Benzathine Penicillin G (BPG) has been used as a prophylactic agent against Group A Streptococcal (GAS) infections for over 50 years. Recurrent and untreated GAS infections can lead to the development of Acute Rheumatic Fever and Rheumatic Heart Disease with lifelong impact. Māori and Pacific children have higher rates of ARF and RHD. Painful monthly injections of BPG maintain a protective level of Penicillin in the body protecting against GAS infections. These injections are given for at least 10 years or more. Early Pharmacokinetic studies focused on findings in fit young men without ARF or RHD. This project will explore the pharmacokinetics of BPG and the current state of knowledge the is needed to help inform global efforts to reformulate BPG and make a more appropriate version for use in children and young people for ARF/RHD prevention.