There's a new option for treating systemic fungal infections

April 18, 2005

According to a recent study, invasive candidiasis kills approximately 10% to 40% of infected immunocompromised patients. Fortunately, there's a new treatment available. The Food & Drug Administration recently approved micafungin (Mycamine, Astellas Pharma US) for injection for the treatment of patients with esophageal candidiasis and the prophylaxis of Candida infections in those undergoing hematopoietic stem cell transplantation (HSCT).

The company plans to launch the product within the next month. Micafungin will be one of the first product launches for Astellas Pharma US, the company resulting from the merger of Fujisawa Healthcare and Yamanouchi Pharma America. The company will co-market the drug with Roche.

"Until the approval of caspofungin (Cancidas, Merck) and voriconazole (Vfend, Pfizer), the treatment options for systemic fungal infections were very limited," said Raymond Cha, Pharm.D., an assistant professor of pharmacy at the Eugene Applebaum College of Pharmacy & Health Sciences at Wayne State University in Detroit. "This represents a move to develop more therapeutic options against these infections." Cha mentioned that micafungin has a broad spectrum of antifungal activity, most notably against Candida and Aspergillus species.

The other echinocandin available in the United States is caspofungin. Micafungin and caspofungin inhibit the synthesis of 1,3-beta-D-glucan, an integral part of the fungal cell wall.

The labeling for micafungin contains a warning about the risk of serious hypersensitivity reactions. Astellas Pharma recommends that if these reactions occur, infusion of micafungin should be discontinued immediately. The labeling for caspofungin does not carry a comparable warning.

"Overall, the safety profile of micafungin is very good," said Cha. In addition to isolated cases of hypersensitivity reactions and anemia, the manufacturer reported that the most common adverse effects experienced in clinical trials were changes in renal and liver function. Clinicians may also want to monitor patients' bilirubin levels, said Cha.

The company said that possible histamine-mediated symptoms have been reported with micafungin, among them rash, pruritus, facial swelling, and vasodilation. Cha added that injection-site reactions, including phlebitis and thrombophlebitis, have also been reported.

The recommended dose of micafungin for the treatment of esophageal candidiasis is 150 mg per day. For the prophylaxis of Candida infections in those undergoing HSCT, the recommended dose is 50 mg per day. Cha said that the dosing range of micafungin is still under investigation, and that dose-escalation options are being evaluated because of micafungin's excellent safety profile.

Cha pointed out that micafungin is not associated with significant drug-drug interactions and does not require dosage adjustments, as do other antifungals. The manufacturer advised that no dosage adjustment for micafungin is necessary with the concomitant use of mycophenolate (CellCept, Roche), cyclosporine, tacrolimus (Protopic/Prograf, Astellas Pharma US), prednisolone, sirolimus (Rapamune, Wyeth Pharmaceuticals), nifedipine, fluconazole, ritonavir (Norvir, Abbott Laboratories), or rifampin.

"A limitation of micafungin is that it is not available orally," Cha noted. The company said that micafungin should be administered by intravenous infusion over a one-hour period. Micafungin is available in cartons of 10 individually packaged 50-mg single-use vials.