Pharmacokinetics of oral posaconazole in neutropenic patients receiving chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome

Pharmacokinetics of different dosing strategies of oral posaconazole in patients with compromised gastrointestinal function and who are at high risk for invasive fungal infection

The aim of this study was to assess different dosing strategies that may result in increased posaconazole bioavailability in patients with compromised gastrointestinal function and at high risk for invasive fungal infections. Patients undergoing chemotherapy and at risk for compromised gastrointestinal function received open-label posaconazole at 200 mg three times daily (TID) on days 1 to 8. Patients were randomized to one of three open-label dosing regimens of posaconazole on days 9 to 15: 200 mg TID, 400 mg twice daily (BID), or 400 mg TID. The plasma concentrations of interest on days 8 and 15 were 500 and 700 ng/ml, respectively; day 2 plasma concentrations of 250 and 350 ng/ml were chosen as levels that might result in steady-state concentrations of >500 and >700 ng/ml, respectively. A total of 75 patients enrolled; 52/75 (69%) completed the study, and 49/75 were included in the pharmacokinetic analyses. Mean plasma concentrations were 230, 346, and 637 ng/ml on days 2, 3, and 8, respectively. The day 15 values were 660, 930, and 671 ng/ml for 200 mg TID, 400 mg BID, and 400 mg TID, respectively. In 12 patients with a day 8 posaconazole concentration of <250 ng/ml, an overall benefit of the higher two doses was not apparent, suggesting that a subset of patients has low steady-state plasma concentrations. A change in dosing regimen on day 9 did not lead to higher exposures in these "poor absorbers" on day 15. Poor absorption may be enhanced with a high-fat meal, a nutritional supplement, or acidification.

Prophylaxis and treatment of invasive aspergillosis with voriconazole, posaconazole and caspofungin: review of the literature

Major progress for the management of invasive aspergillosis has come from the introduction of new antifungals since the late 1990s. Although mortality of invasive aspergillosis remains as high as 30-50%. Backbone of management are prophylaxis, early diagnosis and early initiation of antifungals for reduction of invasive aspergillosis related mortality. Randomized trials have been undertaken for the prophylaxis as well as treatment of invasive aspergillosis in the last two decades. Posaconazole is recommended for prophylaxis against aspergillosis in patients treated for acute myelogenous leukemia, myelodysplastic syndrome or patients with graft versus host disease after allogeneic transplantation. Efficacy has been shown for first-line therapy of invasive aspergillosis with voriconazole and liposomal amphotericin B. Gastrointestinal resorption for the azoles posaconazole, voriconazole and itraconazole differ considerably. While oral voriconazole resportion is reduced when taken with food, posaconazole has to be taken with fatty food for optimal intestinal resorption. Beside all advances in the management of invasive aspergillosis important questions remain unresolved. This article reviews the current state of prophylaxis and treatment of invasive aspergillosis and points out clinicians unmet needs.

Posaconazole: when and how? The clinician's view

Posaconazole is the newest triazole antifungal agent available as an oral suspension with an extended spectrum of activity against Candida species, Aspergillus species, Cryptococcus neoformans, Zygomycetes and endemic fungi. Among posaconazole advantages are the relatively low potential of cross-resistance with other azoles, few drug interactions compared with other azoles and its activity against Zygomycetes. Randomised, double-blind trials have shown that posaconazole is effective for prophylaxis against invasive fungal infections (IFI), especially aspergillosis, in high-risk patients. Results of Phase III clinical trials and case/series reports indicate that posaconazole is effective in treating oesophageal candidiasis, including azole-refractory disease, and other IFI refractory to standard antifungal therapies. To date, posaconazole has appeared to be well tolerated even in long-term courses; it has an excellent safety profile with gastrointestinal disturbances being the most common adverse events reported. The dose of posaconazole is 200 mg three times daily for prophylaxis, 800 mg daily in two or four divided doses for the treatment of IFI and 100 mg daily (200 mg loading dose) for the treatment of oropharyngeal candidiasis. On the basis of early clinical experience, it appears that posaconazole will be a valuable aid in the management of life-threatening fungal infections.

Therapeutic drug monitoring of posaconazole in hematology adults under posaconazole prophylaxis: influence of food intake

Posaconazole (PCZ) is given at 200 mg three times daily as a fungal prophylaxis in neutropenic hematologic malignancy patients. A relationship between exposure, plasma concentration, and efficacy is suggested. The objectives of this prospective study were to analyze the PCZ plasma concentration in hematology adults at high risk of developing invasive fungal infections (IFIs), and factors that could have an impact on the PCZ plasma concentration. PCZ plasma concentrations were measured after 2, 7, 10, 14, and 21 days of PCZ prophylaxis. Factors such as gender, age, body weight, posology, treatment duration, mucositis, proton pump inhibitor (PPI) use, and food intake were studied. Sixty-three patients were included, with a median age of 52 years (range 17-70) and a median weight of 75 kg (range 47-150). The median PCZ plasma concentration of the 63 patients ranged from 0.42 to 0.48 mg/L. At day 2, 30% of PCZ plasma concentration were under 0.35 mg/L, and at day 7, 74% were <0.70 mg/L. PCZ plasma concentrations were not affected by gender, age, body weight, or treatment duration. We found that food intake had a high influence on PCZ plasma concentrations (p = 0.0049). PCZ was well tolerated. One patient has developed a probable IFI, probably related to a low exposure to PCZ. PCZ therapeutic drug monitoring (TDM) is essential in order to early detect patients with low concentrations, to assess the etiology of such results, and to decide on the treatment strategy to apply.

Therapeutic drug monitoring of voriconazole and posaconazole

Despite the availability of newer antifungal agents, invasive fungal diseases remain a leading cause of morbidity and mortality in immunocompromised patients. Voriconazole and posaconazole are two extended-spectrum triazoles indicated for treatment and prophylaxis of invasive fungal diseases. Recently, there has been increased interest in the utility of therapeutic drug monitoring to optimize safety and efficacy of antifungals in an attempt to improve patient outcomes. We reviewed the pharmacokinetic and pharmacodynamic characteristics of voriconazole and posaconazole in the context of clinical indications for therapeutic drug monitoring. In addition, the most recent evidence examining the relationship between serum concentrations of voriconazole and posaconazole and their efficacy or toxicities was evaluated. This information was then integrated to formulate recommendations for use of therapeutic drug monitoring in clinical settings.

Relevance of timing for determination of posaconazole plasma concentrations

For posaconazole, drug monitoring is suggested, but the relevance of timing for the determination of posaconazole concentration (PC) remains unclear. We investigated the variation of PC before and 4 and 8 h after the administration of 400 mg of posaconazole. Mean concentrations were 645, 678, and 616 ng/ml. The differences between trough and maximum concentrations were below 20% in 17 and below 30% in 20 of 25 patients. Hence, untimed posaconazole plasma concentrations give reliable information for most patients.

Clinical pharmacodynamics and pharmacokinetics of the antifungal extended-spectrum triazole posaconazole: an overview

In recent years, the antifungal triazole posaconazole has become increasingly important for the prophylaxis and treatment of systemic mycoses. Although oral bioavailability of posaconazole can be enhanced by concomitant food intake and administration in divided daily doses, increased gastric pH or gut motility, as well as enzyme-inducing drugs, can result in lower plasma concentrations than expected. Whether therapeutic drug monitoring can reduce the risk of treatment failures by avoiding sub-therapeutic plasma concentrations needs further examination. Based on the ability of posaconazole to inhibit cytochrome P450 3A4, several drug interactions can be expected, especially with agents that undergo extensive first-pass effect through the gut and the liver. However, more information is needed regarding dose modifications during concomitant administration of posaconazole with drugs in certain categories, such as vinca alkaloids and retinoids, along with selected individual drugs such as everolimus.

Posaconazole serum concentrations among cardiothoracic transplant recipients: factors impacting trough levels and correlation with clinical response to therapy

Fifty-six serum posaconazole trough levels were measured in 17 cardiothoracic transplant recipients. Initial levels were ≤ 0.5, 0.51 to 0.99, and ≥ 1 μg/ml for 47, 29, and 24% of patients, respectively. Median trough levels associated with therapeutic success were higher than those associated with failure (1.55 versus 0.34 μg/ml; P = 0.006). Patients with levels consistently >0.5 μg/ml were more likely to have successful outcome (P = 0.055). Age ≥ 65 years, oral administration, and absence of proton pump inhibitors were associated with higher levels of posaconazole (P = 0.006, 0.006, and 0.001, respectively).

Steady-state intrapulmonary pharmacokinetics and pharmacodynamics of posaconazole in lung transplant recipients

This prospective study evaluated the plasma and intrapulmonary pharmacokinetics and pharmacodynamics (PKPD) of posaconazole (POS) in lung transplant recipients. Twenty adult lung transplant patients were instructed to take a 400-mg POS oral suspension twice daily (BID) with a high-fat meal for a total of 14 doses. Pulmonary epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage, and blood samples were collected at the approximate time of bronchoscopy. POS concentrations were assayed using liquid chromatography with tandem mass spectrometry. The maximum concentrations (C(max)) (mean +/- standard deviation [SD]) in plasma, ELF, and AC were 1.3 +/- 0.4, 1.3 +/- 1.7, and 55.4 +/- 44.0 microg/ml. POS concentrations in plasma, ELF, and AC did not decrease significantly, indicating slow elimination after multiple dosing. Mean concentrations of POS in plasma, ELF, and AC were above the MIC(90) (0.5 microg/ml) for Aspergillus species over the 12-h dosing interval and for 24 h following the last dose. Area under the concentration-time curve from 0 to 12 h (AUC(0-12))/MIC(90) ratios in plasma, ELF, and AC were 21.98, 22.42, and 1,060. We concluded that a dose of 400 mg BID resulted in sustained plasma, ELF, and AC concentrations above the MIC(90) for Aspergillus spp. during the dosing interval. Confirmation of the therapeutic value of these observations requires further investigation. The intrapulmonary PKPD of POS may be favorable for treatment or prevention of aspergillosis, although further research on the relevant PKPD parameters and the effect of POS protein binding is required.

Exposure-response of posaconazole used for prophylaxis against invasive fungal infections: evaluating the need to adjust doses based on drug concentrations in plasma

The purpose of this article is to report the exposure-response (E-R) relationship of posaconazole oral suspension (POS) for prophylaxis against invasive fungal infections (IFIs), on the basis of the US Food and Drug Administration (FDA) clinical pharmacology review of two randomized, active-controlled clinical studies. Posaconazole average steady state plasma concentrations (C(avg)) ranged from 22 to 3,650 ng/ml after administration of POS 200 mg three times daily (t.i.d.). In a double-blind, randomized clinical trial, the quartile ranges of C(avg) with midpoint values of 289, 736, 1,239, and 2,607 ng/ml had clinical failure rates of 44, 21, 18, and 18%, respectively, indicating an inverse association between C(avg) and clinical failure rate. There were no significant relationships between C(avg) and posaconazole-related major adverse events. Determining posaconazole concentrations in plasma will aid in assessing the need for either POS dose adjustment (e.g., increasing the POS dose) or switching to another systemic antifungal drug, thereby improving the effectiveness of prophylaxis against IFIs.

Clinical safety and tolerability issues in use of triazole derivatives in management of fungal infections

There has been an increase in the number of patients susceptible to invasive fungal infections (IFIs) leading to a greater need for effective, well tolerated, and easily administered antifungal agents. The advent of triazoles has revolutionized the care of patients requiring treatment or prophylaxis for IFIs. However, triazoles have been associated with a number of adverse events and significant drug–drug interactions. While commonly used, physicians and patients should be aware of the distinct properties of these agents in order to ensure that patients are optimally treated with the least amount of toxicity possible. Clinicians should have a full understanding of the basic pharmacokinetics, absorption, and bioavailability of triazoles. Moreover, knowledge of the drug–drug interactions and potential toxicities of each agent is critical prior to administering a triazole. Careful history taking, thorough review of the patient’s medication list, and detailed discussion with the patients and their families about the efficacy, safety, and tolerability of these agents should be performed. Clinicians treating patients with triazoles should closely follow them, monitor pertinent laboratory tests, and consider measuring drug levels as needed. This article will review the basic pharmacokinetic properties and most frequently encountered adverse events and pitfalls associated with triazoles in clinical practice.

Skin concentrations and pharmacokinetics of posaconazole after oral administration

A randomized, single-center, open-label study of posaconazole (POS) was performed to determine the concentration of POS in the skin of 30 healthy adult human subjects receiving 400 mg POS oral suspension twice daily for 8 days with a high-fat meal. Blood samples for plasma POS level determination were collected at prespecified times on day 1 and day 8. From each subject, two 4-mm skin punch biopsy samples were obtained, one immediately before or after both the first and last doses of POS. A MIC(90) value of 250 ng/ml, which encompasses the majority of common dermatophytes, was used to calculate the time above the MIC(90) in plasma and skin. On days 1 and 8, POS attained peak plasma concentrations at median times of 8 and 5 h, respectively. On days 1 and 8, POS peak skin concentrations were attained at 12 and 3 h, respectively; peak skin concentrations were produced from a single composite profile. On day 8, POS concentrations in skin and plasma for the entire dosing interval were severalfold higher than the MIC(90). POS dosed at 400 mg twice daily per os was well tolerated in healthy subjects. Two subjects reported increased alanine aminotransferase (ALT) levels. The findings of this study demonstrate adequate skin penetration and have certain implications for the treatment of dermatophytic skin and nail infections.

Population pharmacokinetics of posaconazole in neutropenic patients receiving chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome

OBJECTIVE

The relationship between patient characteristics and posaconazole exposures was evaluated in a population pharmacokinetic (PK) model using trial data from neutropenic patients administered oral posaconazole suspension as antifungal prophylaxis.

METHODS

Data were analyzed using nonlinear mixed-effects modeling. Covariates were tested using the forward addition, Objective Function (OF) cut-off of 3.84, followed by the backward elimination (OF cut-off 10.88) steps in NONMEM. These covariates included demographics, mucositis, neutropenia, vomiting, diarrhea, proton pump inhibitor (PPI) or H(2)-receptor antagonist usage and baseline bilirubin or baseline gamma-glutamyl transferase (GGT) levels > or =2 x upper limit of normal (ULN). A correlation between posaconazole PK and the occurrence of invasive fungal infection (IFI) was also examined.

RESULTS

Statistically significant associations were demonstrated between posaconazole PK and diarrhea, PPI intake, race, and baseline GGT and bilirubin levels. These covariates did not predominate in patients who developed IFI.

CONCLUSION

This analysis provides information regarding the correlation of patient covariates with posaconazole exposures estimated in a clinical setting. The results of this analysis agree with previously reported analyses. However, because of the successful prophylaxis and the low number of posaconazole-treated patients with IFI proven or probable (IFIPP), the absence of a statistically significant relationship between IFIPP and exposure may not mean this relationship does not exist. A meta-analysis of several efficacy trials or exploring alternate composite endpoints for efficacy may be needed to answer this question.

Efficacy of posaconazole as treatment and prophylaxis against Fusarium solani

Invasive fusariosis is a highly aggressive fungal infection associated with high mortality in heavily immunocompromised patients. Although posaconazole is efficacious as salvage therapy against infections caused by Fusarium species, concerns remain regarding this agent in the setting of reduced potency. To evaluate the efficacy of posaconazole as treatment or prophylaxis against invasive fusariosis caused by Fusarium solani, we utilized a neutropenic murine model of disseminated disease. ICR mice were administered escalating doses of posaconazole (6.25, 12.5, 25, or 50 mg/kg of body weight twice daily [BID]) by oral gavage beginning 2 days prior to inoculation in the prophylaxis studies or beginning 12 h after inoculation as treatment. Therapy was continued until day 9 postinoculation, and animals were monitored off therapy until day 15 for survival. Fungal burden was assessed as CFU in the kidneys. A clear dose-response relationship was observed, as the highest dose of posaconazole (50 mg/kg) was the most effective in prolonging survival and reducing tissue fungal burden both as prophylaxis and as treatment. This dose response was associated with high posaconazole serum concentrations as measured by bioassay. However, the extent of efficacy was also dependent on the infecting inoculum, as greater increases in survival and reductions in fungal burden were observed with the lower inocula tested. In this model high dosages of posaconazole were effective as treatment and prophylaxis against disseminated fusariosis caused by F. solani.

Pediatric antifungal agents

PURPOSE OF REVIEW

In immunocompromised hosts, invasive fungal infections are common and fatal. In the past decade, the antifungal armamentarium against invasive mycoses has expanded greatly. The purpose of the present report is to review the most recent literature addressing the use of antifungal agents in children.

RECENT FINDINGS

Most studies evaluating the safety and efficacy of antifungal agents are limited to adults. However, important progress has been made in describing the pharmacokinetics and safety of newer antifungal agents in children, including the echinocandins.

SUMMARY

Dosage guidelines for newer antifungal agents are currently based on adult and limited pediatric data. Because important developmental pharmacology changes occur throughout childhood impacting the pharmacokinetics of these agents, antifungal studies specifically designed for children are necessary.

Factors influencing pharmacokinetics of prophylactic posaconazole in patients undergoing allogeneic stem cell transplantation

The objectives of the present study were to elucidate the factors influencing the pharmacokinetics of prophylactically administered posaconazole in allogeneic hematopoietic stem cell transplant (SCT) recipients. Between May 2007 and November 2008, clinical data were obtained from all SCT recipients at the University Hospital of Cologne undergoing therapeutic drug monitoring (TDM) of serum prophylactic posaconazole concentrations. The posaconazole concentrations were determined by high-performance liquid chromatography. We developed a population pharmacokinetic model using nonlinear mixed-effect modeling (NONMEM). The list of covariates tested included age; body weight; body height; gender; posaconazole dose; race; coadministration of antineoplastic chemotherapy; day of stem cell transplantation; concomitant ranitidine, pantoprazole, cyclosporine, or tacrolimus administration; coincident fever; diarrhea; and plasma gamma-glutamyltransferase activity. A total of 149 serum posaconazole concentrations from 32 patients were obtained. A one-compartment model with first-order absorption and elimination as the basic structural model appropriately described the data, with the apparent clearance being 75.8 liters/h (95% confidence interval [CI], 65.2 to 86.4 liters/h) and the apparent volume being distribution of 835 liters (95% CI, 559 to 1,111 liters). Among the covariates tested, significant effects were found for age (decrease in the volume of distribution of 123 liters per year of age) and the presence of diarrhea (59% loss of bioavailability). A basis for prediction of the mean posaconazole concentrations in allogeneic SCT recipients with hematological malignancies is provided for a given dose. Corresponding adjustments of the starting dose according to the presence of diarrhea and according to age appear to be justified before TDM results are available.

Pharmacokinetics of a single dose of the antifungal posaconazole as oral suspension in subjects with hepatic impairment

OBJECTIVE

To evaluate posaconazole pharmacokinetics in subjects with different degrees of hepatic impairment compared with matched healthy subjects.

RESEARCH DESIGN AND METHODS

A total of 37 subjects were enrolled in this open-label, single-dose, parallel-group study; 19 with hepatic impairment and 18 healthy subjects with matching demographics. Each subject received a single 400-mg oral dose of posaconazole after a high-fat meal. Blood samples for analysis were taken up to 648 h ( approximately 4 weeks) postdose.

RESULTS

Compared with maximum plasma concentration (C(max)) values in matched subjects with normal hepatic function, values were higher among subjects with moderate hepatic impairment (517 vs. 724 ng/mL) but lower among subjects with severe hepatic impairment (608 vs. 403 ng/mL). No clear trend toward increased or decreased exposure was observed with increasingly severe hepatic impairment, and extensive overlap occurred between normal and hepatically impaired subjects. Therefore, pharmacokinetic variables C(max) and area under the curve from time 0 to the time of final quantifiable sample (AUC(tf)) values were pooled for subjects with hepatic impairment. Pooled C(max) values were similar to the pooled normal groups (607 vs. 605 ng/mL), whereas there was an overall 36% increase in exposure (AUC(tf)) for the pooled hepatic impairment group compared with the pooled normal group. Posaconazole was well-tolerated, with six (33%) healthy subjects and six (32%) hepatically impaired subjects reporting adverse events.

CONCLUSIONS

The data from this small single-dose study suggest posaconazole is safe. Furthermore, although limited by the small number of subjects enrolled, the authors feel that dose adjustments are probably not necessary in patients with hepatic impairment; however, physicians should continue to monitor posaconazole use in patients with hepatic impairment.

Therapeutic drug monitoring of posaconazole: a monocentric study with 54 adults

Posaconazole is a potent broad-spectrum triazole antifungal. Little is known about the prevalence and risk factors for low plasma posaconazole concentrations (PPCs). We retrospectively reviewed all adult patients whose PPCs were measured after at least 5 days of treatment between April 2006 and July 2008 at the Hôpital Necker Enfants Malades. A low PPC was defined as a concentration lower than 500 ng/ml. Fifty-four patients were included: 36 receiving prophylactic (200 mg three times a day) and 18 receiving curative (400 mg twice a day) posaconazole therapy. The prevalence of low PPCs was 44% (16/36) in the prophylaxis group and 22% (4/18) in the curative-treatment group. In the prophylaxis group, low PPCs tended to be more frequent in cases of digestive disease (62.5% versus 30%; P = 0.051) and were significantly more frequent among patients with diarrhea (71.4% versus 27%; P = 0.009) or mucositis (100% versus 33%; P = 0.004). In the curative-treatment group, low PPCs were significantly more frequent in cases of diarrhea (75% versus 7%; P = 0.018). In the prophylaxis group, the only two patients who subsequently developed invasive fungal infections exhibited low PPCs. The only adverse event was hepatotoxicity for 2/54 patients (3.7%), which was not related to high plasma drug concentrations. In conclusion, low PPC is common, significantly more frequent in cases of diarrhea or mucositis, and potentially associated with subsequent invasive fungal infection. Therapeutic drug monitoring of posaconazole is therefore mandatory for immunosuppressed adults, at least for those with gastrointestinal disorders.

Pharmacokinetics and absorption of posaconazole oral suspension under various gastric conditions in healthy volunteers

A four-part, randomized, crossover study with healthy subjects evaluated the effects of gastric pH, the dosing frequency and prandial state, food consumption timing, and gastric motility on the absorption of posaconazole. In part 1, a single dose (SD) of posaconazole (400 mg) was administered alone or with an acidic beverage or a proton pump inhibitor (PPI), or both. In part 2, posaconazole (400 mg twice daily and 200 mg four times daily) was administered for 7 days with and without a nutritional supplement (Boost). In part 3, an SD of posaconazole (400 mg) was administered while the subjects were fasting and before, during, and after a high-fat meal. In part 4, an SD of posaconazole (400 mg) and the nutritional supplement were administered alone, with metoclopramide, and with loperamide. Compared to the results obtained with posaconazole alone, administration with an acidic beverage increased the posaconazole maximum concentration in plasma (C(max)) and the area under the concentration-time curve (AUC) by 92% and 70%, respectively, whereas a higher gastric pH decreased the posaconazole C(max) and AUC by 46% and 32%, respectively. Compared to the results obtained with posaconazole alone, posaconazole at 400 mg or at 200 mg plus the nutritional supplement increased the posaconazole C(max) and AUC by 65% and 66%, respectively, and by up to 137% and 161%, respectively. Administration before a high-fat meal increased the C(max) and the AUC by 96% and 111%, respectively, while administration during and after the meal increased the C(max) and the AUC by up to 339% and 387%, respectively. Increased gastric motility decreased the C(max) and the AUC by 21% and 19%, respectively. Strategies to maximize posaconazole exposure in patients with absorption difficulties include administration with or after a high-fat meal, with any meal or nutritional supplement, with an acidic beverage, or in divided doses and the avoidance of proton pump inhibitors.