Ketoconazole Stats & Data
CC(=O)N1CCN(CC1)c1ccc(OCC2COC(O2)(Cn2ccnc2)c2ccc(Cl)cc2Cl)cc1XMAYWYJOQHXEEK-OZXSUGGESA-NPharmacology
DrugBankDescription
Ketoconazole is an imidazole antifungal agent used in the prevention and treatment of a variety of fungal infections. It functions by preventing the synthesis of ergosterol, the fungal equivalent of cholesterol, thereby increasing membrane fluidity and preventing growth of the fungus. Ketoconazole was first approved in an oral formulation for systemic use by the FDA in 1981. At this time it was considered a significant improvement over previous antifungals, miconazole and clotrimazole, due to its broad spectrum and good absorption. However, it was discovered that ketoconazole produces frequent gastrointestinal side effects and dose-related hepatitis. These effects combined with waning efficacy led to its eventual replacement by triazole agents, fluconazole, itraconazole, voriconazole, and posaconazole. Ketoconazole and its predecessor clotrimazole continue to be used in topical formulations.
Mechanism of Action
Ketoconazole interacts with 14-α-sterol demethylase, a cytochrome P-450 enzyme necessary for the conversion of lanosterol to ergosterol. This results in inhibition of ergosterol synthesis and increased fungal cellular permeability due to reduced amounts of ergosterol present in the fungal cell membrane. This metabolic inhibition also results in accumulation of 14α-methyl-3,6-diol, a toxic metabolite. The increase in membrane fluidity is also thought to produce impairment of membrane-bound enzyme systems as components become less closely packed.
Pharmacodynamics
Ketoconazole, similarly to other azole antifungals, is a fungistatic agent which causes growth arrest in fungal cells thereby preventing growth and spread of the fungus throughout the body.
Metabolism
The major metabolite of ketoconazole appears to be M2, an end product resulting from oxidation of the imidazole moiety. CYP3A4 is known to be the primary contributor to this reaction with some contribution from CYP2D6. Other metabolites resulting from CYP3A4 mediated oxidation of the imidazole moiety include M3, M4, and M5. Ketoconazole may also undergo N-deacetylation to M14, , alkyl oxidation to M7, N-oxidation to M13, or aromatic hydroxylation to M8, or hydroxylation to M9. M9 may further undergo oxidation of the hydroxyl to form M12, N-dealkylation to form M10 with a subsequent N-dealkylation to M15, or may form an iminium ion. No metabolites are known to be active however oxidation metabolites of M14 have been implicated in cytotoxicity.
Absorption
Ketoconazole requires an acidic environment to become soluble in water. At pH values above 3 it becomes increasingly insoluble with about 10% entering solution in 1 h. At pH less than 3 dissolution is 85% complete in 5 min and entirely complete within 30 min. A single 200 mg oral dose produces a Cmax of 2.5-3 mcg/mL with a Tmax of 1-4 h. Administering ketoconazole with food consistently increases Cmax and delays Tmax but literature is contradictory regarding the effect on AUC, which may experience a small decrease. A bioavailablity of 76% has been reported for ketoconazole.
Toxicity
Symptoms of overdose include acute liver injury, which may include both hepatocellular and cholestatic injury, accompanied by anorexia, fatigue, nausea, and jaundice. In case of overdose, gastric lavage with activated charcoal may be used if within one hour of ketoconazole ingestion otherwise provide supportive care.FDA Label,L7736 If the patient shows signs of adrenal insufficiency, administer 100 mg hydrocortisone once together with saline and glucose infusion and monitor the patient closely. Blood pressure and fluid and electrolyte balance should be monitored over the next few days.
Indication
Ketoconazole is used in the treatment or prevention of fungal infections including blastomycosis, candidiasis, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis. In Europe, it is also used in the treatment of endogenous Cushing's syndrome.
Half-life
Ketoconazole experiences biphasic elimination with the first phase having a half-life of 2 hours and a terminal half life of 8 hours.
Protein Binding
Ketoconazole is approximately 84% bound to plasma albumin with another 15% associated with blood cells for a total of 99% binding within the plasma.
Elimination
Only 2-4% of the ketoconazole dose is eliminated unchanged in the urine. Over 95% is eliminated through hepatic metabolism.
Volume of Distribution
Ketoconazole has an estimated volume of distribution of 25.41 L or 0.36 L/kg. It distributes widely among the tissues, reaching effective concentrations in the skin, tendons, tears, and saliva. Distribution to vaginal tissue produces concentrations 2.4 times lower than plasma. Penetration into the CNS, bone, and seminal fluid are minimal. Ketoconazole has been found to enter the breast milk and cross the placenta in animal studies.
Clearance
Ketoconazole has an estimated clearance of 8.66 L/h.
Effect Profile
CuratedStrong euphoria with moderate itching/nausea, mild sedation