a large part was due to cost concern.
because most docs bought the preservative free formulations from compounding pharmacies as a cost savings measure.
the drug implicated was preservative free methylprednisolone.
previously, you could purchase "preservative free" methylprednisolone directly from the drug company but it was quite expensive. this system did purchase it initially after a similar contaminated steroid scare in 2002.
the contaminated compounded steroids were preservative free. and dirt cheap, pun intended.
(for newbies, as this is a rehash of past posts, you could and can purchase preservative free dexamethasone, but preservative free dexamethasone does have preservatives - namely, citric acid, which is not labeled as a preservative but as a food additive by the FDA).