Systematic (IUPAC) name
Clinical data
AHFS/ Micromedex Detailed Consumer Information
Pregnancy cat.  ?
Legal status  ?
Routes IV
Pharmacokinetic data
Bioavailability  ?
Metabolism  ?
Half-life 35 hours
Excretion Renal
CAS number 494-79-1 YesY
ATC code P01CD01 QP51AD04
PubChem CID 10311
ChemSpider 9889 YesY
KEGG D00832 YesY
Chemical data
Formula C12H15AsN6OS2 
Mol. mass 398.341 g/mol
SMILES eMolecules & PubChem
 N(what is this?)  (verify)

Melarsoprol (INN) is a medicinal drug used in the treatment of human African trypanosomiasis.[1] It is also sold under the trade names “Mel B” and “Melarsen Oxide-BAL.”

Melarsoprol is also used in the treatment of trypanosomiasis, such as Chagas disease and West African sleeping sickness, the former caused by Trypanosoma cruzi and the latter by Trypanosoma brucei gambiense.

Side effects

Being a toxic organic compound of arsenic, melarsoprol is a highly dangerous treatment which is only administered by injection under the supervision of a physician, as it can produce similar effects as arsenic poisoning.

It is known to cause a range of side effects including convulsions, fever, loss of consciousness, rashes, bloody stools, nausea, and vomiting. It is fatal in and of itself in around 8% of cases.[2]


Eflornithine is a more modern and far less dangerous treatment for sleeping sickness,[3] but it is expensive, it is not widely available on the market, and most of its supply comes from donations from its manufacturer. Moreover, eflornithine is effective only for West African sleeping sickness (caused by Trypanosoma brucei gambiense); it has no effect on East African sleeping sickness (caused by Trypanosoma brucei rhodesiense).


  1. ^ Bisser S, N'Siesi FX, Lejon V et al. (2007). "Equivalence trial of melarsoprol and nifurtimox monotherapy and combination therapy for the treatment of second-stage Trypanosoma brucei gambiense sleeping sickness". J. Infect. Dis. 195 (3): 322–9. doi:10.1086/510534. PMID 17205469. 
  2. ^ Bulletin of the World Health Organization vol.84 no.10 Genebra Oct. 2006 - Melarsoprol versus eflornithine for treating late-stage Gambian trypanosomiasis in the Republic of the Congo.
  3. ^ Chappuis F, Udayraj N, Stietenroth K, Meussen A, Bovier PA (2005). "Eflornithine is safer than melarsoprol for the treatment of second-stage Trypanosoma brucei gambiense human African trypanosomiasis". Clin. Infect. Dis. 41 (5): 748–51. doi:10.1086/432576. PMID 16080099.