My son had a similar experience with a drug that went to $170 per month. I found one solution for that particular drug through a website, which generated a coupon, lowering the cost to <$30 for a 3 months supply. Google Goodrx. I don't want to seem like I'm plugging it, but it worked for us.
I have been printing coupons from Goodrx for several months and it does work. Save >$100/month on one of my medications. The whole thing seems to be too good to be true but no problems with it so far. In fact, my clinic has started to recommend to other patients that they use the service.
GoodRx blog a handy source of news on prescription drugs
Note - I have no affiliation with the Self-Pay Patient blog other than I find it a useful and helpful source of info.