Drug interactions in the treatment and chemoprophylaxis of malaria in HIV infected individuals in sub Saharan Africa

Malaria: A focused review for the emergency medicine clinician

INTRODUCTION

Malaria is a potentially fatal parasitic disease transmitted by the Anopheles mosquito. A resurgence in locally acquired infections has been reported in the U.S.

OBJECTIVE

This narrative review provides a focused overview of malaria for the emergency clinician, including the epidemiology, presentation, diagnosis, and management of the disease.

DISCUSSION

Malaria is caused by Plasmodium and is transmitted by the Anopheles mosquito. Disease severity can range from mild to severe. Malaria should be considered in any returning traveler from an endemic region, as well as those with unexplained cyclical, paroxysms of symptoms or unexplained fever. Patients most commonly present with fever and rigors but may also experience cough, myalgias, abdominal pain, fatigue, vomiting, and diarrhea. Hepatomegaly, splenomegaly, pallor, and jaundice are findings associated with malaria. Although less common, severe malaria is precipitated by microvascular obstruction with complications of anemia, acidosis, hypoglycemia, multiorgan failure, and cerebral malaria. Peripheral blood smears remain the gold standard for diagnosis, but rapid diagnostic tests are available. Treatment includes specialist consultation and antimalarial drugs tailored depending on chloroquine resistance, geographic region of travel, and patient comorbidities. Supportive care may be required, and patients with severe malaria will require resuscitation. Most patients will require admission for treatment and further monitoring.

CONCLUSION

Emergency medicine clinicians should be aware of the presentation, diagnosis, evaluation, and management of malaria to ensure optimal outcomes.

Initiation of anti-retroviral/Trimethoprim-Sulfamethoxazole therapy in a longitudinal cohort of HIV-1 positive individuals in Western Kenya rapidly decreases asymptomatic malarial parasitemia

Interactions between malaria and HIV-1 have important public health implications. Our previous cross-sectional studies showed significant associations between HIV-1 positivity and malarial parasitemia with an increased risk of gametocytemia. In this follow-up longitudinal study, we evaluated these associations to determine the magnitude of asymptomatic parasitemia over time, and to examine the effects of initiating Antiretroviral Therapy (ART) together with the broad-spectrum antibiotic Trimethoprim Sulfamethoxazole (TS) on asymptomatic parasitemia. 300 adult volunteers in a malaria holoendemic region in Western Kenya were enrolled and followed for six months. The study groups were composed of 102 HIV-1 negatives, 106 newly diagnosed HIV-1 positives and 92 HIV-1 positives who were already stable on ART/TS. Blood samples were collected monthly and asymptomatic malarial parasitemia determined using sensitive 18S qPCR. Results showed significantly higher malaria prevalence in the HIV-1 negative group (61.4%) (p=0.0001) compared to HIV-1 positives newly diagnosed (36.5%) and those stable on treatment (31.45%). Further, treatment with ART/TS had an impact on incidence of asymptomatic parasitemia. In volunteers who were malaria PCR-negative at enrollment, the median time to detectable asymptomatic infection was shorter for HIV-1 negatives (149 days) compared to the HIV-1 positives on treatment (171 days) (p=0.00136). Initiation of HIV treatment among the newly diagnosed led to a reduction in malarial parasitemia (expressed as 18S copy numbers/μl) by over 85.8% within one week of treatment and a further reduction by 96% after 2 weeks. We observed that while the impact of ART/TS on parasitemia was long term, treatment with antimalarial Artemether/Lumefantrine (AL) among the malaria RDT positives had a transient effect with individuals getting re-infected after short periods. As was expected, HIV-1 negative individuals had normal CD4+ levels throughout the study. However, CD4+ levels among HIV-1 positives who started treatment were low at enrollment but increased significantly within the first month of treatment. From our association analysis, the decline in parasitemia among the HIV-1 positives on treatment was attributed to TS treatment and not increased CD4+ levels per se. Overall, this study highlights important interactions between HIV-1 and malaria that may inform future use of TS among HIV-infected patients in malaria endemic regions.

HIV prevention clinical trials' community engagement guidelines: inequality, and ethical conflicts

In 2004 and 2005, the first clinical trials were launched to investigate the use of tenofovir for HIV prevention in Cambodia, Cameroon, Nigeria and Thailand. Controversies erupted over the ethical integrity of the research protocol. We reflect on the events that led to the controversies and identified that scientific and ethical concerns raised by members of local communities at each of these sites were erased by trialists, causing crisis that led to premature shut down the early PrEP trials. In the aftermath of these trials, the World Health Organisation, UNAIDS, and AVAC developed ethics guidelines intended to recognize the concerns as authentic, and developed guidelines to improve researchers’ engagement of communities in biomedical HIV prevention trial design and implementation. Our findings suggest that the ethics guidelines are limited in its ability to address power inequalities that leads to voice erasures and non-recognition of local competencies. Rather the ethical documents enabled trialists to gain a new sense of authority through the interpretations of ethical research conduct enabling trialists regain power that can further entrench inequality and voice erasures. To address concerns with what seems an intractable problem, we suggested models of engagement for off-shored research may be the option.

Malaria care-seeking behaviour among HIV-infected patients receiving antiretroviral treatment in South-Eastern Nigeria: A cross-sectional study

This study assesses malaria prevention and treatment behaviour among people living with HIV/AIDS (PLWHA) in Owerri, South Eastern Nigeria. Although Nigeria bears one of the world’s largest burdens of both malaria and HIV, there is almost no research studying how co-infected patients manage their care. We systematically sampled 398 PLWHA receiving care at Imo State Specialist Hospital and the Federal Medical Centre in Owerri to complete a structured, pre-tested questionnaire on malaria care-seeking behaviour. Descriptive statistics were reported and chi-square tests and multivariate logistic regressions were also used. The majority of HIV-infected patients (78.9%) reported having had an episode of suspected malaria quarterly or more often. There was a large variation in care-seeking patterns: on suspicion of malaria, 29.1% of participants engaged in self-medication; 39.2% went to drug shops, and only 22.6% visited HIV/AIDS care centres. Almost 40% waited more than 24 hours before initiating treatment. Most (60.3%), reported taking recommended artemisinin-based combination treatments (ACT) but a significant minority took only paracetamol (25.6%) or herbal remedies (3.5%). Most (80%) finished their chosen course of treatment; and completion of treatment was significantly associated with the frequency of suspected malaria occurrence (p = 0.03). Most (62.8%) did not take anti-malaria medication while taking antiretroviral treatment (ART) and almost all (87.6%) reported taking an ACT regimen that could potentially interact with Nigeria’s first-line ART regimen. Our findings suggest the need to pay more attention to malaria prevention and control as a crucial element in HIV/AIDS management in this part of Nigeria and other areas where malaria and HIV/AIDS are co-endemic. Also, more research on ART-ACT interactions, better outreach to community-level drug shops and other private sector stakeholders, and clearer guidelines for clinicians and patients on preventing and managing co-infection may be needed. This will require improved collaboration between programmes for both diseases.

Short Communication: Reduced Nevirapine Concentrations Among HIV-Positive Women Receiving Mefloquine for Intermittent Preventive Treatment for Malaria Control During Pregnancy

Clinical trials demonstrated intermittent preventive treatment in pregnancy with mefloquine (MQ) reduced malaria rates among pregnant women, yet an unexpected higher risk of mother-to-child transmission (MTCT) of HIV among HIV-positive women receiving MQ has also been observed. To determine if interactions between antiretroviral drugs (ARVs) and MQ could contribute to the increased MTCT observed in women receiving MQ, we performed a retrospective cross-sectional analysis of ARV plasma concentrations in peripheral blood (maternal plasma) and cord blood (cord plasma) collected at delivery from 186 mothers participating in a randomized clinical trial of MQ (n = 102) compared with placebo (n = 84) in Kenya. Plasma zidovudine (AZT), lamivudine (3TC), and nevirapine (NVP) concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Although only 4% (7/186) reported not using these ARVs, AZT, 3TC, and NVP were all below the limit of detection in 44% of maternal plasma and 42% of cord plasma samples, and proportions were similar between the two study arms. Median concentrations of AZT and 3TC were not significantly lower in the MQ arm compared with the placebo arm for maternal plasma and cord plasma (p > .05). However, median NVP concentrations were significantly lower in the MQ study arm compared with the placebo study arm in both maternal plasma (1,597 ng/mL vs. 2,353 ng/mL, Mann-Whitney Rank Sum, p = .023) and cord plasma (2,038 ng/mL vs. 2,434 ng/mL, p = .048). Reduced NVP concentrations in maternal and cord plasma of women receiving MQ suggest MQ may affect NVP metabolism for both mother and infant. These results highlight the need to evaluate potential drug-drug interactions between candidate antimalarials and ARVs for use in pregnant women.

Pharmaceutical interactions between antiretroviral and antimalarial drugs used in chemoprophylaxis

Human immunodeficiency virus (HIV) is the causative agent of the Acquired Immunodeficiency Syndrome (AIDS). The pandemic is believed to have originated within the Northern Congo basin covering large parts of the Democratic Republic of Congo, the Republic of Congo, the Central African Republic, Cameroon and Gabon. Although over decades, HIV-1 has spread throughout the World leaving no country unaffected, sub-Saharan Africa remains the region with more than 80% of all infected individuals. The HIV-2 epidemic has largely remained restricted to West Africa along the Upper Guinean forests. Co-incident with these regions of highest HIV distribution is a part of the malaria belt and therefore, co-infections are common. In this review we carve out the consequences of HIV transmission prevention and synchronous malaria prophylaxis during occupational or leisure travelling activities within this World region. In particular, we elaborate on considering pre-existing drug resistances of both, the malaria parasites and the immunodeficiency viruses, when determining a combination for prophylactic and, if necessary, post-expositional measures with a focus on the compatibility of both medications.

Synthesis of zinc-carboxylate metal-organic frameworks for the removal of emerging drug contaminant (amodiaquine) from aqueous solution

We herein report the removal of amodiaquine, an emerging drug contaminant from aqueous solution using [Zn₂(fum)₂(bpy)] and [Zn₄O(bdc)₃] (fum=fumaric acid; bpy=4,4-bipyridine; bdc=benzene-1,4-dicarboxylate) metal-organic frameworks (MOFs) as adsorbents. The adsorbents were characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, and powder X-ray diffraction (PXRD). Adsorption process for both adsorbents were found to follow the pseudo-first-order kinetics, and the adsorption equilibrium data fitted best into the Freundlich isotherm with the R² values of 0.973 and 0.993 obtained for [Zn₂(fum)₂(bpy)] and [Zn₄O(bdc)₃] respectively. The maximum adsorption capacities foramodiaquine in this study were found to be 0.478 and 47.62mg/g on the [Zn₂(fum)₂(bpy)] and [Zn₄O(bdc)₃] MOFs respectively, and were obtained at pH of 4.3 for both adsorbents. FT-IR spectroscopy analysis of the MOFs after the adsorption process showed the presence of the drug. The results of the study showed that the prepared MOFs could be used for the removal of amodiaquine from wastewater.

Inhibition of Plasmodium Hepatic Infection by Antiretroviral Compounds

Recent WHO guidelines on control of human immunodeficiency virus (HIV) call for the widespread use of antiretroviral (AR) therapy (ART) for people living with HIV. Given the considerable overlap between infections by HIV and Plasmodium, the causative agent of malaria, it is important to understand the impact of AR compounds and ART regimens on infections by malaria parasites. We undertook a systematic approach to identify AR drugs and ART drug combinations with inhibitory activity against the obligatory hepatic stage of Plasmodium infection. Our in vitro screen of a wide array of AR drugs identified the non-nucleoside reverse transcriptase inhibitors efavirenz and etravirine (ETV), and the protease inhibitor nelfinavir, as compounds that significantly impair the development of the rodent malaria parasite P. berghei in an hepatoma cell line. Furthermore, we show that WHO-recommended ART drug combinations currently employed in the field strongly inhibit Plasmodium liver infection in mice, an effect that may be significantly enhanced by the inclusion of ETV in the treatment. Our observations are the first report of ETV as an anti-Plasmodial drug, paving the way for further evaluation and potential use of ETV-containing ARTs in regions of geographical overlap between HIV and Plasmodium infections.

Pharmacokinetic interactions between artesunate-mefloquine and ritonavir-boosted lopinavir in healthy Thai adults

Background

Concomitant use of anti-malarial and antiretroviral drugs is increasingly frequent in malaria and HIV endemic regions. The aim of the study was to investigate the pharmacokinetic interaction between the anti-malarial drugs, artesunate-mefloquine and the antiretroviral drug, lopinavir boosted with ritonavir (LPV/r).

Methods

The study was an open-label, three-way, sequential, cross-over, pharmacokinetic study in healthy Thai adults. Subjects received the following treatments: Period 1: standard 3-day artesunate-mefloquine combination; Period 2 (2 months wash-out): oral LPV/r 400 mg/100 mg twice a day for 14 days; and, Period 3: artesunate-mefloquine and LPV/r twice a day for 3 days. Sixteen subjects (eight females) were enrolled and pharmacokinetic parameters were determined by non-compartmental analysis.

Results

In the presence of LPV/r, artesunate C_max and systemic exposure were significantly increased by 45–80 %, while the metabolic ratio of dihydroartemisinin to artesunate was significantly reduced by 72 %. In addition, mefloquine C_max and systemic exposure were significantly reduced by 19–37 %. In the presence of artesunate-mefloquine, lopinavir C_max was significantly reduced by 22 % but without significant change in systemic drug exposure. The 90 % CI of the geometric mean ratio (GMR) of AUC_0−∞ and C_max were outside the acceptable bioequivalent range for each drug. Drug treatments were generally well tolerated with no serious adverse events. Vertigo, nausea and vomiting were the most common adverse events reported.

Conclusion

The reduction in systemic exposure of all investigated drugs raises concerns of an increased risk of treatment failure rate in co-infected patients and should be further investigated.

Does a significant reduction in malaria risk make lopinavir/ritonavir-based ART cost-effective for children with HIV in co-endemic, low-resource settings?

BACKGROUND

HIV infection and malaria co-infection is not uncommon among children in co-endemic regions, and evidence suggests that HIV is a risk factor for severe malaria among children. HIV protease inhibitors (PIs) are highly effective in pediatric HIV treatment regimens, however, their effectiveness against malaria has been mixed, with some PIs demonstrating in vitro activity against Plasmodium falciparum. Recent findings suggest lopinavir/ritonavir (LPV/r)-based treatment regimens reduce the incidence of malaria infection by over 40% in pediatric HIV patients compared to non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens.

METHODS

We assessed whether a significant reduction in malaria risk makes LPV/r-based ART regimens cost-effective compared to NNRTI-based regimens in co-endemic, low-resource settings. We modeled the difference in unit cost per disability adjusted life year (DALY) gained among two theoretical groups of HIV+ children under 5 years old receiving ART in a resource-limited setting co-endemic for malaria. The first group received standard NNRTI-based antiretrovirals, the second group received a standard regimen containing LPV/r. We used recent cohort data for the incidence reduction for malaria. Drug costs were taken from the 2011 Clinton Health Access Initiative Antiretroviral (ARV) ceiling price list. DALYs for HIV and malaria were derived from WHO estimates.

RESULTS

Our model suggests a unit cost of US$147 per DALY gained for the LPV/r-based group compared to US$37 per DALY gained for the NNRTI-based group.

CONCLUSION

In HIV and malaria co-endemic settings, considerations of PI cost effectiveness incorporating known reductions in malaria mortality suggest a nominal increase in DALYs gained for PIs over NNRTI-based regimens for HIV positive children under five on ART. Our analysis was based on several assumptions due to lack of sound data on malaria and HIV DALY attribution among pediatric populations. Further study in this area is required.

Potential P-glycoprotein-mediated drug-drug interactions of antimalarial agents in Caco-2 cells

Antimalarials are widely used in African and Southeast Asian countries, where they are combined with other drugs for the treatment of concurrent ailments. The potential for P-glycoprotein (P-gp)-mediated drug-drug interactions (DDIs) between antimalarials and P-gp substrates was examined using a Caco-2 cell-based model. Selected antimalarials were initially screened for their interaction with P-gp based on the inhibition of rhodamine-123 (Rho-123) transport in Caco-2 cells. Verapamil (100 μM) and quinidine (1 μM) were used as positive inhibition controls. Lumefantrine, amodiaquin, and artesunate all showed blockade of Rho-123 transport. Subsequently, the inhibitory effect of these antimalarials on the bi-directional passage of digoxin (DIG) was examined. All of the drugs decreased basal-to-apical (B-A) P-gp-mediated DIG transport at concentrations of 100 μM and 1 mM. These concentrations may reflect therapeutic doses for amodiaquin and artesunate. Therefore, clinically relevant DDIs may occur between certain antimalarials and P-gp substrates in general.

Unresolved antiretroviral treatment management issues in HIV-infected children

Antiretroviral therapy in children has expanded dramatically in low-income and middle-income countries. The World Health Organization revised its pediatric HIV guidelines to recommend initiation of antiretroviral therapy in all HIV-infected children younger than 2 years, regardless of CD4 count or clinical stage. The number of children starting life-long antiretroviral therapy should therefore expand dramatically over time. The early initiation of antiretroviral therapy has indisputable benefits for children, but there is a paucity of definitive information on the potential adverse effects. In this review, a comprehensive literature search was conducted to provide an overview of our knowledge about the complications of treating pediatric HIV. Antiretroviral therapy in children, as in adults, is associated with enhanced survival, reduction in opportunistic infections, improved growth and neurocognitive function, and better quality of life. Despite antiretroviral therapy, HIV-infected children may continue to lag behind their uninfected peers in growth and development. In addition, epidemic concurrent conditions, such as tuberculosis, malaria, and malnutrition, can combine with HIV to yield more rapid disease progression and poor treatment outcomes. Additional studies are required to evaluate the long-term effects of antiretroviral therapy in HIV-infected infants, children, and adolescents, particularly in resource-limited countries where concomitant infections and conditions may enhance the risk of adverse effects. There is an urgent need to evaluate drug-drug interactions in children to determine optimal treatment regimens for both HIV and coinfections.