Baros 2007: taking naltrexone reliably and how well it works

What they tested

In the original trial, 160 patients got naltrexone or a placebo (a dummy pill) plus either cognitive behavioral therapy (CBT), which teaches skills to avoid drinking, or motivational enhancement therapy (MET), which builds motivation to change. Of them, 137 completed the 12 weeks.

Pill-taking was measured two ways at once: a urine test for riboflavin (a vitamin) in weeks 2, 6 and 12, and a pill bottle cap that recorded every time the bottle was opened. The team compared results in people judged compliant by one method, the other, or both, with the original analysis that ignored pill-taking.

What they found

Using the urine test (riboflavin of 1,500 ng/mL or more), 105 people counted as compliant. Using the bottle cap (80% of openings), 87 did, and 77 met both. Compliance didn't differ significantly between treatment groups, and older age predicted better compliance.

In the most compliant patients, the combination of naltrexone and CBT stood out: more abstinent days, fewer heavy drinking days and fewer total drinks than the other groups (p<0.03 for each).

The size of that effect grew from about 0.2 in the analysis of everyone randomized to about 0.4 to 0.5 in the compliant groups. The two ways of measuring pill-taking gave similar results.

Limits

• The compliant groups weren't randomized. People who take their pills reliably may differ in other ways that also affect drinking.
• The benefit appeared in one specific pairing, naltrexone with CBT, and not in naltrexone overall.
• It is a single trial of 160 people, and only 137 completed the 12 weeks.

What it means if you're considering naltrexone

For someone starting naltrexone, the practical message is that it can only work if it's taken. In this trial, the people who took it consistently alongside CBT saw roughly double the benefit of the group as a whole.

The authors called for more attention to ways of helping people take their medicine during treatment.