Posaconazole is the name given to an antifungal drug. It belongs to the group of triazoles.
What is posaconazole?
Posaconazole antifungal drug is used to treat specific fungal infections that prove resistant to other drugs. The antifungal drug posaconazole is used to treat specific fungal infections that prove resistant to other drugs. In medicine, the active ingredient is also called posaconazole. Posaconazole has been approved in Germany since the end of 2005 under the trade name Noxafil and was launched by the company Essex Pharma. The drug is mostly used against fungi that are resistant to common antifungal agents such as itraconazole or amphotericin B. The drug is subject to prescription. The drug is subject to prescription.
Pharmacologic action
Posaconazole belongs to the triazole and imidazole group of drugs. Thus, just like itraconazole and voriconazole, the drug is a synthetic triazole antifungal agent. Its positive properties include its broad spectrum of activity, which can also be used for prophylaxis, and its good tolerability. Fungi are equipped with a cell wall composed of polysaccharides and the insect carapace material chitin. The cell membrane of fungi extends into the interior of the cell and forms part of the cell wall. It contains the important substance ergosterol. This structure is a serious difference between the fungal cell membrane and the human cell membrane. The latter contains cholesterol. Ergosterol, which is extremely important for the cell membrane of fungi, is formed step by step from the substance squalene. It is at this point that posaconazole exerts its effect. The antifungal substance has the ability to inhibit the third conversion step of squalene by blocking an enzyme required for this. In this process, instead of the required ergosterol, false building materials are formed. In the further course, the wrong building materials cause a disturbance of the metabolic processes within the cell membrane, which are important for the reproduction of the fungi. Thus, although the fungi are not killed by posaconazole, they can no longer multiply undisturbed.
Medical application and use
Posaconazole is administered for the treatment of various fungal infections. However, the antifungal drug is usually not one of the first-choice remedies. Only when other treatment measures show no success does posaconazole come into use. Indications for posaconazole include Aspergillus fungi that have invaded the patient’s organism and cannot be effectively treated by administration of itraconazole or amphotericin B. Likewise, there is a possibility that the patient cannot tolerate these agents. Other indications include mycetomas (soft tissue tumors), which consist of fungal tissue, and mold infections that cannot be successfully treated with itraconazole. The same applies to fusarioses (tubular fungal infections), the treatment of which with amphotericin B is not possible. Posaconazole is also suitable for the treatment of parasites such as coccidia. These are protozoa in body cells that are insensitive to antifungal agents such as fluconazole, itraconazole, or amphotericin B. Posaconazole is the first-choice treatment for fungal infections in the mouth and throat. This is especially true for individuals whose immune system is compromised or who have a severe medical condition. Posaconazole can also be used prophylactically to protect certain groups of people from fungal infections. These are patients suffering from blood cancer or acute myeloid leukemia who are undergoing chemotherapy. Because there is a permanent lack of neutrophils in the blood, there is a risk of aggressive fungal infections. The same applies to recipients of bone marrow donations. Thus, their immune system must be suppressed to counteract rejection of the donor bone marrow. Posaconazole is usually administered orally by tablets. Together with food, the patient takes 400 milligrams of the active ingredient twice a day.
Risks and side effects
The use of posaconazole may result in unwanted side effects in some cases.Patients often suffer from nausea, vomiting, loss of appetite, which sometimes leads to food refusal, dizziness, taste disorders, headaches, abdominal pain, drowsiness, constipation, flatulence, anal discomfort, dry mouth, feelings of weakness, itching, skin rash and fever. Mineral imbalances, neutrophil deficiency, magnesium and potassium deficiency, and hypertension are also not uncommon. Occasionally, tremors, anemia, cardiac arrhythmias, convulsions, a hiccup, cough, liver inflammation, jaundice, mouth ulcers, hair loss and confusion may also occur. Posaconazole should not be used if the patient is hypersensitive to the drug. A consistent weighing of risk and benefit by the physician is also required if the patient suffers from hypersensitivity to other triazoles and imidazoles or if liver dysfunction, cardiac arrhythmias and severe diarrhea exist. Animal studies during pregnancy revealed a dangerous effect of posaconazole on the unborn child. The extent of the risk in humans could not be determined. For this reason, women of childbearing potential are recommended to use contraception consistently during posaconazole treatment. During pregnancy, the antifungal drug is only administered if the physician estimates the benefit for the patient to be higher than the risk for the baby. During breastfeeding, the mother must wean before posaconazole therapy. There are intense interactions between posaconazole and numerous other drugs. Therefore, the antifungal drug must not be administered together with benzodiazepines such as alprazolam, midazolam, and triazolam; antiepileptic drugs such as carbamazepine, primidone, phenytoin, and phenobarbital; tuberculosis drugs such as rifabutin and rifampecin; or H1 anithistamines such as astemizole or terfenadine. The same applies to ergot alkaloids such as dihydroergotamine and ergotamine, cytostatic drugs such as vinblastine and vincristine, and the stomachic agent cisapride.
