Artemether-lumefantrine versus artemisinin-naphthoquine in Papua New Guinean children with uncomplicated malaria: a six months post-treatment follow-up study

Artemisinin-naphthoquine plus lower-dose primaquine to treat and prevent recurrence of Plasmodium vivax malaria: an open-label randomized and non-inferiority trial

BACKGROUND

Plasmodium vivax malaria, with the widest geographic distribution, can cause severe disease and death. Primaquine is the main licensed antimalarial drug that can kill hypnozoites. The dose-dependent acute haemolysis in individuals with glucose-6-phospate dehydrogenase (G6PD) deficiency is the main safety concern when using primaquine. The recommended treatment regimen for P. vivax malaria is chloroquine plus primaquine for 14 days (CQPQ14) in Myanmar. The study aimed to evaluate the therapeutic efficacy, safety and adherence for the regimen of artemisinin-naphthoquine plus primaquine for 3 days (ANPQ3) in patients with P. vivax infections compared to those with CQPQ14.

METHODS

The patients in the ANPQ3 group were given fixed-dose artemisinin-naphthoquine (a total 24.5 mg/kg bodyweight) plus a lower total primaquine dose (0.9 mg/kg bodyweight) for 3 days. The patients in the CQPQ14 group were given a total chloroquine dose of 30 mg/kg body weight for 3 days plus a total primaquine dose of 4.2 mg/kg bodyweight for 14 days. All patients were followed up for 365 days.

RESULTS

A total of 288 patients completed follow-up, 172 in the ANPQ3 group and 116 in the CQPQ14 group. The first recurrence patients were detected by day 58 in both groups. By day 182, 16 recurrences had been recorded: 12 (7.0%) patients in the ANPQ3 group and 4 (3.4%) in the CQPQ14 group. The difference in recurrence-free patients was 3.5 (-8.6 to 1.5) percentage points between ANPQ3 and CQPQ14 group (P = 0.2946). By day 365, the percentage of recurrence-free patients was not significant between the two groups (P = 0.2257). Mean fever and parasite clearance time of ANPQ3 group were shorter than those in CQPQ14 group (P ≤ 0.001). No severe adverse effect was observed in ANPQ3 group, but five (3.9%) patients had acute haemolysis in CQPQ14 group (P = 0.013). Medication percentage of ANPQ3 group was significantly higher than that of CQPQ14 group (P < 0.0001).

CONCLUSIONS

Both ANPQ3 and CQPQ14 promised clinical cure efficacy, and the radical cure efficacy was similar between the ANPQ3 and CQPQ14 group. ANPQ3 clears fever and parasites faster than CQPQ14. ANPQ3 is safer and shows better patient adherence to the regimen for treatment of P. vivax malaria along the China-Myanmar border.

TRIAL REGISTRATION

ChiCTR-INR-17012523. Registered 31 August 2017, https://www.chictr.org.cn/showproj.html?proj=21352.

Evaluation of the Combination of Azithromycin and Naphthoquine in Animal Malaria Models

Combination therapy using drugs with different mechanisms of action is the current state of the art in antimalarial treatment. However, except for artemisinin-based combination therapies, only a few other combinations are now available. Increasing concern regarding the emergence and spread of artemisinin resistance in Plasmodium falciparum has led to a need for the development of new antimalarials. Moreover, the efficacy of current available chemoprophylaxis is compromised by drug resistance and noncompliance due to intolerable adverse effects or complicated dosing regimens.

Artemisinin-naphthoquine combination: A directly observed treatment option in malaria

Resistance to standard antimalarials has led to the need for newer options. Artemisinin-based combination therapies (ACTs), which require a tedious three-day treatment schedule, have been introduced for the treatment of drug-resistant malaria. Of late, the new generation artemisinin-naphthoquine (ANQ) combination has been developed, which requires a single dose treatment. Artemisinin initiates the action through the cleavage of the endoperoxide bridge while naphtoquine maintains the process by getting concentrated in the digestive vacuole of the parasite. One ANQ tablet contains 50 mg naphthoquine and 125 mg of artemisinin in the ratio of 1:2.5. The optimal dosage in adults is 400 mg of naphthoquine and 1000 mg artemisinin; which amounts to 8 tablets in a single dose. The dosage for children is adjusted based on the body-weight. The combination has been found to be quite effective with and safe. Studies have demonstrated an adequate clinical and parasitologic response of 98.1-100% in both adults and children. However, further trials are required to confirm its non-inferiority with other ACTs. Adverse reactions with ANQ have been mild. Further studies are needed before safety can be established during pregnancy. ANQ increases the compliance rates because of single dosage. It may be administered by the peripheral health workers as a directly observed therapy, which would be of special benefit to troops in the North-Eastern Sector.

Risk factors for Plasmodium falciparum and Plasmodium vivax gametocyte carriage in Papua New Guinean children with uncomplicated malaria

There are limited data on gametocytaemia risk factors before/after treatment with artemisinin combination therapy in children from areas with transmission of multiple Plasmodium species. We utilised data from a randomised trial comparing artemether-lumefantrine (AL) and artemisinin-naphthoquine (AN) in 230 Papua New Guinean children aged 0.5-5 years with uncomplicated malaria in whom determinants of gametocytaemia by light microscopy were assessed at baseline using logistic regression and during follow-up using multilevel mixed effects modelling. Seventy-four (32%) and 18 (8%) children presented with P. falciparum and P. vivax gametocytaemia, respectively. Baseline P. falciparum gametocytaemia was associated with Hackett spleen grade 1 (odds ratio (95% CI) 4.01 (1.60-10.05) vs grade 0; P<0.001) and haemoglobin (0.95 (0.92-0.97) per 1g/L increase; P<0.001), and P. falciparum asexual parasitaemia in slide-positive cases (0.36 (0.19-0.68) for a 10-fold increase; P=0.002). Baseline P. vivax gametocytaemia was associated with Hackett grade 2 (12.66 (1.31-122.56); P=0.028), mixed P. falciparum/vivax infection (0.16 (0.03-1.00); P=0.050), P. vivax asexual parasitaemia (5.68 (0.98-33.04); P=0.053) and haemoglobin (0.94 (0.88-1.00); P=0.056). For post-treatment P. falciparum gametocytaemia, independent predictors were AN vs AL treatment (4.09 (1.43-11.65)), haemoglobin (0.95 (0.93-0.97)), presence/absence of P. falciparum asexual forms (3.40 (1.66-0.68)) and day post-treatment (0.086 (0.82-0.90)) (P<0.001). Post-treatment P. vivax gametocytaemia was predicted by presence of P. vivax asexual forms (596 (12-28,433); P<0.001). Consistent with slow P. falciparum gametocyte maturation, low haemoglobin, low asexual parasite density and higher spleen grading, markers of increased prior infection exposure/immunity, were strong associates of pre-treatment gametocyte positivity. The persistent inverse association between P. falciparum gametocytaemia and haemoglobin during follow-up suggests an important role for bone marrow modulation of gametocytogenesis. In P. vivax infections, baseline and post-treatment gametocyte carriage was positively related to the acute parasite burden, reflecting the close association between the development of asexual and sexual forms.

A systematic review of the efficacy of a single dose artemisinin-naphthoquine in treating uncomplicated malaria

Background

This study aimed to synthesize the existing evidence on the efficacy and safety of a single dose artemisinin–naphthoquine (ASNQ) for treatment of uncomplicated malaria in endemic countries.

Methods

A meta-analysis of randomized, controlled trials (RCT), assessing efficacy and safety of single dose ASNQ was carried out. Comparator drugs included artemether–lumefentrine (AL), chloroquine plus sulfadoxine-pyrimethamine (CQSP) and dihydroartemisinin–piperaquine (DHP). The efficacy and safety profile of non-comparator, single-arm studies on the single dose ASNQ was also assessed. The primary endpoint was efficacy defined as an absence of PCR-confirmed parasitaemia. The methodological quality of the included studies was assessed using the six domains for the risk of bias.

Results

Five RCTs and three single-arm studies were included in this review. As RCT studies did not compare the same anti-malarial drugs, it was difficult to do a pooled analysis. At day 28, a pooled analysis of two RCTs (n = 271) showed a comparable efficacy on PCR-confirmed parasitaemia between ASNQ and AL. Another RCT, which compared ASNQ and CQSP or ASNQ and DHP, also showed comparable efficacy. At day 42, one RCT comparing ASNQ and DHP and another RCT comparing ASNQ and AL reported comparable levels of efficacy. The proportion of parasite clearance was faster in the ASNQ groups than the comparators at day 1, and almost all parasites were cleared by day 3 in the ASNQ groups.

Conclusions

The present review provides some evidence to support that there is similar efficacy and safety of the single dose ASNQ compared to other anti-malarial drugs in treating uncomplicated malaria. Larger, adequately powered, well-designed studies are recommended to substantiate the efficacy and safety in different populations and in different epidemiological settings. As the potential evolution of drug resistance is a great concern and this cannot be addressed in a short-term study, the use of single dose ASNQ needs further evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0919-5) contains supplementary material, which is available to authorized users.