Question
Posted on: March 6 2013I would like to have obtained your advice in connection with the following preparation.
Folcodine 300 mg Promethazine 300 mg ascorbic acid 600 mg sodium benzoate 2 g codeine syrup 100 g, Tolusyrup AD 200 ml < br/> precipitation occurs. What beats (benzoic acid, promethazine)? How can precipitation be prevented?
Answer
The possibilities you propose yourself and a pH measurement may bring us near the solution. If it is not acidic then the amount of ascorbic acid should be increased to a pH 4 to 5 obtained. If these are very acidic eg = 3 then presumably benzoeic acid is precipitated and the amount of ascorbic acid should be reduced. I suspect the first scenario but the pH measurement should confirm this.