Add 17 ml of water for injection to the vial containing 6.36 g of sodium benzylpenicillin. Shake the vial to dissolve the powder in the water. This provides 21 ml of a solution for injection with a concentration of 300 mg/ml. When the solution turns clear, it is ready for use. Give 10-20 mg/kg bodyweight by slow intravenous injection, equivalent to 3.3-6.7 ml/100 kg bodyweight, twice daily, for at least four days.