The same thing happened for a while with asthma inhalers. HFA propellant requirements took the OTC Primatine Mist off the shelves and despite promises that cheap inhalers and OTC HFA inhalers would appear in a couple of years, big pharma reformulated the propellant every 10 years to keep it perpetually under patent. Primatine had to develop and patent their own HFA to return to the OTC market.

Incidentally, asthma inhalers are kind of a directed epi and do help with anaphylaxis in the lungs. For example, Fel-D-1 is a common protein in cat saliva that can trigger anaphylaxis in asthmatics. For me, I also get red eyes and congestion with sneezing along with gasping for breath. Dogs produce less allergens for me, but I definitely notice when they haven't been bathed in a while. Dogs may be more of a fur allergy than saliva, cats are definitely saliva.