Decline in Efficacy
The investigators were unsure why citicoline’s effect diminished over time. Patients were given an initial dose of 500 mg/day, which was gradually increased by week 6 to a maximum of 2000 mg/day.
“One possibility for the decline in efficacy was that patients developed tolerance to the effects. The other possibility is that the higher doses were too high,” said Dr Brown.
The investigators note that magnetic resonance spectroscopy data suggest that 500 mg/day is associated with a greater change in membrane phospholipids than the higher dose of 2000 mg/day.
There were no differences between the group receiving citicoline and the group receiving placebo in mood symptoms, which were measured using the Inventory of Depressive Symptomatology–Self Report, the Hamilton Depression Rating Scale, and the Young Mania Rating Scale.
There were also no differences in cocaine craving between the two study groups, as measured by the Cocaine Craving Questionnaire. This negative finding suggests that “the effects of citicoline on cocaine use are not mediated through a reduction in craving,” the authors write.
“Two areas may be most important specifically for its use in cocaine dependence, its increase of acetylcholine levels in the brain, and its stabilization of cell membranes via its effects on phospholipid metabolism,” said Dr Brown.
The investigators also found that citicoline was safe and well tolerated. There were no differences between groups on the Somatic Symptom Scale. Several prior studies of citicoline for indications other than cocaine dependence showed that adverse events were higher in the placebo groups than the citicoline groups.
Overall, the results suggest that citicoline alone may best be used in the acute phase of treatment and that other treatments should be considered for the long term. Dr Brown observed that citicoline may be “a useful addition to standard treatment in some patients.”
Now that there are two controlled clinical trials showing beneficial effects for cocaine use in BD patients, Dr Brown would like to see citicoline trials in other mood disorders, cocaine dependence in general, and other addictive disorders.
Large Clinical Problem
Commenting on the findings for Medscape Medical News, Ihsan Salloum, MD, MPH, professor of psychiatry and chief of treatment and research in the Division of Alcohol and Drug Abuse, University of Miami School Miller School of Medicine, noted that substance abuse in BD is a “very big clinical problem.”
“We see it often in clinical practice but don’t have a lot to offer patients. This is the first study showing that a medication has an effect,” he said.
Dr Salloum also noted that BD patients with cocaine dependence are difficult to study and are hard to recruit and retain in a clinical trial.
Further, he noted that the current trial was labor intensive because of the requirement for thrice-weekly urine screens.
“The fact that the authors still found a positive effect using a conservative methodology - classifying a missing drug screen as positive - is very important,” said Dr Salloum.
Dr Salloum emphasized that the study findings are a significant advance because citicoline is available over the counter and does not interact with other medications.
However, before recommending citicoline’s use in clinical practice, Dr Salloum said he would like to see confirmation of the findings in a multicenter clinical trial that examines the supplement’s most effective dose.
The study was funded by the National Institutes of Health. Dr Brown and Dr Salloum report no relevant financial relationships.
Am J Psychiatry. Published online May 22, 2015. Abstract