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IUPAC name
(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26R,27S,28E)-5,12,21,23-tetrahydroxy-27-methoxy-2,4,16,20,22,24,26-heptamethyl-10-[4-(2-methylpropyl)piperazin-1-yl]-1,6,15-trioxo-1,2-dihydro-6H-2,7-(epoxypentadeca[1,11,13]trienoimino)[1]benzofuro[4,5-a]phenoxazin-25-yl acetate
Systematic IUPAC name
(7S,9E,11S,12R,13S,14R,15R,16R,17S,18S,19E,21Z)-2,15,17,32-Tetrahydroxy-30-(4-isobutyl-1-piperazinyl)-11-methoxy-3,7,12,14,16,18,22-heptamethyl-6,23,37-trioxo-8,27,38-trioxa-24,34-diazahexacyclo[23.11;.1.14,7.05,36.026,35.028,33]octatriaconta-1(36),2,4,9,19,21,25,28,30,32,34-undecaen-13-yl acetate
3D model (JSmol)
  • InChI=1S/C51H64N4O13/c1-24(2)23-54-16-18-55(19-17-54)32-21-33(57)39-35(22-32)67-48-40(52-39)36-37-44(60)30(8)47-38(36)49(62)51(10,68-47)65-20-15-34(64-11)27(5)46(66-31(9)56)29(7)43(59)28(6)42(58)25(3)13-12-14-26(4)50(63)53-41(48)45(37)61/h12-15,20-22,24-25,27-29,34,42-43,46,57-60H,16-19,23H2,1-11H3,(H,53,63)/b13-12+,20-15+,26-14-/t25-,27+,28+,29+,34-,42-,43+,46+,51-/m0/s1
  • C[C@H]1C=CC=C(C(=O)N=C2C3=C(C4=C5C(=C(C(=C4C2=O)O)C)O[C@@](C5=O)(OC=C[C@@H]([C@H]([C@H]([C@@H]([C@@H]([C@@H]([C@H]1O)C)O)C)OC(=O)C)C)OC)C)NC6=C(O3)C=C(C=C6O)N7CCN(CC7)CC(C)C)C
Molar mass 941.088 g·mol−1
Very high water solubility around 2000 mg/mL at a pH of 2 and a low solubility of 0.5 mg/mL at a pH of 5
8.7±2.7 hours[2]
Legal status
  • Development terminated
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Rifalazil (also known as KRM-1648 and AMI-1648)[2] is an antibiotic substance that kills bacterial cells by blocking off the β-subunit in RNA polymerase.[3] Rifalazil is used as treatments for many different diseases. Of the most common are Chlamydia infection, Clostridium difficile associated diarrhea (CDAD), and tuberculosis (TB). Using rifalazil and the effects that coincide with taking rifalazil for treating a bacterial disease vary from person to person, as does any drug put into the human body. Food interactions and genetic variation are a few causes for the variation in side effects from the use of rifalazil.[4] Its development was terminated in 2013 due to severe side effects.[5]

Biological properties

Rifalazil works well alone, and in conjunction with other antibiotics alone. In a study conducted in 2005, it was found that combining rifalazil with vancomycin increased bacterial killing by a factor of 3.[medical citation needed] Rifalazil also has a very long half-life which allows more infrequent dosages as opposed to frequent small dosages of antibiotics.[6]

Many different studies have been conducted that researched the effect of rifalazil on certain strains of bacterial diseases. In a study conducted in 2004, it was found that rifalazil reduces C. difficile strains when studied in vitro.[7]


Rifalazil has been developed to treat cases of tuberculosis and chlamydia. It is very good treatment for tuberculosis because rifalazil achieves very high concentration in the blood cells and the lungs. In addition, rifalazil is becoming more widely used because it can be used along with many other indications, such as HIV, TB, and MRSA.[8] Rifalazil has a very long half-life which is very useful for certain medications. The drug is administered orally which is also convenient in terms of drug administration. A longer half-life allows for few treatments and dosage which makes this an up-and-coming drug for tuberculosis, CDAD, and chlamydia. Although the uses for rifalazil seem very effective, there are negative side effects which make the use limited. Rifalazil interacts with other drugs and on top of that, rapid resistance develops to other drugs.[medical citation needed]

Tested diseases for rifalazil treatment


  1. ^ "Rifalazil - 129791-92-0".
  2. ^ a b "Rifalazil". Tuberculosis. 88 (2): 148–150. 2008. doi:10.1016/S1472-9792(08)70023-4. PMID 18486057.
  3. ^ Osburne, Marcia S; Murphy, Christopher K; Rothstein, David M (2006). "Enhanced Activity of Rifalazil in Combination with Levofloxacin, Linezolid, or Mupirocin against Staphylococcus aureus in vitro". The Journal of Antibiotics. 59 (5): 303–8. doi:10.1038/ja.2006.43. PMID 16883781.
  4. ^ "Cannabis Ministry Amsterdam : Home : THC Ministry Amsterdam".
  5. ^ "AdisInsight: Rifalazil (ABI 1648; KRM 1648; PA 1648)". Adis Insight. Springer International Publishing AG. Retrieved 30 January 2016.
  6. ^ Osburne, MS; Rothstein, DM; Farquhar, R; Murphy, CK (2006). "In vitro time-kill activities of rifalazil, alone and in combination with vancomycin, against logarithmic and stationary cultures of Staphylococcus aureus". J. Antibiot. 59 (2): 80–85. doi:10.1038/ja.2006.11. PMID 16629407.
  7. ^ Anton, P. M.; O'Brien, M.; Kokkotou, E.; Eisenstein, B.; Michaelis, A.; Rothstein, D.; Paraschos, S.; Kelly, C. P.; Pothoulakis, C. (2004). "Rifalazil Treats and Prevents Relapse of Clostridium difficile-Associated Diarrhea in Hamsters". Antimicrobial Agents and Chemotherapy. 48 (10): 3975–9. doi:10.1128/AAC.48.10.3975-3979.2004. PMC 521872. PMID 15388461.
  8. ^ "Archived copy". Archived from the original on 2013-02-03. Retrieved 2012-11-20.{{cite web}}: CS1 maint: archived copy as title (link)
  9. ^ "Archived copy". Archived from the original on 2013-08-10. Retrieved 2012-11-20.{{cite web}}: CS1 maint: archived copy as title (link)