•Contrast that situation with the hypothetical ophthalmic eye-drop. The most commoncontainer resin for ophthalmic products ìs LDPE as descrìbed in the European Pharmaco'poeiα (PhEur)6 . As discussed before ,a primary purpose of in-use stabìlity testing is to establìsh that the active ingredients or preservatìve are not degraded by exposure to oxygen while beìng dispensed.LDPE is known to be readily permeable to oxygena 7 ,and ophthalmic containers are ìntentionallyprepared with a 2-5 mL air headspace.This allows the bottle to be more ' squeezable' and helps to ensure that drops are dispensed instead of a 'liquid stream'. In this situation any oxidative degra dation of an active ingredient or preservative due to exposure to oxygen would be readily evident during normal stability studies which extend over 36 months or longer at storageconditions of 25 ℃ ,40 ℃ and possibly 30℃ ,at various humidity conditions.It is not clear what additional stability information the simulation of in-use conditions wonld provide for this type of product.