Clioquinol Chemical formula
Synonyms: Chinoform; Chloroiodoquine; Cliochinolum; Clioquinolum; Iodochlorhydroxyquin; Iodochlorhydroxyquinoline; Kliochinol; Kliokinol; Kliokinoli; Kliokvinolis; PBT-1; Quiniodochlor. 5-Chloro7-iodoquinolin-8-ol.
Cyrillic synonym: Клиохинол.

💊 Chemical information

Chemical formula: C9H5ClINO = 305.5.
CAS — 130-26-7.
ATC — D08AH30; D09AA10; G01AC02; P01AA02; S02AA05.
ATC Vet — QD08AH30; QD09AA10; QG01AC02; QS02AA05.


In Chin., Eur., and US.

Ph. Eur. 6.2

(Clioquinol). An almost white, light yellow, brownish-yellow, or yellowish-grey powder. Practically insoluble in water; very slightly soluble or slightly soluble in alcohol; sparingly soluble in dichloromethane. Protect from light.

USP 31

(Clioquinol). A voluminous, spongy, yellowish-white to brownish-yellow powder having a slight characteristic odour. It darkens on exposure to light. Practically insoluble in water; soluble 1 in 3500 of alcohol, 1 in 120 of chloroform, and 1 in 4500 of ether; soluble in hot ethyl acetate and in hot glacial acetic acid. Store in airtight containers. Protect from light.

💊 Adverse Effects and Precautions

Clioquinol may rarely cause iodism in sensitive patients. Local application of clioquinol in ointments or creams may occasionally cause severe irritation or hypersensitivity and there may be cross-sensitivity with other halogenated hydroxyquinolines. Clioquinol stains clothing and linen yellow on contact and may stain the skin and discolour fair hair. Clioquinol given by mouth has been associated with severe neurotoxicity. In Japan, the epidemic development of subacute myelo-opticoneuropathy (SMON) in the 1960s was associated with the ingestion of normal or high doses of clioquinol for prolonged periods, and the sale of clioquinol and related hydroxyquinolines was subsequently banned there. Symptoms of SMON are principally those of peripheral neuropathy, including optic atrophy, and myelopathy. Abdominal pain and diarrhoea often precede neurological symptoms, such as paraesthesias in the legs progressing to paraplegia in some patients, and loss of visual acuity sometimes leading to blindness. A characteristic green pigment, a chelate of clioquinol with iron, is often seen on the tongue and in the urine and faeces. Cerebral disturbances, including confusion and retrograde amnesia, have also been reported. Although many patients improved when clioquinol was withdrawn, others had residual disablement. It was suggested that the Japanese epidemic might be due to genetic susceptibility, but a few similar cases of SMON associated with clioquinol or related hydroxyquinoline derivatives, such as broxyquinoline or diiodohydroxyquinoline have been reported from other countries. Oral preparations of clioquinol have now been banned in most countries.


Clioquinol is classified as a contact allergen which can commonly cause sensitisation, especially when applied to eczematous skin; chlorquinaldol can also cause sensitisation, although less frequently.1 It is important to include clioquinol and chlorquinaldol in routine patch testing since the clinical reaction may be relatively mild and sensitivity easily missed, particularly in the presence of a corticosteroid which suppresses or attenuates the reaction.
1. Anonymous. Skin sensitisers in topical corticosteroids. Drug For a discussion of the risks from topical application of clioquinol, see Adverse Effects and Precautions, above. Clioquinol was formerly given by mouth in the treatment of intestinal amoebiasis. It was also formerly used for the prophylaxis and treatment of traveller’s diarrhoea and similar infections but was of doubtful value. Oral preparations have now been withdrawn because of neurotoxicity (see Adverse Effects and Precautions, above). However, clioquinol by mouth has been investigated for its action as a chelator of copper and zinc in the treatment of Alzheimer’s disease (see below). Alzheimer’s disease. A systematic review1 to evaluate the efficacy of metal protein attenuating compounds, such as clioquinol, for the treatment of cognitive impairment due to Alzheimer’s disease, evaluated only one small randomised controlled study comparing clioquinol and placebo; no significant differences were found. Further studies with clioquinol have now been stopped, but studies are on-going with a successor compound, PBT2.
1. Sampson E, et al. Metal protein attenuating compounds for the treatment of Alzheimer’s disease. Available in The Cochrane Database of Systematic Reviews; Issu
1. Chichester: John Wiley; 2008 (accessed 14/05/08).

💊 Preparations

BP 2008: Betamethasone and Clioquinol Cream; Betamethasone and Clioquinol Ointment; Hydrocortisone and Clioquinol Cream; Hydrocortisone and Clioquinol Ointment; USP 31: Clioquinol and Hydrocortisone Cream; Clioquinol and Hydrocortisone Ointment; Clioquinol Cream; Clioquinol Ointment; Compound Clioquinol Topical Powder.

Proprietary Preparations

Ger.: Linola-sept; Hung.: Linola-sept†; India: Dermoquinol; Entero-Quinol; Entrozyme Plain; Mex.: Bagton; Bionder-C; Cortifung-C; Lasalar-Y Simple; Luzolona Simple; Nolil; Quindoleina†; Vioformo; Port.: Quinodermil†. Multi-ingredient: Arg.: Betnovate-C; Locorten Vioformo†; Quadriderm†; Austral.: Hydroform; Locacorten Vioform; Quinaband†; Austria: Betnovate-C; Locacorten Vioform; Belg.: Betnelan-VC†; Locacortene Vioforme†; Braz.: Betnovate-Q; Cremederme; Dreniformio; Hidrocorte; Locorten Vioformio; Permut; Poliderms; Predmicin; Quadriderm; Quadrikin; Quadrilon; Quadriplus; Qualiderm; Tetraderm; Vioformio-Hidrocortisona; Canad.: Locacorten Vioform; Phenoris; Vioform-Hydrocortisone; Cz.: Lorinden C†; Prednisolon J†; Denm.: Betnovat med Chinoform; Celeston med Chinoform; Locacorten Vioform; Synalar med Chinoform; Fin.: Bemetson-K; Betnovat-C; Celestoderm cum Chinoform†; Locacorten Vioform; Fr.: Diprosept†; Locacortene Vioforme; Ger.: Locacorten Vioform; Gr.: Betnovate-C; Myco-Synalar; Hong Kong: Betnovate-C†; Clobeta-G; Dermafacte; Quadriderm; Hung.: Lorinden C; Prednisolon J; India: Beclate-C; Betnederm C; Betnovate-C; Cortoquinol; Fourderm; MillicortenVioform; Polyderm†; Quiss; Indon.: Benoson V; Krimbeson; Viohydrocort; Visancort; Irl.: Betnovate-C; Synalar C†; Vioform-Hydrocortisone; Israel: Betnovate-C; Topicorten V; Ital.: Diproform; Locorten; Locorten Vioformio; Mex.: Bentix; Cetoquina Y; Clio-Betnovate; Clioderm-H; Contefur†; Cortifung-Y; Cortilona Compuesta; Dealan; Diprosone Y; Ditayod; Farmacorti YC; Fluccinol C†; Flunal†; Lasalar-Y; Luzolona Y; Sebryl; Sebryl Plus; Sebstopp; Solfurol; Sultroquin†; Suyodil; Synalar C; Taliviform†; Topsyn-Y; Trilor†; Ultracortin; Vioformo-Cort; Yderm; Yodozona; Neth.: Locacorten Vioform; Norw.: Betnovat med Chinoform; Synalar med Chinoform; NZ: Betnovate-C; Locorten Vioform; Philipp.: Aplosyn C; Betnovate-C; Dermalin; Diproform; Quadriderm; Quadrotopic; Pol.: Betnovate-C; Lorinden C; Viosept; Port.: Betnovate-C; Dexaval V; Locorten Vioformio†; Quinodermil-AS; Rus.: Dermosolon (Дермозолон); Lorinden C (Лоринден С); S.Afr.: Betnovate-C; Cortoderm-C; Locacorten Vioform; Quadriderm; Synalar C; Singapore: Dermanol-C; Hydroderm-C; Quadriderm†; Spain: Cuatroderm; Menaderm Clio; Menaderm Otologico; Synobel†; Swed.: Betnovat med Chinoform; Celeston valerat med chinoform; Locacorten Vioform; Switz.: Betnovate-C; Quadriderm; Thai.: Banocin; Beta-C; Betnovate-C; Betosone-CE; Chlorotracin; Endothalyl; Genquin; Turk.: Betnovate-C; Locacortene Vioform; Prednol-A; UK: Betnovate-C; Locorten Vioform; Quinaband†; Synalar C; Vioform-Hydrocortisone; USA: 1 + 1-F; Corque; Hysone; Venez.: Dermosupril C; Diproformo; Locorten Vioformo; Neo-Synalar con Yodoclorohidroxiquina†; Propioformo†; Quadriderm; Tridetarmon; Vio Celestoderm†.
Published January 26, 2019.