My friend spends part of every conversation try to convince me that her husband is not on drugs, What to say?

Having been a former amphetamine user I feel that he is out doing drugs. What it does sound like is he has a problem with meth-amphetamines maybe cocaine (I say coke because he has to travel out of town to get it meaning not easily acquired locally where amphetamines can be easily manufactured/ meth-amphetamines because of his insomnia during and after use). What you might could do is report him to the authorities because it is going to hurt him and her eventually. He has a problem and definitely should seek help. The mood swings might be from withdrawal when he doesn't have his fix. you can also tell this by the fact that there may be periods where he eats a lot (during withdrawal), and times when he eats very little if not nothing at all(while hes high/coming down).