Question
Posted on: March 6 2013A cloudy solution arises in the following preparation, how to avoid? Locoid Lotion 30ml Salicylic acid 900mg Benzalkonium chloride 75mg Aqua 30ml
Answer
Based on the composition of Locoid Lotion and taking into account the insolubility in water of hydrocortisone butyrate, I must conclude that in Locoid Lotion there is very little water in it, given that the lotion is a clear liquid. But you dilute 30 ml of lotion with 30 ml of water and so...
In addition, I doubt that in this diluted medium 1 part Locoid Lotion + 1 part water also salicylic acid is still soluble.
Consequently, I believe that a clear liquid is only possible if you do not dilute with water but with a mixture of water-isopropanol, in which Isopropanol is the main constituent. You can also prepare a suspension and add a small extra amount of PVP (present in Locoid) or of Hydroxypropylcellulose.
In addition, I doubt that in this diluted medium 1 part Locoid Lotion + 1 part water also salicylic acid is still soluble.
Consequently, I believe that a clear liquid is only possible if you do not dilute with water but with a mixture of water-isopropanol, in which Isopropanol is the main constituent. You can also prepare a suspension and add a small extra amount of PVP (present in Locoid) or of Hydroxypropylcellulose.