Itragen

Symptoms:

In general, adverse events reported with overdose have been consistent with adverse drug reactions already listed in this SmPC for Itragen.

Treatment:

In the event of an overdose, supportive measures should be employed. Activated charcoal may be given if considered appropriate. Itragen cannot be removed by haemodialysis. No specific antidote is available.

Symptoms and signs

Treatment

In the event of overdosage, supportive measures should be employed. Activated charcoal may be given if considered appropriate. Itraconazole cannot be removed by haemodialysis. No specific antidote is available.

Pharmacotherapeutic group: Antimycotic for systemic use, triazole derivative.

ATC code: J02A C02

Mode of action

Itragen inhibits fungal 14α-demethylase, resulting in a depletion of ergosterol and disruption of membrane synthesis by fungi.

PK/PD relationship

The PK/PD relationship for Itragen, and for triazoles in general, is poorly understood and is complicated by limited understanding of antifungal pharmacokinetics.

Mechanism(s) of resistance

Resistance of fungi to azoles appears to develop slowly and is often the result of several genetic mutations. Mechanisms that have been described are

- Over-expression of ERG11, the gene that encodes 14-alpha-demethylase (the target enzyme)

- Point mutations in ERG11 that lead to decreased affinity of 14-alpha-demethylase for Itragen

- Drug-transporter over-expression resulting in increased efflux of Itragen from fungal cells (i.e., removal of Itragen from its target)

- Cross-resistance. Cross-resistance amongst members of the azole class of drugs has been observed within Candida species though resistance to one member of the class does not necessarily confer resistance to other azoles.

Breakpoints

Breakpoints for candida species are in preparation.

The prevalence of acquired resistance may vary geographically and with time for selected species, and local information on resistance is desirable, particularly when treating severe infections. As necessary, expert advice should be sought when the local prevalence of resistance is such that the utility of the agent in at least some types of infections is questionable.

The in vitro susceptibility of fungi to Itragen depends on the inoculum size, incubation temperature, growth phase of the fungi, and the culture medium used. For these reasons, the minimum inhibitory concentration of Itragen may vary widely. Susceptibility in the table below is based on MIC₉₀ < 1 mg Itragen/L. There is no correlation between in vitro susceptibility and clinical efficacy.

¹ These organisms may be encountered in patients who have returned from travel outside Europe.

² Itragen-resistant strains of Aspergillus fumigatus have been reported.

³ Natural intermediate susceptibility.

Paediatric Population

The tolerability and safety of Itragen oral solution was studied in the prophylaxis of fungal infections in 103 neutropenic paediatric patients aged 0 to14 years (median 5 years) in an open-label uncontrolled phase III clinical study. Most patients (78%) were undergoing allogenic bone marrow transplantation for haematological malignancies. All patients received 5 mg/kg/day of Itragen oral solution as a single or divided dose. Due to the design of the study, no formal conclusion with regard to efficacy could be derived. The most common adverse events considered definitely or possibly related to Itragen were vomiting, abnormal liver function, and abdominal pain.

Pharmacotherapeutic classification: (Antimycotics for systemic use, triazole derivatives).

ATC code: J02A C02

Itraconazole, a triazole derivative, has a broad spectrum of activity.

In vitro studies have demonstrated that itraconazole impairs the synthesis of ergosterol in fungal cells. Ergosterol is a vital cell membrane component in fungi. Impairment of its synthesis ultimately results in an antifungal effect.

For itraconazole, breakpoints have only been established for Candida spp. from superficial mycotic infections (CLSI M27-A2, breakpoints have not been established for EUCAST methodology). The CLSI breakpoints are as follows: susceptible ≤0.125; susceptible, dose-dependent 0.25-0.5 and resistant > 1μg/mL. Interpretive breakpoints have not been established for the filamentous fungi.

In vitro studies demonstrate that itraconazole inhibits the growth of a broad range of fungi pathogenic for humans at concentrations usually ≤ 1 µg/ml. These include:

dermatophytes (Trichophyton spp., Microsporum spp., Epidermophyton floccosum); yeasts (Candida spp., including C. albicans, C. tropicalis, C. parapsilosis and C. krusei, Cryptococcus neoformans, Malassezia spp., Trichosporon spp., Geotrichum spp.); Aspergillus spp.; Histoplasma spp., including H. capsulatum; Paracoccidioides brasiliensis; Sporothrix schenckii; Fonsecaea spp.; Cladosporium spp.; Blastomyces dermatitidis; Coccidiodes immitis; Pseudallescheria boydii; Penicillium marneffei; and various other yeasts and fungi.

Candida krusei, Candida glabrata and Candida tropicalis are generally the least susceptible Candida species, with some isolates showing unequivocal resistance to itraconazole in vitro.

The principal fungus types that are not inhibited by itraconazole are Zygomycetes (e.g. Rhizopus spp., Rhizomucor spp., Mucor spp. and Absidia spp.), Fusarium spp., Scedosporium proliferans and Scopulariopsis spp.

Azole resistance appears to develop slowly and is often the result of several genetic mutations. Mechanisms that have been described are overexpression of ERG11, which encodes the target enzyme 14α-demethylase, point mutations in ERG11 that lead to decreased target affinity and/or transporter overexpression resulting in increased efflux. Cross resistance between members of the azole class has been observed within Candida spp., although resistance to one member of the class does not necessarily confer resistance to other azoles. Itraconazole-resistant strains of Aspergillus fumigatus have been reported.

Use in patients with renal impairment

Limited data are available on the use of oral Itragen in patients with renal impairment. Caution should be exercised when this drug is administered in this patient population.

Itragen oral solution is contraindicated in patients with a known hypersensitivity to Itragen or to any of the excipients.

Co-administration of the following drugs is contraindicated with Itragen oral solution (see also 4.5 Interaction with other medicinal products and other forms of interaction):

- CYP3A4 metabolised substrates that can prolong the QT-interval e.g., astemizole, bepridil, cisapride, dofetilide, levacetylmethadol (levomethadyl), mizolastine, pimozide, quinidine, sertindole and terfenadine are contraindicated with Itragen oral solution.).

Cross-hypersensitivity

There is no information regarding cross hypersensitivity between Itragen and other azole antifungal agents. Caution should be used in prescribing Itragen Oral Solution to patients with hypersensitivity to other azoles.

Cardiac effects

In a healthy volunteer study with Itragen IV, a transient asymptomatic decrease of the left ventricular ejection fraction was observed.

Itragen has been shown to have a negative inotropic effect and has been associated with reports of congestive heart failure. Interaction with other medicinal products).

Hepatic effects

Very rare cases of serious hepatotoxicity, including some cases of fatal acute liver failure, have occurred with the use of Itragen. Some of these cases involved patients with no pre-existing liver disease. Some of these cases have been observed within the first month of treatment, including some within the first week. Liver function monitoring should be considered in patients receiving Itragen treatment. Patients should be instructed to promptly report to their physician signs and symptoms suggestive of hepatitis such as anorexia, nausea, vomiting, fatigue, abdominal pain or dark urine. In these patients treatment should be stopped immediately and liver function testing should be conducted. Most cases of serious hepatotoxicity involved patients who had pre-existing liver disease, were treated for systemic indications, had significant other medical conditions and/or were taking other hepatotoxic drugs. In patients with raised liver enzymes or active liver disease, or who have experienced liver toxicity with other drugs, treatment should not be started unless the expected benefit exceeds the risk of hepatic injury. In patients with impaired hepatic function liver enzyme should be carefully monitored when taking Itragen.

Use in children

Since clinical data on the use of Itragen oral solution in paediatric patients is limited, its use in children is not recommended unless the potential benefit outweighs the potential risks.

Use in elderly

Since clinical data on the use of Itragen oral solution in elderly patients is limited, it is advised to use Itragen oral solution in these patients only if the potential benefit outweighs the potential risks.

Hepatic impairment

Limited data are available on the use of oral Itragen in patients with hepatic impairment. Caution should be exercised when the drug is administered in this patient population. (See 5.2 Pharmacokinetic properties, Special populations, Hepatic impairment)

Renal impairment

Limited data are available on the use of oral Itragen in patients with renal impairment. Caution should be exercised when this drug is administered in this patient population.

Prophylaxis in neutropenic patients

In clinical trials diarrhoea was the most frequent adverse event. This disturbance of the gastrointestinal tract may result in impaired absorption and may alter the microbiological flora potentially favouring fungal colonisation. Consideration should be given to discontinuing Itragen oral solution in these circumstances.

Treatment of severely neutropenic patients

Itragen oral solution as treatment for oral and/or esophageal candidosis was not investigated in severely neutropenic patients. Due to the pharmacokinetic properties (See 5.2 Pharmacokinetic properties), Itragen oral solution is not recommended for initiation of treatment in patients at immediate risk of systemic candidosis.

Hearing Loss

Transient or permanent hearing loss has been reported in patients receiving treatment with Itragen. Several of these reports included concurrent administration of quinidine which is contraindicated. The hearing loss usually resolves when treatment is stopped, but can persist in some patients.

Neuropathy

If neuropathy occurs that may be attributable to Itragen oral solution, the treatment should be discontinued.

Cross-resistance

In systemic candidosis, if fluconazole-resistant strains of Candida species are suspected, it cannot be assumed that these are sensitive to Itragen, hence their sensitivity should be tested before the start of Itragen therapy

Interaction potential

Itragen Oral Solution has a potential for clinically important drug interactions.

Itragen should not be used within 2 weeks after discontinuation of treatment with CYP 3A4 inducing agents (rifampicin, rifabutin, phenobarbital, phenytoin, carbamazepine, Hypericum perforatum (St. John´s wort)). The use of Itragen with these drugs may lead to subtherapeutic plasma levels of Itragen and thus treatment failure.

Itragen oral solution contains sorbitol. Patients with rare hereditary problems of fructose intolerance should not take this medicine. Also contains ethanol less than 100mg per dose.

4.5.1. Drugs affecting the metabolism of Itragen:

Itragen is mainly metabolised through the cytochrome CYP3A4. Interaction studies have been performed with rifampicin, rifabutin and phenytoin, which are potent enzyme inducers of CYP3A4. Since the bioavailability of Itragen and hydroxy-Itragen was decreased in these studies to such an extent that efficacy may be largely reduced, the combination of Itragen with these potent enzyme inducers is not recommended. No formal study data are available for other enzyme inducers, such as carbamazepine, Hypericum perforatum (St John's Wort), phenobarbital and isoniazid, but similar effects should be anticipated.

Potent inhibitors of this enzyme such as ritonavir, indinavir, clarithromycin and erythromycin may increase the bioavailability of Itragen.

4.5.2. Effect of Itragen on the metabolism of other drugs:

4.5.2.1 Itragen can inhibit the metabolism of drugs metabolised by the cytochrome 3A family. Pharmacokinetic Properties). This should be taken into account when the inhibitory effect of Itragen on co-medicated drugs is considered.

The following drugs are contraindicated with Itragen:

- Astemizole, bepridil, cisapride, dofetilide, levacetylmethadol (levomethadyl), mizolastine, pimozide, quinidine, sertindole and terfenadine are contraindicated with Itragen oral solution since co-administration may result in increased plasma concentrations of these substrates, which can lead to QT prolongation and rare occurrences of torsade de pointes.

- CYP3A4 metabolized HMG-CoA reductase inhibitors such as atorvastatin, lovastatin and simvastatin.

- Triazolam and oral midazolam.

- Ergot alkaloids such as dihydroergotamine, ergometrine (ergonovine), ergotamine and methylergometrine (methylergonovine).

- Eletriptan

- Nisoldipine

Caution should be exercised when co-administering Itragen with calcium channel blockers due to an increased risk of congestive heart failure. In addition to possible pharmacokinetic interactions involving the drug metabolising enzyme CYP3A4, calcium channel blockers can have negative inotropic effects which may be additive to those of Itragen.

The following drugs should be used with caution, and their plasma concentrations, effects or side effects should be monitored. Their dosage, if co-administered with Itragen, should be reduced if necessary:

- Oral anticoagulants;

- HIV protease inhibitors such as ritonavir, indinavir, saquinavir;

- Certain antineoplastic agents such as busulfan, docetaxel, trimetrexate and vinca alkaloids;

- CYP3A4 metabolised calcium channel blockers such as dihydropyridines and verapamil;

- Certain immunosuppressive agents: ciclosporin, tacrolimus, rapamycin (also known as sirolimus);

- Certain glucocorticosteroids such as budesonide, dexamethasone, fluticasone and methylprednisolone;

- Digoxin (via inhibition of P-glycoprotein)

- Others: cilostazol, disopyramide, carbamazepine, buspirone, alfentanil, alprazolam, brotizolam, midazolam IV, rifabutin, ebastine, repaglinide, fentanyl, halofantrine, reboxetine and loperamide. The importance of the concentration increase and the clinical relevance of these changes during the co-administration with Itragen remain to be established.

4.5.2.2 No interaction of Itragen with zidovudine (AZT) and fluvastatin has been observed.

No inducing effects of Itragen on the metabolism of ethinyloestradiol and norethisterone were observed.

4.5.3. Effect on protein binding:

In vitro studies have shown that there are no interactions on the plasma protein binding between Itragen and imipramine, propranolol, diazepam, cimetidine, indometacin, tolbutamide and sulfamethazine.

Pregnancy:

Itragen oral solution must not be used during pregnancy except for life-threatening cases where the potential benefit to the mother outweighs the potential harm to the foetus (see 4.3 Contraindications).

In animal studies Itragen has shown reproduction toxicity (see

General pharmacokinetic characteristics

Peak plasma concentrations of itraconazole are reached within 2 to 5 hours following oral administration. As a consequence of non-linear pharmacokinetics, itraconazole accumulates in plasma during multiple dosing. Steady-state concentrations are generally reached within about 15 days, with C_max values of 0.5 µg/ml, 1.1 µg/ml and 2.0 µg/ml after oral administration of 100 mg once daily, 200 mg once daily and 200 mg b.i.d., respectively. The terminal half-life of itraconazole generally ranges from 16 to 28 hours after single dose and increases to 34 to 42 hours with repeated dosing. Once treatment is stopped, itraconazole plasma concentrations decrease to an almost undetectable concentration within 7 to 14 days, depending on the dose and duration of treatment. Itraconazole mean total plasma clearance following intravenous administration is 278 ml/min. Itraconazole clearance decreases at higher doses due to saturable hepatic metabolism.

Absorption

Distribution

Most of the itraconazole in plasma is bound to protein (99.8%) with albumin being the main binding component (99.6% for the hydroxy- metabolite). It has also a marked affinity for lipids. Only 0.2% of the itraconazole in plasma is present as free drug. Itraconazole is distributed in a large apparent volume in the body (> 700 L), suggesting its extensive distribution into tissues: Concentrations in lung, kidney, liver, bone, stomach, spleen and muscle were found to be two to three times higher than corresponding concentrations in plasma, and the uptake into keratinous tissues, skin in particular, is up to four times higher than in plasma. Concentrations in the cerebrospinal fluid are much lower than in plasma, but efficacy has been demonstrated against infections present in the cerebrospinal fluid.

Metabolism

Itraconazole is extensively metabolised by the liver into a large number of metabolites. In vitro studies have shown that CYP3A4 is the major enzyme involved in the metabolism of itraconazole. The main metabolite is hydroxy-itraconazole, which has in vitro antifungal activity comparable to Itraconazole; trough plasma concentrations of the hydroxy-itraconazole are about twice those of itraconazole.

Excretion

Itraconazole is excreted mainly as inactive metabolites in urine (35%) and faeces (54%) within one week of an oral solution dose. Renal excretion of itraconazole and the active metabolite hydroxy-itraconazole account for less than 1% of an intravenous dose.Based on an oral radiolabelled dose, faecal excretion of unchanged drug varies between 3 - 18% of the dose.

Special Populations

Paediatrics:

Limited pharmacokinetic data are available on the use of itraconazole in the paediatric population. Clinical pharmacokinetic studies in children and adolescents aged between 5 months and 17 years were performed with itraconazole capsules, oral solution or intravenous formulation. Individual doses with the capsule and oral solution formulation ranged from 1.5 to 12.5 mg/kg/day, given as once-daily or twice-daily administration. The intravenous formulation was given either as a 2.5 mg/kg single infusion, or a 2.5 mg/kg infusion given once daily or twice daily. For the same daily dose, twice daily dosing compared to single daily dosing yielded peak and trough concentrations comparable to adult single daily dosing. No significant age dependence was observed for itraconazole AUC and total body clearance, while weak associations between age and itraconazole distribution volume, C_max and terminal elimination rate were noted. Itraconazole apparent clearance and distribution volume seemed to be related to weight.

In the absence of compatibility studies, this medicinal product must not be mixed with other medicinal products.

Not applicable.

Any unused product or waste material should be disposed of in accordance with local requirements.

No special requirements.