Dolutegravir Interactions With Artemisinin-based Combination Therapies

Overview

Malaria and HIV are found in the same regions of the world and developing countries are most affected by both diseases. For malaria, new drugs have been introduced called ACTs. These drugs are effective against malaria but little is known about how the levels of these drugs in blood relate to how effective these drugs are. For HIV, a new drug has been developed called dolutegravir which has potential to be widely used in developing countries. This proposal will explore how dolutegravir affects the drug levels of these antimalarial drugs and vice versa. In total, 46 healthy volunteers will participate in this study.

More than 90% of the malaria occurs in sub-Saharan Africa (WHO 2008), the region bearing 67% of the global HIV burden (WHO 2011). Given the extensive overlap in geographical distribution of these diseases, interactions between them could have profound public health consequences. Significant biological interactions exist between HIV and malaria. HIV is known to increase susceptibility to malaria infection (Whitworth, Morgan et al. 2000), compromise the host's ability to clear malaria parasites (characterised by higher parasite densities) (Francesconi, Fabiani et al. 2001), increase the risk of symptomatic malaria and contribute to malaria treatment failure (Hewitt, Steketee et al. 2006). In areas of unstable transmission, malaria mortality is higher in HIV-positive individuals. Additionally, placental malaria infection in HIV positive individuals is associated with higher perinatal mortality, low birth weight and HIV transmission, and this effect is not attenuated in subsequent pregnancies, in contrast with HIV-negative individuals. Conversely, malaria infection has been shown to increase HIV viral load (Hoffman, Jere et al. 1999, Kublin, Patnaik et al. 2005), with the potential for both accelerated HIV disease progression and increased HIV transmission (Abu-Raddad, Patnaik et al. 2006). As of September 2011, Uganda had 1.4 million people living with HIV/AIDS; of those with clinically advanced disease, 54% (313 117) were receiving ART (WHO). As southern African countries are scaling up coverage of ART, they have also stepped up the fight against Pf malaria by increasing the coverage of Insecticide Treated Nets and by adopting the use of artemisinin-based combination therapies (ACTs) as first line treatment of malaria (USAID 2011). AL and AS-AQ are the most commonly utilized regimens in sub-Saharan Africa for first line treatment for malaria (WHO 2008). As a consequence of high rates of HIV-malaria co-infection and increasing availability of both ACTs and ART in southern Africa, progressively more co-infected people will receive both classes of drugs. However, the pharmacokinetics, safety and/or efficacy of ACTs such as AL, AS-AQ and DHA-piperaquine in HIV-infected individuals who are on ART are poorly understood. Many efficacy studies conducted as part of the drug development process of ACTs have either not assessed the HIV status of study participants or systematically excluded HIV-infected individuals. Few studies have systematically evaluated for potential drug-drug interactions in a healthy volunteer setting. Study Design Open label, fixed sequence healthy volunteer study to compare pharmacokinetic interactions between DTG and AL (Study A; crossover design), or AS-AQ (Study B; parallel group design). Whilst a cross-over study design would be theoretically ideal for investigating both ACTs in combination with DTG, desethylamodiaquine, an active metabolite of AQ has an extensive terminal t1/2 of approximately 10 days; therefore it is not considered feasible to undertake a cross-over design for this arm of the study, since the washout period between the two phases would exceed two months, risking subject attrition. Furthermore, during that time period, intercurrent illnesses and other important changes may occur within a subject, leading changes in eligibility for the study. Therefore, two study designs are planned as detailed in the Study Design Section.