I claim no knowledge of these drugs, but I have a friend who is on Naltrexone, and it seems to be helping her with cravings? At least, she told me yesterday she had missed three days and was obsessing about drinking. I believe she went home and took the Naltrexone. As for Phenobarbitol, if this is your 4th day you should be pretty well de-toxed. A pint a day is not much compared to many I know who de-toxed for 3 days.
Do speak to your Doctor.