My pharmacist explained how some of these drugs are so outrageous. We had one prescribed that was a combination of two OTC medicines. Should be cheap right, a 1 month supply was $3,000 and not covered by insurance because it was a combination of two OTC drugs.
Enter govt regulations; they have some kind of compliance which drug makers have to comply with which effect pricing. By making this rarely prescribed medicine $3,000 they improve their average according to some formula.