The most widely used drug for antifungal therapy is still Amphotericin B or AB. This antifungal agent is available in different forms:
· Abelcet or ABLC or Amphotericin B lipid complex
· ABCD = Amphotericin B colloidal dispersion. This is developed with sodium cholesteryl sulphate. The effectiveness is similar to conventional AB.
· AmBisome or liposomal AB. It is less toxic than conventional Amphotericin B but more expensive though the effectiveness is similar.
Amphotericin B is most beneficial in the infection treatment like Coccidioides, Blastomyces, Paraoccidioides, Histoplasma, Cryptococcus and Candida without associated toxicity. Amphotericin B is a polyene which works by binding in the cell membrane of the fungi specifically in ergosterol, disrupting the membrane leading to fungus death.
Persons taking Amphotericin B may experience some adverse effects such as fever in about 50% of people, anaphylaxis in 1 in 100 ratio, vomiting, nausea, and nephrotoxicity. Nephrotoxicity includes the lowering of glomelur filtration rate (GFR) of the kidney, increased magnesium and potassium loss and sometimes distal renal tubular acidosis. If the use of Amphotericin B is prolonged, nephrotoxicity is irreversible.
Fluconazoles and Azoles
Azoles like fluconazole inhibit the growth of fungi by preventing the ergosterol formation, a vital cell membrane integrity of a fungi. Fluconazole is known to be the “first generation azole” and in the later years it was supplemented with a new azole called vorizonazole with a wider spectrum activity.
Fluconazole is generally used for Candida albicans. But Candida albicans usually develop resistance to this drug especially to persons who are undergoing treatment for AIDS. It is also effective against Coccidiodomycosis and Cryptoccocus neoformans meningitis.
The gastrointestinal tract is able to absorb fluconazole easily and is excreted through urine. For adults who have severe infection, the dose range from 200mg to 400 mg per day. 800mg is sometimes used.
Voriconazole is an antifungal which also belongs to the azole family. Voriconazole is effective against Candida and Aspergillus. It is absorbed orally. It is also effective against Histoplasma, Blastomyces, Coccidioides, Paracoccidiodes, dermatophytes and Cryptococcus.
The dosage is 200mg to 400mg per day. Reversible side effects include mild to moderate visual disturbances in 14% of people taking this drug such as blurred vision and enhanced brightness, increased bilirubin, rashes in 4% of people, photosensitivity and erythema.
Systemic Candida Infection Treatment
Amphotericin B is still the treatment for systemic Candida infection. The new azole, voriconazole are also used if the fungi is resistant to Amphotericin B but it is uncommon. The major problem of using Amphotericin B is the toxicity in prolonged used.
Invasive Aspergillosis Treatment
The drug of choice in Aspergillosis is still Amphotericin B, though voriconazole and posaconazole are very effective. Some patients are recommended to have resection surgeries in cases of invasive pulmonary aspergillosis. A person having aspergillosis with a compromised immune system is an emergency and should be treated urgently.
Sequential therapy starts with Amphotericin B followed by a longterm fluconazole or voriconazole. This is most effective in cryptococcal meningitis in patients with AIDS. Amphotericin B followed by itraconazole is used in aspergillosis patients.