Piperaquine Population Pharmacokinetics and Cardiac Safety in Cambodia.

Despite the rising rates of resistance to dihydroartemisinin-piperaquine (DP), DP remains a first-line therapy for uncomplicated malaria in many parts of Cambodia. While DP is generally well tolerated as a 3-day DP (3DP) regimen, compressed 2-day DP (2DP) regimens were associated with treatment-limiting cardiac repolarization effects in a recent clinical trial. To better estimate the risks of piperaquine on QT interval prolongation, we pooled data from three randomized clinical trials conducted between 2010 and 2014 in northern Cambodia. A population pharmacokinetic model was developed to compare exposure-response relationships between the 2DP and 3DP regimens while accounting for differences in regimen and sample collection times between studies. A 2-compartment model with first-order absorption and elimination without covariates best fit the data. The linear slope-intercept model predicted a 0.05-ms QT prolongation per ng/ml of piperaquine (5 ms per 100 ng/ml) in this largely male population. Though the plasma half-life was similar in both regimens, peak and total piperaquine exposures were higher in those treated with the 2DP regimen. Furthermore, the correlation between the plasma piperaquine concentration and the QT interval prolongation was stronger in the population receiving the 2DP regimen. Neither the time since the previous meal nor the baseline serum magnesium or potassium levels had additive effects on QT interval prolongation. As electrocardiographic monitoring is often nonexistent in areas where malaria is endemic, 2DP regimens should be avoided and the 3DP regimen should be carefully considered in settings where viable alternative therapies exist. When DP is employed, the risk of cardiotoxicity can be mitigated by combining a 3-day regimen, enforcing a 3-h fast before and after administration, and avoiding the concomitant use of QT interval-prolonging medications. (This study used data from three clinical trials that are registered at ClinicalTrials.gov under identifiers NCT01280162, NCT01624337, and NCT01849640.).

Vanachayangkul P ，Lon C ，Spring M ，Sok S ，Ta-Aksorn W ，Kodchakorn C ，Pann ST ，Chann S ，Ittiverakul M ，Sriwichai S ，Buathong N ，Kuntawunginn W ，So M ，Youdaline T ，Milner E ，Wojnarski M ，Lanteri C ，Manning J ，Prom S ，Haigney M ，Cantilena L ，Saunders D ... -  《-》

Randomized, double-blind, placebo-controlled clinical trial of a two-day regimen of dihydroartemisinin-piperaquine for malaria prevention halted for concern over prolonged corrected QT interval.

Dihydroartemisinin-piperaquine, the current first-line drug for uncomplicated malaria caused by Plasmodium falciparum and Plasmodium vivax in Cambodia, was previously shown to be of benefit as malaria chemoprophylaxis when administered as a monthly 3-day regimen. We sought to evaluate the protective efficacy of a compressed monthly 2-day treatment course in the Royal Cambodian Armed Forces. The safety and efficacy of a monthly 2-day dosing regimen of dihydroartemisinin-piperaquine were evaluated in a two-arm, randomized, double-blind, placebo-controlled cohort study with 2:1 treatment allocation. Healthy military volunteers in areas along the Thai-Cambodian border where there is a high risk of malaria were administered two consecutive daily doses of 180 mg dihydroartemisinin and 1,440 mg piperaquine within 30 min to 3 h of a meal once per month for a planned 4-month period with periodic electrocardiographic and pharmacokinetic assessment. The study was halted after only 6 weeks (69 of 231 projected volunteers enrolled) when four volunteers met a prespecified cardiac safety endpoint of QTcF (Fridericia's formula for correct QT interval) prolongation of >500 ms. The pharmacodynamic effect on the surface electrocardiogram (ECG) peaked approximately 4 h after piperaquine dosing and lasted 4 to 8 h. Unblinded review by the data safety monitoring board revealed mean QTcF prolongation of 46 ms over placebo at the maximum concentration of drug in serum (Cmax) on day 2. Given that dihydroartemisinin-piperaquine is one of the few remaining effective antimalarial agents in Cambodia, compressed 2-day treatment courses of dihydroartemisinin-piperaquine are best avoided until the clinical significance of these findings are more thoroughly evaluated. Because ECG monitoring is often unavailable in areas where malaria is endemic, repolarization risk could be mitigated by using conventional 3-day regimens, fasting, and avoidance of repeated dosing or coadministration with other QT-prolonging medications. (This study has been registered at ClinicalTrials.gov under registration no. NCT01624337.).

Manning J ，Vanachayangkul P ，Lon C ，Spring M ，So M ，Sea D ，Se Y ，Somethy S ，Phann ST ，Chann S ，Sriwichai S ，Buathong N ，Kuntawunginn W ，Mitprasat M ，Siripokasupkul R ，Teja-Isavadharm P ，Soh E ，Timmermans A ，Lanteri C ，Kaewkungwal J ，Auayporn M ，Tang D ，Chour CM ，Prom S ，Haigney M ，Cantilena L ，Saunders D ... -  《-》

Dihydroartemisinin-piperaquine failure associated with a triple mutant including kelch13 C580Y in Cambodia: an observational cohort study.

Dihydroartemisinin-piperaquine has been adopted as first-line artemisinin combination therapy (ACT) for multidrug-resistant Plasmodium falciparum malaria in Cambodia because of few remaining alternatives. We aimed to assess the efficacy of standard 3 day dihydroartemisinin-piperaquine treatment of uncomplicated P falciparum malaria, with and without the addition of primaquine, focusing on the factors involved in drug resistance. In this observational cohort study, we assessed 107 adults aged 18-65 years presenting to Anlong Veng District Hospital, Oddar Meanchey Province, Cambodia, with uncomplicated P falciparum or mixed P falciparum/Plasmodium vivax infection of between 1000 and 200,000 parasites per μL of blood, and participating in a randomised clinical trial in which all had received dihydroartemisinin-piperaquine for 3 days, after which they had been randomly allocated to receive either primaquine or no primaquine. The trial was halted early due to poor dihydroartemisinin-piperaquine efficacy, and we assessed day 42 PCR-corrected therapeutic efficacy (proportion of patients with recurrence at 42 days) and evidence of drug resistance from the initial cohort. We did analyses on both the intention to treat (ITT), modified ITT (withdrawals, losses to follow-up, and those with secondary outcomes [eg, new non-recrudescent malaria infection] were censored on the last day of follow-up), and per-protocol populations of the original trial. The original trial was registered with ClinicalTrials.gov, number NCT01280162. Between Dec 10, 2012, and Feb 18, 2014, we had enrolled 107 patients in the original trial. Enrolment was voluntarily halted on Feb 16, 2014, before reaching planned enrolment (n=150) because of poor efficacy. We had randomly allocated 50 patients to primaquine and 51 patients to no primaquine groups. PCR-adjusted Kaplan-Meier risk of P falciparum 42 day recrudescence was 54% (95% CI 45-63) in the modified ITT analysis population. We found two kelch13 propeller gene mutations associated with artemisinin resistance--a non-synonymous Cys580Tyr substitution in 70 (65%) of 107 participants, an Arg539Thr substitution in 33 (31%), and a wild-type parasite in four (4%). Unlike Arg539Thr, Cys580Tyr was accompanied by two other mutations associated with extended parasite clearance (MAL10:688956 and MAL13:1718319). This combination triple mutation was associated with a 5·4 times greater risk of treatment failure (hazard ratio 5·4 [95% CI 2·4-12]; p<0·0001) and higher piperaquine 50% inhibitory concentration (triple mutant 34 nM [28-41]; non-triple mutant 24 nM [1-27]; p=0·003) than other infections had. The drug was well tolerated, with gastrointestinal symptoms being the most common complaints. The dramatic decline in efficacy of dihydroartemisinin-piperaquine compared with what was observed in a study at the same location in 2010 was strongly associated with a new triple mutation including the kelch13 Cys580Tyr substitution. 3 days of artemisinin as part of an artemisinin combination therapy regimen might be insufficient. Strict regulation and monitoring of antimalarial use, along with non-pharmacological approaches to malaria resistance containment, must be integral parts of the public health response to rapidly accelerating drug resistance in the region. Armed Forces Health Surveillance Center/Global Emerging Infections Surveillance and Response System, Military Infectious Disease Research Program, National Institute of Allergy and Infectious Diseases, and American Society of Tropical Medicine and Hygiene/Burroughs Wellcome Fund.

Spring MD ，Lin JT ，Manning JE ，Vanachayangkul P ，Somethy S ，Bun R ，Se Y ，Chann S ，Ittiverakul M ，Sia-ngam P ，Kuntawunginn W ，Arsanok M ，Buathong N ，Chaorattanakawee S ，Gosi P ，Ta-aksorn W ，Chanarat N ，Sundrakes S ，Kong N ，Heng TK ，Nou S ，Teja-isavadharm P ，Pichyangkul S ，Phann ST ，Balasubramanian S ，Juliano JJ ，Meshnick SR ，Chour CM ，Prom S ，Lanteri CA ，Lon C ，Saunders DL ... -  《-》

Efficacy of two versus three-day regimens of dihydroartemisinin-piperaquine for uncomplicated malaria in military personnel in northern Cambodia: an open-label randomized trial.

Lon C ，Manning JE ，Vanachayangkul P ，So M ，Sea D ，Se Y ，Gosi P ，Lanteri C ，Chaorattanakawee S ，Sriwichai S ，Chann S ，Kuntawunginn W ，Buathong N ，Nou S ，Walsh DS ，Tyner SD ，Juliano JJ ，Lin J ，Spring M ，Bethell D ，Kaewkungwal J ，Tang D ，Chuor CM ，Satharath P ，Saunders D ... -  《PLoS One》

Dihydroartemisinin/Piperaquine: a review of its use in the treatment of uncomplicated Plasmodium falciparum malaria.

Keating GM 《-》