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The effect of the menstrual cycle on low dose psilocybin

An open-label trial to test menstrual cycle effects and tolerance to low dose psilocybin in healthy menstruating persons (PsiMen).

Status
Not yet recruiting
Phases
Phase 1
Study type
Interventional
Source
ANZCTR
Registry ID
ACTRN12625000991415
Acronym
PsiMen
Enrollment
21
Registered
2025-09-08
Start date
2025-09-08
Completion date
2026-08-07
Last updated
2025-09-22

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

None listed

Brief summary

The menstrual cycle causes major fluctuations in hormones. Changes to progesterone and estrogen in particular are known to dramatically affect not just reproductive systems but brain function. Females are majorly overrepresented in adverse reactions to common medications which suggests that menstrual cycle linked hormones may not just change disorder symptoms but also the response to drug therapies. We will study how the brain’s response to a drug changes over the menstrual cycle. In this study we will examine how the menstrual cycle may change how females are affected by the drug psilocybin. We will study this by taking blood samples and using standardised questionnaires. We will test the hypotheses that the pharmacokinetics and pharmacodynamics of psilocybin are modified across the menstrual cycle. This research may help to improve treatments by taking the menstrual cycle into account and potentially reduce symptoms and adverse reactions over the menstrual cycle.

Interventions

Oral psilocybin capsules. 5 mg psilocybin capsules taken orally. Adherence is through supervised administration. One dose administered in each of the ovulatory and luteal phases and three doses administered on consecutive days in the follicular phase. Follicular visits are timed to the onset of last menses (5-9 days after) Ovulatory visits are timed from ovulation measured through home ovulation testing (day or day after a positive test) Luteal visits are timed 10-14 days after ovulation Se

Oral psilocybin capsules. 5 mg psilocybin capsules taken orally. Adherence is through supervised administration. One dose administered in each of the ovulatory and luteal phases and three doses administered on consecutive days in the follicular phase. Follicular visits are timed to the onset of last menses (5-9 days after) Ovulatory visits are timed from ovulation measured through home ovulation testing (day or day after a positive test) Luteal visits are timed 10-14 days after ovulation Sessions will be collected from one menstrual cycle (ideally) but a further two menstrual cycles can be used in the case of missed visits.

Sponsors

The University of Auckland
Lead SponsorUniversity

Study design

Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Treatment
Masking
Open (masking not used)

Eligibility

Sex/Gender
All
Age
18 Years to 46 Years
Healthy volunteers
Yes

Inclusion criteria

1. Provision of signed and dated informed consent form. 2. Stated willingness to comply with all study procedures and availability for the duration of the study. 3. Aged, 18-46 years. 4. For heterosexually active persons of child-bearing potential: agree to use non-hormonal contraception. 5. To have regular menstrual cycles

Exclusion criteria

1. Inability to adequately communicate in English (both written and spoken). 2. Any item 1-13 of the Premenstrual Symptoms Screening Tool scoring above “mild” and any item A-E scoring above mild. 3. Any current psychiatric diagnosis 4. Confirmed diagnosis of (or first degree relative with) schizophrenia or other psychotic disorder, or bipolar I or II disorder. 5. Risk of suicide as determined by The Columbia-Suicide Severity Rating Scale (C-SSRS). 6. Substance dependence in the previous 6 months as assessed by clinical interview with a New Zealand modified version of the NIDA (National Institute of Drug Abuse) Modified Alcohol, Smoking and Substance. Involvement Screening Test (NM-ASSIST). 7. Problematic use of alcohol defined as a score on the Alcohol Use Disorders Identification Test (AUDIT) of 16 or greater. 8. Body Mass Index (BMI) 35. 9. Planned or current pregnancy or lactation. 10. Cardiovascular conditions including abnormal heart rate or blood pressure to be checked at screening. A threshold of exceeding 160 mmHg (systolic) and 90 mmHg (diastolic), averaged across three assessments taken on the screening day will be used. Participants with well-managed hypertension would not be excluded. 11. Significant renal or hepatic impairment. 12. Diagnosed or probable polycystic ovary syndrome (PCOS) 13. Clinically relevant abnormal 12-lead electrocardiogram as judged by a study physician. 14. Clinically relevant abnormal laboratory test findings as judged by a study physician. 15. Any unstable medical or neurological condition. 16. Regular use of any Central Nervous System active medications in the last three months 17. Use of hormonal contraceptives/steroid hormones in the last three months 18. Regular use of any medication/supplements deemed to be contraindicating as judged by a study physician. 19. Treatment with another investigational drug /intervention within the last 3 months. 20. Use of serotonergic psychedelic drugs in the last 3 months. 21. Any other condition judged by the treating clinician as likely to impact on the ability of the participant to complete the trial.

Outcome results

None listed

Source: ANZCTR · Data processed: Feb 4, 2026