How is it that aminophylline in codeine syrup does not, but in Codeïnoformsyrup does green color? Does this mean that the active operation disappears due to instability?

Codeïnoform contains beside two flavours, which are to mimic the bromoform, also liquid klaproos extract. This extract contains several colored compounds and is supposedly responsible for the discoloration. This could be confirmed by making a syrup with the same amount of liquid extract. After dilution with water (to better perceive color change), Aminophylline was added to this syrup. And effectively the reddish purple color struck to a blue-green color. I do not suspect that this colour cover has any influence on the activity. But maybe Green-purple is not an attractive colour? But I have found that adding citric acid again makes the color turn to red purple. The amount of citric acid to be added must be tried, taking into account that Aminophylline is converted to theophylline, which possesses a lesser water solubility and can therefore precipitate from a certain concentration. Another possibility exists in the preparation of a codeine syrup with a codeine content as in the Codeïnoform and this without Klaproos extract possibly also without the aromas.