Abstract
BACKGROUND: Ivermectin, an effective treatment for scabies, is not licensed for children weighing <15 kg. Pharmacokinetic modelling has shown a 3 mg dose in young children (2-4 years, weighing 10-14 kg) achieves comparable drug exposure to a 200 μg/kg dose in children aged ≥5 years. This trial evaluated a 3 mg dose in young children. METHODS: Multicentre, phase 2 trial in five health centres in Lao PDR. Children aged 2-4 years, weighing 10-14 kg with scabies received 3 mg ivermectin and had two plasma concentrations determined (Clinicaltrials.gov ID NCT05500326). On day 14, clinical outcomes and adverse effects were assessed, and a second dose given to complete treatment. The primary outcome was the mean plasma ivermectin exposure (AUC(0-∞)) after the first dose (compared to a historical control of Indigenous Australian children aged ≥5 years weighing ≥15 kg receiving 200 μg/kg). Secondary outcomes were clinical improvement and adverse effects. FINDINGS: Overall, 100 children with a median age of 3.0 years (IQR 2.6-3.9) and weight of 11.9 kg (IQR 11.0-13.1) were enrolled. The mean observed ivermectin AUC(0-∞) was comparable to the historical control group aged 5-11 years (815 μg h/L vs 953 μg h/L, p = 0.256). Complete resolution of scabies occurred in 90/99 children by day 14. Adverse effects were mild, occurring in 7/99. INTERPRETATION: A 3 mg ivermectin dose in children aged 2-4 years and weighing 10-14 kg achieved a mean plasma AUC(0-∞) comparable to older children, was highly effective in treating scabies and well tolerated. This study supports extending ivermectin treatment to younger children improving global efforts to control this neglected disease. FUNDING: Project funding provided by a Thrasher Foundation Early Career Research Award.