For healthcare professionals

Not all PGA eye drops are the same

The European Glaucoma Society (EGS) states that: “Generic drops can differ from brand drops, and it may be necessary to monitor patients more closely after switching”. 9

Generics must be `bioequivalent' to the branded reference product, in order to gain marketing authorisation. The European Medicines Agency (EMA) considers a range of 80% to 125% active to be bioequivalent.

They don't have to prove efficacy or tolerability in clinical studies.

There is variability of active ingredient concentration, excipients (preservatives, phosphates), pH, osmolarity, viscosity, bottles, drop size, drop volume, etc.10

Reason

Impact

Bioequivalence

Only tested within a range, with no confirmed efficacy, therapeutic equivalence or tolerability4

Excipients

Differences between formulations affect penetration, absorption, retention time in the eye, bioavailability, viscosity, osmolarity and tolerability4

Container design

Packaging variations between manufacturers affect drop size, ease of administration and stability

Preservatives

Contributes to adverse events in susceptible patients

Drug content

Significant variations in the stability of latanoprost have been recorded9