Postpartum 8-aminoquinoline Breast Milk Study

In Papua New Guinea, administration of primaquine (PQ) or tafenoquine (TQ) to breastfeeding mothers is contraindicated during the first six months postpartum, when infants are recommended to be exclusively breastfed, because of a lack of comprehensive pharmacokinetic data on PQ/TQ neonatal and infant exposure via breast milk. The therapeutic restriction of PQ/TQ use in lactating women during the first six months postpartum effectively translates into \~10% of females being excluded from radical cure in endemic areas at any time. This is because many at risk women live in remote areas, are frequently lost to follow-up, or may have conceived again before they reattend. As a result, radical cure is rarely achieved and women are exposed to recurrent infections and cumulative risk of anaemia. Relapses may occur for years, placing subsequent pregnancies at risk and perpetuating intergenerational failure of fetal growth. They also contribute to malaria transmission, thus household and community exposure to vivax malaria.

The goal of the present study is to determine how much PQ/TQ is transferred to a suckling baby, if a mother receives a treatment course of PQ/TQ at time of delivery. We also want to confirm that this treatment is safe and has no major side effects for babies in Papua New Guinea.

The study Interventions areas follows: Group 1 - Participants receive PNG standard of care; PQ given 6-months postpartum; Group 2 - Participants receive a 14-day treatment regimen of PQ, at the standard dose prescribed in PNG for vivax radical cure (0.5 mg/kg/day for 14 days); Group 3 - Participants receive an accelerated high-dose 7-day treatment regimen of PQ, as per current WHO recommendations (1.0 mg/kg/day for 7 days); Group 4 - Participants receive a single dose of 300mg tafenoquine.

All participants will be monitored for a total duration of 6 months, with the safety, tolerability, pharmacokinetics and preliminary relapse efficacy of PQ/TQ evaluated at standardised time points over this period (Day 0, 1, 3, 6, 8, 15, 20, 28, and Month 2, 3, 4, 5 and 6). At each of these time points, participants will be asked to describe any symptoms they may be experiencing, participate in a medical examination, and provide a blood and breast milk sample for drug analysis and safety (biochemistry and haematology testing). The investigators will also collect a small blood sample (heel prick) from the infant to measure drug concentrations and safety testing.