Uptake of itraconazole by alveolar macrophages

Abstract

Itraconazole is a broad-spectrum potent triazole antifungal agent. Its efficacy in treatment cannot always be explained by body fluid drug levels. In this study, itraconazole was shown to accumulate into host cells. Its intracellular accumulation in cells is greater than that of the antibacterial agent clindamycin, which is known for intracellular localization, and the uptake process does not appear to be active. This ability to reach high concentrations intracellularly may be an important property for the in vivo efficacy of itraconazole.Itraconazole is a promising new triazole antifungal agent which has been used successfully to treat a variety of deep-seated mycoses in animals and humans. In animal models, it has been as effective as fluconazole for treatment of cryptococcal meningitis despite undetectable drug levels in the cerebrospinal fluid (6); this finding contrasts with the high penetration of fluconazole into the subarachnoid space. These experiments showing success of itraconazole in treatment of central nervous system infections in animals (2, 6) were confirmed in human cases of cryptococcal meningitis (1,7,8). Possible explanations for the efficacy of itraconazole in the central nervous system include an effect of itraconazole on host cells by immune stimulation or intracellular accumulation of drug which is not detected by drug assays of biological fluids. We believe that part of the explanation resides in the latter hypothesis. Previously, we have shown that host cells can accumulate a large amount of itraconazole (5). The present study measured the uptake of itraconazole by alveolar macrophages and the factors which influence this interaction. Itraconazole was also compared with clindamycin, an antimicrobial agent known to accumulate inside macrophages. Alveolar macrophages were obtained by lung lavage from 2-to 3-kg New Zealand White rabbits which had received 108 to 109 CFU of Mycobactenum bovis BCG intravenously 3 to 4 weeks before. In each assay, 107 cells per ml were used; each variable was tested in triplicate, and a mean value was recorded. A velocity gradient centrifugation assay was used to test for the partition of drug (4). Macrophages in Hanks' balanced salt solution containing tritium-labelled itraconazole supplied by Janssen Pharmaceutica, Beerse, Belgium, or tritium-labelled clindamycin supplied by Upjohn Co., Kalamazoo, Mich., were layered over a phthalate bed in microcentrifuge tubes. Cells and labelled drug were incubated in 5% CO2 at 37°C for 10 min except as stated otherwise below. The cells were pelleted through phthalate at 15,000 x g. The supernatants and cell pellets were cut off at the bottom of the tube and placed in a 0.5% deoxycholate solution to lyse the cells. The supernatants and lysed cells were added to scintillation fluid for counting of disintegrations per minute. The compounds examined were f3H]itraconazole (1 ,ug/ml), [3H]clindamycin (10 ,ug/rml), [ H] Figure 1 shows the kinetics of intracellular uptake of itraconazole by alveolar macrophages. The uptake is ...

Intracellular Concentrations of Posaconazole in Different Compartments of Peripheral Blood

“…Beyond that, it was also shown that the uptake depended on the medium, with alveolar macrophage C/E ratios of 18 for 5% serum and 3 for 100% serum. The effect of different medium compositions on the uptake of itraconazole by RBCs was not studied (11). The observations on the uptake of itraconazole by alveolar macrophages are consistent with those made by Conte et al (3), who studied intracellular levels of itraconazole in alveolar macrophages of healthy subjects.…”

“…It may be speculated that highly liposoluble posaconazole accumulates in cell organelles and membranes without major involvement of active transport mechanisms; a similar model was discussed for the intracellular uptake of voriconazole (1). The uptake of itraconazole by alveolar macrophages (AM) was previously studied using cells obtained from New Zealand White rabbits, which were infected with Mycobacterium bovis (11). The uptake was both rapid and substantial, with a C/E ratio of 87.9 Ϯ 5.3 for the alveolar macrophages and 90.4 Ϯ 10.1 for RBCs in serum-free medium.…”

Iatrogenic adrenal insufficiency as a side-effect of combined treatment of itraconazole and budesonide

“…After itraconazole withdrawal, the tetracosactid-stimulated cortisol level initially only reached subnormal levels. Itraconazole, given its long half-life in plasma (days), specific kinetic properties and high accumulation in various tissues [32,33] may act intracellularly for an extended period of time, which may explain why the suppression of the axis persists for a long period after treatment withdrawal. ACTH production reached normal levels earlier which may reflect decreased serum budesonide and thus, reestablishment of an intact pituitary-adrenal negative feedback mechanism.…”

Tissue Penetration of Antifungal Agents

“…(ii) physiological factors, such as inflammation, which may increase tissue permeability, i.e., by disruption of normal physiological barriers such as the blood-brain barrier (29,40); the underlying disease (41), which may result in a range of effects, including modification of plasma protein composition and hence drug binding (42,43,44); the recruitment of drug-containing phagocytic cells, i.e., the "dump truck phenomenon," which may increase drug concentrations at the site of infection (12,13,32,45,46); drug export via pumps, e.g., for itraconazole and P-glycopro- Fluid multiples are from g/ml concentrations. *, autopsy data; in these cases, the multiples are based on plasma C max values at the same dose in volunteers (188).…”