“A 2022 Cochrane review of pharmacological interventions for the prevention of AIWG (antipsychotic-induced weight gain) found that metformin was the only pharmacological agent that may be effective for preventing weight gain when started with an antipsychotic,” wrote Aoife Carolan, M.Pharm., at Saint John of God Hospital and the Royal College of Surgeons in Dublin, and colleagues. “Despite this, metformin for the prevention of AIWG is not routinely offered in psychiatric practice.”
Carolan and colleagues developed the guideline utilizing the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument to ensure a high standard was followed. This included undertaking a comprehensive review of the literature and having the guideline findings reviewed by an independent panel of experts.
The guideline offered three core recommendations:
- Initiate metformin when prescribing a high-risk weight-inducing antipsychotic, such as olanzapine or clozapine.
- Initiate metformin with a medium-risk antipsychotic (quetiapine, paliperidone or risperidone) in patients with one or more cardiometabolic risk factors; in people ages 10 to 25 years; or for those with a BMI between 25 and 30.
- Initiate metformin with any antipsychotic if >3% increase in baseline body weight is observed during the first year of treatment.
In terms of dose, the new guideline recommends escalating from 500 mg daily to 500 mg twice daily over two weeks, followed by biweekly increases of 500 mg as tolerated up to 1 g twice daily at week 6. Metformin should be discontinued if risks for lactic acidosis are present, or the condition is suspected; if body mass index falls below 20; or if the antipsychotic medicine is discontinued. Metformin should be avoided where there is harmful use of alcohol.
Though the guideline focused on metformin, it also recommended that, if available, GLP-1 agonists should be considered for patients with a BMI above 30, certain cardiometabolic diseases, or obstructive sleep apnea.
For related information, see the Psychiatric News article “Metformin May Reduce Weight Gain in Youth Taking Antipsychotics.”
(Image: Getty Images/iStock/patrickheagney)
Don't miss out! To learn about newly posted articles in Psychiatric News, please sign up here.