Small syringes should not be used to mix intracameral antibiotic solutions

This was a prospective study in which nurses from two different hospitals in Glasgow, Scotland tested two different dilution protocols for their accuracy in determining dosage of intracameral antibiotic agents. Analytical grade potassium chloride was used as a surrogate for cefuroxime.  Protocol 1 used a significantly higher amount of a saline in the dilution than Protocol 2 (12.5 mL versus 2.5 mL) and a larger syringe (2.0 mL versus 1.0 mL).

While both protocols were mathematically accurate and conducted under close supervision, only the first protocol had an acceptable range of variability for median dose after dilution (1.173 mg, range=0.616 to 1.773) when compared  to the intended dose of 1.0 mg in 0.1 mL. The median and range of the second protocol was significantly higher (2.05 mg, range= 0.52 to 7.25). The authors believe inadequate mixing in the smaller, 1.0 mL syringe was the most likely cause.

The authors concluded that small syringes should not be used to mix intracameral antibiotic solutions, and they urge clinicians who use homemade intracameral antibiotics to evaluate their protocol using the simple, inexpensive method used in this study to test the accuracy of their intracameral antibiotic preparations.