Products
Clioquinol was available in many countries in combination with the glucocorticoid betamethasone as a cream or ointment (Betnovate-C). It was also formerly contained in Quadriderm (out of trade) and marketed under the name Vioform. In Germany, Linola Sept is approved as a monopreparation. Magistral formulations are commonly used in dermatology. The DMS contains some preparations, for example, Clioquinol Shaking Brush 5%.
Structure and properties
Clioquinol is 5-chloro-7-iodoquinolin-8-ol (C
9
H
5
INO, M
r
= 305.5 g/mol). It is a chlorinated and iodinated hydroxyquinoline. It is a white, light yellow, brownish yellow or yellowish gray powder. With a log P of 3.5, it is lipophilic. It has structural similarities to chlorquinaldol.
Effects
Clioquinol (ATC D08AH30) has antibacterial, antifungal, and antiseptic properties. Taken orally, it is antiparasitic (amebicidal) against the protozoan , the causative agent of amebiasis, and neurotoxic. It forms chelates after absorption into the bacterial or fungal cell with metal ions such as Zn
2+
and Cu
2+
and thus interferes with the function of enzymes.
Indications
Clioquinol is used for the external treatment of bacterially or mycotically infected skin diseases. It was used internally during the 1950s to 1970s for the treatment of amebiasis, prevention of traveler’s diarrhea, and diarrheal disease, but was withdrawn in the 1970s because of oral neurotoxicity (subacute myeloopticoneuropathy, SMON disease). This syndrome manifests itself in sensory and motor disturbances and occurred mainly in Japanese, for which genetic causes and endemic vitamin B12 deficiency, among others, have been blamed. In recent years, the use of clioquinol has been investigated in malignancies and in Alzheimer’s disease. The compound complexes copper ions, which play a role in the pathogenesis of Alzheimer’s disease. It has not been adequately studied in these indications and should not be administered off-label.
Dosage
Apply 1-2 times daily. It should be noted that clioquinol may cause yellow to brown stains on clothing that are difficult to remove. If stains appear, they should be washed out immediately.
Contraindications
Clioquinol is contraindicated in case of hypersensitivity. Disorders of thyroid function are possible with long-term use. It should not be used over large areas, in overdose, under occlusion, in the inguinal region, or in diaper dermatitis. Clioquinol should not be taken. For complete precautions, see the drug label.
Interactions
None known to date.
Adverse effects
External use: Possible adverse effects include hypersensitivity reactions and transient reddish discoloration of white scalp hair and skin.