Incompatibility of Y-site-administered drugs: the case of acyclovir and ciprofloxacin

Abstract Objectives Multiple drug administration is a common practice in hospitals and clinics. This is the case when multiple pathologies are treated. In this context, frequently, antivirals and antibiotics are co-administrated either simultaneously or sequentially ignoring potential incompatibilities. In this study, we focused on an antiviral (acyclovir) and an antibiotic (ciprofloxacin) compatibility/incompatibility when they are co-administrated. Methods In this study, we focused on the effect of drug ratio, pH, and delay by implementing robust high-performance liquid chromatography methods to determine the main factors leading to potential modification of concentration of one of the two drugs in the mixture. Key findings The results showed that acyclovir is quantitatively recovered in all conditions related to pH, concentration, and time (up to 24 hours). However, ciprofloxacin is strongly altered depending on the acidic and basic conditions, the quantity of ciprofloxacin used, and the time after mixing the two drugs. The most valuable piece of information is that the ratio of acyclovir/ciprofloxacin is crucial. Conclusions The volume ratio of acyclovir/ciprofloxacin (prepared at 2 mg/ml each) should be calculated and managed to provide at least two-fold quantity of acyclovir versus ciprofloxacin or at least nine-fold quantity of ciprofloxacin versus acyclovir to maintain the administrated doses and prevent physicochemical interactions.