Safety and tolerability of voriconazole in patients with baseline renal insufficiency and candidemia

Acutely ill patients with candidemia frequently suffer from renal insufficiency. Voriconazole's intravenous formulation with sulfobutylether beta-cyclodextrin (SBECD) is restricted in patients with renal insufficiency. We evaluated the use of intravenous voriconazole formulated with SBECD in candidemic patients with renal insufficiency and compared treatment outcome and safety to those who received a short course of amphotericin B deoxycholate followed by fluconazole. We reviewed data on treatment outcome, survival, safety, and tolerability from the subset of patients with moderate (creatinine clearance [CrCl], 30 to 50 ml/min) or severe (CrCl, <30 ml/min) renal insufficiency enrolled in a trial of voriconazole compared to amphotericin B deoxycholate followed by fluconazole for treatment of candidemia in 370 patients. Fifty-eight patients with renal impairment were identified: 41 patients on voriconazole and 17 on amphotericin B/fluconazole. The median duration of treatment was 14 days for voriconazole (median, 7 days intravenous) and 11 days for amphotericin B/fluconazole, 3 days of which were for amphotericin B. Despite the short duration of exposure, worsening of renal function or newly emerged renal adverse events were reported in 53% of amphotericin B-treated patients compared to 39% of voriconazole-treated patients. During treatment, median serum creatinine decreased in the voriconazole arm, whereas creatinine increased in the amphotericin B/fluconazole arm, before return to baseline at week 3. All-cause mortality at 14 weeks was 49% in the voriconazole arm compared to 65% in the amphotericin B/fluconazole arm. Intravenous voriconazole formulated with SBECD was effective in patients with moderate or severe renal insufficiency and candidemia and was associated with less acute renal toxicity than amphotericin B/fluconazole.     

Treatment of Invasive Fungal Infections in Renally Impaired Patients with Amphotericin B Colloidal Dispersion

Amphotericin B colloidal dispersion (ABCD) is a new formulation of conventional amphotericin B designed to minimize drug distribution in the kidney and reduce nephrotoxicity. We studied the safety and efficacy of ABCD in 133 renally compromised patients with invasive fungal infections. Patients had either nephrotoxicity from amphotericin B or preexisting renal disease. Intravenous treatment with ABCD (4 mg/kg of body weight daily) was administered for up to 6 weeks. Evaluations included clinical response to treatment and adverse events, with emphasis on changes in serum creatinine levels. ABCD did not appear to have an adverse effect on renal function: mean serum creatinine level tended to decrease slightly with days on therapy, and increases were not dose related. Complete or partial response to treatment was reported for 50% of the 133 intent-to-treat patients and 67% of the 58 evaluable patients.     

Therapeutic monitoring of experimental invasive pulmonary aspergillosis by ultrafast computerized tomography, a novel, noninvasive method for measuring responses to antifungal therapy.

Pulmonary infiltrates in neutropenic hosts with invasive aspergillosis are due to vascular invasion and hemorrhagic infarction. In order to measure the effect of antifungal compounds on this organism-mediated tissue injury, we monitored the course of pulmonary infiltrates by serial ultrafast computerized tomography (UFCT) in persistently granulocytopenic rabbits with experimental invasive pulmonary aspergillosis. The course of pulmonary lesions measured by serial UFCT scans was compared with those measured by conventional chest radiography, histopathological resolution of lesions, and microbiological clearance of Aspergillus fumigatus. Treatment groups included either amphotericin B colloidal dispersion in dosages of 1, 5, and 10 mg/kg of body weight per day intravenously or conventional desoxycholate amphotericin B at 1 mg/kg/day intravenously. Therapeutic monitoring of pulmonary lesions by UFCT demonstrated a significant dose-response relationship. Lesions continued to progress in untreated controls, whereas lesions in treated rabbits initially increased and then decreased in response to antifungal therapy in a dosage-dependent manner (P < or = 0.05 to P < or = 0.005, depending upon the groups compared). This same trend of resolution of lesions in response to antifungal therapy was also demonstrated by postmortem examination and by microbiological clearance of the organism. These data indicated that amphotericin B colloidal dispersion at 5 and 10 mg/kg/day exerted a more rapid rate of clearance of lesions than conventional amphotericin B. UFCT was more sensitive than conventional chest radiography in detecting lesions due to invasive pulmonary aspergillosis (P < 0.05 to P < 0.005, depending upon the groups compared). These findings establish a correlation among UFCT-defined lesions, microbiological response, and resolution of pathologically defined lesions in experimental invasive pulmonary aspergillosis. Serial monitoring of UFCT-defined lesions of aspergillosis provides a novel system for determining the antifungal response of organism-mediated tissue injury.     

Effect of obesity on vancomycin pharmacokinetic parameters as determined by using a Bayesian forecasting technique.

Few data exist concerning the effect of obesity on the pharmacokinetic parameters of vancomycin. The purpose of this investigation was to assess the effect of obesity on vancomycin pharmacokinetic parameters in 95 nonobese and 135 obese adult patients (age range, 18 to 92 years) receiving vancomycin. All subjects had normal renal function as defined by a creatinine concentration in serum of < or = 1.5 mg/dl (mean estimated creatinine clearance +/- 1 standard deviation, 76 +/- 34; range, 23 to 215 ml/min). Vancomycin concentrations in serum were determined by the fluorescence polarization immunoassay. All data for vancomycin concentration in serum versus time for each course of therapy were fitted by using a two-compartment Bayesian forecasting program. Subjects were stratified into nine groups on the basis of the percent difference between actual body weight (ABW) and lean body weight (LBW) (> -10%, -10 to 0%, > 0 to 10%, > 10 to 20%, > 20 to 30%, > 30 to 40%, > 40 to 50%, > 50 to 60%, > 60%). Analysis of variance with post hoc Scheffe's testing revealed that statistically significant differences occurred in terminal disposition half-life (t1/2 beta) between the extremes of modestly obese (group 4) and morbidly obese (group 9, P < 0.05) patients. Similar analysis with distribution volume (V) identified significant differences in patients at or near their LBW (groups 2 to 4) and patients who were morbidly obese (groups 8 and 9, P < 0.05). Multiple regression models for the pharmacokinetic parameters V, t1/2beta, and vancomycin total body clearance were developed to assess the joint predictive power of LBW, ABW, and percent over LBW, controlling for the effects of age, initial creatinine concentration in serum, initial creatinine clearance, and gender. In the final model for V, both ABW and percent over LBW were independent and significant predictors. For total body clearance, only ABW was significant and predictive. Percent over LBW was a significant and independent predictor of t1/2beta. LBW is not predictive of these pharmacokinetic parameters and should not be used for initial dosing. On the basis of these data, ABW appears to be superior to LBW for calculating initial dose requirements for vancomycin.     

Pharmacokinetics of sparfloxacin in patients with renal impairment.

The pharmacokinetics of sparfloxacin were studied in 14 renal failure patients (group I, 7 with creatinine clearance of > 10 to 30 ml/min; and group II, 7 with creatinine clearance of < or = 10 ml/min) after a single oral dose of 400 mg. Plasma and urine samples were collected up to 144 h postdosing for determination of parent and total (parent-plus-glucuronide-conjugated) sparfloxacin levels, by high-pressure liquid chromatography assay and UV detection. The elimination of the drug in patients compared with that in healthy volunteers was markedly impaired. The mean elimination half-lives of sparfloxacin were 34.9 and 38.5 h in group I and group II, respectively, versus 19.1 h in healthy volunteers. Conjugated drug half-lives were 23.7, 35.0, and 15.3 h, respectively. The renal clearance of the drug was markedly reduced in the patients, with values of 6.8, 4.8, and 21.2 ml/min determined for group I, group II, and healthy subjects, respectively, for parent sparfloxacin and with values of 31.5, 14.0, and 327 ml/min for conjugated sparfloxacin. The nonrenal clearance of sparfloxacin was moderately, but not significantly, decreased in group II renal failure patients. No difference between the two groups of patients was detected in sparfloxacin levels in plasma. A significant relationship between pharmacokinetic parameters and creatinine clearance was observed only for renal clearance of parent or conjugated sparfloxacin.     

Pharmacokinetics of vancomycin in adult cystic fibrosis patients.

Although the depositions of many antibiotics are altered in cystic fibrosis patients, that of vancomycin has not been studied. To assess vancomycin pharmacokinetics, 10 adult cystic fibrosis patients were given a parenteral dose of vancomycin (15 mg/kg) during the first 72 h of hospitalization for acute bronchopulmonary exacerbation. Blood samples were obtained at 0, 1, 1.25, 1.5, 2, 3, 4, 6, 8, 12, 15, and 24 h. The mean (standard deviation) weight, measured creatinine clearance, and Taussig clinical score were 51 (13) kg, 130 (39) ml/min/1.73 m2, and 64 (13), respectively. Multicompartmental pharmacokinetic parameters were best described by a two-compartment model. The mean (standard deviation) volume of distribution, total body clearance, and terminal elimination rate constant were 0.58 (0.15) liter/kg, 91 (19) ml/min/1.73 m2, and 0.123 (0.05) h-1, respectively. These values were consistent with vancomycin pharmacokinetic parameters obtained in previous studies of healthy adult volunteers. Vancomycin dosages predicted by using a two-compartment Bayesian model were approximately 15 mg/kg every 8 to 12 h. There were poor correlations between clinical score or creatinine clearance and any pharmacokinetic parameter (r values of < 0.32). The coefficient of correlation between urine flow rate and total body clearance was 0.7 (P < 0.05). Adult cystic fibrosis patients exhibit a disposition of vancomycin similar to that exhibited by healthy adults, and thus cystic fibrosis does not alter vancomycin pharmacokinetics.     

Comparative efficacy of amphotericin B colloidal dispersion and amphotericin B deoxycholate suspension in treatment of murine coccidioidomycosis.

The efficacy of a novel sterol-complexed preparation of amphotericin B, amphotericin B colloidal dispersion, was compared with that of deoxycholate-complexed amphotericin B in an acute murine model of systemic coccidioidomycosis. Mice (CD-1, female) were infected intravenously with 180 or 200 arthroconidia of Coccidioides immitis, and intravenous therapy was begun 3 days later. Six doses in various regimens of either preparation were given over 14 days, and deaths were tallied for an additional 35 days. All regimens that were not acutely lethal prolonged the survival of mice over that of controls (P less than 0.001). Quantitative determination of residual burdens of C. immitis in the spleen, liver, and lungs of survivors revealed that the colloidal dispersion was not as effective as the deoxycholate suspension on a milligram-per-kilogram basis. Deoxycholate suspension at 1.3 mg/kg cleared the organs in all mice, whereas colloidal dispersion at 5.0 mg/kg was the lowest dose that cleared organisms from all animals. Lower doses cleared organisms from fewer animals or cleared only selected organs. Deoxycholate suspension was more efficacious than colloidal dispersion in clearing C. immitis from the liver or lungs (P less than 0.05 to 0.01, dose and organ dependent) at identical doses. No overt toxicity was observed in mice treated with colloidal dispersion at 10 mg/kg. In contrast, deoxycholate suspension at 2.0 mg/kg was acutely toxic; 50% of the treated mice died after treatment. The two complexes were not equivalent on a milligram-per-kilogram basis; the deoxycholate suspension was three to four times more efficacious and also greater than 5- to greater than or equal to 8-fold more toxic. Thus, the therapeutic index of the colloidal dispersion complex is greater than that of the deoxycholate complex. The amount of amphotericin B per dose could also be increased when given as a colloidal dispersion to an optimally level. Amphotericin B colloidal dispersion shows promise for the therapy of disseminated coccidioidomycosis and should be tested in other animal models and in humans.     

Meropenem and piperacillin/tazobactam prescribing in critically ill patients: does augmented renal clearance affect pharmacokinetic/pharmacodynamic target attainment when extended infusions are used?

Background

Correct antibiotic dosing remains a challenge for the clinician. The aim of this study was to assess the influence of augmented renal clearance on pharmacokinetic/pharmacodynamic target attainment in critically ill patients receiving meropenem or piperacillin/tazobactam, administered as an extended infusion.

Methods

This was a prospective, observational, pharmacokinetic study executed at the medical and surgical intensive care unit at a large academic medical center. Elegible patients were adult patients without renal dysfunction receiving meropenem or piperacillin/tazobactam as an extended infusion. Serial blood samples were collected to describe the antibiotic pharmacokinetics. Urine samples were taken from a 24-hour collection to measure creatinine clearance. Relevant data were drawn from the electronic patient file and the intensive care information system.

Results

We obtained data from 61 patients and observed extensive pharmacokinetic variability. Forty-eight percent of the patients did not achieve the desired pharmacokinetic/pharmacodynamic target (100% fT_>MIC), of which almost 80% had a measured creatinine clearance >130 mL/min. Multivariate logistic regression demonstrated that high creatinine clearance was an independent predictor of not achieving the pharmacokinetic/pharmacodynamic target. Seven out of nineteen patients (37%) displaying a creatinine clearance >130 mL/min did not achieve the minimum pharmacokinetic/pharmacodynamic target of 50% fT_>MIC.

Conclusions

In this large patient cohort, we observed significant variability in pharmacokinetic/pharmacodynamic target attainment in critically ill patients. A large proportion of the patients without renal dysfunction, most of whom displayed a creatinine clearance >130 mL/min, did not achieve the desired pharmacokinetic/pharmacodynamic target, even with the use of alternative administration methods. Consequently, these patients may be at risk for treatment failure without dose up-titration.     

Population pharmacokinetics of conventional and intermittent dosing of liposomal amphotericin B in adults: a first critical step for rational design of innovative regimens

There is increased interest in intermittent regimen of liposomal amphotericin B, which may facilitate use in ambulatory settings. Little is known, however, about the most appropriate dosage and schedule of administration. Plasma pharmacokinetic data were acquired from 30 patients receiving liposomal amphotericin B for empirical treatment of suspected invasive fungal infection. Two cohorts were studied. The first cohort received 3 mg of liposomal amphotericin B/kg of body weight/day; the second cohort received 10 mg of liposomal amphotericin B/kg at time zero, followed by 5 mg/kg at 48 and 120 h. The levels of liposomal amphotericin B were measured by high-pressure liquid chromatography (HPLC). The pharmacokinetics were estimated by using a population methodology. Monte Carlo simulations were performed. D-optimal design was used to identify maximally informative sampling times for both conventional and intermittent regimens for future studies. A three-compartment pharmacokinetic model best described the data. The pharmacokinetics for both conventional and intermittent dosing were linear. The estimates for the mean (standard deviation) for clearance and the volume of the central compartment were 1.60 (0.85) liter/h and 20.61 (15.27) liters, respectively. Monte Carlo simulations demonstrated considerable variability in drug exposure. Bayesian estimates for clearance and volume increased in a linear manner with weight, but only the former was statistically significant (P = 0.039). D-optimal design provided maximally informative sampling times for future pharmacokinetic studies. The pharmacokinetics of a conventional and an intermittently administered high-dose regimen liposomal amphotericin B are linear. Further pharmacokinetic-pharmacodynamic preclinical and clinical studies are required to identify safe and effective intermittent regimens.     

Successful treatment of cryptococcal meningitis with amphotericin B colloidal dispersion: report of four cases.

Four patients with cryptococcal meningitis were treated with amphotericin B colloidal dispersion because of nephrotoxicity from prior treatment with conventional amphotericin B. The limited experience presented here suggests that amphotericin B colloidal dispersion is efficacious for the treatment of cryptococcal meningitis, despite being undetectable in cerebrospinal fluid, and offers a potential therapeutic alternative for patients who cannot tolerate conventional amphotericin B.     

Elimination of amphotericin B in impaired renal function

The influence of impaired renal function on the steady-state plasma clearance of amphotericin B was determined in seven patients with creatinine clearances ranging from zero to normal. Contrary to previous reports, steady-state plasma concentrations of total drug were lower in uremic patients than in patients with normal renal function. Total plasma clearance of amphotericin B ranged from 16.7 to 39.9 ml/min, correlated directly with the plasma creatinine concentration, and correlated inversely with the creatinine clearance. Urinary excretion of unchanged drug accounted for less than 10% of the dose. In 10 healthy subjects, mean percent of amphotericin B unbound in plasma was 3.55 +/- 0.32 (SD). Binding was determined in a further group of 10 uremic patients. Mean unbound percent (4.15 +/- 0.73, SD) was higher than in the healthy subjects, and the binding ratio (molar concentration of bound to unbound drug) correlated weakly with the creatinine clearance. This suggests that plasma clearance of unbound amphotericin B and, therefore, steady-state plasma concentrations of unbound drug are not affected by renal impairment, and that dosage requirements will be overestimated if based on measurements of total drug plasma concentration.     

Amphotericin B lipid formulations in critically ill patients on continuous veno-venous haemofiltration

OBJECTIVES: The pharmacokinetics of lipid-formulated amphotericin B (AMB), and of AMB that has dissociated from its lipid moiety and bound to lipoproteins in plasma, were separately determined in critically ill patients. PATIENTS AND METHODS: Eleven patients required continuous veno-venous haemofiltration (CVVH). Five of them were treated with liposomal AMB (AmBisome) and seven with AMB colloidal dispersion (Amphocil). Six of the critically ill were not undergoing CVVH (three of them treated with liposomal AMB and three with AMB colloidal dispersion). RESULTS: Significant amounts of AMB are liberated from liposomes or colloidal dispersion during circulation in plasma, where pharmacokinetics mimic that of AMB deoxycholate. Elimination of the remaining lipid-formulated fraction is different and differentially affected by CVVH. Plasma levels of lipid-formulated AMB were significantly higher in patients treated with liposomal AMB than in those treated with AMB colloidal dispersion; clearance of liposomal AMB is enhanced by haemofiltration, whereas elimination of AMB colloidal dispersion is not significantly affected. CONCLUSIONS: The pharmacokinetics of AMB that has been liberated from its lipid moiety is similar under treatment with either liposomal AMB or AMB colloidal dispersion. Since no significant influence of haemofiltration on the pharmacokinetics of liberated AMB has been found, a standard dose of lipid-formulated AMB can be recommended for patients on haemofiltration.     

Serum pharmacology of amphotericin B applied in lipid emulsions.

Application of amphotericin B in lipid emulsions (AmB/L) reduced membrane toxicity in vitro and decreased amphotericin B-associated toxic side effects in vivo when compared to that of amphotericin B applied in 5% glucose (AmB/G). Therefore, a comparative analysis of the pharmacological parameters of AmB/L and AmB/G was performed. Thirteen patients were analyzed, and nine of these patients received a subsequent treatment with AmB/G and AmB/L. In patients in both treatment groups amphotericin B showed a biphasic elimination from serum, with a prolonged terminal half-life of approximately 27 h. Patients treated with AmB/L showed significantly lower peak concentrations (44.2%; P = 0.008) and correspondingly lower area under the drug concentration-time curve (AUC) values (64.3%; P = 0.015) compared to the values for the same patients treated with AmB/G at a dose range of 0.6 to 1.5 mg/kg of body weight. The enhanced clearance of AmB/L may be due to a faster initial elimination of amphotericin B-lipid aggregates by the reticuloendothelial system. Lower peak concentrations and AUC values in serum and a correspondingly faster deposition of AmB/L in tissues may at least partly explain the lower toxicity of AmB/L. A comparative pharmacokinetic analysis with data for a single patient treated with AmB/L demonstrated that hemodialysis did not significantly affect the disposition of amphotericin B.     

Amphotericin B tissue distribution in autopsy material after treatment with liposomal amphotericin B and amphotericin B colloidal dispersion

OBJECTIVES: Tissue concentrations of amphotericin B were determined in autopsy material of patients who had been treated with liposomal amphotericin B or amphotericin B colloidal dispersion (colloidal amphotericin B) for suspected or proven invasive fungal infection. PATIENTS AND METHODS: Amphotericin B tissue levels were measured in liver, spleen, lung, kidney, and myocardial and brain tissue of 20 patients who had been treated with lipid-formulated amphotericin B, before they died from multi-organ failure. Seven patients had been treated with liposomal amphotericin B (AmBisome) and thirteen with colloidal amphotericin B (Amphocil). Tissue samples were obtained during routine autopsy, homogenized and extracted with methanol. Amphotericin B concentrations were measured using HPLC after purification by solid phase extraction. RESULTS: The highest amphotericin B levels were found in liver and spleen, followed by kidney, lung, myocardium and brain. In the lung higher amphotericin B concentrations were found after treatment with amphotericin B colloidal dispersion than after therapy with liposomal amphotericin B. CONCLUSIONS: The choice of lipid formulation may influence amphotericin B penetration into the lung.     

Pharmacokinetics of liposomal amphotericin B (Ambisome) in critically ill patients.

The liposomal formulation of amphotericin B (AmBisome) greatly reduces the acute and chronic side effects of the parent drug. The present study describes the pharmacokinetic characteristics of AmBisome applied to 10 patients at a dose of 2.8 to 3.0 mg/kg of body weight and compares them to the pharmacokinetics observed in 6 patients treated with amphotericin B deoxycholate at the standard dose of 1.0 mg/kg. Interpatient variabilities of amphotericin B peak concentrations (Cmax) and areas under concentration-time curves (AUC) were 8- to 10-fold greater for patients treated with AmBisome than for patients treated with amphotericin B deoxycholate. At the threefold greater dose of AmBisome, median Cmaxs were 8.4-fold higher (14.4 versus 1.7 microg/ml) and median AUCs exceeded those observed with amphotericin B deoxycholate by 9-fold. This was in part explained by a 5.7-fold lower volume of distribution (0.42 liters/kg) in AmBisome-treated patients. The elimination of amphotericin B from serum was biphasic for both formulations. However, the apparent half-life of elimination was twofold shorter for AmBisome (P = 0.03). Neither hemodialysis nor hemofiltration had a significant impact on AmBisome pharmacokinetics as analyzed in one patient. In conclusion, the liposomal formulation of amphotericin B significantly (P = 0.001) reduces the volume of drug distribution, thereby allowing for greater drug concentrations in serum. The low toxicity of AmBisome therefore cannot readily be explained by its serum pharmacokinetics.     

Treatment of candidaemia in premature infants: comparison of three amphotericin B preparations

OBJECTIVE: The objective of this study was to compare the effectiveness and tolerability of three antifungal preparations, amphotericin B, liposomal amphotericin B (LamB) and amphotericin B colloidal dispersion (ABCD), in the treatment of neonatal Candida bloodstream infection (CBSI). PATIENTS AND METHODS: All patients hospitalized in the neonatal intensive care unit from 1996 to 2000 with CBSI were enrolled. Patients with a serum creatinine concentration of <1.2 mg/dL received amphotericin B, and those with serum creatinine > or =1.2 mg/dL received LamB or ABCD. Complete blood counts, and renal and hepatic function tests were obtained before, during and after treatment; blood cultures were performed daily until three consecutive cultures were negative. If cultures were positive for more than 10 days with clinical signs of fungal infection and/or persistent thrombocytopenia, a second antifungal drug was added. RESULTS: Fifty-six infants met the study criteria: four term and 52 preterm, including 36 extremely low birth weight infants. Amphotericin B was the initial treatment for 34, LamB for 6 and ABCD for 16 infants. No differences in mortality were found between the three groups. Sterilization of the blood was achieved with amphotericin B in 67.6% of patients, LamB in 83.3% and ABCD in 57.1%, when used as monotherapy; with the addition of a second antifungal agent, success rates were 100%, 83.3% and 92.8%, respectively. There were no differences between the groups in the time to resolution of fungaemia. No patients had immediate local or systemic adverse events and none showed deterioration in renal function. CONCLUSION: ABCD and LamB appear to be effective, safe and well tolerated in premature infants with CBSI and renal dysfunction. Larger trials are needed before routine use can be recommended.     

Risk factors for amphotericin B-induced nephrotoxicity

The association of amphotericin B with nephrotoxicity is well known, but risk factors for this complication are not well characterized. One hundred and seventy-eight patients who received > 3 days of intravenous amphotericin B and a minimal total cumulative dose > 100 mg were reviewed retrospectively. The mean age, average cumulative dose of amphotericin B and duration of therapy were 46 +/- 22 years, 536 +/- 547 mg and 16.6 +/- 8.2 days, respectively. Eighty-six percent of patients received amphotericin B for empirical therapy of febrile neutropenia. Various definitions of nephrotoxicity were used; these were as follows (the incidence of nephrotoxicity as determined by the given definition is given in parentheses): definition 1, a change in creatinine of > 46 mumol/L over baseline (50%); definition 2, a doubling of creatinine over baseline (49%); definition 3, a change in creatinine of > 92 mumol/L (29%); definition 4, a doubling and/or a change in creatinine of > 92 mumol/L (49%); definition 5, an increase in creatinine to > 230 mumol/L (8%). Multivariate analysis showed that nephrotoxicity was associated with a greater cumulative dose of amphotericin B and receipt of concomitant nephrotoxic drugs for all definitions (P < 0.05). In those patients who experienced severe nephrotoxicity (creatinine increased to > 230 mumol/L), cyclosporin therapy was the most significant risk factor (odds ratio 18.8, P = 0.022). Haemodialysis was necessary in one patient, but multiple concomitant risk factors for renal dysfunction were present. No patient experienced irreversible nephrotoxicity. These findings allow for stratification of patients at risk for amphotericin B-induced nephrotoxicity and rational use of alternative agents.     

Single-dose pharmacokinetics and tolerance of a cholesteryl sulfate complex of amphotericin B administered to healthy volunteers.

Twenty-three healthy volunteer subjects received a single dose of amphotericin B colloidal dispersion or placebo (4:2) in a double-blind, randomized, dose-escalating design. Doses ranged from 0.25 to 1.5 mg/kg of body weight. The medication was administered via intravenous infusion at a rate of 0.5 mg/kg/h. Plasma amphotericin B concentrations increased with increasing doses, resulting in a linear increase in the amphotericin B area under the curve. Concentrations in plasma decreased rapidly upon discontinuation of the infusion, indicating rapid tissue distribution. A log-linear biexponential elimination phase was observed. A three-compartment open model was used to describe the distribution and elimination of amphotericin B. The mean terminal elimination half-life ranged from 86 h at the 0.25-mg/kg dose level to 244 and 235 h at the 1.0- and 1.5-mg/kg dose levels, respectively. Mean total body clearance ranged from 219 to 284 ml/kg/h. The volume of distribution increased with dose, from 3.37 liter/kg at the 0.25-mg/kg dose to 7.92 liter/kg at the 1.5-mg/kg dose. At the lowest dose level, 0.25 mg/kg, the medication was generally well tolerated. Progressive increases in the dose led to increasing side effects. At the 1.5-mg/kg dose level, 50% of the patients on active medication experienced nausea, vomiting, and chills. Physical examinations, ophthalmologic examinations, and clinical laboratory parameters remained within normal limits compared with those obtained during prestudy examinations.     

Pharmacokinetics and pharmacodynamics of recombinant soluble thrombomodulin in disseminated intravascular coagulation patients with renal impairment

Recombinant human soluble thrombomodulin (TM-α) was recently developed as an anticoagulant for patients with disseminated intravascular coagulation (DIC). However, the pharmacokinetics and pharmacodynamics of TM-α in DIC patients with severe renal impairment have not yet been elucidated. We investigated the pharmacokinetics and pharmacodynamics of TM-α in DIC patients with severe renal impairment. Eleven DIC patients with severe renal impairment (creatinine clearance <30 mL/min) and 10 DIC patients without severe renal impairment (creatinine clearance ≥30 mL/min) were included in this study. In all patients, a dose of 380 U/kg of TM-α was administered during a 30-min infusion. Blood samples were taken before the start of the first TM-α administration, and at 0.5, 2, 4, 8, and 24 h after the start of administration. Although the clearance of TM-α in the patients with renal impairment was 80% of that in the patients without renal impairment, none of the pharmacokinetic values were significantly different between the groups. In the pharmacokinetic simulation, however, the trough levels of TM-α increased gradually in the patients with renal impairment when the same dose of TM-α was repeatedly administered. After the administration of TM-α, the prothrombinase activities in the patients in both groups were sufficiently inhibited during the observation period. Although the pharmacokinetic values in DIC patients with severe renal impairment were only slightly different from those in DIC patients without severe renal impairment, we need to pay attention to the elevation of the trough levels of TM-α when the same dose of TM-α is repeatedly administered.     

Amphotericin B Colloidal Dispersion Combined with Flucytosine with or without Fluconazole for Treatment of Murine Cryptococcal Meningitis

Studies with animals and in vitro studies have demonstrated that flucytosine plus amphotericin B or fluconazole has significantly improved mycologic activity against meningitis caused by Cryptococcus neoformans compared to the activity of amphotericin B or fluconazole used alone. However, few doses have been tested in combination. This study evaluated the antifungal efficacy of amphotericin B colloidal dispersion (ABCD) combined with flucytosine with and without fluconazole in a murine model of cryptococcal meningitis. The following dosages were tested: ABCD at 0 to 12.5 mg/kg of body weight given intravenously 3 days/week, flucytosine at 0 to 110 mg/kg/day, and fluconazole at 0 to 50 mg/kg/day. Meningitis was established in male BALB/c mice by intracerebral injection of C. neoformans. Treatment with flucytosine with or without fluconazole dissolved in the sole source of drinking water was started on day 2; animals were sacrificed at 16 days, and the numbers of fungal colonies in the brain were quantified. A survival rate of 100% was achieved with ABCD plus flucytosine without fluconazole; however, the addition of fluconazole was required to prevent weight loss (P < 0.00001) and to achieve the maximum antifungal effect (P < 0.00001). The only region of dose combinations for which the 99% confidence intervals were less than 100 CFU/g of brain was defined by ABCD at 5.0 to 7.5 mg/kg combined with flucytosine at 20 to 60 mg/kg/day and fluconazole at 30 to 40 mg/kg/day. The triple combination of ABCD plus flucytosine and fluconazole was necessary to achieve the greatest antifungal activity.