High-dose baclofen for the treatment of alcohol dependence (BACLAD study): A randomized, placebo-controlled trial.
Müller C.A, Geisel O., Pelz P. et al.
European Neuropsychopharmacology: 2015, 25, p. 1167–1177.
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From Germany the first trial to rigorously test high doses of the muscle relaxant baclofen for the treatment of dependent drinking found post-detoxification drinking reductions of a magnitude rarely seen; safety issues remain, but it seems these can be managed with close monitoring and individualised dosing.
SUMMARY In the USA and Europe few medications have been approved for the treatment of dependent drinking: disulfiram, acamprosate, nalmefene, and naltrexone oral and injectable. Some have repeatedly been found effective in rigorous clinical trials, but effects have been modest – there is room for improvement through additions to this range.
From Germany the first trial to rigorously test high-dose baclofen for the treatment of dependent drinking found substantial increases in abstinence after detoxification.
However, the trial lasted just 16 weeks in total and any patient who drank had to leave treatment.
It is unclear whether high doses are generally more effective than typical doses or only for a few patients, and whether they can sustain abstinence longer term.
In high doses baclofen can dangerously augment alcohol’s sedative effects, though in trials risks have proved manageable and few patients have left treatment due to side effects.
One possible addition is baclofen, a medication taken by mouth as tablets. The drug relaxes muscles and is approved for preventing muscle spasms resulting from neurological conditions. The few trials which have randomly allocated alcohol-dependent patients to baclofen versus placebo have found patients can take the drug without experiencing deterrent side effects (ie, they ‘tolerated ’ the drug well), but also found inconsistent impacts on drinking. Given its low ability to cross the blood-brain barrier, these might be related to the low doses of baclofen (30mg to 80mg per day) used in the trials.
Against this background, researchers decided to test high-dose baclofen (up to 270mg a day in three daily doses) for the treatment of alcohol dependence by randomly allocating 56 patients seen at a psychiatric centre in Berlin to the medication or to an inactive placebo. Patients and research assessors were not told which patients were taking baclofen, an attempt to eliminate expectation effects and leave only the effects of the medication. To join the trial, patients had to be adults dependent on alcohol who had just completed a medically managed withdrawal from alcohol (detoxification) and who were not legally required to attend for treatment nor suffering serious psychiatric problems. Averaging in their late 40s, about 70% were men. Most were employed and had close family who had been dependent on alcohol. Before treatment they were very heavy drinkers, averaging 199g alcohol per day, nearly 25 UK units.
The 24-week trial consisted of four phases. For up to the first four weeks, doses of baclofen and placebo were increased to a maximum 270mg a day depending on how well the patient tolerated the dose. Then the dose was maintained for 12 weeks before being tapered to zero over the next four weeks, after which patients were followed up for another four weeks. Tapering was instigated prematurely if patients started drinking. Patients were scheduled to visit the clinic from 13 to 17 times, where they were offered nine sessions of structured, supportive clinical care intended to influence them to take the medication as intended.
Abstinence from drinking was the main outcome assessed, based not just on the patients’ accounts but also breathalyser and blood tests. At the end of the trial just five patients could not be followed up. On the assumption that patients who left the study had relapsed to drinking, all 56 were included in the analysis of outcomes.
Of the 28 patients prescribed each of the preparations, during the initial dose-setting phase about the same number allocated to baclofen or placebo (6 or 7) dropped out of treatment or started drinking and had to leave. After that, lapse to drinking became more common among placebo patients, meaning that in all 24 left treatment early (18 due to resumed drinking) compared to 16 prescribed baclofen (10 due to resumed drinking). After medication ended and during the four-week follow-up, a further two baclofen patients and one prescribed placebo started drinking. Across the entire study period 19 placebo patients were known to have started drinking versus 12 prescribed baclofen, and 3 versus 10 were known to have remained abstinent.
Focusing on the period when medication was prescribed, 12 of the 28 baclofen patients remained abstinent compared to four allocated to a placebo, a statistically significant advantage for baclofen, so unlikely to have been a chance finding. Baclofen patients also lasted longer before starting drinking – 83 out of the 141 scheduled medication days versus 67 – but this difference fell short of statistical significance. The picture was similar when the analysis was confined to the 12 high-dose weeks, except that the difference in time to resumed drinking (favouring baclofen) became statistically significant.
Baclofen had no statistically significant effects on craving for alcohol, or symptoms of anxiety or depression. No baclofen patients said the drug had produced alcohol-like effects (euphoria or stimulation), and none reported craving for the drug after dosing ended. Though the drug was not associated with any serious adverse events, two baclofen patients ended treatment due to fatigue, a complaint reported by seven placebo patients but nearly twice as many (13) allocated to baclofen. Among the other most common complaints, seven placebo and four baclofen patients reported headaches, while four placebo versus nine baclofen patients reported disturbed sleep.
During the high-dose phase baclofen doses averaged 180mg a day and peaked at an average 192mg, significantly lower than corresponding ‘doses’ of placebo and below the potential maximum of 270mg a day. The dose of baclofen reached did not predict who would remain abstinent.
The authors’ conclusions
Individually adjusted, high-dose baclofen supported alcohol-dependent patients in maintaining abstinence and was well tolerated, even when patients resumed drinking, results which might extend pharmacological treatment options. Compared to previous studies, baclofen doses were relatively high, possibly why it was more effective than placebo in this study but not in a larger US trial which prescribed 30mg a day. The drug’s impacts do not seem to depend on reaching a set dose, so dose can probably be individually adjusted without jeopardising effects on drinking.
Findings suggest baclofen does not work primarily by reducing craving or anxiety. Another suggested mechanism is substituting for alcohol by producing similar effects, yet in this study no patient reported alcohol-like effects, or craving or withdrawal symptoms after the drug was withdrawn.
Results confirm the good safety profile of baclofen found in previous trials, though lack of data on safety at high doses demands care and close monitoring; in this study about two-thirds of the baclofen patients (but just a third prescribed a placebo) did not reach the maximum 270mg per day dose. Alcohol-dependent patients with psychiatric conditions have been known to take dangerously high doses of baclofen to induce intoxication, suggesting extra care before prescribing it to alcohol-dependent patients with psychiatric conditions and/or who have previously attempted suicide.
Despite clear-cut results favouring baclofen, the study’s sample was too small to be definite about the drug’s future role in the treatment of alcohol dependence, and the study was conducted at a single site; elsewhere results might differ. Only abstinence was assessed, not whether baclofen curbs drinking in patients who continue to drink.
In this trial, and even at just 30mg a day in trials in Italy, baclofen has greatly reduced drinking among alcohol-dependent patients, though not in a US trial among less heavily dependent drinkers recruited through ads rather than at treatment clinics; details below. It is rare for any medication or psychosocial therapy to register such large impacts. However, as an anti-relapse medication the drug seems so far to have been tested only against an inactive placebo, not against established medications like disulfiram, acamprosate or naltrexone, and not against structured psychosocial therapies. Such therapies have been shown to have impacts as great as those of some medications. Trials have mostly been at a single centre in Italy and involved just 12 weeks of medication with little or no post-treatment follow-up period.
Limitations of trials to date and safety concerns in respect of high doses ( below) mean it would be premature to prefer baclofen to the established medications, though it does offer an alternative when these have proved insufficiently effective or are contraindicated. It remains unclear whether high doses of baclofen are generally more effective in suppressing drinking than usual doses, or only among patients who do not respond to lower doses, and if the latter, what proportion these are of all patients who might be prescribed the drug.
Safety is an issue
The authors’ caution that more needs to be known about the safety of high doses of baclofen – and especially so among heavy drinkers – is an important consideration. Baclofen is not licensed in the UK for the treatment of alcohol dependence, though it has been used by some clinicians. In its mainstream use to prevent muscle spasms, the drug is recommended to be taken in doses no greater than 100mg a day; most of the data on safety will have been gathered at doses below this level.
In the featured study, two-thirds of baclofen patients did not reach maximum doses, presumably because many were starting to feel too unwell to further increase these dose. Despite the care the study exercised to adjust doses, nearly half the baclofen patients complained of fatigue, leading two of the 28 to terminate treatment. At lower doses too, fatigue can be a problem among a minority of alcohol-dependent patients (1 2) and is a recognised side-effect among patients prescribed the drug to prevent spasms.
The UK’s prescribing guide warns that taking baclofen while drinking can magnify alcohol’s effects. Anaccount of baclofen-induced intoxication among alcohol-dependent emergency department patients in France indicates that fatal overdose is a risk when high doses of baclofen are taken in the presence of other drugs which depress the nervous system, including alcohol and benzodiazepine tranquilisers.
A recognised advantage of baclofen that it is only minimally metabolised by the liver, meaning it can and has been recommended for the prevention of relapse to drinking among patients with alcoholic liver disease. There has however been an apparently isolated case of baclofen-induced hepatitis in an alcohol-dependent patient in France at doses of just 30mg a day. Cases of reversible psychiatric disturbance have also been reported with higher (120mg or 275mg per day) doses.
Despite these risks, in alcohol treatment trials with typically rigorous monitoring, and which like the featured trial have usually excluded seriously medically or mentally ill patients, baclofen’s safety and side effects have not been a major issue and patients have not experienced psychoactive effects, become dependent on the drug, or developed a desire to continue taking it. A review conducted for the British Association for Psychopharmacology concluded that baclofen has generally been well tolerated by patients.
At usual doses, these findings from treatment trials have generally been confirmed by studies which have closely monitored how heavy or dependent drinkers respond to baclofen while drinking in laboratory conditions. However, these studies have also confirmed that even when tolerance has developed to alcohol, there can be additive effects of the kind which at higher doses escalated central nervous system depression to the dangerous levels seen in France ( above) and which magnify alcohol’s detrimental effects on performance in manual or intellectual tasks (1 2).
Experience with high dose baclofen in alcohol dependence is not confined to the featured trial, though it does seem the only rigorous assessment. Successful treatment has been reported in Australia of patients who had been failed by other treatments and who did not respond well to baclofen until doses were raised to 72mg to 125mg a day. The featured study notes that in 2014 baclofen received temporary approval in France for the treatment of alcohol-dependent patients in doses up to 300mg a day. Approval was pending French trials and stipulated baclofen be tried only after the failure of other treatments, and that doses over 120mg a day are subject to specialist advice. The move followedpopularisation of the drug instigated by the account of a French alcohol-dependent cardiologist who treated himself with a maximum of 270mg a day of baclofen. Despite soaring sales and patient demand, the French authorities at first refused to sanction such usage due to insufficient evidence.
In Italy the first rigorous trial of baclofen in the treatment of alcohol dependence found that at 30mg a day the drug substantially promoted abstinence over a 30-day trial and dramatically reduced drinking to on average practically zero drinks per day.
Also in Italy the same lead researcher has trialled the drug at doses of 30mg a day among alcohol-dependent patients with cirrhosis as a means of sustaining abstinence after detoxification. In this relatively large 12-week trial involving 84 patients, baclofen substantially promoted abstinence and prevented relapse to heavy drinking; 60 days after treatment started 6 of 42 baclofen patients had relapsed compared to 19 of 42 prescribed a placebo. In the four weeks after the 12 weeks of medication, one baclofen patient relapsed and two prescribed a placebo. No baclofen-induced aggravation of medical problems was reported.
In the USA, records of the treatment of 35 alcohol-dependent patients with liver disease showed allbut one sustained abstinence while being prescribed up to 30mg a day of baclofen for on average nearly six months, a long-term course which did not lead to a serious adverse effects and was tolerated well by the patients.
Not all the trials at the Italian unit have proved convincing. It hosted the Italian arm of a multi-national trial, for which it recruited 42 patients. For 12 weeks they were randomly allocated to placebo, the 30mg a day dose the unit had previously trialled, or to twice this dose, 60mg a day. Possibly because numbers were so few, no statistically significant effects were noted on the number of heavy drinking days, days not drinking, time to first lapse and relapse, or on craving. Later anunplanned analysis of the average number of drinks per day across the trial period found a significantly greater reduction among baclofen patients, which peaked at the highest dose. However, even the placebo patients averaged only about half a drink per day, and this analysis could have capitalised on prior knowledge of the outcomes to select one which perhaps by chance registered a statistically significant difference.
The Australian arm of the same trial also recruited 42 patients but was able to follow-up just 28. There were no overall statistically significant benefits of baclofen, but it did further reduce drinking among the 4 in 10 patients who had ever suffered or were suffering a diagnosable anxiety disorder, thought to indicate a particular role for baclofen among morbidly anxious patients. As well as the small follow-up number, this was another unplanned analysis which could have capitalised on what were really chance variations in outcomes.
Unlike the Italian trials, a US trial recruited participants not at alcohol treatment clinics but through advertisements. At about 98g a day most days, their drinking was relatively modest. Prescribed for 12 weeks at up to 30mg a day, compared to a placebo baclofen did not further reduce drinking or heavy drinking or reduce craving for alcohol.
Trials have generally tried the drug as a way of sustaining rather than achieving abstinence, but the Italian research team has also compared 30mg a day baclofen for 10 days to the ‘gold-standard’ diazepam treatment for mitigating withdrawal symptoms from alcohol, and found it about equally effective. The results seem to promise an unbroken pharmacological route from withdrawal through to maintaining abstinence, but whether baclofen can match the benzodiazepines in preventing or mitigating severe symptoms including seizures and delirium tremens remains unclear.
Last revised 12 August 2015. First uploaded 12 August 2015