Comparison of fluconazole pharmacokinetics in serum, aqueous humor, vitreous humor, and cerebrospinal fluid following a single dose and at steady state

Lipo-PEG nano-ocular formulation successfully encapsulates hydrophilic fluconazole and traverses corneal and non-corneal path to reach posterior eye segment

The present study describes a special lipid-polyethylene glycol matrix solid lipid nanoparticles (SLNs; 138 nm; -2.07 mV) for ocular delivery. Success of this matrix to encapsulate (entrapment efficiency - 62.09%) a hydrophilic drug, fluconazole (FCZ-SLNs), with no burst release (67% release in 24 h) usually observed with most water-soluble drugs, is described presently. The system showed 164.64% higher flux than the marketed drops (Zocon^®) through porcine cornea. Encapsulation within SLNs and slow release did not compromise efficacy of FCZ-SLNs. Latter showed in vitro and in vivo antifungal effects, including antibiofilm effects comparable to free FCZ solution. Developed system was safe and stable (even to sterilisation by autoclaving); and showed optimal viscosity, refractive index and osmotic pressure. These SLNs could reach up to retina following application as drops. The mechanism of transport via corneal and non-corneal transcellular pathways is described by fluorescent and TEM images of mice eye cross sections. Particles streamed through the vitreous, crossed inner limiting membrane and reached the outer retinal layers.

Antifungal drugs: An updated review of central nervous system pharmacokinetics

Invasive fungal infections (IFIs) in the central nervous system (CNS) are particularly hard to treat and are associated with high morbidity and mortality rates. Four chemical classes of systemic antifungal agents are used for the treatment of IFIs (eg meningitis), including polyenes, triazoles, pyrimidine analogues and echinocandins. This review will address all of these classes and discuss their penetration and accumulation in the CNS. Treatment of fungal meningitis is based on the antifungal that shows good penetration and accumulation in the CNS. Pharmacokinetic data concerning the entry of antifungal agents into the intracranial compartments are faulty. This review will provide an overview of the ability of systemic antifungals to penetrate the CNS, based on previously published drug physicochemical properties and pharmacokinetic data, for evaluation of the most promising antifungal drugs for the treatment of fungal CNS infections. The studies selected and discussed in this review are from 1990 to 2019.

Overview of antifungal dosing in invasive candidiasis

In the past, most antifungal therapy dosing recommendations for invasive candidiasis followed a 'one-size fits all' approach with recommendations for lowering maintenance dosages for some antifungals in the setting of renal or hepatic impairment. A growing body of pharmacokinetic/pharmacodynamic research, however now points to a widespread 'silent epidemic' of antifungal underdosing for invasive candidiasis, especially among critically ill patients or special populations who have altered volume of distribution, protein binding and drug clearance. In this review, we explore how current adult dosing recommendations for antifungal therapy in invasive candidiasis have evolved, and special populations where new approaches to dose optimization or therapeutic drug monitoring may be needed, especially in light of increasing antifungal resistance among Candida spp.

Acanthamoeba endophthalmitis during treatment for cutaneous disease in a renal transplant patient

Acanthamoeba infections are difficult to diagnose and treat. We present a renal transplant patient who developed Acanthamoeba endophthalmitis on therapy with posaconazole and miltefosine for cutaneous acanthamobiasis. The patient was maintained on intracameral voriconazole injections, and oral azithromycin, fluconazole, and flucytosine. This case highlights novel presentations and treatments for acanthamoebic infection.

Exogenous fungal endophthalmitis: an analysis of isolates and susceptibilities to antifungal agents over a 20-year period (1990-2010)

PURPOSE

To describe the isolates and susceptibilities to antifungal agents for patients with culture-proven exogenous fungal endophthalmitis.

DESIGN

Noncomparative case series.

METHODS

The clinical records of all patients treated for culture-proven exogenous fungal endophthalmitis at a university referral center from 1990 to 2010 were reviewed. Specimens initially used for diagnosis were recovered from the microbiology department and then underwent antifungal sensitivity analysis.

RESULTS

The antifungal susceptibilities of 47 fungal isolates from culture-positive fungal endophthalmitis are reported. Included are 14 isolates from yeast and 33 from mold. The mean (±standard deviation) minimum inhibitory concetrations (MICs) for amphotericin B (2.6 ± 3.5 μg/mL), fluconazole (36.9 ± 30.7 μg/mL), and voriconazole (1.9 ± 2.9 μg/mL) are reported. Presumed susceptibility to oral fluconazole, intravenous amphotericin B, intravitreal amphotericin B, oral voriconazole, and intravitreal voriconazole occurred in 34.8%-43.5%, 0-8.3%, 68.8%, 69.8%, and 100% of isolates, respectively.

CONCLUSIONS

Based on this laboratory study of isolates from exogenous fungal endophthalmitis, intravitreal voriconazole appears to provide the broadest spectrum of antifungal coverage and, as such, may be considered for empiric therapy of endophthalmitis caused by yeast or mold.

Fluconazole pharmacokinetics and safety in premature infants

Invasive candidiasis (IC) in the premature infant population is a common infection that results in substantial morbidity and mortality. For these patients, fluconazole is among the first line therapies to treat and prevent IC, and yet few prospective studies investigating its pharmacokinetics (PK) and safety have been performed in this vulnerable population. We review five phase I studies examining the PK of fluconazole in premature infants, which demonstrate markedly differing kinetics compared to adults. Based on these data, a treatment dose of 12 mg/kg/day, with the potential need of a loading dose of 25 mg/kg to achieve rapid steady state concentrations, achieves surrogate pharmacodynamic targets. Additionally, fluconazole appears to be safe to use in this population, with only minimal reversible hepatobiliary effects.

Effects of immunomodulatory and organism-associated molecules on the permeability of an in vitro blood-brain barrier model to amphotericin B and fluconazole

Amphotericin B (AMB) is used to treat fungal infections of the central nervous system (CNS). However, AMB shows poor penetration into the CNS and little is known about the factors affecting its permeation through the blood-brain barrier (BBB). Therefore, we studied immunomodulatory and organism-associated molecules affecting the permeability of an in vitro BBB model to AMB. We examined the effects of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), lipopolysaccharide (LPS), lipoteichoic acid (LTA), zymosan (ZYM), dexamethasone (DEX), cyclosporine, and tacrolimus on transendothelial electrical resistance (TEER); endothelial tight junctions; filamentous actin; and permeability to deoxycholate AMB (DAMB), liposomal AMB (LAMB), and fluconazole. Proinflammatory cytokines and organism-associated molecules significantly decreased the mean TEER by 40.7 to 100% (P < or = 0.004). DEX increased the mean TEER by 18.2 to 26.4% (P < or = 0.04). TNF-alpha and LPS increased the permeability to AMB by 8.2 to 14.5% compared to that for the controls (1.1 to 2.4%) (P < or = 0.04). None of the other molecules affected the model's permeability to AMB. By comparison, the BBB model's permeability to fluconazole was >78% under all conditions studied, without significant differences between the controls and the experimental groups. LPS and TNF-alpha decreased tight-junction protein zona occludens 1 (ZO-1) between endothelial cells. In conclusion, IL-1beta, ZYM, and LTA increased the permeability of the BBB to small ions but not to AMB, whereas TNF-alpha and LPS, which disrupted the endothelial layer integrity, increased the permeability to AMB.

Antimicrobial resistance: resistance to antifungal agents: mechanisms and clinical impact

Despite advances in preventive, diagnostic, and therapeutic interventions, invasive fungal infections cause significant morbidity and mortality in immunocompromised patients. The burden of antifungal resistance in such high-risk patients is becoming a major concern. A better understanding of the mechanisms and clinical impact of antifungal resistance is essential to the prompt and efficient treatment of patients with invasive mycoses and to improving the outcome of such infections. Although recent guidelines have attempted to standardize antifungal susceptibility testing, limitations still exist as a result of the incomplete correlation between in vitro susceptibility and clinical response to treatment. Four major mechanisms of resistance to azoles have been identified, all of which rely on altered gene expression. Mechanisms responsible for polyene and echinocandin resistance are less well understood. In addition to discussing the molecular mechanisms of antifungal resistance, this article elaborates on the concept of clinical resistance, which is critical to the understanding of treatment failure in patients with invasive fungal infections.

Pharmacokinetics and efficacy of ifosfamide or trofosfamide in patients with intraocular lymphoma

BACKGROUND

The prognosis of intraocular lymphoma (IOL) is poor, and the optimal treatment has not yet been defined. The study assesses ifosfamide (IFO) and trofosfamide (TRO) for treating IOL.

PATIENTS AND METHODS

We prospectively evaluated the efficacy and aqueous penetration of intravenous IFO, oral TRO and their active 4-hydroxy (4-OH) metabolites in 10 patients with IOL. Doses varied from 1500 to 2000 mg/m2/day on days 1-3 for IFO and from 150 to 400 mg/day (continuous or intermittent administration) for TRO. Four patients had newly diagnosed disease, and six had relapsed after pretreatment.

RESULTS

All patients responded to first treatment with IFO or TRO, and both of two patients responded to re-treatment with IFO on ocular relapse. Progression-free survival from the first treatment with IFO or TRO was > or = 6-18 months. In six of six patients, 4-OH metabolites were detected in the aqueous humor at a concentration of 0.32-1.56 microM immediately after IFO infusion with an aqueous/serum ratio of 0.19-0.54. 4-OH metabolites could be detected in one of three patients at a concentration of 7.2 microM 3-16 h after ingestion of TRO.

CONCLUSIONS

IFO and TRO are active in IOL. IOL patients evidence aqueous penetration of 4-OH metabolites after intravenous administration of IFO.

Successful Treatment of Naegleria fowleri Meningoencephalitis by Using Intravenous Amphotericin B, Fluconazole and Rifampicin

BACKGROUND

Primary amebic meningoencephalitis (PAM) is an emerging disease with a rapidly fatal outcome. Only eight reports of cured cases have appeared in the medical literature to date.

METHODS

A 10-year-old boy developed PAM caused by Naegleria fowleri 1 week after swimming in an irrigation canal. He was admitted to our hospital after 9 h of severe headache and vomiting, fever, ataxic gait, mild confusion, and seizures were evident. Trophozoites were identified in the cerebrospinal fluid (CSF). Treatment with intravenous (i.v.) dexamethasone, amphotericin B, fluconaloze, and oral rifampicin was started. After several hours of conflicting clinical signs, recovery began, and on the third day he was conscious again. Hospital discharge occurred on day 23, after a normal brain CT scan. There was no sequel to the disease during the following 12 months.

RESULTS

The amebas present in the CSF were identified and confirmed as N. fowleri after observation of wet mounts and of cultures seeded on 1.5% non-nutrient agar plates covered with Escherichia coli, vegetative and cystic forms, enflagellation experiments in distilled water at 98 degrees F, temperature tolerance testing and by indirect immunofluorescence using N. fowleri LEE antibody. The genotype was determined by PCR amplification and sequencing of the internal transcribed spacers (ITS) including the 5.8S rDNA.

CONCLUSIONS

Early treatment of PAM by i.v. administration of amphotericin B and fluconazole, and oral administration of rifampicin can offer some hope of cure for this devastating disease.

Fungicidal activity of fluconazole against Candida albicans in a synthetic vagina-simulative medium

Fluconazole (FLZ) has emerged as a highly successful agent in the management of systemic infections of Candida. Cure rates for symptomatic candidiasis following single 150-mg FLZ dose therapy exceed 90%. In vitro, however, FLZ is fungistatic only in a narrow pH range and is not effective at vaginal pH, 4.2. This study evaluated the effect of FLZ on Candida albicans under in vitro conditions resembling the vaginal microenvironment, using vagina-simulative medium (VS). We found that FLZ was fungicidal for C. albicans in VS, but not in other media at the same pH, 4.2. In VS, FLZ was fungicidal at concentrations of >/=8 micro g/ml and reduced viability by greater than 99.9%. Analysis of the components of VS indicated that 17 mM acetic acid, a concentration achieved in the vagina, was responsible for the synergistic, fungicidal effect. This effect was not seen at neutral pH. Other substrates were not effective substitutes for acetic acid; however, short-chained carboxylic acids, glyoxylate and malonate, were effective. Most strains of C. albicans that were resistant to FLZ under standard conditions were killed by FLZ plus acetate. Other species of Candida were also killed, except C. krusei and C. glabrata. This study shows that FLZ has fungicidal activity for Candida species under in vitro conditions that mimic the vaginal microenvironment. This raises the possibility that FLZ may also have fungicidal effects during treatment of vaginal candidiasis. Elucidating the mechanism by which FLZ and acetate interact may disclose vulnerable pathways that could be exploited in drug development.

Current perspectives on ophthalmic mycoses

Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.

Efficacies of high-dose fluconazole plus amphotericin B and high-dose fluconazole plus 5-fluorocytosine versus amphotericin B, fluconazole, and 5-fluorocytosine monotherapies in treatment of experimental endocarditis, endophthalmitis, and pyelonephritis due to Candida albicans

We compared the efficacies of fluconazole (Flu), amphotericin B (AmB), and 5-fluorocytosine (5FC) monotherapies with the combination of Flu plus 5FC and Flu plus AmB in a rabbit model of Candida albicans endocarditis, endophthalmitis, and pyelonephritis. The dose of Flu used was that which resulted in an area under the concentration-time curve in rabbits equivalent to that seen in humans who receive Flu at 1,600 mg/day, the highest dose not associated with central nervous system toxicity in humans. Quantitative cultures of heart valve vegetations, the choroid-retina, vitreous humor, and kidney were conducted after 1, 5, 14, and 21 days of therapy. All untreated controls died within 6 days of infection; animals treated with 5FC monotherapy all died within 18 days. In contrast, 93% of animals in the other treatment groups appeared well and survived until they were sacrificed. At day 5, the relative decreases in CFU per gram in the vitreous humor were greater in groups that received Flu alone and in combination with 5FC or AmB than in groups receiving AmB or 5FC monotherapies (P < 0. 005) but were similar thereafter. In the choroid-retina, 5FC was the least-active drug. However, there were no differences in choroidal fungal densities between the other treatment groups. On days 5 and 14 of therapy, fungal densities in kidneys of AmB recipients were lower than those resulting from the other therapies (P < 0.001 and P < or = 0.038, respectively) and AmB-plus-Flu therapy was antagonistic; however, all therapies for fungal pyelonephritis were similar by treatment day 21. While fungal counts in cardiac valves of Flu recipients were similar to those of controls on day 5 of therapy and did not change from days 1 to 21, AmB therapy significantly decreased valvular CFUs versus Flu at days 5, 14, and 21 (P < 0.005 at each time point). 5FC plus Flu demonstrated enhanced killing in cardiac vegetations compared with Flu or 5FC as monotherapies (P < 0. 03). Similarly, the combination of AmB and Flu was more active than Flu in reducing the fungal density in cardiac vegetations (P < 0.03). However, as in the kidney, AmB plus Flu demonstrated antagonism versus AmB monotherapy in the treatment of C. albicans endocarditis (P < 0.05, P = 0.036, and P < 0.008 on days 5, 14, and 21, respectively).