Methamphetamine use disorder (MUD) is a significant public health concern with burden to individuals, families and health systems estimated to cost over $5 billion annually in Australia. In 2016/17 there were 49,670 Australian treatment episodes for MUD, the first step of which typically involves inpatient withdrawal. Currently there are no approved medications to help manage methamphetamine withdrawal and consequently many people drop out of treatment prematurely, leaving them vulnerable to relapse.

Oxytocin is a candidate medication that has the potential to increase treatment retention, reduce withdrawal syndrome severity, increase post-withdrawal treatment engagement and reduce relapse rates.

The aim of this pilot study is to investigate whether intranasal oxytocin can improve withdrawal treatment outcomes in adult women with MUD. The study will examine the feasibility of intranasal oxytocin as a treatment for methamphetamine withdrawal in women. This will be explored by assessing length of stay in residential withdrawal, withdrawal symptom severity, post-discharge treatment engagement and relapse rates in a group of women who are prescribed intranasal oxytocin during their medically supervised methamphetamine withdrawal at a residential detoxification program. The safety of intranasal oxytocin will also be assessed. A secondary objective of the study is to conduct an exploratory analysis regarding participants' capacity to interact effectively with others, as well as changes in social networks and/or engagement with therapeutic services.

There is an observational sub-study affiliated with this main pilot study that is optional for individuals recruited to the main pilot trial to additionally participate in. This sub-study aims to investigate how sleep quality and patterns change before, during, and after detoxification from methamphetamine in women. MUD and sleep disturbances have a complex bidirectional relationship. The use of methamphetamine is known to disrupt sleep quality and the circadian rhythm, although withdrawal from methamphetamine also induces significant sleep-wake cycle changes. There is evidence that methamphetamine disrupts functions regulated by the circadian rhythm. Furthermore, disruptions in circadian rhythms, including mutations in key genes, increases the propensity for addiction. Evaluation of how chronic methamphetamine use may disrupt rhythmicity, and vice versa, may provide invaluable information with regard to potential treatment options of methamphetamine use disorder. There has been little focus, so far, on the therapeutic potential of circadian rhythm modifiers as treatment options in the addiction space, as sleep disturbances have often been merely viewed as a consequence of substance use.

Specific to the sub-study, participants will be asked to wear an actigraphy watch. The actigraphy watch device will be worn for at least 7 days prior to, 7 days during, and 7 days post methamphetamine detoxification. This is the only difference between the sub-study and the main pilot study; there are no other additional requirements or assessments involved in the actigraphy sub-study.

Inclusion Criteria:

• Adult females (sex assigned at birth) aged ≥18 to ≤65 years, admitted to the Turning Point Addiction Medicine Unit.
• Meeting DSM-5 criteria for Methamphetamine Use Disorder, moderate or severe (assessed by treating physician on pre-admission to residential withdrawal).
• Able to comply with study protocols.
• Able to provide informed consent to participate.

Exclusion Criteria:

• Non-English-speaking women.
• Women lactating, pregnant or of childbearing potential who are not willing to use an effective means of contraception for the duration of the trial.
• Meeting DSM-5 criteria for moderate-severe substance use disorder other than methamphetamine, nicotine and cannabis, as assessed by treating physician on pre-admission to residential withdrawal.
• Clinically significant or unmanaged medical or psychiatric illness (e.g., renal insufficiency, cirrhosis, unstable hypertension, unstable diabetes mellitus, seizure disorder, history of DSM-5 psychotic or bipolar disorder, current severe major depression, current suicidal ideation), assessed by treating physician on pre-admission to residential withdrawal.
• Current participation in another trial.