Posaconazole
Indications
Posaconazole is an antifungal medicine used to prevent serious fungal infections (such as Aspergillus and Candida) in people with very weak immunity, for example during chemotherapy for leukaemia or after a stem cell transplant. It is also used to treat invasive aspergillosis and other serious fungal infections, including mucormycosis, when other treatments are unsuitable, and to treat thrush of the mouth and throat that has not responded to other antifungals. It is available as delayed release tablets, oral suspension and an injection for infusion.
How It Works
Posaconazole is a triazole antifungal. It blocks an enzyme fungi need to make ergosterol, an essential part of their cell membrane. Without ergosterol the membrane becomes weak and leaky, so the fungus stops growing and dies.
Dosage and Administration
The dose depends on the form, the reason for use and the patient, and is decided by the doctor; use as prescribed. Tablets and suspension are not interchangeable, so use only the form prescribed. Delayed release tablets are swallowed whole with food. The suspension should be shaken well and taken with a meal or nutritional drink. The injection is given in hospital by a doctor or nurse as a slow infusion into a vein. Blood levels may be checked.
Interactions
Posaconazole strongly affects other medicines. It must not be used with Simvastatin, Atorvastatin or Lovastatin, Ergotamine, Pimozide, Quinidine, Sirolimus, or Venetoclax at the start of treatment. It greatly raises levels of Tacrolimus, Ciclosporin, Midazolam, Vincristine, some heart medicines such as Digoxin, and some HIV medicines, so doses must be adjusted. Rifampicin, Rifabutin, Phenytoin, Efavirenz, Carbamazepine and some acid reducers (for the suspension) can lower its levels.
Contraindications
- Allergy to Posaconazole or other azole antifungals.
- Use with the medicines listed above that must not be combined.
Side Effects
Common effects include nausea, vomiting, diarrhoea, abdominal pain, headache, fever, rash, low potassium or magnesium and changes in liver tests. The injection may cause irritation at the infusion site.
Get urgent medical help if you have yellowing of the skin or eyes, dark urine, severe tiredness, a fast or irregular heartbeat or fainting, severe rash or blistering, or swelling of the face or throat.
Pregnancy and Lactation
Posaconazole should not be used during pregnancy unless the benefit clearly outweighs the risk to the baby. Women who could become pregnant should use effective contraception during treatment. Breastfeeding should be stopped during treatment.
Precautions and Warnings
Your doctor will check liver function, salts (potassium, magnesium, calcium) and sometimes the heart tracing (ECG). Tell your doctor about heart rhythm problems, liver disease or kidney disease (the injection is avoided in moderate to severe kidney disease). Severe diarrhoea or vomiting can reduce absorption of the oral forms. Take with food for best absorption.
Overdose
No specific antidote exists, and it is not removed by dialysis. Contact a doctor or hospital immediately; treatment is supportive with heart monitoring.
Therapeutic Class
Triazole antifungal.
Storage
Store tablets and suspension below 30°C in a dry place, away from light and out of the reach of children. Do not freeze the suspension. Store the injection as directed on the pack, usually in a refrigerator at 2 to 8°C.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.
All brands of Posaconazole