Concentration Accuracy of Compounded Mitomycin C for Ophthalmic Surgery

Area of Science:

• Ophthalmology
• Pharmaceutical Compounding
• Analytical Chemistry

Background:

• Accurate mitomycin C (MMC) concentrations are crucial for preventing scarring in trabeculectomy surgery.
• The actual concentration and variability of compounded MMC are not well-established.

Purpose of the Study:

• To determine if the measured concentration of ophthalmic MMC differs from the expected 0.4 mg/mL.
• To assess the accuracy and variability of compounded MMC across different preparation and storage methods.

Main Methods:

• A laboratory investigation analyzed 60 samples of 0.4 mg/mL MMC prepared using various compounding and storage techniques.
• High-performance liquid chromatography (HPLC) with a C18 reversed-phase column was used to measure MMC concentrations.
• Calibration curves were generated using pure MMC and sulfanilamide as an internal standard.

Main Results:

• HPLC analysis demonstrated acceptable accuracy (92%-100%) and linearity (r²=0.99) for the method.
• The measured MMC concentration was, on average, 12.5% lower than the expected 0.4 mg/mL (mean [SD], 0.35 [0.04] mg/mL).
• A wide range of MMC concentrations (0.26-0.46 mg/mL) was observed across all samples.

Conclusions:

• Common compounding and storage methods for MMC lead to lower accuracy and greater concentration variability than anticipated.
• Potential causes include compounding techniques and/or MMC degradation.
• This variability may affect glaucoma surgical outcomes, though clinical relevance requires further investigation.