Clioquinol tradename Entero-Vioform 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. Clioquinol (5-chloro-7-iodo-8-quinolinol, CAS 130-32-5, MW ~305.5 g mol) is a lipophilic 8-hydroxyquinoline derivative that chelates divalent metal ions and interferes with metal dependent enzymes including certain metalloproteinases and topoisomerase functions implicated in nucleic acid metabolism; this metal chelation also underpins its broad spectrum antifungal, antiprotozoal and limited antibacterial activity. The compound is sparingly soluble in water, typically formulated for topical use or as enteric preparations for intestinal amoebiasis in historical practice, and is analyzed and controlled using HPLC for assay and related substances, GC for residual solvents, and ICP based methods for heavy metals. Key physicochemical properties include the phenolic OH enabling metal coordination, aromatic conjugation affecting membrane permeability, and halogenation (Cl and I) that modifies lipophilicity and biological target interactions. Clinical and regulatory use has been constrained by reports of subacute myelo-optic neuropathy with high systemic exposure, so modern usage emphasizes topical or limited intestinal routes, controlled dosing, and impurity and exposure monitoring.
Parent: Clioquinol
Typical pharmaceutical quality specifications for clioquinol reference an assay of not less than 98.0 percent on a dry basis, loss on drying generally below 0.5 percent, and limits for impurities and related substances established to control safety and efficacy; commonly applied limits are individual related substances not greater than 0.5 percent, total related substances not greater than 2.0 percent, and unspecified or potentially genotoxic impurities controlled to below 0.05 percent where applicable. Related compounds expected in synthesis or degradation profiles include mono dehalogenated species, 8-hydroxyquinoline, 5-chloro-8-hydroxyquinoline, 7-iodo-8-hydroxyquinoline, N oxide derivatives and small amounts of oxidative dimers; each is typically monitored by validated HPLC methods. Residual solvents are controlled to ICH Q3C class limits, heavy metals are typically limited to 20 parts per million or lower depending on the monograph, and microbial limits apply for non-sterile topical forms. Suppliers and manufacturers publish batch specific certificates of analysis that list measured amounts for each impurity and the tests used for quantitation.
Clioquinol is used primarily as a topical antifungal and antiprotozoal agent and historically was used orally for certain intestinal protozoal infections; contemporary applications favor topical dermatologic formulations for superficial fungal and mixed infections and limited localized use where systemic exposure is minimal.
Clioquinol is not a conventional antibiotic in the sense of modern beta lactams or aminoglycosides, but it does have antimicrobial activity against fungi, protozoa and some bacteria via metal chelation and enzyme inhibition; it is classified as an antifungal and antiprotozoal agent rather than a standard antibacterial antibiotic.
Betamethasone and clioquinol cream combines a potent topical corticosteroid (betamethasone) with an antifungal/antiprotozoal (clioquinol) to treat inflammatory skin conditions that have a superimposed or suspected superficial fungal or protozoal component, providing both anti inflammatory relief and antimicrobial action.
When used as directed for limited durations and limited surface area, clioquinol topical formulations are generally considered safe for many patients, but safety considerations include local irritation, potential for steroid related adverse effects when combined with betamethasone, and historical concerns about neurotoxicity with high systemic exposure; avoid prolonged, large area, or unmonitored use and consult a healthcare professional if there are concerns or for use in children, pregnant or breastfeeding patients.
