Assessing the accuracy of intracameral antibiotic preparation for use in cataract surgery.
OBJECTIVE
To evaluate 2 local dilution protocols to assess the accuracy and variability of intracameral antibiotic dosage in cataract surgery.


METHODS
Tennent Institute of Ophthalmology, Glasgow, United Kingdom.


METHODS
Ten ophthalmic operating room nurses from 2 local hospitals participated. Oven-dried analytical grade potassium chloride (KCl) was used as a surrogate for cefuroxime. Solutions intended for intracameral use (1.0 mg in 0.1 mL) were prepared according to the 2 protocols. Twenty samples were obtained for each protocol. Ten analytical chemists also performed both dilutions. Concentrations of KCl in each 0.1 mL sample were analyzed by flame photometry.


RESULTS
Thirty samples were obtained for each protocol. The median dose after dilution was 1.17 mg (range 0.62 to 1.77 mg) for protocol 1 and 2.05 mg (range 0.52 to 7.25 mg) for protocol 2. The median was significantly higher for protocol 2 (P < .001). There was also greater variability with protocol 2.


CONCLUSIONS
This study shows that the mathematical accuracy of a dilution protocol does not ensure dosage accuracy in the clinical scenario. Inadequate mixing in a 1.0 mL syringe was probably responsible for the inaccuracy of protocol 2, indicating that small-volume syringes should not be used for mixing. However, protocol 1 had an acceptable range of variability. Replication of this study could evaluate other protocols and address concerns regarding the accuracy of intracameral antibiotic preparations.
Lockington
David
D
Tennent Institute of Ophthalmology, Gartnavel General Hospital, 1053 Great Western Road, Glasgow, G12 0YN, United Kingdom. davidlockington@hotmail.com
Flowers
Hugh
H
Young
David
D
Yorston
David
D
D000867:Anterior Chamber / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000592:standards*; D002387:Cataract Extraction; D002626:Chemistry, Pharmaceutical; D004339:Drug Compounding / Q000592:standards*; D054796:Drug Dosage Calculations; D009877:Endophthalmitis / Q000517:prevention & control; D015818:Eye Infections, Bacterial / Q000517:prevention & control; D006801:Humans; D011183:Postoperative Complications / Q000517:prevention & control; D011189:Potassium Chloride; D015203:Reproducibility of Results
D000900:Anti-Bacterial Agents; D011189:Potassium Chloride