The diagnosis of malaria needs to be considered for every returning traveller with a fever. Compliance with prevention, both pharmaceutical and non-pharmaceutical, is essential for every traveller. New tests for diagnosis are now available. Treatment options have recently expanded to include the artemisinin derivatives that used to be unavailable in the western countries.

Malaria: an update on treatment of adults in non-endemic countries

Every year people die from malaria in Britain and other industrialised countries. Most of these deaths are avoidable: they occur because a patient or doctor has underestimated the severity of the disease or has not considered the diagnosis early enough. This article provides the essential facts on treating malaria in adults in a non-endemic setting and is based on the best available evidence

Efficacy and safety of atovaquone-proguanil compared with mefloquine in the treatment of nonimmune patients with uncomplicated P. falciparum malaria in Japan

Malaria treatment is becoming increasingly difficult due to the widespread drug resistance of Plasmodium falciparum. In Japan, only three antimalarials are approved for treatment: oral quinine, sulfadoxine-pyrimethamine, and mefloquine. Recently, however, the Research Group on Chemotherapy of Tropical Diseases introduced atovaquone-proguanil for treating drug-resistant P. falciparum malaria. This research group had also introduced mefloquine before it was licensed nationally. Using data obtained from the research group, we analyzed the efficacy and safety of atovaquone-proguanil, as compared with mefloquine, in nonimmune patients with uncomplicated P. falciparum malaria. Cures were attained in all (100%) of 20 atovaquone-proguanil-treated and 49 (98%) of 50 mefloquine-treated adults. The mean fever clearance time (FCT) and parasite clearance time (PCT) appeared to be longer in the atovaquone-proguanil group than in the mefloquine group, but the differences were not statistically significant. Three (15%) of the 20 atovaquone-proguanil-treated adults had adverse events (AEs), all of which were transient elevations of liver enzymes, while 19 (38%) of the 50 mefloquine-treated adults had AEs, including dizziness in 8 (16%) and nausea/vomiting in 7 (14%). All 3 children treated with atovaquone-proguanil were cured without developing AEs. Despite the limitations of this study in not being a formal clinical trial, atovaquone-proguanil seemed to be at least equal to, or even better than, mefloquine for the treatment of uncomplicated P. falciparum malaria in nonimmune patients, including children. Its marketing in Japan could be beneficial in offering an alternative therapeutic option. However, vigilance should be maintained on the possible occurrence of rare but severe AEs, and also of the possible spread of drug resistance.

Acute hepatitis and atovaquone/proguanil

A 31-year-old healthy man developed acute hepatitis after receiving atovaquone (250 mg) and proguanil (100 mg) for malaria prophylaxis daily for 25 days. Although atovaquone/proguanil is generally well-tolerated, this case highlights the hepatotoxic potential with considerable morbidity and should alert physicians to this harmful side effect.

Falciparum malaria: current therapeutic challenges

PURPOSE OF REVIEW

Malaria remains a major cause of death in much of the world. The routine treatment of malaria is currently threatened by rising rates of drug resistance. Moreover, mortality among children with severe and complicated malaria remains unacceptably high. Here we review trends in antimalarial drug resistance and report on the progress of newer drugs and drug combinations. We then review some recent literature regarding the pathological processes involved in the aetiology of severe malaria that may lead to improvements in the management of children with severe disease.

RECENT FINDINGS

Resistance to first line therapies, including chloroquine and sulphadoxine/pyramethamine, continues to rise in many parts of the world. The availability of newer and more effective drugs and fixed drug combinations is hampered by financial and political considerations. Nevertheless, a number of promising drugs and supportive treatments for both mild and severe malaria are at various stages of development.

SUMMARY

A range of newer drugs and fixed drug combinations are now available that are safe and effective. However, these drugs remain expensive and their introduction will require political and financial support at every level. Considerable work is still required to achieve a better understanding of the processes involved in the pathogenesis of severe and complicated malaria. Only then will it be possible to develop new and appropriate therapies that will be widely applicable.