Кетоконазол химические свойства, назначение, производство
Описание
Ketoconazole (Nizoral), an orally effective broadspectrum antifungal agent, blocks hydroxylating enzyme systems by interacting with cytochrome P450 at the heme iron site to inhibit steroid and/or androgen synthesis in adrenals, gonads, liver, and kidney. The most sensitive site of action appears to be the C17-20 lyase reaction involved in the formation of sex steroids. This explains the greater suppressibility of testosterone production than with cortisol. Cholesterol side-chain cleavage and 11β/18-hydroxylase are secondary sites of inhibition.
Химические свойства
White or almost white powder.
Использование
Ketoconazole is used to treat candidiasis, chronic mucocutaneous candidiasis, oral thrush, candiduria, blastomycosis, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis. Ketoconazole is an antifungal agent.
Показания
Ketoconazole (Nizoral) is approved for treating dermatophyte infections unresponsive to griseofulvin and for patients unable to tolerate that drug. It is a broad-spectrum antifungal agent that in very high doses inhibits several steps in the biosynthesis of both adrenal and gonadal steroids. While the normal antifungal dose is 200 mg/day, testosterone biosynthesis in both the adrenal and testis is completely abolished by doses of 800 to 1,600 mg/day. This drug is used most commonly for large virilizing adrenal tumors that cannot be surgically removed.
Всемирная организация здравоохранения(ВОЗ)
Ketoconazole, an imidazole antifungal agent, was introduced in
1978 for the topical and systemic treatment of a wide variety of fungal infections.
Its use by mouth has been associated with hepatotoxicity, including cases of
hepatitis, which have usually been reversible on discontinuation of the drug, but
some fatalities have also occurred. Ketoconazole is widely marketed.
Антимикробная активность
The spectrum includes dermatophytes, some dimorphic fungi
and Candida spp.
Приобретенная устойчивость
Resistance has been documented in patients treated for
chronic mucocutaneous candidosis and AIDS patients with
oropharyngeal or esophageal candidosis. Some fluconazoleresistant
C. albicans and C. glabrata are cross-resistant to
ketoconazole.
Общее описание
Ketoconazole is an imidazole antifungal agent administered through topical or oral means. It is used for the treatment of chronic mucocutaneous candidiasis, fungal infections of the gastro-intestinal tract, dermatophyte infections, systemic infections, and fungal infections in immuno-compromised patients.
Фармацевтические приложения
A synthetic dioxolane imidazole available for oral and topical
use.
Биологическая активность
Antifungal agent; potent inhibitor of cytochrome P450c17.
Механизм действия
Ketoconazole has little effect on Aspergillus or Cryptococcus. Ketoconazole is highly dependent on low stomach pH for absorption, and antacids or drugs that raise stomach pH will lower the bioavailability of ketoconazole. As with other azoles, it is extensively metabolized by microsomal enzymes. All the metabolites are inactive. Evidence that CYP3A4 plays a significant role in metabolism of ketoconazole is that coadministration of CYP3A4 inducers, such as phenytoin, carbamazepine, and rifampin, can cause as much as a 50% reduction in levels of ketoconazole.
Фармакокине?тика
Oral absorption: Variable
Cmax 400 mg oral: c. 5–6 mg/L after 2 h
Plasma half-life: 6–10 h
Volume of distribution: 0.36 L/kg
Plasma protein binding: >95%
It is erratically absorbed after oral administration. Absorption
is favored by an acid pH. Food delays absorption, but does not
significantly reduce the peak serum concentration. Absorption
is reduced if it is given with compounds that reduce gastric
acid secretion. Penetration into CSF is generally
poor
and unreliable, although effective concentrations have been recorded with high doses in some cases of active meningitis. It
is extensively metabolized by the liver, and the metabolites are
excreted in the bile. Less than 1% of an oral dose is excreted
unchanged in the urine.
Клиническое использование
Ketoconazole remains useful in the treatment of cutaneous
and mucous membrane dermatophyte and yeast
infections, but it has been replaced by the newer triazoles
in the treatment of most serious Candida infections
and disseminated mycoses. Ketoconazole is usually
effective in the treatment of thrush, but fluconazole
is superior to ketoconazole for refractory thrush.
Widespread dermatophyte infections on skin surfaces
can be treated easily with oral ketoconazole when the
use of topical antifungal agents would be impractical.
Treatment of vulvovaginal candidiasis with topical imidazoles
is less expensive.
Побочные эффекты
Nausea, vomiting, and anorexia occur commonly with
ketoconazole, especially when high doses are prescribed.
Epigastric distress can be reduced by taking ketoconazole
with food. Pruritis and/or allergic dermatitis
occurs in 10% of patients. Liver enzyme elevations during
therapy are not unusual and are usually reversible.
Severe ketoconazole-associated hepatitis is rare.
At high doses, ketoconazole causes a clinically significant
reduction in testosterone synthesis and blocks
the adrenal response to corticotropin. Gynecomastia,
impotence, reduced sperm counts, and diminished libido
can occur in men, and prolonged drug use can result
in irregular menses in women. These hormonal effects
have led to the use of ketoconazole as a potential
adjunctive treatment for prostatic carcinoma.
Метаболизм
Ketoconazole is extensively degraded by the liver, and very little active
drug is excreted in either the urine or bile; the dose need not be modified
for renal insufficiency. Adverse reactions to topical ketoconazole are very
rare.
Меры предосторожности
Both rifampin and isoniazid lower plasma ketoconazolelevels, and concomitant administration should be avoided.Phenytoin serum levels should be monitored closelywhen ketoconazole is prescribed.Ketoconazole causes increasesin serum concentrations of warfarin, cyclosporine,and sulfonylureas. Because of its ability to increase serumcyclosporine levels, ketoconazole has been given to cyclosporine-dependent cardiac transplant recipients to reducethe dose of cyclosporine needed and as a cost-savingmeasure.
Кетоконазол препаратная продукция и сырье
сырьё
препарат