Danny,
So I assume your trying to make an assumption that these problems are caused by men using propecia and an asthma medication. Sorry, but you are terribly wrong. The loss of sensation in the penis during sex is directly caused by propecia. I have this problem and have never taken any other medications.
Read through some of the posts. There are hundreds of men here that experienced this problem and they are not using asthma medications. I’m sure Mew or someone else could give you a medical description of what hormones are blocked to cause this.