Open main menu

Clioquinol (iodochlorhydroxyquin) is an antifungal drug and antiprotozoal drug. It is neurotoxic in large doses. It is a member of a family of drugs called hydroxyquinolines which inhibit certain enzymes related to DNA replication. The drugs have been found to have activity against both viral and protozoal infections.[2]

Skeletal formula of clioquinol
Ball-and-stick model of the clioquinol molecule
Clinical data
Trade namesCortin
AHFS/Drugs.comMicromedex Detailed Consumer Information
  • US: C (Risk not ruled out) [1]
Routes of
topical only
ATC code
Legal status
Legal status
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.004.533 Edit this at Wikidata
Chemical and physical data
Molar mass305.50 g·mol−1
3D model (JSmol)
 ☒N☑Y (what is this?)  (verify)


Antiprotozoal useEdit

A 1964 report described the use of Clioquinol in both the treatment and prevention of shigella infection and Entamoeba histolytica infection in institutionalized individuals at Sonoma State Hospital in California. The report indicates 4000 individuals were treated over a 4-year period with few side effects.[3]

Several recently reported journal articles describing its use as an antiprotozoal include:

Subacute myelo-optic neuropathyEdit

Clioquinol's use as an antiprotozoal drug has been restricted or discontinued in some countries due to an event in Japan where over 10,000 people developed subacute myelo-optic neuropathy (SMON) between 1957 and 1970. The drug was used widely in many countries before and after the SMON event without similar reports.[7] As yet, no explanation exists as to why it produced this reaction, and some researchers have questioned whether clioquinol was the causative agent in the disease, noting that the drug had been used for 20 years prior to the epidemic without incident, and that the SMON cases began to reduce in number prior to the discontinuation of the drug.[8] Theories suggested have included improper dosing, the permitted use of the drug for extended periods of time,[9] and dosing which did not consider the smaller average stature of Japanese; however a dose dependant relationship between SMON development and clioquinol use was never found, suggesting the interaction of another compound. Researchers have also suggested the SMON epidemic could have been due to a viral infection with an Inoue-Melnick virus.[10]

Topical useEdit

Clioquinol is a constituent of the prescription medicine Vioform, which is a topical antifungal treatment. It is also used in the form of a cream (and in combination with betamethasone or fluocinolone) in the treatment of inflammatory skin disorders.

Potential use as a preventative or treatment in prostate cancerEdit

It has long been recognized that normal prostate cells have high zinc content through ZIP1 mediated uptake, and have low respiration (OXPHOS ATP generation is diverted to citrate export for sperm energetics). Prostate cancer cells have downregulated ZIP1 transporters which leads to greater ATP generation which is diverted to cancer proliferation. An example of a normal-like metabolic phenotype instead being malignant (disguised Warburg effect?). The zinc ionophore clioquinol was shown in mice to restore zinc levels and stop the growth of prostate tumors (see Figure 13).[11]

Use in neurodegenerative diseasesEdit

Research at UCSF indicates that clioquinol appears to block the genetic action of Huntington's disease in mice and in cell culture.[12]

Recent animal studies have shown that clioquinol can reverse the progression of Alzheimer's, Parkinson's and Huntington's diseases.[13] According to Dr. Siegfried Hekimi and colleagues at McGill's Department of Biology, clioquinol acts directly on a protein called Clk-1, often informally called “clock-1,” and might slow down the aging process. They theorize that this may explain the apparent ability of the drug to be effective in the above conditions, but warn against individuals experimenting with this drug.[14]

In addition, a study performed in Drosophila [15] by Huang and Wu, two researchers from Tsinghua University and Stanford University, demonstrates that Clioquinol can slower the pathogenesis of Tauopathy model by removing the excessive Zinc in the cell.

Continued use and manufacture around the worldEdit

Country Comments
United States In August 2004, Prana Biotechnology, an Australian company and P.N Gerolymatos S.A (PNG) agreed to recognize each other's rights to market clioquinol in their respective territories, with PNG holding right for European territories, and Prana holding rights for US and Japan.
Canada In 2001, the Canadian company Paladin Labs bought the rights to market Vioform from Novartis. Vioform is licensed for use in Canada as a topical anti-fungal.
Netherlands 2004 and 2005 reports describe use in treatment of Dientamoeba fragilis and Entamoeba histolytica infection.[5]
India Manufactured by Eskay Iodine Pvt. Ltd., Vishal Laboratories, DNS Fine Chemicals [16] and LASA Laboratory[17]
Colombia Manufactured by "Altea Farmacéutica C.A." for "Scandinavia Pharma"[18]

See alsoEdit

  • PBT2, a related 8-hydroxyquinoline


  1. ^ "Clioquinol topical medical facts from". Retrieved 15 May 2015.
  2. ^ Rohde W, Mikelens P, Jackson J, Blackman J, Whitcher J, Levinson W (1976). "Hydroxyquinolines inhibit ribonucleic acid-dependent deoxyribonucleic acid polymerase and inactivate Rous sarcoma virus and herpes simplex virus". Antimicrob. Agents Chemother. 10 (2): 234–40. doi:10.1128/aac.10.2.234. PMC 429727. PMID 185949.
  3. ^ GHOLZ LM, ARONS WL (1964). "Prophylaxis And Therapy Of Amebiasis And Shigellosis With Iodochlorhydroxyquin". Am. J. Trop. Med. Hyg. 13 (3): 396–401. doi:10.4269/ajtmh.1964.13.396. PMID 14162901.
  4. ^ Kager PA (2005). "[Outbreak of amoebiasis in a Dutch family; tropics unexpectedly nearby]". Nederlands Tijdschrift voor Geneeskunde (in Dutch and Flemish). 149 (1): 51–2, author reply 52–3. PMID 15651505.CS1 maint: Unrecognized language (link)
  5. ^ a b Bosman DK, Benninga MA, van de Berg P, Kooijman GC, van Gool T (2004). "[Dientamoeba fragilis: possibly an important cause of persistent abdominal pain in children]". Nederlands Tijdschrift voor Geneeskunde (in Dutch and Flemish). 148 (12): 575–9. PMID 15074181.CS1 maint: Unrecognized language (link)
  6. ^ Masters DK, Hopkins AD (1979). "Therapeutic trial of four amoebicide regimes in rural Zaire". The Journal of Tropical Medicine and Hygiene. 82 (5): 99–101. PMID 226725.
  7. ^ Wadia NH (1984). "SMON as seen from Bombay". Acta Neurol. Scand. Suppl. 100: 159–64. PMID 6091394.
  8. ^ Meade TW (1975). "Subacute myelo-optic neuropathy and clioquinol. An epidemiological case-history for diagnosis". British Journal of Preventive & Social Medicine. 29 (3): 157–69. doi:10.1136/jech.29.3.157. PMC 478909. PMID 127638.
  9. ^ Takasu T (2003). "[SMON--a model of the iatrogenic disease]". Rinsho Shinkeigaku (in Japanese). 43 (11): 866–9. PMID 15152488.
  10. ^ Ito M, Nishibe Y, Inoue YK (1998). "Isolation of Inoue-Melnick virus from cerebrospinal fluid of patients with epidemic neuropathy in Cuba". Arch. Pathol. Lab. Med. 122 (6): 520–2. PMID 9625419.
  11. ^ Costello LC, Franklin RB (2016). "A comprehensive review of the role of zinc in normal prostate function and metabolism; and its implications in prostate cancer". Arch Biochem Biophys. 611 (1): 100–112. doi:10.1016/ PMC 5083243. PMID 27132038.
  12. ^ Nguyen T, Hamby A, Massa SM (2005). "Clioquinol down-regulates mutant huntingtin expression in vitro and mitigates pathology in a Huntington's disease mouse model". Proc. Natl. Acad. Sci. U.S.A. 102 (33): 11840–5. doi:10.1073/pnas.0502177102. PMC 1187967. PMID 16087879.
  13. ^ Rapid restoration of cognition in Alzheimer's transgenic mice with 8-hydroxy quinoline analogs is associated with decreased interstitial Abeta.
  14. ^ [1]
  15. ^ [2] Zinc Binding Directly Regulates Tau Toxicity Independent of Tau Hyperphosphorylation, Cell Reports, Volume 8, Issue 3, 7 August 2014, Pages 831-842
  16. ^ Vinaysagar, DNS Fine Chemicals (2016-01-06). "Manufacturers of Clioquinol". Dns Fine. Retrieved 23 December 2017.
  17. ^ Herlekar, Omkar. "Clioquinol manufacturers India". Lasa labs. Retrieved 12 March 2013.
  18. ^ "Dermosupril C 0,1% desonide + 3% clioquinol for topical use" (PDF). Medihealth laboratories. Retrieved 19 September 2016.