If I may interject,
SDN1977, you have a "clue." Pharmacy needs more people like you and Kwizard
Zpack - thank you!! I think, however, it has more to do with experience in which we gain knowledge beyond that which is found in books.
WVU - sorry...I don't think its as simple as you described in drugs A & B. It involves not only efficacy or spectrum, but also other factors which have nothing apparently to do with the drug itself.
For example...."bundling" of medications can affect which choice of drug you allow on the formulary. Lets say drug A & B are in the same class - ciprofloxacin & levofloxacin. Drug a (ciproflox..) is cheaper if bought independently. However, the wholesaler might "bundle" the purchase of famotidine with levofloxacin. If a certain amount of famotidine is purchased, the levofloxacin is cheaper. These are unrelated drugs...but this is not an uncommon scenario...which may generate usage of an apparently more expensive drug, altho it is cheaper due to wholesaler agreements.
In my situation - when my hospital was purchased, we became one of 6 hospitals located in 3 west coast states. Our drug purchases & formulary became influenced by the contractual agreements already in place with the prior 5 hospitals. Because of this, we changed many of our formulary drugs.
Likewise...one thing which is often overlooked by pharmacists is the actual "cost" of IV tubing. Hositals, generally, do not purchase IV pumps - they are given without cost. However, the cost is recouped by the price of the tubing. If you have a drug which requires its own, dedicated tubing, or is given so frequently that another drug cannot reasonably be administered thru that tubing, you now increase your cost to the facility - usually far beyond the actual price of the drugs administered thru said tubings.
I could go on and on and on....bottom line - pharmacists need to be on the P&T committees & each medical subcommittee to provide not just pharmacologic info (which most physicians already know), but to also provide an economic perspective they have no way of knowing.
Aaaaaah - where is Caverject - I go on tooooooo long
!