This is a very good question.
The short answer is that from a strictly pharmacological point of
view, is that either 50mg or 100mg, or, for that matter, 150mg doses of naltrexone can be taken in one dose; and what time of day matters not at all.
While the usual dose of naltrexone is 50 mg per day, there is
anecdotal evidence that higher doses of 100 mg or even 150 mg are
effective in relieving craving in cases where the 50 mg dose was
ineffective or only partially effective. For example, read the story of
Moderation Management member "Netty"
who got a better result from a higher dose:
So, doses higher than 50 mg per day are sometimes used and it is interesting
to note, in this regard, that before we used naltrexone for alcohol problems, we had
several decades of experience using it in the treatment of opiate (mostly heroin) dependence. When used for that purpose, and when strict monitoring, that is
watching the patient take the medication, is crucial (for example, MD's who were addicted to opiates and who were only permitted to continuing working if we were positive they were taking their naltrexone) we routinely gave naltrexone 3 times a week as follows:
Monday --> 100 mg, Wednesday --> 100 mg, Friday --> 150 mg
In a hectic environment like a hospital, only having to supervise
naltrexone ingestion three times a week was a whole lot easier than
arranging for daily supervision. This schedule also provided good opiate
receptor blockade throughout the week because naltrexone, when taken
regularly, remains effective for about 72 hours after the last dose.
The point is that MD's in supervised settings routinely take 150 mg
doses of naltrexone, and I am not aware of any harm that ever came to anyone using this dosing schedule.
The reason that what time of day the naltrexone is taken doesn't really matter has to do with the pharmaco-dynamics of "steady state blood levels,"
which means that if you keep taking a drug regularly you achieve steady state blood levels and missing a dose by half a day or even an entire day matters less than one might expect.
In the case of naltrexone, taking 50 mg daily or 100 mg daily or three times a week as outlined above will all give you good opiate receptor blockade, which is presumably why it helps with craving.
However, psychologically speaking, I think that what time of day
can make a difference for certain people. For example, taking the naltrexone
is, to a greater or lesser extent, a symbolic act. If you take you
naltrexone in the morning in the presences of your spouse you are making a
statement: "I am taking this action (swallowing this pill) because I want to do everything I can to successfully moderate my alcohol intake
or abstain from alcohol today." Even if you are taking it alone, as opposed to in the presence of a loved one, you are consciously or unconsciously making this statement to yourself.
To the extent that such powerful symbolic acts are easier and more appropriately
done in the morning with breakfast as opposed to in the evening with dinner when you are tired and worn out from the day's events; to this extent, it is probably better for most people to take their naltrexone in one dose in the morning every day.
Again, thank you for this excellent question; thank you. I hope I've answered it to your satisfaction.
Alexander DeLuca, M.D.