Itraconazole

Itraconazole

Itraconazole (marketed as Sporanox by Janssen Pharmaceutica), invented in 1984, is a triazole antifungal agent that is prescribed to patients with fungal infections. The drug may be given orally or intravenously.

Pharmacology

The mechanism of action of itraconazole is the same as the other azole antifungals: it inhibits the fungal cytochrome P450 oxidase-mediated synthesis of ergosterol. Because of its ability to inhibit cytochrome P450 3A4, caution should be used when considering interactions with other medications.

Indication

Itraconazole has a broader spectrum of activity than fluconazole (but not as broad as voriconazole or posaconazole). In particular, it is active against aspergillus, which fluconazole is not. It is also licenced for use in blastomycosis, histoplasmosis and onychomycosis. Itraconazole is over 99% protein bound and has virtually no penetration into cerebrospinal fluid. Therefore, it should never be used to treat meningitis or other central nervous system infections. According to the Johns Hopkins Abx Guide, it has "negligible CSF penetration, however treatment has been successful for cryptococcal and coccidioidal meningitis".

Dosing

Itraconazole is available as capsules or as an oral solution. The dose is 200 mg once a day, to 400 mg in severe infection. There is an intravenous preparation available in the US, but not in the UK. In the UK, if an intravenous preparation is required, then an alternative antifungal drug should be used.

Itraconazole has relatively low bioavailability after oral administration, especially when given in capsule form on empty stomach. The oral solution is better absorbed.The cyclodextrin contained in the oral solution can cause an osmotic diarrhea, and if this is a problem, then half the dose can be given as oral solution and half as capsule in order to reduce the amount of cyclodextrin given. Itraconazole capsules should always be taken with food, as this improves absorption. Itraconazole oral solution should be taken an hour before food, or two hours after food (and likewise if a combination of capsules and oral solution are used). Itraconazole may be taken with orange juice or cola, as absorption is also improved by acid. Absorption of itraconazole is impaired when taken with an antacid, H2-blocker or proton pump inhibitor.

Some doctors give an oral loading dose of 200 mg three times a day for three days, before dropping down to the usual dose. Because itraconazole absorption is unreliable, blood levels should be monitored at least once a week in those patients who are being treated for life-threatening (or potentially life-threatening) fungal infections.

In intravenous dosing, four doses of itraconazole 200 mg are given 12 hours apart, before changing the dose to once daily. There is no safety data for giving the intravenous preparation for more than 14 days continuously.

Adverse effects

Itraconazole is a relatively well-tolerated drug (although not as well tolerated as fluconazole or voriconazole) and the range of adverse effects it produces is similar to the other azole antifungals.

The cyclodextrin that is used to make the syrup preparation can cause diarrhea. Side-effects that may indicate a greater problem include:

Production and marketing

Itraconazole can be consumed orally in blue ⅞ in (22 mm) capsules with tiny 1.5 mm blue pellets inside. Each capsule contains 100 mg and is usually taken multiple times a day such as every twelve hours. Sporanox, the brand name of Itraconazole, has been developed and marketed by Janssen Pharmaceutica Products, L.P. a subsidiary of Johnson and Johnson. Apparently, the three layer structure of these blue capsules are quite complex because Itraconazole is insoluble and is sensitive to pH. The complicated procedure not only requires a specialized machine to create it, but the method used has manufacturing problems. Also, the pill is quite large, making it difficult for many patients to swallow. Parts of the processes of creating Sporanox were discovered by the Korean Patent Laid. The contents of the capsule, the tiny blue pellets, are manufactured in Beerse, Belgium.

Consumption

Roughly 180 generic capsules costs $360. If a patient is prescribed three capsules twice daily for the minimum of three months, the patient would spend more than $1080 and consume over 540 capsules. The possible loss of motivation to spend thousands of dollars for continued use therefore constitutes a threat and a risk for the fungus to regrow in the body.

See also

General pharmacologic information about itraconazole

Treatment of aseptic meningitis

Footnotes

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