Primaquine’s Gametocytocidal Efficacy in Malaria Asymptomatic Carriers

Overview

In this study, the investigators are interested to know if lower doses of Primaquine together with dihydroartemisinin-piperaquine can produce a similar effect of clearing both sexual and asexual parasites in asymptomatic carriers compared to the recommended dose of primaquine but with a decreased risk of haemolysis. Children (> 1 year) and adults with normal Glucose-6-phosphate dehydrogenase enzyme levels but with asexual Plasmodium falciparum parasites on the day of screening will be invited to take part in this study.

Full Title of Study: “Primaquine’s Gametocytocidal Efficacy in Malaria Asymptomatic Carriers Treated With Dihydroartemisinin-piperaquine in The Gambia”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: February 2015

Detailed Description

To date, primaquine (PQ), an 8-aminoquinoline, is the only currently registered product able to clear P. falciparum mature gametocytes. However, its use has been and is still limited by its haematological toxicity (haemolytic anaemia), particularly but not exclusively in individuals with glucose-6-phosphate dehydrogenase deficiency (G6PDd), in whom haemolysis can occur after a single PQ dose. Such an effect is dose-dependent. Considering that the current recommended dose was established several decades ago on a small number of experimentally challenged volunteers, it may be possible to obtain the same effect with a lower dose and hence decrease the risk of haemolysis. The proposed study is a four-arm, open label, randomized, controlled trial. G6PD-normal asymptomatic P. falciparum infected individuals identified through population screening will be randomized to receive either a complete course of dihydroartemisinin-piperaquine (DHA-PPQ) alone (control arm) or a complete course of DHA-PPQ plus a single dose of PQ at 3 differing dose strengths (intervention arms), i.e. 0.75mg/kg, 0.4mg base/kg and 0.2mg base/kg. The study is planned to enroll 1,200 individuals with an asymptomatic malaria infection during the rainy /transmission season (June – December) from villages around the MRC's field stations at Walikunda and Basse in The Gambia. Asymptomatic parasite carriers identified by qualitative (RDT) and quantitative (parasites counts >20/µl by slide microscopy) methods during population screening exercises at the villages will be invited for a written informed consent and further screening to confirm eligibility, including tests for qualitative G6PD enzyme function (fluorescence spot test) and haemoglobin. If eligible, they will be assigned to one of four study arms using a block randomization scheme in a 1:1:1:1 ratio ensuring a balance in enrollment between the four groups. Enrolled participants will receive ACT treatment on days 0, 1 and 2. On day 2, participants allocated to the PQ arms will receive a dose of primaquine based on determined body weight. Each participant involvement consists of a maximum of 11 visits over a 42 day period after initiation of treatment. The primary end point is the prevalence of P. falciparum gametocyte carriers at day 7, as determined by QT-NASBA.

Interventions

  • Drug: DHA-PPQ
    • Participants will receive a 3 day course of DHA-PPQ
  • Drug: PQ (0.75)
    • Participants will receive a single dose of PQ at 0.75mg base/kg body weight
  • Drug: PQ (0.4)
    • Participants will receive a single dose of PQ at 0.4mg base/kg body weight
  • Drug: PQ (0.2)
    • Participants will receive a single dose of PQ at 0.2mg base/kg body weight

Arms, Groups and Cohorts

  • Other: Eurartesim (control)
    • All participants will receive a complete course of DHA-PPQ (Eurartesim)
  • Experimental: Primaquine 0.75mg base/kg
    • Participants will be randomized to receive a complete course of DHA-PPQ plus a single dose of PQ at 0.75mg/kg body weight
  • Experimental: Primaquine 0.4mg base /kg
    • Participants will be randomized to receive a complete course of DHA-PPQ plus a single dose of PQ at 0.4mg base/kg Body weight
  • Experimental: Primaquine 0.2mg base/kg
    • Participants will be randomized to receive a complete course of DHA-PPQ plus a single dose of PQ at 0.2mg base/kg body weight

Clinical Trial Outcome Measures

Primary Measures

  • Prevalence of P. falciparum gametocyte carriers (QT-NASBA)
    • Time Frame: Day 7
    • Proportion of study participants in each arm with P. falciparum gametocyte carriers as determined by quantitative nucleic acid sequence based amplification assay (QT-NASBA)

Secondary Measures

  • Prevalence of P.Falciparum gametocytes carriers
    • Time Frame: Days 3, 10, 14, 28 and 42
    • Prevalence of P. falciparum gametocyte carriers on days 3, 10, 14, 28 and 42, as determined by QT-NASBA
  • Proportion of individuals infectious to mosquitoes (DMFA)
    • Time Frame: Day 7
    • % of individuals whose day 7 blood samples when fed to mosquitoes by direct membrane feeding assay
  • Haemoglobin change
    • Time Frame: Day 0 and days 3, 7, 10, 14, 21, 28, 35 and 42
    • Mean (±SD) difference in haemoglobin measured between baseline (day 0) and each follow up visit day by study arm
  • Prevalence of infection (asexual stages)
    • Time Frame: Day 3
    • Proportion of participants carrying asexual forms of P. Falciparum on day 3
  • Proportion of participants with recurrent infection (PCR adjusted and unadjusted)
    • Time Frame: Day 7 to Day 42
    • % of participants previously negative for parasites with detectable parasite (by microscopy and PCR) in samples after day 7
  • Occurrence of adverse events (AEs) and serious adverse events (SAEs)
    • Time Frame: Day 3 to Day 42
    • Occurrence of adverse events (AEs) and serious adverse events (SAEs) during follow up

Participating in This Clinical Trial

Inclusion Criteria

Age ≥1 year

  • Weight >10 Kg – P. falciparum mono-infection, density of at least 20 parasites/μL – Axillary temperature < 37.5ºC – Resident in the study area and willingness to reside for the duration of the study – Written informed consent (plus an assent in children >12years of age) Exclusion Criteria:

  • G6PD Deficiency Haemoglobin <8g/dl – Known allergy to any of the study medications – Known Pregnancy or breastfeeding – Clear/documented history of anti-malarial treatment 2 weeks before contact with study team – History of blood transfusion in the previous 3 months – Any chronic or acute conditions that might interfere with the study as judged by the research clinician – History of sickle cell anaemia

Gender Eligibility: All

Minimum Age: 12 Months

Maximum Age: N/A

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • London School of Hygiene and Tropical Medicine
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Umberto D’Alessandro, MD, PhD, Principal Investigator, MRC Unit, Fajara The Gambia

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