What is the field experience of treating disseminated microsporidiosis (cerebral involvement includ

Fråga: What is the field experience of treating disseminated microsporidiosis (cerebral involvement included) with albendazole? Does albendazole penetrate to the CNS? What doses are recommended? How long should treatment proceed?

Sammanfattning: Albendazole has been used to treat disseminated microsporidiosis. The active metabolite albendazole sulphoxide, which mediates the systemic effect of the drug, passes the blood brain barrier. The clinical effect of albendazole therapy has been variable, but it has been reported to be more efficacious than metronidazole, especially against E. intestinalis (4). In most reports, regarding disseminated microsporidiosis, treatment with albendazole 400 mg twice a day for one month has been given. In some cases, despite initial good clinical effects, signs of recurrence of the microsporidial infection have appeared. In one case recurrence occurred with cerebral involvement, despite continuous use of albendazole (6).

Svar: Albendazole is a benzimidazole carbamate derivative which is structurally related to mebendazole. The mechanism of action is thought to be binding to the parasite tubules with inhibition of the polymerisation to microtubules which are in turn vital to the function of the parasite cell (1,2).

When taken orally, albendazole has a low absorption and also undergoes an extensive first pass metabolism. The parent drug is therefore, in most cases, undetectable in human plasma. An active metabolite, albendazole sulphoxide, is formed. This metabolite is considered to mediate the systemic effect of albendazole therapy. When albendazole is given with a fatty meal a 2-4 fold increase in the plasma concentration of the metabolite has been observed (1,2). Albendazole sulphoxide crosses the blood brain barrier and attains a cerebral spinal fluid concentration one third of that in plasma (2).

Albendazole has been used for several years as an anthelmintic drug, especially against intestinal nematodes. Recently, as described in several case reports, it has also been used in the treatment of microsporidial infections.

Microsporidia are obligate intracellular protozoa that parasitize multiple species of vertebrates and invertebrates. Microsporidial infections are very rare in immunocompetent humans. However, lately an increased number of human microsporidioses have been reported, in HIV-infected or other immunocompromised patients. The most common microsporidian parasites that have been reported to infect humans are; Encephalitozoon (E. intestinalis, formerly septata intestinalis, E. hellum, E. cuniculi), Enterocytozoon (E. bieneusi), Nosema (N. corneum, N. ocularum) and Pleistophora (see 3). A recent paper reviews 39 cases of multiorgan microsporidiosis (4). In this review E. bieneusi was the most commonly identified species of microsporidia followed by E. intestinalis, E. hellum, E. cuniculi, in subsequent order. The sites most commonly involved, in order of decreasing frequency, were the small bowel, urinary tract, eyes, colon and the central nervous system. In some cases, but not all, positive therapeutic effects of albendazole were reported. Infections with E. bieneusi seem to be more resistant to albendazole therapy (4,5).