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Antimicrobial Agents and Chemotherapy, December 2006, p. 4096-4102, Vol. 50, No. 12
0066-4804/06/$08.00+0 doi:10.1128/AAC.00630-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Pharmacokinetics of Itraconazole and Hydroxyitraconazole in Healthy Subjects after Single and Multiple Doses of a Novel Formulation
J. W. Mouton,1*
A. van Peer,2
K. de Beule,2
A. Van Vliet,3
J. P. Donnelly,4 and
P. A. Soons2
Canisius Wilhelmina Ziekenhuis Nijmegen, Nijmegen, The Netherlands,1
Johnson & Johnson Pharmaceutical Research & Development, Beerse, Belgium,2
Pharma Bio-Research, Zuidlaren, The Netherlands,3
Department of Haematology, UMC St. Radboud, Radboud University Nijmegen, Nijmegen, The Netherlands4
Received 23 May 2006/
Returned for modification 8 July 2006/
Accepted 8 September 2006

ABSTRACT
Originally, itraconazole for parenteral administration was licensed
in a 40% hydroxypropyl-beta-cyclodextrin (HPBCD) solution for
intravenous administration. A novel formulation, the NanoCrystal
formulation (NCF), was prepared. NCF consists of drug particles
of approximately 200 to 300 nm. The pharmacokinetics of itraconazole
and its hydroxy metabolite in healthy subjects were evaluated
after single and multiple doses of itraconazole as NCF. In the
single-ascending-dose (SAD) study, itraconazole doses were planned
to range from 50 to 500 mg, while in the multiple-ascending-dose
(MAD) study, itraconazole doses of 100, 200, and 300 mg as NCF
were studied, as was one dose level (200 mg) as an HBPCD solution.
Samples were collected in heparinized tubes at various time
points and were analyzed by high-performance liquid chromatography
to allow full pharmacokinetic analysis both after the first
dose and on day 7. The results of both the SAD and the MAD studies
indicated that there was a dose dependency in the half-life
of itraconazole from the novel formulation, increasing from
44 h (100 mg) to more than 150 h (300 mg) once steady state
was achieved. Similar dose-dependent effects were observed for
the hydroxy metabolite. The areas under the concentration-time
curves for itraconazole and hydroxyitraconazole were also dose
dependent. The pharmacokinetic profiles after 200-mg doses of
itraconazole as NCF and HPBCD formulations were comparable with
respect to the terminal half-life, both after a single dose
and at steady state. NCF may provide an alternative to the HPBCD
solution for the further optimization of antifungal treatment
with itraconazole.

INTRODUCTION
Itraconazole is a broad-spectrum antimycotic triazole that has
been in use for almost two decades for both the prophylaxis
and treatment of invasive fungal diseases. Initially, itraconazole
was available as an oral agent only. The formulation used initially
was an encapsulated form, but the absorption of itraconazole
in a subset of immunocompromised patients was not optimal, and
its pharmacokinetics varied considerably between patients (
3,
10,
16,
18). In addition, absorption was highly influenced by
gastric pH and the use of antacids (
11,
12), as well as by concomitant
food intake (
27,
28). An oral solution based on hydroxypropyl-beta-cyclodextrin
(HPBCD) became available in the late 1990s. That formulation
showed a more favorable pharmacokinetic profile than capsules
(
4-
6,
8,
13,
20,
22,
25) and is superior to capsules in preventing
invasive
Aspergillus infections (
9). However, the variability
in pharmacokinetics was still high in some patient groups, and
oral treatment was not suitable for those high-risk patients
who were unable to tolerate food and drink due to chemotherapy-induced
mucosal barrier injury.
The development of formulations for intravenous use was hampered by the poor solubility of itraconazole in water, but eventually, a 40% HPBCD solution was made available in the United States and elsewhere. However, the presence of large amounts of HPBCD can limit the use of higher doses, even though the dextrin compound is readily eliminated (26) and can be dialyzed (15). This led to the exploration for an alternative parenteral formulation of itraconazole in which larger crystals of the drug substance were milled in the surfactant pluronic F108, generating physically stable dispersions consisting of medium-size crystals (i.e., 50% were <200 nm and 90% were <335 nm). This so-called NanoCrystal formulation (NCF) provided a suitable delivery system for all commonly used routes of administration (14). Studies with several animal species showed that the drug particles were specifically trapped in Kupffer cells in the liver and spleen (Johnson & Johnson Pharmaceutical Research & Development, data on file). This might result in significant changes in the pharmacokinetics of itraconazole compared to that of the HPBCD formulation. Animal studies indicated that pharmacokinetic changes were related to the size of the particles and were most pronounced for larger crystals (i.e., those
340 nm).
The objective of the present studies was to investigate the pharmacokinetics of itraconazole and its hydroxy metabolite after NCF was administered intravenously to healthy subjects. In the first study, the drug was given in escalating doses (single-ascending-dose [SAD] study). In the second study, the drug was given as a single dose and, after a washout of at least 2 weeks, as multiple ascending doses over 7 days (multiple-ascending-dose [MAD] study). In addition, the pharmacokinetics of the HPBCD formulation were determined in a parallel group of subjects to identify any major differences in pharmacokinetics between the two formulations.

MATERIALS AND METHODS
Subjects and samples.
Two studies were performed. Study 1 was a SAD study with three
planned sequential dose levels of itraconazole as NCF and two
groups of nine healthy subjects each, with six subjects in each
group receiving vero and three subjects in each group receiving
placebo. The subjects in group A were scheduled to receive 50,
200, and 400 mg or placebo; and the subjects in group B were
scheduled to receive 100, 300, or 500 mg or placebo. Study 2
was a single-MAD and a multiple-MAD study (MAD
s and MAD
m, respectively)
with 100, 200, and 300 mg of itraconazole as NCF and groups
of six subjects each, with four subjects in each group receiving
vero and two subjects in each group receiving placebo. In addition,
one group of four subjects was given 200 mg itraconazole as
in the HPBCD formulation. The washout between the single-dose
and multiple-dose assessments was at least 2 weeks. Multiple
doses were given every 24 h except on days 1 and 2, when the
dose was given every 12 h. Both studies were performed as single-center,
open-label, randomized, placebo-controlled studies.
Healthy male and female subjects were randomly assigned to receive itraconazole or placebo at each dose level. The itraconazole NCF was administered intravenously over 1 h (SAD study) or as a 100-mg/h infusion (MAD study). The itraconazole HPBCD formulation was administered as a 1-h infusion (single dose) or a 2-h infusion (multiple doses). Subjects fasted overnight for at least 10 h before and for 2 h after dosing on the day of the full pharmacokinetic analysis. Venous blood samples were taken from an indwelling cannula from the arm opposite that used to infuse the itraconazole. In the single-dose studies, samples were collected in heparinized tubes immediately before the start of the infusion; at 0.5, 1, and 2 h during the infusion, when applicable; at 0, 0.08, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, and 8 h after the end of the infusion; and at 24, 32, 72, 96, and 168 h after the start of the infusion. In the multiple-dose study, samples were collected just before and 1 h after the infusion on days 1 to 7. On the 7th day, additional blood samples were taken at times similar to those used in the single-dose studies. The blood samples were allowed to remain undisturbed at room temperature for at least 2 h to ensure the complete dissolution of the itraconazole NCF and minimal bioanalytical variability in these early clinical studies. Unpublished research and pharmacokinetic modeling at Johnson & Johnson indicate that nanocrystals rapidly release itraconazole, with half-lives of 9 and 2 min in human and dog plasma, respectively. The blood samples were then centrifuged at 1,000 x g for 10 min, and the resulting plasma was transferred into polypropylene tubes and stored at 20°C until analysis. Both studies were conducted in full compliance with good clinical practice guidelines and with prior ethics committee approval.
Analytical procedure.
Itraconazole and hydroxyitraconazole concentrations were measured by high-performance liquid chromatography, as described previously (24). The assay of itraconazole in plasma had lower limits of quantification (LOQ) of 2 and 5 µg/liter. The calibration curve ranged from 2 to 5,000 µg/liter. The LOQ applies to the concentration in plasma obtained after the blood is left for 2 h at room temperature, followed by centrifugation. The accuracy of the assay ranged from 97.1% to 98.7% for independently prepared itraconazole quality control samples with concentrations ranging between 13.8 and 717 µg/liter and from 94.7% to 99.5% for hydroxyitraconazole control samples with concentrations ranging between 14.5 and 753 µg/liter. The precisions (coefficients of variation) ranged between 1.0% and 3.4% for itraconazole and between 1.4% and 3.1% for hydroxyitraconazole.
Pharmacokinetic and statistical analyses.
Pharmacokinetic parameters were derived by noncompartmental analysis. The area under the concentration-time curve (AUC) from time zero to infinity (AUC0-
) was determined by use of the linear trapezoidal rule with extrapolation to infinity by using the elimination rate constant. The elimination rate constant (
z) was determined by linear regression of the terminal points of the log-linear plasma concentration-time curve. The terminal half-life was defined as 0.693/
z. Clearance (CL) was calculated as dose/AUC0-
or as dose/AUC144-168 (where AUC144-168 is the AUC from 144 to 168 h) and the volume of distribution (V) as dose/(AUC0-
.
z) (21). Differences in terminal half-lives were determined from the linear regressions of log-transformed concentrations. Statistical analysis was performed by using SAS software for nonparametric or parametric procedures when applicable. A two-sided P value of <0.05 was considered statistically significant.

RESULTS
Subject characteristics, treatment compliance, and safety assessments.
The demographic data for the subjects randomized in the studies
and receiving vero are shown in Table
1. There were no significant
differences in the characteristics between the subjects in the
different dose groups in either of the two studies. In the SAD
study the only adverse events reported were in two subjects
receiving 300 mg itraconazole as NCF, who developed acute severe
localized back pain shortly after the start of the infusion,
accompanied by lumbar muscular spasms. These events led to the
discontinuation of the infusion. Treatment at the 300-mg level
and higher was therefore suspended. No clinically relevant abnormalities
in laboratory or cardiovascular measurements were observed.
It was concluded that these events were related to the relative
high infusion rate at the higher dose levels. Consequently,
the infusion time for the MAD study was prolonged to 2 h and
3 h for the 200- and 300-mg doses, respectively; and no further
localized back pain or lumbar muscular spasms were reported.
Except for these events, treatment compliance was 100% in both
studies. In the MAD study, several subjects reported mild to
moderate local reactions at the site of infusion (swelling,
redness, pain, phlebitis), and these were approximately equally
divided over all treatments, including the placebo; headache
and dizziness, known adverse reactions to itraconazole, were
reported by two subjects each.
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TABLE 1. Demographics and dosing regimens for subjects participating in the SAD and MAD studies receiving the itraconazole NCF and the HPBCF formulation
|
SAD and MADs studies.
Figure
1 shows the concentration-time plots for itraconazole
and hydroxyitraconazole for the SAD study. During the infusion
of NCF, the concentrations in plasma increased rapidly, reaching
about 80% of the maximum concentration in plasma (
Cmax) after
0.5 h and reaching
Cmax at the end of the infusion. After the
infusion was stopped, the concentrations declined rapidly to
about 1/10 of the
Cmax in less than 1 h and then decreased more
slowly. Table
2 shows the pharmacokinetic parameter values for
single-dose itraconazole for each of the treatment groups during
both the SAD study and the MAD
s study.
V was comparable across
the treatment groups, with an overall mean of about 600 liters.
The clearance appeared to be somewhat lower at higher doses.
This is also apparent from Fig.
2, which shows AUC/dose as a
function of dose. The increase in AUC was slightly more than
dose proportional (
P = 0.02 for the two studies combined). However,
this was entirely due to the relatively low AUC
0-
at the 50-mg
dose level; there was no significant increase over the 100-
to 300-mg range. For hydroxyitraconazole there was no difference
in the dose-normalized peak concentrations in plasma between
the dose groups.
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TABLE 2. Pharmacokinetic parameters of itraconazole in various treatment groups after a single dose of NCF in the SAD study and the single-dose part of the MAD studya
|
Multiple-ascending-dose study.
Itraconazole and its metabolite, hydroxyitraconazole, could
not be detected in any plasma sample before the administration
of itraconazole at each dosing phase, indicating that a minimum
of 2 weeks of washout between both phases was sufficient to
prevent the carryover of itraconazole and hydroxyitraconazole
in plasma. Figure
3 shows the concentration-time plots for itraconazole
and hydroxyitraconazole for the 100- and 300-mg doses of itraconazole
as NCF. Table
3 shows the mean estimated pharmacokinetic parameter
values for itraconazole and hydroxyitraconazole for the three
NCF treatment groups and the group receiving the HPBCD formulation.
The results indicate that there was no accumulation of itraconazole
over the treatment period studied once steady state is achieved,
which is after approximately 48 to 72 h, while the steady state
of the metabolite was achieved after only 1 week of treatment.
The pharmacokinetic parameter values at steady state in the
MAD study differed from those obtained in the SAD study. The
AUCs were higher, and in particular, the half-life was associated
with a dose-dependent increase. This was also true for hydroxyitraconazole.
This is more apparent in Fig.
4, which shows the terminal-phase
concentration-time profile of itraconazole during the MAD
m study
for the three dose levels. It is evident that the half-life
was increased at increasing dose levels, which was statistically
significant (
P < 0.001 for both itraconazole and hydroxyitraconazole).
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TABLE 3. Pharmacokinetic parameters of itraconazole after treatment with the NCF or the HPBCD formulation after noncompartmental analysis at steady state
|
Comparison of NCF and HPBCD formulation.
Comparison of the 200-mg doses for the two formulations showed
that the mean peak concentrations in plasma during the infusion
of NCF were substantially higher than those during the infusion
of the HPBCD formulation (Fig.
5). However, during the first
30 min after the infusion of NCF, there was a more rapid decline,
and as a consequence, the difference between the two formulations
for the other pharmacokinetic parameters was less pronounced
or was not significant at all. Both formulations were comparable
with respect to the terminal half-life, both after a single
dose (results not shown) and during steady state (Table
3).

DISCUSSION
We describe the pharmacokinetics of itraconazole and hydroxyitraconazole
after single and multiple ascending doses of the NCF. We also
compared the pharmacokinetics of NCF to that of the HPBCD formulation
for one dose level. Each study group comprised a number of subjects
receiving placebo to determine whether there were relevant and
significant side effects. Although the study design was initially
double blinded in that respect, the appearance of the placebo
formulation was different from that of the itraconazole formulation
and blinding could not be achieved. Thus, both studies were
essentially open label. Itraconazole was well tolerated except
in the SAD study at the higher dose of 300 mg, where two subjects
complained of severe localized back pain immediately after infusion.
This was thought to be related to the duration of infusion,
and subsequently, the infusion time was restricted to 100 mg
per hour. No clinically relevant side effects were observed
by using the prolonged infusion time at higher doses up to 300
mg, and we conclude that the initial hypothesis that the infusion
time was too short for the higher dose was plausible.
Although the terminal half-life of itraconazole and, in particular, that of hydroxyitraconazole were somewhat longer after the administration of NCF than those after the administration of the HPBCD formulation, the differences were not significant. One might therefore conclude that the formulation itself has no significant effect on the elimination of the drug. However, there were only few subjects in each group, with wide variation in the half-lives between them. Since the study was not designed to compare the two formulations but, rather, was designed to describe the pharmacokinetic profile of NCF, a more extensive study is required to be conclusive in this respect. The AUC0-
values at steady state were comparable between the two formulations.
The steady-state concentrations of itraconazole were reached after 48 h (four doses) during both treatments, while for hydroxyitraconazole, 7 days was needed to reach steady state. This is in agreement with the findings of earlier pharmacokinetic studies (6, 7, 23), which documented trough concentrations over a 7-day treatment with the HPBCD formulation in various patient groups. The concentrations in those studies were slightly lower, however, with mean trough levels between 316 and 620 µg/liter after 48 h and 337 to 644 µg/liter after 7 days of treatment, whereas the trough levels were 916 µg/liter after 7 days of treatment with the HPBCD formulation in the current study. The 200-mg dose of itraconazole as NCF resulted in even higher mean trough concentrations (1,249 µg/liter). Similarly, the concentrations of hydroxyitraconazole were higher than those reported in the previous studies. This might simply be an artifact related to the small sample size in the current studies or might be due to the fact that the current studies were performed with healthy subjects, while the other studies were performed with various patient groups. The fraction of unbound drug is known to be smaller (1, 2) in healthy subjects, and renal elimination may thus be slower.
The mean maximum plasma itraconazole concentrations at the end of the infusion of NCF were 1,410, 3,510, and 6,220 µg/liter for doses of 50, 100, and 200 mg, respectively, and were considerably higher than that reported earlier for a single dose of 100 mg itraconazole as the HPBCD formulation, which resulted in a mean plasma concentration of 660 µg/liter at the end of infusion (Johnson & Johnson Pharmaceutical Research & Development, data on file). This difference, if it is indeed true, could be explained by assuming that during infusion not all itraconazole particles are dissolved. Nondissolved itraconazole is trapped in plasma and is therefore not available for diffusion and distribution to the peripheral tissues, resulting in higher concentrations in plasma. Another explanation could be that the particles are taken up by the mononuclear phagocyte system through opsonization. However, itraconazole in NCF dissolves relatively quickly, as can be concluded from the observation that peak concentrations in plasma were reached before the end of infusion, when there was equilibrium between the rate of infusion and the rate of dissolution of the drug particles in blood.
The pharmacokinetics of itraconazole after the infusion of single doses in the SAD and the MAD studies were slightly more than dose proportional over the range of 50 to 300 mg in a combined analysis. However, this seems to be entirely due to the relatively low AUCs at the 50-mg dose level. One explanation could be the lower level of quantification reached relatively earlier at the low dose than at the higher doses and therefore resulted in a slight underestimation of AUC0-
. On the other hand, a more-than-dose-proportional increase in AUC0-
does fit with the longer half-life observed after higher doses during the MAD study (Fig. 4). Surprisingly, the dose-normalized AUC0-
for the 100-mg dose compared to that for the 300-mg dose appeared to be higher for hydroxyitraconazole as well, indicating that conversion from itraconazole to the hydroxy metabolite is not the rate-limiting step in this case but must be sought in the elimination of both components. One explanation could be the formulation itself, as explained above, whereby the drug particles take some time to dissolve in blood. At higher concentrations, this process might take slightly longer, if the crystals are, as indicated in animal studies, trapped in liver and spleen cells, which may then act as a deep compartment, thereby explaining the significant longer half-lives at higher doses.
In clinical studies, it assumed that a trough value of at least 500 µg/liter itraconazole is required to successfully prevent or treat invasive fungal disease (17, 19), which both formulations achieve with doses of 200 mg or higher. Moreover, the variance in trough levels of the NCF of itraconazole was relatively low, which is in contrast to what is observed after oral treatment. The wide variability for oral itraconazole is probably due to variation in bioavailability after oral dosing, indicating the necessity of starting treatment of high-risk patients intravenously. As with the HPBCD formulation, such trough levels of at least 500 µg/liter itraconazole can readily be achieved by using the NCF of itraconazole, which may be a viable alternative to the existing HPBCD formulation for the further optimization of antifungal treatment.

ACKNOWLEDGMENTS
NanoCrystal itraconazole was developed by using Elan Pharma
International Limited's proprietary NanoCrystal technology.
NanoCrystal is a registered trademark of Elan Corporation, plc.
We thank the subjects who volunteered to take part in these studies and K. Groen and R. Crabbe (Janssen Research Foundation) and N. M. Griep (Pharma Bio-Research) for their indispensable contributions to the original studies.

FOOTNOTES
* Corresponding author. Mailing address: Department of Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Ziekenhuis Nijmegen, Weg door Jonkerbos 100, 6532 SZ Nijmegen, The Netherlands. Phone: 31-(0)24-3657514. Fax: 31-(0)24-3657516. E-mail:
Mouton{at}cwz.nl.

Published ahead of print on 18 September 2006. 

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Antimicrobial Agents and Chemotherapy, December 2006, p. 4096-4102, Vol. 50, No. 12
0066-4804/06/$08.00+0 doi:10.1128/AAC.00630-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
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Chen, J., Song, X., Yang, P., Wang, J.
(2009). Appearance of Anaphylactic Shock after Long-Term Intravenous Itraconazole Treatment. The Annals of Pharmacotherapy
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