Study protocol for a randomised controlled trial to determine the efficacy of lisdexamfetamine for the treatment of acute methamphetamine withdrawal in inpatient settings.

Abstract

Harms due to methamphetamine use disorder (MAUD) are rising globally. Untreated withdrawal symptoms perpetuate the cycle of dependence and are a barrier to treatment. There is no pharmacotherapy approved for methamphetamine withdrawal. Lisdexamfetamine (LDX) dimesylate has potential as an agonist therapy to ameliorate symptom severity during acute methamphetamine withdrawal and increase duration of initial abstinence and retention in treatment. We will conduct a double-blind, randomised, controlled trial to evaluate the efficacy of LDX in reducing symptom severity during acute methamphetamine (MA) withdrawal. One hundred eighty-four adults with moderate to severe MAUD presenting to a health service requesting MA withdrawal treatment who report use of MA within the last 72 hours will be recruited. Participants will be randomised 1:1 to receive a tapering dose of lisdexamfetamine (250 mg on day 1, reducing by 50 mg per day to 50 mg on day 5, followed by 2 days of placebo washout on days 6 and 7), or placebo for 7 days. The study will be conducted over 7 days in an inpatient unit, and all participants will also receive standard inpatient withdrawal care. Participants will be followed up in the community to day 84. The primary outcome is efficacy, defined as the between-group difference in average withdrawal severity measured over the 7-day admission by the Amphetamine Withdrawal Questionnaire. Secondary outcomes are retention in treatment, treatment satisfaction, sleep and concomitant medication use (symptomatic medications and medications for other indications to day 7); safety, craving for MA, post-treatment withdrawal symptoms, depression, anxiety and stress, insomnia and cost effectiveness (to day 28) and MA use, mental, physical and social health and post-withdrawal treatment utilisation (to day 84). A First Nations qualitative substudy will assess the experiences of Aboriginal and Torres Strait Islander participants, ensuring the treatment meets the needs of First Nations people. This protocol was first approved by the St Vincent's Hospital Human Research Ethics Committee on 15/05/2024 (2024/ETH00788). All participants will be provided with a participant information sheet and consent form, be fully informed about the study and given ample time to consider participation. Results will be published in peer-reviewed journals and presented at national and international conferences. Findings will be presented such that individual participants will not be identifiable. ACTRN12624001061527.