Itraconazole CAPSULES
Congestive Heart Failure
Itraconazole Capsules should not be administered for the treatment of onychomycosis in patients with evidence of ventricular dysfunction such as congestive heart failure (CHF) or a history of CHF. If signs or symptoms of congestive heart failure occur during administration of Itraconazole capsules, discontinue administration. When Itraconazole was administered intravenously to dogs and healthy human volunteers, negative inotropic effects were seen. (See CLINICAL PHARMACOLOGY, Special Populations; CONTRAINDICATIONS; WARNINGS; PRECAUTIONS, Drug Interactions and ADVERSE REACTIONS, Post-Marketing Experience for more information.)
Drug Interactions: Co-administration of cisapride, pimozide, quinidine, dofetilide or levacetylmethadol (levomethadyl) with Itraconazole capsules, injection or oral solution is contraindicated. Itraconazole, a potent cytochrome P450 3A4 isoenzyme system (CYP3A4) inhibitor, may increase plasma concentrations of drugs metabolized by this pathway. Serious cardiovascular events, including QT prolongation, torsades de pointes, ventricular tachycardia, cardiac arrest and/or sudden death have occurred in patients using cisapride, pimozide, levacetylmethadol (levomethadyl) or quinidine concomitantly with Itraconazole and/or other CYP3A4 inhibitors. See CONTRAINDICATIONS; WARNINGS and PRECAUTIONS, Drug Interactions for more information.
Itraconazole Description
Itraconazole is a synthetic triazole antifungal agent. Itraconazole is a 1:1:1:1 racemic mixture of four diastereomers (two enantiomeric pairs), each possessing three chiral centers. It may be represented by the following structural formula and nomenclature:
(±) - 1 - [(R*) - sec - butyl] - 4 - [p - [4 - [p - [[(2R*,4S*) - 2 - (2,4 - dichlorophenyl) - 2 - (1H - 1,2,4 - triazol - 1 - ylmethyl) - 1,3 - dioxolan - 4 - yl]methoxy]phenyl] - 1 - piperazinyl]phenyl] - Δ2 - 1,2,4 - triazolin - 5 - one mixture with (±) - 1 - [(R*) - sec - butyl] - 4 - [p - [4 - [p - [[(2S*,4R*) - 2 - (2,4 - dichlorophenyl) - 2 - (1H - 1,2,4 - triazol - 1 - ylmethyl) - 1,3 - dioxolan - 4 - yl]methoxy]phenyl] - 1 - piperazinyl]phenyl] - Δ2 - 1,2,4 - triazolin - 5 - one
or
(±) - 1 - [(RS) - sec - butyl] - 4 - [p - [4 - [p - [[(2R,4S) - 2 - (2,4 - dichlorophenyl) - 2 - (1H - 1,2,4 - triazol - 1 - ylmethyl) - 1,3 - dioxolan - 4 - yl]methoxy]phenyl] - 1 - piperazinyl]phenyl] - Δ2 - 1,2,4 - triazolin - 5 - one.
Itraconazole has a molecular formula of C35H38Cl2N8O4 and a molecular weight of 705.64. It is a white to slightly yellowish powder. It is insoluble in water, very slightly soluble in alcohols and freely soluble in dichloromethane. It has a pKa of 3.7 (based on extrapolation of values obtained from methanolic solutions) and a log (n-octanol/water) partition coefficient of 5.66 at pH 8.1.
Each capsule, for oral administration, contains 100 mg of Itraconazole. In addition, each capsule contains the following inactive ingredients: corn starch, hypromellose, polyethylene glycol (PEG) 20,000 and sugar spheres. The capsule shell contains: D&C yellow No. 10 aluminum lake, FD&C blue No. 1, FD&C blue No. 2, FD&C red No. 40, gelatin, iron oxide black, pharmaceutical glaze, propylene glycol and titanium dioxide.
Itraconazole - Clinical Pharmacology
Pharmacokinetics and Metabolism
NOTE: The plasma concentrations reported below were measured by high-performance liquid chromatography (HPLC) specific for Itraconazole. When Itraconazole in plasma is measured by a bioassay, values reported are approximately 3.3 times higher than those obtained by HPLC due to the presence of the bioactive metabolite, hydroxyItraconazole (see MICROBIOLOGY).
The pharmacokinetics of Itraconazole after intravenous administration and its absolute oral bioavailability from an oral solution were studied in a randomized crossover study in 6 healthy male volunteers. The observed absolute oral bioavailability of Itraconazole was 55%.
The oral bioavailability of Itraconazole is maximal when Itraconazole capsules are taken with a full meal. The pharmacokinetics of Itraconazole were studied in 6 healthy male volunteers who received, in a crossover design, single 100 mg doses of Itraconazole as a polyethylene glycol capsule, with or without a full meal. The same 6 volunteers also received 50 mg or 200 mg with a full meal in a crossover design. In this study, only Itraconazole plasma concentrations were measured. The respective pharmacokinetic parameters for Itraconazole are presented in the table below:
| ||||
| 50 mg (fed) | 100 mg (fed) | 100 mg (fasted) | 200 mg (fed) | |
| Cmax (ng/mL) | 45 ± 16* | 132 ± 67 | 38 ± 20 | 289 ± 100 |
| Tmax (hours) | 3.2 ± 1.3 | 4.0 ± 1.1 | 3.3 ± 1.0 | 4.7 ± 1.4 |
| AUC0-∞ (ng•h/mL) | 567 ± 264 | 1899 ± 838 | 722 ± 289 | 5211 ± 2116 |
Doubling the Itraconazole dose results in approximately a three-fold increase in the Itraconazole plasma concentrations.
Values given in the table below represent data from a crossover pharmacokinetics study in which 27 healthy male volunteers each took a single 200 mg dose of Itraconazole capsules with or without a full meal:
| ||||
| Itraconazole | HydroxyItraconazole | |||
| Fed | Fasted | Fed | Fasted | |
| Cmax (ng/mL) | 239 ± 85* | 140 ± 65 | 397 ± 103 | 286 ± 101 |
| Tmax (hours) | 4.5 ± 1.1 | 3.9 ± 1.0 | 5.1 ± 1.6 | 4.5 ± 1.1 |
| AUC0-∞ (ng•h/mL) | 3423 ± 1154 | 2094 ± 905 | 7978 ± 2648 | 5191 ± 2489 |
| t1/2 (hours) | 21 ± 5 | 21 ± 7 | 12 ± 3 | 12 ± 3 |
Absorption of Itraconazole under fasted conditions in individuals with relative or absolute achlorhydria, such as patients with AIDS or volunteers taking gastric acid secretion suppressors (e.g., H2 receptor antagonists), was increased when Itraconazole capsules were administered with a cola beverage. Eighteen men with AIDS received single 200 mg doses of Itraconazole capsules under fasted conditions with 8 ounces of water or 8 ounces of a cola beverage in a crossover design. The absorption of Itraconazole was increased when Itraconazole capsules were co-administered with a cola beverage, with AUC0-24 and Cmax increasing 75% ± 121% and 95% ± 128%, respectively.
Thirty healthy men received single 200 mg doses of Itraconazole capsules under fasted conditions either 1) with water; 2) with water, after ranitidine 150 mg b.i.d. for 3 days; or 3) with cola, after ranitidine 150 mg b.i.d. for 3 days. When Itraconazole capsules were administered after ranitidine pretreatment, Itraconazole was absorbed to a lesser extent than when Itraconazole capsules were administered alone, with decreases in AUC0-24 and Cmax of 39% ± 37% and 42% ± 39%, respectively. When Itraconazole capsules were administered with cola after ranitidine pretreatment, Itraconazole absorption was comparable to that observed when Itraconazole capsules were administered alone (see PRECAUTIONS, Drug Interactions).
Steady-state concentrations were reached within 15 days following oral doses of 50 mg to 400 mg daily. Values given in the table below are data at steady-state from a pharmacokinetics study in which 27 healthy male volunteers took 200 mg Itraconazole capsules b.i.d. (with a full meal) for 15 days:
| ||
| Itraconazole | HydroxyItraconazole | |
| Cmax (ng/mL) | 2282 ± 514* | 3488 ± 742 |
| Cmin (ng/mL) | 1855 ± 535 | 3349 ± 761 |
| Tmax (hours) | 4.6 ± 1.8 | 3.4 ± 3.4 |
| AUC0-12 h (ng•h/mL) | 22569 ± 5375 | 38572 ± 8450 |
| t1/2 (hours) | 64 ± 32 | 56 ± 24 |
The plasma protein binding of Itraconazole is 99.8% and that of hydroxyItraconazole is 99.5%. Following intravenous administration, the volume of distribution of Itraconazole averaged 796 ± 185 liters.
Itraconazole is metabolized predominantly by the cytochrome P450 3A4 isoenzyme system (CYP3A4), resulting in the formation of several metabolites, including hydroxyItraconazole, the major metabolite. Results of a pharmacokinetics study suggest that Itraconazole may undergo saturable metabolism with multiple dosing. Fecal excretion of the parent drug varies between 3% to 18% of the dose. Renal excretion of the parent drug is less than 0.03% of the dose. About 40% of the dose is excreted as inactive metabolites in the urine. No single excreted metabolite represents more than 5% of a dose. Itraconazole total plasma clearance averaged 381 ± 95 mL/minute following intravenous administration. (See CONTRAINDICATIONS and PRECAUTIONS, Drug Interactions for more information.)
Special Populations
Renal Insufficiency
Limited data are available on the use of oral Itraconazole in patients with renal impairment. A pharmacokinetic study using a single 200 mg dose of Itraconazole (four 50 mg capsules) was conducted in three groups of patients with renal impairment (uremia: n=7; hemodialysis: n=7; and continuous ambulatory peritoneal dialysis: n=5). In uremic subjects with a mean creatinine clearance of 13 mL/min. × 1.73m2, the exposure, based on AUC, was slightly reduced compared with normal population parameters. This study did not demonstrate any significant effect of hemodialysis or continuous ambulatory peritoneal dialysis on the pharmacokinetics of Itraconazole (Tmax, Cmax and AUC0-8). Plasma concentration-versus-time profiles showed wide intersubject variation in all three groups. Caution should be exercised when the drug is administered in this patient population (see PRECAUTIONS and DOSAGE AND ADMINISTRATION).
Hepatic Insufficiency
Itraconazole is predominately metabolized in the liver. Patients with impaired hepatic function should be carefully monitored when taking Itraconazole. A pharmacokinetic study using a single oral 100 mg capsule dose of Itraconazole was conducted in 6 healthy and 12 cirrhotic subjects. A statistically significant reduction in mean Cmax (47%) and a twofold increase in the elimination half-life (37 ± 17 hours vs. 16 ± 5 hours) of Itraconazole were noted in cirrhotic subjects compared with healthy subjects. However, overall exposure to Itraconazole, based on AUC, was similar in cirrhotic patients and in healthy subjects. The prolonged elimination half-life of Itraconazole observed in the single oral dose clinical trial with Itraconazole capsules in cirrhotic patients should be considered when deciding to initiate therapy with other medications metabolized by CYP3A4. Data are not available in cirrhotic patients during long-term use of Itraconazole (see BOX WARNING; CONTRAINDICATIONS; PRECAUTIONS, Drug InteractionsandDOSAGE AND ADMINISTRATION).
Decreased Cardiac Contractility
When Itraconazole was administered intravenously to anesthetized dogs, a dose-related negative inotropic effect was documented. In a healthy volunteer study of Itraconazole injection (intravenous infusion), transient, asymptomatic decreases in left ventricular ejection fraction were observed using gated SPECT imaging; these resolved before the next infusion, 12 hours later. If signs or symptoms of congestive heart failure appear during administration of Itraconazole capsules, Itraconazole should be discontinued. (See CONTRAINDICATIONS; WARNINGS; PRECAUTIONS, Drug Interactions and ADVERSE REACTIONS, Post-Marketing Experience for more information.)
MICROBIOLOGY
Mechanism of Action
In vitro studies have demonstrated that Itraconazole inhibits the cytochrome P450-dependent synthesis of ergosterol, which is a vital component of fungal cell membranes.
Activity In Vitro and In Vivo
Itraconazole exhibits in vitro activity against Blastomyces dermatitidis, Histoplasma capsulatum, Histoplasma duboisii, Aspergillus flavus, Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans. Itraconazole also exhibits varying in vitro activity against Sporothrix schenckii, Trichophyton species, Candida krusei and other Candida species.
Candida krusei, Candida glabrata and Candida tropicalis are generally the least susceptible Candida species, with some isolates showing unequivocal resistance to Itraconazole in vitro. Itraconazole is not active against Zygomycetes (e.g., Rhizopus spp., Rhizomucor spp., Mucor spp. and Absidia spp.), Fusarium spp., Scedosporium spp. and Scopulariopsis spp.
The bioactive metabolite, hydroxyItraconazole, has not been evaluated against Histoplasma capsulatum,Blastomyces dermatitidis, Zygomycete, Fusarium spp., Scedosporium spp. and Scopulariopsis spp. Correlation between minimum inhibitory concentration (MIC) results in vitro and clinical outcome has yet to be established for azole antifungal agents.
Itraconazole administered orally was active in a variety of animal models of fungal infection using standard laboratory strains of fungi. Fungistatic activity has been demonstrated against disseminated fungal infections caused by Blastomyces dermatitidis, Histoplasma duboisii, Aspergillus fumigatus, Coccidioides immitis, Cryptococcus neoformans, Paracoccidioides brasiliensis, Sporothrix schenckii, Trichophyton rubrum and Trichophyton mentagrophytes.
Itraconazole administered at 2.5 mg/kg and 5 mg/kg via the oral and parenteral routes increased survival rates and sterilized organ systems in normal and immunosuppressed guinea pigs with disseminated Aspergillus fumigatus infections. Oral Itraconazole administered daily at 40 mg/kg and 80 mg/kg increased survival rates in normal rabbits with disseminated disease and in immunosuppressed rats with pulmonary Aspergillus fumigatus infection, respectively. Itraconazole has demonstrated antifungal activity in a variety of animal models infected with Candida albicans and other Candida species.
Resistance
Isolates from several fungal species with decreased susceptibility to Itraconazole have been isolated in vitro and from patients receiving prolonged therapy.
Several in vitro studies have reported that some fungal clinical isolates, including Candida species, with reduced susceptibility to one azole antifungal agent may also be less susceptible to other azole derivatives. The finding of cross-resistance is dependent on a number of factors, including the species evaluated, its clinical history, the particular azole compounds compared and the type of susceptibility test that is performed. The relevance of these in vitro susceptibility data to clinical outcome remains to be elucidated.
Candida krusei, Candida glabrata and Candida tropicalis are generally the least susceptible Candida species, with some isolates showing unequivocal resistance to Itraconazole in vitro.
Itraconazole is not active against Zygomycetes (e.g., Rhizopus spp., Rhizomucor spp., Mucor spp. and Absidia spp.), Fusarium spp., Scedosporium spp. and Scopulariopsis spp.
Studies (both in vitro and in vivo) suggest that the activity of amphotericin B may be suppressed by prior azole antifungal therapy. As with other azoles, Itraconazole inhibits the 14C-demethylation step in the synthesis of ergosterol, a cell wall component of fungi. Ergosterol is the active site for amphotericin B. In one study the antifungal activity of amphotericin B against Aspergillus fumigatus infections in mice was inhibited by ketoconazole therapy. The clinical significance of test results obtained in this study is unknown.
Indications and Usage for Itraconazole
Itraconazole capsules are indicated for the treatment of the following fungal infections in immunocompromised and non-immunocompromised patients:
- Blastomycosis, pulmonary and extrapulmonary
- Histoplasmosis, including chronic cavitary pulmonary disease and disseminated, non-meningeal histoplasmosis, and
- Aspergillosis, pulmonary and extrapulmonary, in patients who are intolerant of or who are refractory to amphotericin B therapy.
Specimens for fungal cultures and other relevant laboratory studies (wet mount, histopathology, serology) should be obtained before therapy to isolate and identify causative organisms. Therapy may be instituted before the results of the cultures and other laboratory studies are known; however, once these results become available, antiinfective therapy should be adjusted accordingly.
Itraconazole capsules are also indicated for the treatment of the following fungal infections in non-immunocompromised patients:
- Onychomycosis of the toenail, with or without fingernail involvement, due to dermatophytes (tinea unguium) and
- Onychomycosis of the fingernail due to dermatophytes (tinea unguium).
Prior to initiating treatment, appropriate nail specimens for laboratory testing (KOH preparation, fungal culture, or nail biopsy) should be obtained to confirm the diagnosis of onychomycosis. (See CLINICAL PHARMACOLOGY, Special Populations; CONTRAINDICATIONS; WARNINGS and ADVERSE REACTIONS, Post-Marketing Experience for more information.)
Description of Clinical Studies
Blastomycosis
Analyses were conducted on data from two open-label, non-concurrently controlled studies (N=73 combined) in patients with normal or abnormal immune status. The median dose was 200 mg/day. A response for most signs and symptoms was observed within the first 2 weeks, and all signs and symptoms cleared between 3 and 6 months. Results of these two studies demonstrated substantial evidence of the effectiveness of Itraconazole for the treatment of blastomycosis, compared with the natural history of untreated cases.
Histoplasmosis
Analyses were conducted on data from two open-label, non-concurrently controlled studies (N=34 combined) in patients with normal or abnormal immune status (not including HIV-infected patients). The median dose was 200 mg/day. A response for most signs and symptoms was observed within the first 2 weeks, and all signs and symptoms cleared between 3 and 12 months. Results of these two studies demonstrated substantial evidence of the effectiveness of Itraconazole, for the treatment of histoplasmosis, compared with the natural history of untreated cases.
Histoplasmosis in HIV-Infected Patients
Data from a small number of HIV-infected patients suggested that the response rate of histoplasmosis in HIV-infected patients is similar to that of non-HIV-infected patients. The clinical course of histoplasmosis in HIV-infected patients is more severe and usually requires maintenance therapy to prevent relapse.
Aspergillosis
Analyses were conducted on data from an open-label, “single-patient-use” protocol designed to make Itraconazole available in the U.S. for patients who either failed or were intolerant of amphotericin B therapy (N=190). The findings were corroborated by two smaller open-label studies (N=31 combined) in the same patient population. Most adult patients were treated with a daily dose of 200 mg to 400 mg, with a median duration of 3 months. Results of these studies demonstrated substantial evidence of effectiveness of Itraconazole as a second-line therapy for the treatment of aspergillosis compared with the natural history of the disease in patients who either failed or were intolerant of amphotericin B therapy.
Onychomycosis of the Toenail
Analyses were conducted on data from three double-blind, placebo-controlled studies (N=214 total; 110 given Itraconazole capsules) in which patients with onychomycosis of the toenails received 200 mg of Itraconazole capsules once daily for 12 consecutive weeks. Results of these studies demonstrated mycologic cure, defined as simultaneous occurrence of negative KOH plus negative culture, in 54% of patients. Thirty-five percent (35%) of patients were considered an overall success (mycologic cure plus clear or minimal nail involvement with significantly decreased signs) and 14% of patients demonstrated mycologic cure plus clinical cure (clearance of all signs, with or without residual nail deformity). The mean time to overall success was approximately 10 months. Twenty-one percent (21%) of the overall success group had a relapse (worsening of the global score or conversion of KOH or culture from negative to positive).
Onychomycosis of the Fingernail
Analyses were conducted on data from a double-blind, placebo-controlled study (N=73 total; 37 given Itraconazole capsules) in which patients with onychomycosis of the fingernails received a 1-week course (pulse) of 200 mg of Itraconazole capsules b.i.d., followed by a 3-week period without Itraconazole, which was followed by a second 1-week pulse of 200 mg of Itraconazole capsules b.i.d. Results demonstrated mycologic cure in 61% of patients. Fifty-six percent (56%) of patients were considered an overall success and 47% of patients demonstrated mycologic cure plus clinical cure. The mean time to overall success was approximately 5 months. None of the patients who achieved overall success relapsed.
Contraindications
Congestive Heart Failure
Itraconazole capsules should not be administered for the treatment of onychomycosis in patients with evidence of ventricular dysfunction such as congestive heart failure (CHF) or a history of CHF (see CLINICAL PHARMACOLOGY, Special Populations; WARNINGS; PRECAUTIONS, Drug Interactions, Calcium Channel Blockers, and ADVERSE REACTIONS, Post-Marketing Experience.)
Drug Interactions
Concomitant administration of Itraconazole capsules, injection or oral solution and certain drugs metabolized by the cytochrome P450 3A4 isoenzyme system (CYP3A4) may result in increased plasma concentrations of those drugs, leading to potentially serious and/or life-threatening adverse events. Cisapride, oral midazolam, nisoldipine, pimozide, quinidine, dofetilide, triazolam and levacetylmethadol (levomethadyl) are contraindicated with Itraconazole. HMG CoA-reductase inhibitors metabolized by CYP3A4, such as lovastatin and simvastatin, are also contraindicated with Itraconazole. Ergot alkaloids metabolized by CYP3A4 such as dihydroergotamine, ergometrine (ergonovine), ergotamine and methylergometrine (methylergonovine) are contraindicated with Itraconazole (see BOX WARNING and PRECAUTIONS, Drug Interactions).
Itraconazole should not be administered for the treatment of onychomycosis to pregnant patients or to women contemplating pregnancy.
Itraconazole is contraindicated for patients who have shown hypersensitivity to Itraconazole or its excipients. There is no information regarding cross-hypersensitivity between Itraconazole and other azole antifungal agents. Caution should be used when prescribing Itraconazole to patients with hypersensitivity to other azoles.
Warnings
Itraconazole capsules and Itraconazole oral solution should not be used interchangeably. This is because drug exposure is greater with the oral solution than with the capsules when the same dose of drug is given. In addition, the topical effects of mucosal exposure may be different between the two formulations. Only the oral solution has been demonstrated effective for oral and/or esophageal candidiasis.
Hepatic Effects
Itraconazole has been associated with rare cases of serious hepatotoxicity, including liver failure and death. Some of these cases had neither pre-existing liver disease nor a serious underlying medical condition and some of these cases developed within the first week of treatment. If clinical signs or symptoms develop that are consistent with liver disease, treatment should be discontinued and liver function testing performed. Continued Itraconazole use or reinstitution of treatment with Itraconazole is strongly discouraged unless there is a serious or life threatening situation where the expected benefit exceeds the risk (see PRECAUTIONS, Information for Patients and ADVERSE REACTIONS).
Cardiac Dysrhythmias
Life-threatening cardiac dysrhythmias and/or sudden death have occurred in patients using cisapride, pimozide, levacetylmethadol (levomethadyl) or quinidine concomitantly with Itraconazole and/or other CYP3A4 inhibitors. Concomitant administration of these drugs with Itraconazole is contraindicated (see BOX WARNING; CONTRAINDICATIONS and PRECAUTIONS, Drug Interactions).
Cardiac Disease
Itraconazole capsules should not be administered for the treatment of onychomycosis in patients with evidence of ventricular dysfunction such as congestive heart failure (CHF) or a history of CHF. Itraconazole capsules should not be used for other indications in patients with evidence of ventricular dysfunction unless the benefit clearly outweighs the risk.
For patients with risk factors for congestive heart failure, physicians should carefully review the risks and benefits of Itraconazole therapy. These risk factors include cardiac disease such as ischemic and valvular disease; significant pulmonary disease such as chronic obstructive pulmonary disease; and renal failure and other edematous disorders. Such patients should be informed of the signs and symptoms of CHF, should be treated with caution, and should be monitored for signs and symptoms of CHF during treatment. If signs or symptoms of CHF appear during administration of Itraconazole capsules, discontinue administration.
Itraconazole has been shown to have a negative inotropic effect. When Itraconazole was administered intravenously to anesthetized dogs, a dose-related negative inotropic effect was documented. In a healthy volunteer study of Itraconazole injection (intravenous infusion), transient, asymptomatic decreases in left ventricular ejection fraction were observed using gated SPECT imaging; these resolved before the next infusion, 12 hours later.
Itraconazole has been associated with reports of congestive heart failure. In post-marketing experience, heart failure was more frequently reported in patients receiving a total daily dose of 400 mg although there were also cases reported among those receiving lower total daily doses.
Calcium channel blockers can have negative inotropic effects which may be additive to those of Itraconazole. In addition, Itraconazole can inhibit the metabolism of calcium channel blockers. Therefore, caution should be used when co-administering Itraconazole and calcium channel blockers due to an increased risk of CHF. Concomitant administration of Itraconazole and nisoldipine is contraindicated.
Cases of CHF, peripheral edema and pulmonary edema have been reported in the post-marketing period among patients being treated for onychomycosis and/or systemic fungal infections. (See CLINICAL PHARMACOLOGY, Special Populations; CONTRAINDICATIONS; PRECAUTIONS, Drug Interactions and ADVERSE REACTIONS, Post-Marketing Experience for more information.)
Precautions
General
Itraconazole capsules should be administered after a full meal (see CLINICAL PHARMACOLOGY, Pharmacokinetics and Metabolism).
Under fasted conditions, Itraconazole absorption was decreased in the presence of decreased gastric acidity. The absorption of Itraconazole may be decreased with the concomitant administration of antacids or gastric acid secretion suppressors. Studies conducted under fasted conditions demonstrated that administration with 8 ounces of a cola beverage resulted in increased absorption of Itraconazole in AIDS patients with relative or absolute achlorhydria. This increase relative to the effects of a full meal is unknown (see CLINICAL PHARMACOLOGY, Pharmacokinetics and Metabolism).
Hepatotoxicity
Rare cases of serious hepatotoxicity have been observed with Itraconazole treatment, including some cases within the first week. In patients with elevated or abnormal liver enzymes or active liver disease or who have experienced liver toxicity with other drugs, treatment with Itraconazole is strongly discouraged unless there is a serious or life threatening situation where the expected benefit exceeds the risk. Liver function monitoring should be done in patients with pre-existing hepatic function abnormalities or those who have experienced liver toxicity with other medications and should be considered in all patients receiving Itraconazole. Treatment should be stopped immediately and liver function testing should be conducted in patients who develop signs and symptoms suggestive of liver dysfunction.
Neuropathy
If neuropathy occurs that may be attributable to Itraconazole capsules, the treatment should be discontinued.
Hearing Loss
Transient or permanent hearing loss has been reported in patients receiving treatment with Itraconazole. Several of these reports included concurrent administration of quinidine which is contraindicated (see BOX WARNING, Drug Interactions; CONTRAINDICATIONS, Drug Interactions and PRECAUTIONS, Drug Interactions). The hearing loss usually resolves when treatment is stopped, but can persist in some patients.
Information for Patients
- The topical effects of mucosal exposure may be different between the Itraconazole capsules and oral solution. Only the oral solution has been demonstrated effective for oral and/or esophageal candidiasis. Itraconazole capsules should not be used interchangeably with Itraconazole oral solution.
- Instruct patients to take Itraconazole capsules with a full meal.
- Instruct patients about the signs and symptoms of congestive heart failure, and if these signs or symptoms occur during Itraconazole administration, they should discontinue Itraconazole and contact their healthcare provider immediately.
- Instruct patients to stop Itraconazole treatment immediately and contact their healthcare provider if any signs and symptoms suggestive of liver dysfunction develop. Such signs and symptoms may include unusual fatigue, anorexia, nausea and/or vomiting, jaundice, dark urine or pale stools.
- Instruct patients to contact their physician before taking any concomitant medications with Itraconazole to ensure there are no potential drug interactions.
- Instruct patients that hearing loss can occur with the use of Itraconazole. The hearing loss usually resolves when treatment is stopped, but can persist in some patients. Advise patients to discontinue therapy and inform their physicians if any hearing loss symptoms occur.
Drug Interactions
Itraconazole and its major metabolite, hydroxyItraconazole, are inhibitors of CYP3A4. Therefore, the following drug interactions may occur
(See Table 1. Selected Drugs that Are Predicted to Alter the Plasma Concentration of Itraconazole or Have Their Plasma Concentration Altered by Itraconazolea below and the following drug class subheadings that follow):
- Itraconazole may decrease the elimination of drugs metabolized by CYP3A4, resulting in increased plasma concentrations of these drugs when they are administered with Itraconazole. These elevated plasma concentrations may increase or prolong both therapeutic and adverse effects of these drugs. Whenever possible, plasma concentrations of these drugs should be monitored, and dosage adjustments made after concomitant Itraconazole therapy is initiated. When appropriate, clinical monitoring for signs or symptoms of increased or prolonged pharmacologic effects is advised. Upon discontinuation, depending on the dose and duration of treatment, Itraconazole plasma concentrations decline gradually (especially in patients with hepatic cirrhosis or in those receiving CYP3A4 inhibitors). This is particularly important when initiating therapy with drugs whose metabolism is affected by Itraconazole.
- Inducers of CYP3A4 may decrease the plasma concentrations of Itraconazole. Itraconazole may not be effective in patients concomitantly taking Itraconazole and one of these drugs. Therefore, administration of these drugs with Itraconazole is not recommended.
- Other inhibitors of CYP3A4 may increase the plasma concentrations of Itraconazole. Patients who must take Itraconazole concomitantly with one of these drugs should be monitored closely for signs or symptoms of increased or prolonged pharmacologic effects of Itraconazole.
| |
| Drug plasma concentration increased by Itraconazole | |
| Antiarrhythmics | digoxin, dofetilide†, quinidine†, disopyramide |
| Anticonvulsants | carbamazepine |
| Antimycobacterials | rifabutin |
| Antineoplastics | busulfan, docetaxel, vinca alkaloids |
| Antipsychotics | pimozide† |
| Benzodiazepines | alprazolam, diazepam, midazolam,†,‡ triazolam† |
| Calcium Channel Blockers | dihydropyridines (including nisoldipine†), verapamil |
| Gastrointestinal Motility Agents | cisapride† |
| HMG CoA-Reductase Inhibitors | atorvastatin, cerivastatin, lovastatin,† simvastatin† |
| Immunosuppressants | cyclosporine, tacrolimus, sirolimus |
| Oral Hypoglycemics | oral hypoglycemics |
| Protease Inhibitors | indinavir, ritonavir, saquinavir |
| Other | levacetylmethadol (levomethadyl)†, ergot alkaloids†, halofantrine, alfentanil, buspirone, methylprednisolone, budesonide, dexamethasone, fluticasone, trimetrexate, warfarin, cilostazol, eletriptan, fentanyl |
| Decrease plasma concentration of Itraconazole | |
| Anticonvulsants | carbamazepine, phenobarbital, phenytoin |
| Antimycobacterials | isoniazid, rifabutin, rifampin |
| Gastric Acid Suppressors/Neutralizers | antacids, H2-receptor antagonists, proton pump inhibitors |
| Non-nucleoside Reverse Transcriptase Inhibitors | nevirapine |
| Increase plasma concentration of Itraconazole | |
| Macrolide Antibiotics | clarithromycin, erythromycin |
| Protease Inhibitors | indinavir, ritonavir |
Antiarrhythmics
The class IA antiarrhythmic quinidine and class III antiarrhythmic dofetilide are known to prolong the QT interval. Co-administration of quinidine or dofetilide with Itraconazole may increase plasma concentrations of quinidine or dofetilide which could result in serious cardiovascular events. Therefore, concomitant administration of Itraconazole and quinidine or dofetilide is contraindicated (see BOX WARNING, CONTRAINDICATIONS, and WARNINGS.)
The class IA antiarrhythmic disopyramide has the potential to increase the QT interval at high plasma concentrations. Caution is advised when Itraconazole and disopyramide are administered concomitantly.
Concomitant administration of digoxin and Itraconazole has led to increased plasma concentrations of digoxin via inhibition of P-glycoprotein.
Anticonvulsants
Reduced plasma concentrations of Itraconazole were reported when Itraconazole was administered concomitantly with phenytoin. Carbamazepine, phenobarbital and phenytoin are all inducers of CYP3A4. Although interactions with carbamazepine and phenobarbital have not been studied, concomitant administration of Itraconazole and these drugs would be expected to result in decreased plasma concentrations of Itraconazole. In addition, in vivo studies have demonstrated an increase in plasma carbamazepine concentrations in subjects concomitantly receiving ketoconazole. Although there are no data regarding the effect of Itraconazole on carbamazepine metabolism, because of the similarities between ketoconazole and Itraconazole, concomitant administration of Itraconazole and carbamazepine may inhibit the metabolism of carbamazepine.
Antimycobacterials
Drug interaction studies have demonstrated that plasma concentrations of azole antifungal agents and their metabolites, including Itraconazole and hydroxyItraconazole, were significantly decreased when these agents were given concomitantly with rifabutin or rifampin. In vivo data suggest that rifabutin is metabolized in part by CYP3A4. Itraconazole may inhibit the metabolism of rifabutin. Although no formal study data are available for isoniazid, similar effects should be anticipated. Therefore, the efficacy of Itraconazole could be substantially reduced if given concomitantly with one of these agents. Co-administration is not recommended.
Antineoplastics
Itraconazole may inhibit the metabolism of busulfan, docetaxel and vinca alkaloids.
Antipsychotics
Pimozide is known to prolong the QT interval and is partially metabolized by CYP3A4. Co-administration of pimozide with Itraconazole could result in serious cardiovascular events. Therefore, concomitant administration of Itraconazole and pimozide is contraindicated (see BOX WARNING, CONTRAINDICATIONS and WA
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