Mass variability in drops of multidose eyedrops: a quality and reliability study.

Purpose: This quality and reliability study aimed to identify the mass variability of multidose eyedrops and to verify the existence of a reference pattern for the drop volume of eyedrops using standard lubricant eyedrops available on the Brazilian market.

Methods: Five brands of lubricant eyedrops were evaluated. An ideal standard 20 µL drop of eyedrops from each manufacturer was captured using an adjustable micropipette. The eyedrop bottles were randomly selected, and five measurements of the samples' masses were collected using calibrated precision scales.

Results: The mass of the 20 µL samples varied significantly (p<0.001) among the different manufacturers. However, among eyedrops of the same brand, mass variation was not statistically different. The global mean mass of all weighed drops was 18.24 mg, and non-uniformity was identified across all eyedrop brands.

Conclusion: Significant variations in the drop masses of common lubricant eyedrops were identified using standard laboratory equipment. Heterogeneity in the drop volume of standard eyedrop medications suggest that potential dosage discrepancies exist, possibly altering treatment efficacy. A pre-established reference measure may lead to the production of more appropriately sized eyedrops for use in human eyes.