Understanding antifungal prophylaxis with posaconazole in hematology patients: an evolving bedside to bench story

Antifungal Prophylaxis with Posaconazole Delayed-Release Tablet and Oral Suspension in a Real-Life Setting: Plasma Levels, Efficacy, and Tolerability

We continuously determined posaconazole plasma concentrations (PPCs) in 61 patients with hematological malignancies receiving posaconazole (PCZ) delayed-release tablets (DRT; 48 patients; median duration of intake, 92 days) and PCZ oral solution (OS; 13 patients; median duration of intake, 124 days). PCZ DRT and OS antifungal prophylaxis was efficient and well tolerated. Thirty-four of 48 patients (71%) receiving DRT always had PPCs of >0.7 mg/liter, while 14 of 48 patients (29%) had at least one PPC of ≤0.7 mg/liter. In patients receiving OS, 4 of 13 patients (31%) always had PPCs of >0.7 mg/liter, 6 of 13 patients (46%) had at least one PPC of ≤0.7 mg/liter, and 3 (23%) patients never reached a PPC of 0.7 mg/liter. In patients with at least one determined PPC, the mean proportion of all PPCs of >0.7 mg/liter was 91% for PCZ DRT, whereas it was 52% for PCZ OS (P = 0.001). In the per sample analysis, PPCs were significantly more likely to be >0.7 mg/liter in patients receiving DRT than in patients receiving OS (PPCs were >0.7 mg/liter in 91.4% [297/325] of patients receiving DRT versus 70.3% [85/121] of patients receiving OS; P < 0.001). Patients receiving PCZ DRT had higher proportions of PPCs of >0.7 mg/liter than patients receiving OS both in the per patient and in the per sample analyses. Two patients (3%) had side effects during PCZ prophylaxis, and one (2%) had fungal breakthrough infection. Therapeutic drug monitoring enables detection of extended periods of PPCs of ≤0.7 mg/liter (e.g., due to nonadherence or graft-versus-host disease), which may also be associated with the loss of protective intracellular PCZ concentrations, regardless of the PCZ formulation.

Posaconazole plasma exposure correlated to intestinal mucositis in allogeneic stem cell transplant patients

PURPOSE

Low posaconazole plasma concentrations (PPCs) are frequently encountered in allogeneic hematopoietic stem cell transplant (HSCT) patients, due to variable gastrointestinal absorption. In this study, the impact of intestinal mucositis on posaconazole exposure is investigated.

PATIENTS AND METHODS

A prospective pharmacokinetic study was performed including allogeneic HSCT patients receiving posaconazole prophylaxis with the oral suspension or tablets. Steady state PPCs were determined using high-performance liquid chromatography-fluorescence detection at the day of transplantation (=day 0), day +7, and +14. Citrulline was measured using liquid chromatography-tandem mass spectrometry to evaluate severity of mucositis, at baseline (day -7 or -6), and at day 0, +7 and +14. Additionally, citrulline plasma concentrations and steady state trough PPCs were determined in hematological patients without HSCT or mucositis.

RESULTS

Thirty-four HSCT patients received posaconazole oral suspension together with 25 cL of Coca Cola, 6 HSCT patients received posaconazole tablets and 33 hematological patients not receiving HSCT received posaconazole oral suspension. The median (interquartile range) average PPC was 0.26 mg/L (0.17-0.43), 0.67 mg/L (0.27-1.38), and 1.08 mg/L (0.96-1.38), with suspension in HSCT patients, suspension in hematological patients and tablets in HSCT patients, respectively. A higher trough PPC was encountered with the oral suspension when citrulline plasma concentrations were above 10 μmol/L compared to values below 10 μmol/L (p < 0.001), whereas for tablets, average PPCs remained high with citrulline plasma concentrations below or above 10 μmol/L (p = 0.64).

CONCLUSION

Posaconazole tablets should be preferred to suspension in HSCT patients immediately after transplantation to prevent insufficient plasma exposure due to intestinal mucositis.

Pharmacokinetics of Posaconazole Oral Suspension in Children Dosed According to Body Surface Area

BACKGROUND

Antifungal prophylaxis remains challenging in immunocompromised children as no clear consensus has yet been reached about which drug to be used. Posaconazole has a broad spectrum of activity, a favorable safety profile and excellent prophylactic activity in adults. However, a lack of pharmacokinetic studies in pediatric patients hampers routine implementation. This study investigates the pharmacokinetics of a newly introduced posaconazole dosing regimen based on the body surface area in pediatric hematologic patients.

METHODS

In this prospective pharmacokinetic study, 8 blood samples were taken during 1 dosing interval at steady state in children aged 13 years or younger with hematologic malignancy, who were treated prophylactically with posaconazole oral suspension at a dose of 120 mg/m 3 times daily. Posaconazole plasma concentrations were determined using high-performance liquid chromatography fluorescence detection.

RESULTS

One hundred twelve samples were taken from 14 patients with a mean age of 6.7 ± 2.8 years. A median posaconazole daily dose of 100.0 mg (77.3-100.0) 3 times daily (tid), corresponding to a median of 117.9 mg/m (112.2-120.4) tid, resulted in mean trough posaconazole plasma concentrations of 0.85 ± 0.56 mg/L. Pharmacokinetic analysis revealed a clearance of 0.8 L/(h kg) (0.5-1.4). No invasive fungal infections or adverse events were encountered during treatment.

CONCLUSIONS

Posaconazole is a promising antifungal agent to be used prophylactically in hematologic patients aged 13 years or younger. Administering posaconazole oral suspension in a dosage of 120 mg/m tid results in adequate posaconazole plasma exposure, without significant adverse events.

Posaconazole prophylaxis in experimental azole-resistant invasive pulmonary aspergillosis

We investigated the efficacy of posaconazole prophylaxis in preventing invasive aspergillosis due to azole-resistant Aspergillus fumigatus isolates. Using a neutropenic murine model of pulmonary infection, posaconazole prophylaxis was evaluated using three isogenic clinical isolates, with posaconazole MICs of 0.063 mg/liter (wild type), 0.5 mg/liter (F219I mutation), and 16 mg/liter. A fourth isolate harboring TR34/L98H (MIC of 0.5 mg/liter) was also tested. Posaconazole prophylaxis was effective in A. fumigatus with posaconazole MICs of ≤0.5 mg/liter, where 100% survival was reached. However, breakthrough infection was observed in mice infected with the isolate for which the posaconazole MIC was >16 mg/liter.