Active treatment was divided as low dose ( sodium nitrite , 3 % , with citric acid , 4.5 % , creams applied twice daily ) , middle dose ( sodium nitrite , 6 % , with citric acid , 9 % , creams applied once daily at night , with placebo applied in the morning ) , and high dose ( sodium nitrite , 6 % , with citric acid , 9 % , creams applied twice daily ) .