what saline do i buy to dilute albuterol?

basically my husband has bronchitis and was prescribed albuterol sulfate inhalation solution with a dropper. but for some reason the doctor didn't mention anything about us needing to dilute it. so I legit have him half ml of the albuterol and when he said it didn't affect him like the one in the hospital did and legit was so little it lasted a minute of usage; he used mine while we waited for his, mine are vials that are already diluted and he said he got the same feeling as the one in the hospital. mine was working for him. but I spent $15 on his medicine and I am not letting my money go to waste soooo i was wondering if anyone knew which saline I need to dilute it with cuz I heard about saline for eyes and saline for nose, I just need the one for inhalation

BTW I have albuterol solution in the first place cuz I have asthma.