"Chill packs" self-administered olanzapine as psychiatric harm reduction for methamphetamine-induced psychosis: a narrative review of the existing evidence base.

The prevalence of methamphetamine use disorder has risen across the United States and many other countries, which has led to a concomitant rise in methamphetamine-induced psychosis (MIP). A promising and novel approach to address MIP can be found in 'chill packs', a psychiatric harm reduction intervention for people using methamphetamine. Chill packs consist of several low-dose olanzapine tablets (an antipsychotic medication) that can be self-administered in the event of methamphetamine-induced insomnia, anxiety, paranoia, delusions, or other dysphoric symptoms. One recent study assessed the effectiveness of an implementation of chill packs by the San Francisco Department of Health and found that repeat psychiatric emergency visits dropped by 32% after two-months and 13% after six-months from receipt of a chill pack. While these findings are promising, more research is needed to evaluate the efficacy and generalizability of this intervention. Here we provide a narrative review which synthesizes indirect evidence and contextual information relevant to this intervention, including: the epidemiology of MIP, clinical data supporting the use of olanzapine versus other antipsychotics for MIP, evidence for as-needed outpatient antipsychotic use, as well as qualitative and other data describing the potential for misuse of olanzapine and other antipsychotics. Overall, the literature supports that the prevalence of MIP is rising sharply, causing increased psychiatric burden. This is also linked to overdose risk among patients that use illicit fentanyl or other sedatives to "come down" after periods of heavy methamphetamine use. Olanzapine has demonstrated comparable efficacy for treating MIP compared to other antipsychotics with enhanced short-term sedative effects, despite a higher burden of long-term metabolic side effects. Olanzapine has very little documented misuse risk, although other agents in its class, especially quetiapine, have higher street value. Qualitative research highlights that some groups already self-administer olanzapine as a 'trip killer' to manage distressing psychiatric side effects from illicit drug use. Overall, we find substantial contextual evidence supporting further trials to evaluate chill packs as a harm-reduction intervention for MIP and provide recommendations for research needed to fill gaps in the evidence for this promising emerging intervention.