Surface tension as a parameter for controlling drop dispensing of eye drops
An application report on the optimization of medication recipes with the help of tensiometric measurements
The correct dosing of active pharmaceutical ingredients is a challenge when it comes to eye drops. Not only must the concentration of the solution be correct, but also the drop volume must be defined as accurately as possible. After all, the total amount of active ingredient often has to be placed in the eye with a single drop. The dosed volume depends on the diameter of the dosing opening in the drop bottle and on the surface tension (SFT) of the liquid. The bottles are mass-produced, which means that drug manufacturers cannot easily adapt them to suit their own preparations.
Our new application report presents a study from the research literature in which the drop volume correlates exactly with the SFT for a particular opening diameter. This makes it possible to determine the dependency characteristic between drop volume and SFT for any dosing opening with the help of tensiometric measurements. With this knowledge, manufacturers can specifically adjust the drop volume by adding surfactants and thus optimize the dosing of active ingredient.