The authors have attempted to ensure that the information on medication is accurate; however, physicians should check with the official drug monograph before prescribing any medication mentioned in these guidelines.
Primary care providers should routinely offer medication for moderate and severe alcohol use disorders, even if the patient is not willing to engage in formal psychosocial treatment.
Three medications have been approved for treating patients with alcohol use disorders in primary care practice:
- Naltrexone
- Acamprosate
- Disulfiram.
Some Canadian provinces and territories may require physicians to request coverage of naltrexone and acamprosate. In Ontario, both naltrexone and acamprosate are covered by the Ontario Drug Benefit Formulary with a Limited Use (LU) code.
Naltrexone and Acamprosate
Meta-analyses show that two medications, naltrexone and acamprosate, can reduce the frequency and intensity of binge drinking and increase abstinence rates (Baser et al., 2011; Jonas et al., 2014; Miller et al., 2011; Rösner et al., 2010a, 2010b). Studies show that disulfiram is only effective when a patient takes it under the supervision of a partner or pharmacist (Jorgensen et al., 2011).
Naltrexone
Naltrexone can reduce relapse of heavy drinking and binge drinking, and helps patients achieve abstinence. It is the first-line medication. It can be prescribed while patients are still drinking.
Contraindications for naltrexone include opioid use (whether prescribed, over the counter, or recreational) and significant liver dysfunction.
Liver enzymes should be checked before initiating therapy and during treatment. Do not use naltrexone in acute hepatitis and liver failure. Use with caution and monitor more frequently in hepatic impairment. Stop naltrexone if liver enzymes rise more than three times the patient's baseline.
The initial dose is 25 mg daily for three days (to minimize gastrointestinal upset and to make sure there is no precipitated withdrawal), then 50 mg daily. In some cases, higher doses may be required.
In Ontario, the clinical criteria for the LU code requires that patients have a diagnosis for alcohol use disorder, express a commitment to reduce or abstain from alcohol, and have confirmed counselling and treatment.
Acamprosate
Acamprosate is effective for promoting abstinence. Patients must also have been abstinent for at least several days before beginning acamprosate.
Severe renal dysfunction is a contraindication to using acamprosate. The dose is 666 mg three times a day. Moderate renal dysfunction and low body weight require a dose adjustment.
In Ontario, the clinical criteria for the LU code requires that patients have a diagnosis of alcohol use disorder, express a commitment for alcohol abstinence, have been abstinent for at least 3 days before starting acamprosate, and have confirmed counselling and treatment.
Disulfiram
Disulfiram is effective in achieving abstinence if it is taken under supervision, for example by a pharmacist, partner or mutual aid (e.g., AA) sponsor (Jorgensen et al., 2011).
Use is contraindicated in patients who are elderly, pregnant, or who have cardiac disease, liver dysfunction, psychosis, or cognitive dysfunction. Disulfiram is also contraindicated in patients who take metronidazole.
Liver enzymes should be checked prior to initiating disulfiram, at two weeks and then every three months.
Patients must be abstinent for several days before beginning disulfiram and cannot drink while taking the medication. Reactions if the patient does drink can be severe.
Side-effects of disulfiram include hepatitis, neuropathy, depression and psychosis.
Disulfiram is no longer manufactured in Canada, so patients must obtain it from a compounding pharmacy.
Other medications
Several medications are used off-label to treat moderate or severe alcohol use disorder. These include topiramate, baclofen, and gabapentin. The evidence base for these medications is much smaller and they are considered second-line medications.
Thiamine
Prescribing thiamine is important because heavy alcohol consumption can result in thiamine deficiency, which can lead to alcohol-induced brain damage.
Some primary care providers give thiamine to all patients who continue to drink or who are being treated for alcohol withdrawal. The appropriate dose is unclear from the evidence (Day et al,, 2013), but most physicians give at least 200 mg orally. Patients at higher risk of Wernicke's encephalopathy should be given three days of intramuscular or intravenous thiamine.
Encouraging patients to take medication as prescribed
Take a motivational interviewing approach similar to that you would use to encourage patients to take SSRIs for depression:
- Emphasize that alcohol use disorders are an illness with biological and psychological components.
- Emphasize that medication is an essential component of recovery for many patients.
- Ask about medication use at every visit.
- Ensure that the patient does not run out of medication.