The suitability of some preservatives in chloroquine phosphate syrup

In Third World countries chloroquine phosphate syrup is frequently prepared with chloroform as a preservative. Because of the toxic side effects of chloroform the suitability of a number of possible alternatives were investigated. If the chloroquine phosphate syrup is prepared as such, the combination of sorbic acid (1.5 g/l) and citric acid (2 g/l) is preferred. If, however, the chloroquine phosphate syrup is prepared from a stock solution of simple syrup, the relatively low pH may be undesirable, because it may negatively affect the stability or solubility of other medicinal compounds. For a stock solution of simple syrup the combination of methyl paraben (1.8 g/l) and propyl paraben (0.2 g/l) is preferred. Good care must be taken that a layer of condense water cannot be formed.