Penetration of amphotericin B lipid formulations into pleural effusion

Application and evaluation of topical amphotericin B for the treatment of respiratory fungal infections

BACKGROUND

In recent years, the prevalence of respiratory fungal diseases has increased. Polyene antifungal drugs play a pivotal role in the treatment of these conditions, with amphotericin B (AmB) being the most representative drug. This study aimed to evaluate the efficacy and safety of topical administration of AmB in the treatment of respiratory fungal infections.

METHODS

We conducted a retrospective study on hospitalized patients treated with topical administered AmB for respiratory fungal infections from January 2014 to June 2023.

RESULTS

Data from 36 patients with invasive pulmonary fungal infections treated with topical administration of AmB were collected and analyzed. Nebulization was administered to 27 patients. After the treatment, 17 patients evidenced improved conditions, whereas 10 patients did not respond and died in the hospital. One patient experienced an irritating cough as an adverse reaction. Seven patients underwent tracheoscopic instillation, and two received intrapleural irrigation; they achieved good clinical therapeutic efficacy without adverse effects.

CONCLUSION

The combined application of systemic antifungal treatment and topical administration of AmB yielded good therapeutic efficacy and was well-tolerated by the patients. Close monitoring of routine blood tests, liver and kidney function, and levels of electrolytes, troponin, and B-type natriuretic peptide supported this conclusion.

Intra-amniotic Candida albicans Infection Treated With Liposomal Amphotericin B With a Successful Neonatal Outcome

Intra-amniotic infection with Candida species is an uncommon but severe condition with high fetal morbimortality and no established clinical guidelines for its management. We report a Candida albicans intra-amniotic infection diagnosed in a 25-week pregnant woman, successfully treated with high-dose liposomal amphotericin B. Pregnancy was prolonged until 30 weeks, and despite persistently positive Candida cultures in amniotic fluid, a healthy newborn was delivered without evidence of systemic infection. Amphotericin concentration was determined at birth, revealing levels over 30 times higher in mother's and cord blood than in the amniotic fluid, probably explaining the clinical protection despite failure in obtaining fungal clearance.

Salvage Treatment for Invasive Aspergillosis and Mucormycosis: Challenges, Recommendations and Future Considerations

Invasive mold diseases are devastating systemic infections which demand meticulous care in selection, dosing, and therapy monitoring of antifungal drugs. Various circumstances regarding PK/PD properties of the applied drug, resistance/tolerance of the causative pathogen or host intolerability can lead to failure of the initial antifungal therapy. This necessitates treatment adaption in the sense of switching antifungal drug class or potentially adding another drug for a combination therapy approach. In the current state of drastically limited options of antifungal drug classes adaption of therapy remains challenging. Current guidelines provide restricted recommendations only and emphasize individual approaches. However, novel antifungals, incorporating innovative mechanisms of action, show promising results in late stage clinical development. These will expand options for salvage therapy in the future potentially as monotherapy or in combination with conventional or other novel antifungals. We outline current recommendations for salvage therapy including PK/PD considerations as well as elucidate possible future treatment options for invasive aspergillosis and mucormycosis.

A Case Report of Histoplasma-Associated Empyema Treated With Intravenous Injection and Local Thoracic Irrigation of Amphotericin B Plus Medical Thoracoscopy

Cases of empyema associated with Histoplasma infection are rarely reported. Here, we discuss a case of Histoplasma-associated empyema successfully treated with amphotericin B intravenous and pleural infusion therapy and multiple medical thoracoscopies. A 57-year-old Chinese woman with preexisting diabetes mellitus and gastric cancer had massive left-sided pleural effusion diagnosed by chest computed tomography. Her pleural effusion was purulent through pleural catheter drainage, and the culture of the pleural fluid showed Escherichia coli and Streptococcus constellation. Histopathology of the thoracoscopic pleural biopsy after hexamine silver and PAS staining supported Histoplasma infection. The patient was treated with intravenous injection and local thoracic irrigation of amphotericin B and continuous oral administration of itraconazole. At the same time, the patient received thoracic cannulation, daily thoracic lavage and thoracoscopy for purulent and necrotic tissue removal three times during hospitalization. The patient's pleural effusion and necrotic tissue in the pleural cavity were significantly reduced in a short time, and the clinical symptoms were significantly improved. After discharge, the patient recovered well and had no obvious complications or sequelae. Intravenous injection and local thoracic irrigation of amphotericin B are safe and effective drug therapies to treat fungal-associated empyema such as Histoplasma. Medical thoracoscopy effectively shortens the recovery time of empyema, improving the prognosis and reducing complications.

[Liposomal amphotericin B: Clinical pharmacology, pharmacokinetics and pharmacodynamics]

Liposomal amphotericin B is a lipid formulation of the antifungal drug amphotericin B with some distinguishing characteristics in its pharmacological behavior that entail some clinical differences of great interest. The significant improvement in the systemic and renal tolerability is one of them. This fact is related to the great stability of the liposome, promoted by its negative charge, the presence of cholesterol and the remarkable thermo-stability of the remaining lipids that compose it. In this situation, amphotericin B seems to be released from the liposome not spontaneously but when the liposome binds to the ergosterol in the fungal cell membrane. For this reason, there is almost no free amphotericin B in plasma or tissues, although it seems that its availability is greater when there is fungal infection. As a consequence, when the pharmacokinetic behavior is studied, the concentration and availability of liposomal amphotericin B are very high, and its volume of distribution is reduced in comparison with the other formulations.

Systemic and Target-Site Pharmacokinetics of Antiparasitic Agents

About one-sixth of the world's population is affected by a neglected tropical disease as defined by the World Health Organization and Center for Disease Control. Parasitic diseases comprise most of the neglected tropical disease list and they are causing enormous amounts of disability, morbidity, mortality, and healthcare costs worldwide. The burden of disease of the top five parasitic diseases has been estimated to amount to a total 23 million disability-adjusted life-years. Despite the massive health and economic impact, most drugs currently used for the treatment of parasitic diseases have been developed decades ago and insufficient novel drugs are being developed. The current review provides a compilation of the systemic and target-site pharmacokinetics of established antiparasitic drugs. Knowledge of the pharmacokinetic profile of drugs allows for the examination and possibly optimization of existing dosing schemes. Many symptoms of parasitic diseases are caused by parasites residing in different host tissues. Penetration of the antiparasitic drug into these tissues, the target site of infection, is a prerequisite for a successful treatment of the disease. Therefore, for the examination and improvement of established dosing regimens, not only the plasma but also the tissue pharmacokinetics of the drug have to be considered. For the current paper, almost 7000 scientific articles were identified and screened from which 429 were reviewed in detail and 100 were included in this paper. Systemic pharmacokinetics are available for most antiparasitic drugs but in many cases, not for all the relevant patient populations and only for single- or multiple-dose administration. Systemic pharmacokinetic data in patients with organ impairment and target-site pharmacokinetic data for relevant tissues and body fluids are mostly lacking. To improve the treatment of patients with parasitic diseases, research in these areas is urgently needed.

Anidulafungin Pharmacokinetics in Ascites Fluid and Pleural Effusion of Critically Ill Patients

Anidulafungin concentrations were quantified with high-pressure liquid chromatography (HPLC) and UV detection of the ascites fluid and pleural effusion of 10 adult critically ill patients. Samples were collected from ascites fluid and from pleural drains or during paracentesis and thoracentesis, respectively. Anidulafungin levels in ascites fluid (0.12 to 0.99 μg/ml) and in pleural effusion (0.32 to 2.02 μg/ml) were below the simultaneous levels in plasma (1.04 to 7.70 and 2.48 to 13.36 μg/ml, respectively) and below the MIC values for several pathogenic Candida strains.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

Biliary amphotericin B pharmacokinetics and pharmacodynamics in critically ill liver transplant recipients receiving treatment with amphotericin B lipid formulations

Fungal cholangitis is a potentially life-threatening condition. As amphotericin B (AmB) has a broad antimycotic spectrum, in this study its biliary penetration and activity was determined in two patients treated with liposomal AmB (L-AmB) and in one patient receiving AmB colloidal dispersion (ABCD). Biliary and plasma AmB levels were quantified by high-performance liquid chromatography after purification by solid-phase extraction. For assessment of biliary AmB activity, isolates of Candida albicans, Candida tropicalis, Candida glabrata and Candida krusei were incubated in porcine bile at AmB concentrations of 0.025-5.00 mg/L. In addition, patient bile samples retrieved for AmB quantification were inoculated with the same Candida strains. Biliary AmB concentrations were lower and displayed a slower rise and decline than plasma levels. The highest penetration ratio, as expressed by the ratio between the area under the AmB concentration-time curve in bile and plasma (liberated AmB) over the sampling period (AUC0-n bile/AUC0-n LI plasma), was 0.28. Proliferation of C. albicans and C. tropicalis in bile was similar to that in culture medium, whereas growth of C. glabrata was diminished and proliferation of C. krusei was absent in bile. In comparison with culture medium, AmB activity decreased in spiked porcine bile. In all but one patient bile sample, fungal growth was delayed or lacking even when AmB was not detectable. However, no fungicidal effect was observed in patient bile at AmB concentrations up to 1.28 mg/L. Thus, a reliable response of fungal cholangitis to treatment with L-AmB or ABCD cannot be anticipated.

Tissue penetration of antifungal agents

Understanding the tissue penetration of systemically administered antifungal agents is critical for a proper appreciation of their antifungal efficacy in animals and humans. Both the time course of an antifungal drug and its absolute concentrations within tissues may differ significantly from those observed in the bloodstream. In addition, tissue concentrations must also be interpreted within the context of the pathogenesis of the various invasive fungal infections, which differ significantly. There are major technical obstacles to the estimation of concentrations of antifungal agents in various tissue subcompartments, yet these agents, even those within the same class, may exhibit markedly different tissue distributions. This review explores these issues and provides a summary of tissue concentrations of 11 currently licensed systemic antifungal agents. It also explores the therapeutic implications of their distribution at various sites of infection.

Short imidazolium chains effectively clear fungal biofilm in keratitis treatment

Fungal keratitis is a leading cause of ocular morbidity throughout the world. However, current therapies against fungal keratitis are often ineffective. Herein, we have developed the amphiphilic main-chain imidazolium polymer (PIM-45) and oligomer (IBN-1) materials that can efficiently inhibit the growth of fungi with low minimal inhibition concentration (MIC) values and clear the fungal biofilm, while displaying minimal hemolysis. In vivo keratitis treatment indicates that topical solutions of these polyimidazolium salts (PIMSs) are safe and as effective as that of amphotericin B, the most commonly used agent for the treatment of Candida albicans (C. albicans) keratitis. Compared to the costly and unstable amphotericin B and fluconazole, PIM-45 and IBN-1 are easy to prepare, inexpensive and stable. They can be stored in phosphate-buffered saline (PBS) solutions with long shelf life for routine topical use.

Pharmacokinetics of anidulafungin in pleural fluid during the treatment of a patient with Candida empyema

Candida empyema is a serious complication of disseminated candidiasis. However, little is known about the intrapleural pharmacokinetics of echinocandins. We report the penetration of anidulafungin into the pleural fluid of a patient with Candida tropicalis empyema. The anidulafungin ratio for the area under the concentration-time curve from 0 h to the last measurement between pleural fluid and serum values was only 0.125 (12.5%), with pleural fluid concentrations ranging between 0.67 and 0.88 μg/ml.

Pharmacokinetics of liposomal amphotericin B in pleural fluid

We report the penetration of liposomal amphotericin B into the pleural fluid of a patient with pulmonary zygomycosis and empyema. The ratio of area under the concentration-versus-time curve in pleural fluid (AUC(pleural fluid)) to that in serum (AUC(serum)) for liposomal amphotericin B over 24 h was 9.4%, with pleural fluid concentrations of 2.12 to 4.91 microg/ml. Given the relatively low level of intrapleural penetration of liposomal amphotericin B, chest tube drainage may be warranted for successful treatment of zygomycotic empyema.

A case of Aspergillus empyema successfully treated with combination therapy of voriconazole and micafungin: excellent penetration of voriconazole and micafungin into pleural fluid

A 62-year-old man with empyema caused by Aspergillus fumigatus was successfully treated with a combination of voriconazole (VRCZ) and micafungin (MCFG). Data regarding the penetration of antifungal agents into pleural fluid are limited. Thus, we measured the concentration of VRCZ and MCFG in his plasma and pleural fluid. Penetration of VRCZ and MCFG into the pleural fluid was excellent. Therefore, the combination therapy using VRCZ and MCFG may contribute to successful management of Aspergillus empyema.

Pulmonary epithelial lining fluid concentrations after use of systemic amphotericin B lipid formulations

Amphotericin B (AMB) concentrations were determined in pulmonary epithelial lining fluid (ELF) of 44 critically ill patients, who were receiving treatment with liposomal AMB (LAMB) (n = 11), AMB colloidal dispersion (ABCD) (n = 28), or AMB lipid complex (ABLC) (n = 5). Mean AMB levels (+/- standard errors of the means) in ELF amounted to 1.60 +/- 0.58, 0.38 +/- 0.07, and 1.29 +/- 0.71 microg/ml in LAMB-, ABCD-, and ABLC-treated patients, respectively (differences are not significant).