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Rilmazafone

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Subjective Effects
Interactions
Tolerance
Rilmazafone molecule structureRilmazafone molecule structure
Open in Piru
Chemical Class
1,4-Benzodiazepine

Rilmazafone is a prodrug that can be prescribed in Japan to treat insomnia.1 It produces sedative and hypnotic effects after conversion into active benzodiazepine metabolites in the body. The parent compound is inactive and lacks the diazepine ring characteristic of benzodiazepines, distinguishing its chemical structure from that of its active metabolites. It is classified as a depressant and can be habit-forming.2

Dosage & Duration

Log in Piru

Dosage

Doses are population estimates that vary widely between individuals.

Threshold~0.5 mg
Light0.5-1 mg
Moderate1-2 mg
Strong2-4 mg
Heavy4+ mg

Duration

Onset30-60 minutes
After Effects6-12 hours
Total6-8 hours

Subjective Effects

Subjective Effects not written up yet

Pharmacology

Pharmacodynamics

Rilmazafone is not directly psychoactive but is metabolised to active metabolites.3 Its pharmacological activity depends on the formation of active benzodiazepine metabolites with sedative and hypnotic actions.

Pharmacokinetics

Aminopeptidase enzymes in the small intestine convert rilmazafone into its principal active benzodiazepine metabolite. Several benzodiazepine metabolites are formed in the human body.3

Interactions

Interactions not written up yet

An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.

Check TripSit

Tolerance

Tolerance not written up yet

Harm Potential

Addiction & Dependence

Psychological

Moderate

The extracted TripSit quote classifies rilmazafone as habit-forming.

Toxicity

central nervous system

Amnesia and dystaxia are listed as adverse effects.

History & Culture

Shionogi developed rilmazafone,4 which was previously known as 450191-S.4 It is prescribed in Japan for insomnia5 under the name Rhythmy.4

Legality

By Country

Prescription1
Japan flagJapanPrescription only

References

Citations

  1. Rilmazafone: A designer benzodiazepine pro-drug involved in fatal intoxications. Journal of Analytical Toxicology (2023). https://doi.org/10.1093/jat/bkad0411
  2. リスミー錠1mg／リスミー錠2mg 添付文書 (2025年4月改訂, 第2版). pmda.go.jp (n.d.). https://www.pmda.go.jp/PmdaSearch/iyakuDetail/ResultDataSetPDF/672173_1129006F1021_3_0412
  3. ACMD report: recently encountered uncontrolled novel benzodiazepines and related compounds (2024 update). Advisory Council on the Misuse of Drugs (2024). https://www.drugsandalcohol.ie/40793/1/ACMD-Recently_encountered_novel_benzodiazepines_2024_update.pdf12
  4. リスミー錠1mg・2mg 医薬品インタビューフォーム（2019年8月改訂、第16版）. 共和薬品工業株式会社 (2019). https://www.koizumi-generic-drug-information-research-2nd-ver.com/wp-content/uploads/2021/12/%E3%83%AA%E3%82%B9%E3%83%9F%E3%83%BC%E9%8C%A0%EF%BC%91%EF%BD%8D%EF%BD%87_3_1.pdf123
  5. リスミー錠1mg・2mg 患者向医薬品ガイド（2019年9月更新）. Pharmaceuticals and Medical Devices Agency (PMDA) (2019). https://www.info.pmda.go.jp/downfiles/guide/ph/672173_1129006F1021_3_01G.pdf1
  6. 医薬品、医療機器等の品質、有効性及び安全性の確保等に関する法律第四十九条第一項の規定に基づき厚生労働大臣の指定する医薬品 (平成17年厚生労働省告示第24号), item 8(1221). mhlw.go.jp (n.d.). https://www.mhlw.go.jp/web/t_doc?dataId=81aa6750&dataType=01
  7. 医薬品、医療機器等の品質、有効性及び安全性の確保等に関する法律 (昭和35年法律第145号), Article 49. mhlw.go.jp (n.d.). https://www.mhlw.go.jp/web/t_doc?dataId=81004000&dataType=01

Article Status

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