Have his doctors suggested an SSRI (prozac, lexapro, zoloft, celexa, paxil)? They are a different class of drugs that do not lend themselves to being abused and have been shown to help anxiety. It is something he should ask about.

One book I like about anxiety is by David Burns, MD called "When Panic Attacks." It is not just about panic attacks, it is about other types of anxiety too.

Of course, ideally, he should see a therapist. Is that something he is open to?

Best,
EJ