This cylinder is placed over the penis and helps it fill with blood by creating a vacuum. A comfortable band is used at the base of the penis to keep the blood trapped in. Muse is another possibility and goes up to 1000 mcg dose. Try a higher dose before giving up on this product. They also have a tourniquet that keeps the medicine in the penis.
Injectable agents are very effective with minimal pain for most and are fairly easy to learn to use.
FDA approval a Viagra is still pending as of today. Other oral medications are on the way in the near future. There is also a surgical option which invloves placing a device in his penis to allow him to have erections. Such is unlikely to be needed. There is little question that he can regain his erectile ability, the question is what is the cause of his difficulty and what is the best way to help him.