Desmethylflunitrazepam, which is also referred to as norflunitrazepam, Ro05-4435, and fonazepam, is a benzodiazepine compound. This substance is a metabolite of flunitrazepam and has been made available for purchase online as a designer drug. It exhibits a notable IC50 value of 1.499 nM for its interaction with the GABAA receptor.

IUPAC name
CAS Number2558-30-7
PubChem CID520217
CompTox Dashboard (EPA)DTXSID30180268
ECHA InfoCard100.018.072
Chemical and physical data
Molar mass299.261 g·mol−1


  • What is Desmethylflunitrazepam?
  • Desmethylflunitrazepam, also known as norflunitrazepam, Ro05-4435, and fonazepam, is a benzodiazepine compound. It is a metabolite of flunitrazepam and has been marketed and sold online as a designer drug.
  • How does Desmethylflunitrazepam work?
  • Desmethylflunitrazepam acts on the GABAA receptor, exhibiting an IC50 value of 1.499 nM. This receptor is involved in the regulation of inhibitory neurotransmission in the brain, leading to sedative and anxiolytic effects.
  • Is Desmethylflunitrazepam legal?
  • The legal status of Desmethylflunitrazepam varies by country. It is essential to check your local laws and regulations regarding the possession, sale, or use of this substance. In many places, it may be considered illegal.
  • What are the effects of Desmethylflunitrazepam?
  • As a benzodiazepine derivative, Desmethylflunitrazepam may induce effects such as sedation, relaxation, and anxiolysis. The specific impact and intensity can vary from person to person.
  • Is Desmethylflunitrazepam safe to use?
  • The safety of using Desmethylflunitrazepam is a subject of concern, especially when purchased as a designer drug. Benzodiazepines can lead to adverse effects, dependence, and withdrawal symptoms. It is crucial to consult with a healthcare professional regarding the safety and appropriateness of any substance use.
  • Is Desmethylflunitrazepam addictive?
  • Benzodiazepines, including Desmethylflunitrazepam, have the potential for addiction, particularly when used regularly or at high doses. They can lead to physical and psychological dependence, making it essential to use them under medical supervision and in accordance with prescribed guidelines.
  • What should I do if I have questions about Desmethylflunitrazepam or its effects?
  • If you have concerns about Desmethylflunitrazepam or its effects, it is advisable to consult with a healthcare professional who can provide guidance, information, and support based on your specific situation.
  • Where can I find more information about Desmethylflunitrazepam?
  • For additional information about Desmethylflunitrazepam, you can refer to scientific literature and medical resources or consult with healthcare providers who specialize in substance-related matters. It’s essential to rely on credible sources for information.


  1. Busker RW, van Henegouwen GM, Kwee BM, Winkens JH (May 1987). “Photobinding of flunitrazepam and its major photo-decomposition product N-desmethylflunitrazepam”. This study explores the photobinding properties of flunitrazepam and its primary photo-decomposition product, N-desmethylflunitrazepam.
  2. Coller JK, Somogyi AA, Bochner F (November 1998). “Quantification of flunitrazepam’s oxidative metabolites, 3-hydroxyflunitrazepam and desmethylflunitrazepam, in hepatic microsomal incubations by high-performance liquid chromatography”. This research focuses on quantifying the oxidative metabolites of flunitrazepam, specifically 3-hydroxyflunitrazepam and desmethylflunitrazepam, using high-performance liquid chromatography.
  3. Kilicarslan T, Haining RL, Rettie AE, Busto U, Tyndale RF, Sellers EM (April 2001). “Flunitrazepam metabolism by cytochrome P450S 2C19 and 3A4”. This study delves into the metabolism of flunitrazepam, particularly its interaction with cytochrome P450S 2C19 and 3A4 enzymes.
  4. Moosmann B, Bisel P, Franz F, Huppertz LM, Auwärter V (November 2016). “Characterization and in vitro phase I microsomal metabolism of designer benzodiazepines – an update comprising adinazolam, cloniprazepam, fonazepam, 3-hydroxyphenazepam, metizolam, and nitrazolam”. The research provides insights into the in vitro phase I microsomal metabolism of various designer benzodiazepines, including fonazepam, adinazolam, and more.
  5. Katselou M, Papoutsis I, Nikolaou P, Spiliopoulou C, Athanaselis S (2016). “Metabolites replace the parent drug in the drug arena. The cases of fonazepam and nifoxipam”. This study discusses cases where metabolites replace the parent drug in the illicit drug market, focusing on fonazepam and nifoxipam.
  6. Maddalena DJ, Johnston GA (February 1995). “Prediction of receptor properties and binding affinity of ligands to benzodiazepine/GABAA receptors using artificial neural networks”. The research involves predicting receptor properties and the binding affinity of ligands to benzodiazepine/GABAA receptors, utilizing artificial neural networks.
  7. So SS, Karplus M (December 1996). “Genetic neural networks for quantitative structure-activity relationships: improvements and application of benzodiazepine affinity for benzodiazepine/GABAA receptors”. This study explores genetic neural networks for quantitative structure-activity relationships and their application to benzodiazepine affinity for benzodiazepine/GABAA receptors, including improvements in the methodology.

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