Too long after the fact now but I would have done the hydrogen peroxide method for vomiting. I'd be on the phone with the Vet. I thought Acutane was taken off the market. One of my docs won't even prescribe it. He says it is like a cancer chemo drug.
Unless the animal is showing signs of distress (not eating, vomiting, refusing to drink, etc.) you should not be too concerned. If you wish, you can call up a local vet and ask advice.
If your dog ate this within the last 1/2 hour or so, then make him vomit. Accutane is a vitamin A product, and I am unsure if it would be OK or not, but make the dog vomit to be on the safe side.
Three percent hydrogen peroxide is quite effective in making dogs and cats vomit. You must be sure to use three percent peroxide and not hair coloring strength peroxide. The appropriate dose of hydrogen peroxide is one teaspoon per 10 pounds of body weight.
Alternatively salt and water would work, but do not use syrup of ipecac.
Actually I think it would be wiser and safer to contact your vet immediately for advice. You could phone them rather than taking your dog in, which would be quicker.