Effectiveness of Antimicrobial Preservation of Extemporaneous Diluted Simple Syrup Vehicles for Pediatrics.

OBJECTIVES: Extemporaneous or magistral formulation of active pharmaceutical ingredients using traditional compounding techniques is a common practice when no commercial form is available for pediatrics. For this vulnerable group of patients, the formulation must be prepared with the minimum quantity and lowest proportion of excipients approved for pediatrics, avoiding the use of preservatives. Often the vehicles used for these preparations are dilutions of simple syrup with water. The objective of this study is to assess the effectiveness of antimicrobial preservation in simple syrup diluted with aqua conservans (conserved water), without propylene glycol or with a reduced proportion of parabens.

METHODS: The European Pharmacopoeia test of efficacy of antimicrobial preservation was applied to 5 trial vehicles prepared with simple syrup diluted with water.

RESULTS: Simple syrup is stable during 14 days. Vehicles prepared with simple syrup diluted with purified water did not meet the microbiological quality criteria, but when they are diluted with water that incorporates propylene glycol and parabens (aqua conservans), then they meet the criteria. In addition, if the water is prepared with parabens and without propylene glycol, the criteria for the dilution are met. Nevertheless, if the dilution is done with water prepared with an insufficient proportion of parabens to act as preservatives, the dilution does not meet the pharmacopoeia microbiological criteria.

CONCLUSIONS: Dilution of simple syrup (50:50 v/v) to prepare a vehicle for extemporaneous or magistral preparation is microbiologically safe when water with methylparaben and propylparaben is used in a proportion of 0.08% and 0.02% (w/w), respectively, avoiding the use of propylene glycol as a solvent and thus its toxic effects in pediatrics.