This post was written by Natasha Clarke, an MSc student at the University of Liverpool.
Many current drinkers report drinking to excess, therefore it is important to identify treatments which can reduce these drinking levels, even if the reductions are modest. Medicines derived from natural products that have few side effects and low toxicity are desirable. Kudzu extract, a Chinese herbal medicine, has long been used to treat alcoholism and reduce hangover symptoms in Asian cultures. A previous study reported that treatment with kudzu extract led to significant reductions in alcohol consumption in heavy drinkers over the course of a week (Lukas et al, 2005).
This randomised, double-blind, placebo controlled study was designed to see if treatment with kudzu extract (NPI-031) over a longer period of 4 weeks would reduce alcohol consumption. It was conducted in Boston and published in Psychopharmacology. Authors found a modest reduction in alcohol consumption, and the kudzu extract was well-tolerated with minimal side effects.
The study recruited 21 male heavy drinkers aged 21-33 years, of whom 17 completed the study. Only males could take part because kudzu extract may interfere with oestrogen activity.
The study had a 2-week baseline period, 4 weeks of medication (or placebo) and a 2-week follow up. Participants were assigned to receive either kudzu extract or a placebo, and they attended the laboratory twice per week for the first 6 weeks and once per week in the follow-up fortnight. Alcohol and other drug use were monitored with self-report measures which were validated with breath, urine and blood samples. Safety of the kudzu extract was monitored by assessments of vital signs, daily reports, weekly assessments of adverse events, blood sample testing and an ECG at the end of the study.
• During the 4 weeks when participants received medication (or placebo), participants who received kudzu extract reported significant reductions in drinking compared to baseline. Participants in the placebo group also reported reductions in drinking compared to baseline, although these reductions were not statistically significant. However, differences between the kudzu extract and placebo groups were only statistically significant during the third week of receiving medication. Overall, the interaction between medication group and study week was statistically significant (p=0.034, ηPartiall²= 0.146), which reflects the reduction in drinking compared to baseline in the kudzu extract group only. However, it seems that the study was underpowered to detect differences between kudzu extract and placebo.
• There were also differences between the kudzu-treated and placebo groups in terms of the number of days per week that they drank heavily, as revealed by main effects of time (p<0.005, ηPartiall²= 0.197) and drug (p=0.008, ηPartiall²= 0.386). Relative to baseline, the kudzu group showed a reduction in heavy drinking days on the first, third and fourth treatment weeks (but not the second week). Differences between kudzu and placebo were only statistically significant on week 4, which again seems down to low statistical power.
• Importantly, these reductions in drinking in the kudzu extract group (compared to baseline) were maintained during the two-week follow-up period, after they had stopped taking the medication.
• The medication also influenced the number of days that participants remained abstinent from alcohol during the treatment phase. Nine out of 10 participants in the kudzu extract group achieved three or more consecutive days of abstinence, compared to only three out of seven participants in the placebo group. This difference was statistically significant, although we have to again note the small sample size and the fact that 3 of 10 participants originally assigned to the placebo group did not complete the study, as opposed to only one of the 11 participants assigned to the kudzu group.
• There were no indications that kudzu extract altered desire for alcohol.
• Medication adherence was excellent.
• There were no adverse events and changes in vital signs, blood chemistry and renal or liver function.
The researchers stressed that their most important finding was that 4 weeks treatment with the kudzu extract led to a reduction in self-reported alcohol consumption in heavy drinkers who were not seeking treatment. It also increased the number of consecutive days that participants did not drink alcohol.
Overall, it seems that kudzu extract could be a useful add-on to other treatments for problem drinking. However, the sample size in this study was very small and differences between kudzu extract and placebo were not consistent across time, so a much larger randomised controlled trial (RCT) is needed.
This study suggests that kudzu extract can result in a desirable reduction in drinking (compared to baseline), with no adverse side effects, and it may be beneficial when combined with a comprehensive treatment program. However, this study only tested this effect in Males, and for safety reasons they could not test the drug in Females. Which is a shame!
Link to paper
Lukas SE, Pentair D, Su Z, Geaghan T, Maywalkt M, Tracy M, Rodolico J, Palmer C, Ma Z, Lee DY-W. A standardized kudzu extract (NPI-031) reduces alcohol consumption in nontreatment-seeking male heavy drinkers. Psychopharmacology 2013, 226: 65-73.