Ketoconazole: Package Insert and Label Information

KETOCONAZOLE- ketoconazole tablet
Aidarex Pharmaceuticals LLC

Rx only

WARNING

Ketoconazole tablets USP, 200 mg should be used only when other effective antifungal therapy is not available or tolerated and the potential benefits are considered to outweigh the potential risks.

Hepatotoxicity

Serious hepatotoxicity, including cases with a fatal outcome or requiring liver transplantation has occurred with the use of oral ketoconazole. Some patients had no obvious risk factors for liver disease. Patients receiving this drug should be informed by the physician of the risk and should be closely monitored. See WARNINGS section.

QT Prolongation and Drug Interactions Leading to QT Prolongation

Co-administration of the following drugs with ketoconazole is contraindicated: dofetilide, quinidine, pimozide, cisapride. Ketoconazole can cause elevated plasma concentrations of these drugs and may prolong QT intervals, sometimes resulting in life-threatening ventricular dysrhythmias such as torsades de pointes. See CONTRAINDICATIONS, WARNINGS, and PRECAUTIONS: Drug Interactions sections.

DESCRIPTION

Ketoconazole tablets USP is a synthetic broad-spectrum antifungal agent available in scored white tablets, each containing 200 mg ketoconazole base for oral administration. Inactive ingredients are colloidal silicon dioxide, corn starch, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and povidone. Ketoconazole is cis-1-acetyl-4-[4-[[2-(2,4dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxyl]phenyl] piperazine and has the following structural formula:

Chemical Structure
(click image for full-size original)

Ketoconazole is a white to slightly beige, odorless powder, soluble in acids, with a molecular weight of 531.44.

CLINICAL PHARMACOLOGY

Pharmacokinetics

Mean peak plasma levels of approximately 3.5 µg/mL are reached within 1 to 2 hours, following oral administration of a single 200 mg dose taken with a meal. Subsequent plasma elimination is biphasic with a half-life of 2 hours during the first 10 hours and 8 hours thereafter. Following absorption from the gastrointestinal tract, ketoconazole is converted into several inactive metabolites. The major identified metabolic pathways are oxidation and degradation of the imidazole and piperazine rings, oxidative Odealkylation and aromatic hydroxylation. About 13% of the dose is excreted in the urine, of which 2 to 4% is unchanged drug. The major route of excretion is through the bile into the intestinal tract. In vitro , the plasma protein binding is about 99% mainly to the albumin fraction. Only a negligible proportion of ketoconazole reaches the cerebrospinal fluid. Ketoconazole is a weak dibasic agent and thus requires acidity for dissolution and absorption.

Electrocardiogram

Pre-clinical electrophysiological studies have shown that ketoconazole inhibits the rapidly activating component of the cardiac delayed rectifier potassium current, prolongs the action potential duration, and may prolong the QTc interval. Data from some clinical PK/PD studies and drug interaction studies suggest that oral dosing with ketoconazole at 200 mg twice daily for 3 to 7 days can result in an increase of the QTc interval: a mean maximum increase of about 6 to 12 msec was seen at ketoconazole peak plasma concentrations about 1 to 4 hours after ketoconazole administration.

MICROBIOLOGY

Mechanism of Action

Ketoconazole blocks the synthesis of ergosterol, a key component of the fungal cell membrane, through the inhibition of cytochrome P-450 dependent enzyme lanosterol 14α-demethylase responsible for the conversion of lanosterol to ergosterol in the fungal cell membrane. This results in an accumulation of methylated sterol precursors and a depletion of ergosterol within the cell membrane thus weakening the structure and function of the fungal cell membrane.

Activity In Vitro & In Vivo

Ketoconazole tablets USP, 200 mg are active against clinical infections with Blastomyces dermatitidis , Coccidioides immitis , Histoplasma capsulatum , Paracoccidioides brasiliensis.

INDICATIONS AND USAGE

Ketoconazole tablets USP, 200 mg should be used only when other effective antifungal therapy is not available or tolerated and the potential benefits are considered to outweigh the potential risks.

Ketoconazole tablets USP, 200 mg are indicated for the treatment of the following systemic fungal infections in patients who have failed or who are intolerant to other therapies: blastomycosis, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis. Ketoconazole tablets USP, 200 mg should not be used for fungal meningitis because it penetrates poorly into the cerebrospinal fluid.

CONTRAINDICATIONS

Drug Interactions

Coadministration of a number of CYP3A4 substrates is contraindicated with ketoconazole tablets. Coadministration with ketoconazole can cause elevated plasma concentrations of these drugs and may increase or prolong both therapeutic and adverse effects. For example, increased plasma concentrations of some of these drugs can lead to QT prolongation and ventricular tachyarrhythmias including occurrences of torsades de pointes, a potentially fatal arrhythmia. See WARNINGS section, and PRECAUTIONS: Drug Interactions section for specific examples.

Liver Disease

The use of ketoconazole tablets is contraindicated in patients with acute or chronic liver disease.

Hypersensitivity

Ketoconazole tablets USP, 200 mg is contraindicated in patients who have shown hypersensitivity to the drug.

WARNINGS

Ketoconazole tablets USP, 200 mg should be used only when other effective antifungal therapy is not available or tolerated and the potential benefits are considered to outweigh the potential risks.

Hepatotoxicity

Serious hepatotoxicity, including cases with a fatal outcome or requiring liver transplantation, has occurred with the use of oral ketoconazole. Some patients had no obvious risk factors for liver disease. Serious hepatotoxicity was reported both by patients receiving high doses for short treatment durations and by patients receiving low doses for long durations.

The hepatic injury has usually, but not always, been reversible upon discontinuation of ketoconazole tablets treatment. Cases of hepatitis have been reported in children.

At baseline, obtain laboratory tests (such as SGGT, alkaline phosphatase, ALT, AST, total bilirubin (TBL), Prothrombin Time (PT), International Normalization Ratio (INR), and testing for viral hepatitides). Patients should be advised against alcohol consumption while on treatment. If possible, use of other potentially hepatotoxic drugs should be avoided in patients receiving ketoconazole tablets.

Prompt recognition of liver injury is essential. During the course of treatment, serum ALT should be monitored weekly for the duration of treatment. If ALT values increase to a level above the upper limit of normal or 30 percent above baseline, or if the patient develops symptoms, ketoconazole treatment should be interrupted and a full set of liver tests should be obtained. Liver tests should be repeated to ensure normalization of values. Hepatotoxicity has been reported with restarting oral ketoconazole (rechallenge). If it is decided to restart oral ketoconazole, monitor the patient frequently to detect any recurring liver injury from the drug.

QT Prolongation and Drug Interactions Leading to QT Prolongation

Ketoconazole can prolong the QT interval. Co-administration of the following drugs with ketoconazole is contraindicated: dofetilide, quinidine, pimozide, and cisapride. Ketoconazole can cause elevated plasma concentrations of these drugs which may prolong the QT interval, sometimes resulting in life-threatening ventricular dysrhythmias such as torsades de pointes.

Adrenal Insufficiency

Ketoconazole tablets decrease adrenal corticosteroid secretion at doses of 400 mg and higher. This effect is not shared with other azoles. The recommended dose of 200 mg to 400 mg daily should not be exceeded.

Adrenal function should be monitored in patients with adrenal insufficiency or with borderline adrenal function and in patients under prolonged periods of stress (major surgery, intensive care, etc.).

Adverse Reactions Associated with Unapproved Uses

Ketoconazole has been used in high doses for the treatment of advanced prostate cancer and for Cushing’s syndrome when other treatment options have failed. The safety and effectiveness of ketoconazole have not been established in these settings and the use of ketoconazole for these indications is not approved by FDA.

In a clinical trial involving 350 patients with metastatic prostatic cancer, eleven deaths were reported within two weeks of starting treatment with high doses of ketoconazole tablets (1200 mg/day). It is not possible to ascertain from the information available whether death was related to ketoconazole therapy or adrenal insufficiency in these patients with serious underlying disease.

Hypersensitivity

Anaphylaxis has been reported after the first dose. Several cases of hypersensitivity reactions including urticaria have also been reported.

Enhanced Sedation

Co-administration of ketoconazole tablets with oral midazolam, oral triazolam or alprazolam has resulted in elevated plasma concentrations of these drugs. This may potentiate and prolong hypnotic and sedative effects, especially with repeated dosing or chronic administration of these agents. Concomitant administration of ketoconazole tablets with oral triazolam, oral midazolam, or alprazolam is contraindicated. (See CONTRAINDICATIONS and PRECAUTIONS: Drug Interactions sections.)

Myopathy

Co-administration of CYP3A4 metabolized HMG-CoA reductase inhibitors such as simvastatin, and lovastatin is contraindicated with ketoconazole tablets. (See CONTRAINDICATIONS and PRECAUTIONS: Drug Interactions sections.)

PRECAUTIONS

General

Ketoconazole tablets have been demonstrated to lower serum testosterone. Once therapy with ketoconazole tablets has been discontinued, serum testosterone levels return to baseline values. Testosterone levels are impaired with doses of 800 mg per day and abolished by 1600 mg per day. Clinical manifestations of decreased testosterone concentrations may include gynecomastia, impotence and oligospermia.

Information for Patients

Patients should be instructed to report any signs and symptoms which may suggest liver dysfunction so that appropriate biochemical testing can be done. Such signs and symptoms may include unusual fatigue, anorexia, nausea and/or vomiting, abdominal pain, jaundice, dark urine or pale stools (see WARNINGS section).

Drug Interactions

Drugs that affect the absorption, distribution, metabolism, and excretion of ketoconazole may alter the plasma concentrations of ketoconazole. For example, gastric acid suppressants (e.g., antacids, histamine H2 -blockers, proton pump inhibitors) have been shown to reduce plasma concentrations of ketoconazole.Ketoconazole is a substrate and potent inhibitor of CYP3A4. Therefore, the following drug interactions may occur when ketoconazole is co-administered with other drugs that interact with CYP3A4. (See Table 1 and Table 2 for an overview of these drug interactions; details are provided in the text that follows these tables.)

  • Ketoconazole may decrease the elimination of drugs metabolized by CYP3A4, thereby increasing their plasma concentrations. Increased exposure to these drugs may cause an increase or prolongation of their therapeutic and/or adverse effects. Concomitant use with ketoconazole tablets is contraindicated for drugs known to present a risk of serious side effects with increased exposure (see BOXED WARNING, CONTRAINDICATIONS section, and PRECAUTIONS: Drug Interactions, Table 1). For others, monitoring of plasma concentrations is advised when possible. Clinical signs and symptoms associated with these drugs should be monitored, with dosage adjusted as needed.
  • Inducers of CYP3A4 may decrease the plasma concentrations of ketoconazole (see Table 2). Ketoconazole may not be effective in patients concomitantly taking one of these drugs. Therefore, administration of these drugs with ketoconazole is not recommended.
  • Other inhibitors of CYP3A4 may increase the plasma concentrations of ketoconazole (see Table 2). Patients who must take ketoconazole concomitantly with one of these drugs should be monitored closely for signs or symptoms of increased or prolonged pharmacologic effects of ketoconazole.
Table 1. Selected Drugs That Have Been Shown To or Are Predicted To Have Their Plasma Concentrations Altered By Ketoconazole *
*
This list is not all-inclusive.
Systemic exposure to these drugs is increased significantly by the addition of ketoconazole: Concomitant use with ketoconazole is contraindicated.
Alprazolam, midazolam, triazolam HMG-CoA reductase inhibitors (lovastatin, simvastatin)
Cisapride Nisoldipine
Dofetilide Pimozide
Eplerenone Quinidine
Ergot alkaloids (ergotamine, dihydroergotamine)
Systemic exposure to these drugs is increased by ketoconazole: Careful monitoring, with possible adjustment in dosage, is recommended.
Alfentanil, fentanyl, sulfentanil Indinavir, saquinavir
Amlodipine, felodipine, nicardipine, nifedipine Methylprednisolone
Bosentan Rifabutin
Buspirone Sildenafil
Busulfan Sirolimus (co-administration not recommended)
Carbamazepine Tacrolimus
Cilostazol Telithromycin
Cyclosporine Tolterodine
Digoxin Trimetrexate
Docetaxel, paclitaxel Verapamil
Oral anti-coagulants Vinca alkaloids (vincristine, — vinblastine, vinorelbine)
Table 2. Selected Drugs That Have Been Shown To or Are Predicted To Alter The Plasma Concentration Of Ketoconazole
*This list is not all-inclusive.
Systemic exposure to ketoconazole is reduced significantly by these drugs: Concomitant use with ketoconazole is not recommended.
Carbamazepine Phenytoin
Gastric Acid Suppressants (antacids, antimuscarinics, histamine H2 -blockers, proton pump inhibitors, sucralfate) Rifampin, rifabutin, isoniazid
Nevirapine
Systemic exposure to ketoconazole is increased significantly by this drug: Dose reduction of ketoconazole should be considered
Ritonavir
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