Open Access Articles- Top Results for BIMU8


Systematic (IUPAC) name
N-[(1R,5S)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-2-oxo-3-(propan-2-yl)-2,3-dihydro-1H-benzimidazole-1-carboxamide hydrochloride
Clinical data
134296-40-5 7pxY
PubChem CID 5311028
ChemSpider 4470566 7pxY
Chemical data
Formula C19H26N4O2 · HCl
342.44 g/mol (free base)
378.896 g/mol (HCl)
 14pxY (what is this?)  (verify)

BIMU-8 is a drug which acts as a 5-HT4 receptor selective agonist. BIMU-8 was one of the first compounds of this class.[1][2] The main action of BIMU-8 is to increase the rate of respiration by activating an area of the brain stem known as the pre-Botzinger complex.


The most obvious practical use of BIMU-8 is to combine it with opioid analgesic drugs in order to counteract the dangerous respiratory depression which can occur when opioids are used in excessive doses.[3] BIMU-8 does not affect the painkilling properties of opiates, which means that if combined with BIMU-8, large therapeutic doses of opiates could theoretically be given to humans without risking a decrease in breathing rate. Studies have shown BIMU-8 to be effective in rats at counteracting the respiratory depression caused by the potent opioid fentanyl,[4] which has caused many accidental deaths in humans. However, no human trials of BIMU-8 have yet been carried out.

Other studies have suggested a role for 5-HT4 agonists in learning and memory,[5] and BIMU-8 was found to increase conditioned responses in mice, so this drug might also be useful for improving memory in humans.

Interestingly some other selective 5-HT4 agonists such as mosapride and tegaserod (the only 5-HT4 agonists currently licensed for use in humans) have been found not to reduce respiratory depression.[6] On the other hand, another 5-HT4 agonist, zacopride, does inhibit respiratory depression in a similar manner to BIMU-8.[7]

This suggests that either the anti-respiratory depression action is mediated via a specific subtype of the 5-HT4 receptor which is activated by BIMU-8 and zacopride, but not by mosapride or tegaserod, or alternatively there may be functional selectivity involved whereby BIMU-8 and zacopride produce a different physiological response following 5-HT4 binding compared to other 5-HT4 agonists. Another alternative to this is that the 5-HT4 agonist currently available for use in humans do not have great enough potency or bioavailability in the brain to elicit the same effects.[6]

Other activity

Along with several other 5-HT4 ligands, BIMU-8 was also found to possess significant affinity for the sigma receptors, acting as a σ2 antagonist.[8][9][10] It is unclear as yet what contribution this additional activity makes to the pharmacological profile of BIMU-8 and other 5-HT4 ligands that also show sigma affinity.


  1. Turconi M, Nicola M, Quintero MG, Maiocchi L, Micheletti R, Giraldo E, Donetti A. Synthesis of a new class of 2,3-dihydro-2-oxo-1H-benzimidazole-1-carboxylic acid derivatives as highly potent 5-HT3 receptor antagonists. Journal of Medicinal Chemistry. 1990 Aug;33(8):2101-8. PMID 1695682
  2. Dumuis A, Sebben M, Monferini E, Nicola M, Turconi M, Ladinsky H, Bockaert J. Azabicycloalkyl benzimidazolone derivatives as a novel class of potent agonists at the 5-HT4 receptor positively coupled to adenylate cyclase in brain. Naunyn-Schmiedeberg's Archives of Pharmacology. 1991 Mar;343(3):245-51. PMID 1650917
  3. Manzke T, Guenther U, Ponimaskin E, Haller M, Dutschmann M, Schwarzacher S, Richter D (2003). "5-HT4(a) receptors avert opioid-induced breathing depression without loss of analgesia". Science 301 (5630): 226–9. PMID 12855812. doi:10.1126/science.1084674. 
  4. Wang, X; Dergacheva, O; Kamendi, H; Gorini, C; Mendelowitz, D (2007). "5-Hydroxytryptamine 1A/7 and 4alpha receptors differentially prevent opioid-induced inhibition of brain stem cardiorespiratory function.". Hypertension 50 (2): 368–76. PMID 17576856. doi:10.1161/HYPERTENSIONAHA.107.091033. 
  5. Meneses A, Hong E (1997). "Effects of 5-HT4 receptor agonists and antagonists in learning". Pharmacol Biochem Behav 56 (3): 347–51. PMID 9077568. doi:10.1016/S0091-3057(96)00224-9. 
  6. 6.0 6.1 Lotsch J, Skarke C, Schneider A, Hummel T, Geisslinger G. The 5-hydroxytryptamine 4 receptor agonist mosapride does not antagonize morphine-induced respiratory depression. Clinical Pharmacology and Therapeutics. 2005 Sep;78(3):278-87.
  7. Meyer, LC; Fuller, A; Mitchell, D (2006). "Zacopride and 8-OH-DPAT reverse opioid-induced respiratory depression and hypoxia but not catatonic immobilization in goats.". American journal of physiology. Regulatory, integrative and comparative physiology 290 (2): R405–13. PMID 16166206. doi:10.1152/ajpregu.00440.2005. 
  8. Bonhaus DW, Loury DN, Jakeman LB, Hsu SA, To ZP, Leung E, Zeitung KD, Eglen RM, Wong EH (October 1994). "[3H]RS-23597-190, a potent 5-hydroxytryptamine4 antagonist labels sigma-1 but not sigma-2 binding sites in guinea pig brain". The Journal of Pharmacology and Experimental Therapeutics 271 (1): 484–93. PMID 7965749. 
  9. Weatherspoon JK, Gonzalez-Alvear GM, Werling LL (May 1997). "Regulation of [3H]norepinephrine release from guinea pig hippocampus by sigma2 receptors". Eur. J. Pharmacol. 326 (2-3): 133–8. PMID 9196265. doi:10.1016/S0014-2999(97)85407-6. 
  10. Liu X, Nuwayhid S, Christie MJ, Kassiou M, Werling LL (June 2001). "Trishomocubanes: novel sigma-receptor ligands modulate amphetamine-stimulated [3H]dopamine release". European Journal of Pharmacology 422 (1–3): 39–45. PMID 11430911. doi:10.1016/S0014-2999(01)01071-8.