An emulsion formulation of amphotericin B improves the therapeutic index when treating systemic murine candidiasis

Sixty years of Amphotericin B: An Overview of the Main Antifungal Agent Used to Treat Invasive Fungal Infections

Introduced in the late 1950s, polyenes represent the oldest family of antifungal drugs. The discovery of amphotericin B and its therapeutic uses is considered one of the most important scientific milestones of the twentieth century . Despite its toxic potential, it remains useful in the treatment of invasive fungal diseases owing to its broad spectrum of activity, low resistance rate, and excellent clinical and pharmacological action. The well-reported and defined toxicity of the conventional drug has meant that much attention has been paid to the development of new products that could minimize this effect. As a result, lipid-based formulations of amphotericin B have emerged and, even keeping the active principle in common, present distinct characteristics that may influence therapeutic results. This study presents an overview of the pharmacological properties of the different formulations for systemic use of amphotericin B available for the treatment of invasive fungal infections, highlighting the characteristics related to their chemical, pharmacokinetic structures, drug–target interactions, stability, and others, and points out the most relevant aspects for clinical practice.

Effective management of acute postoperative pain using intravenous emulsions of novel ketorolac prodrugs: in vitro and in vivo evaluations

The aim was to prepare intravenous fat emulsions (IFEs) of ketorolac (KTL) ester prodrugs and to investigate the pharmacokinetics and pharmacodynamics of these formulations. Three prodrugs of KTL (KTL-IS, KTL-AX and KTL-BT) were synthesized as a means to increase the lipid solubility of KTL. All KTL prodrugs with higher Log P values presented increased tendency to partition into a blank IFE using extemporaneous addition method - the encapsulation efficiency of KTL-IS IFE and KTL-BT IFE was more than 97%. The particle sizes and zeta potentials of these two formulations were comparable to that of the blank IFE. PK studies in rabbits showed significant larger AUC0-8h (646.969 ± 154.326 mg/L•h-1 for KTL-IS IFE and 559.426 ± 103.057 mg/L•h-1 for KTL-BT IFE) than that of ketorolac tromethamine (KTL-T) injectable (286.968 ± 63.045 mg/L•h-1) and approximately 2-fold increases in the elimination t1/2 over KTL-T. In a rat postoperative pain model, the paw withdrawal thresholds and the paw withdrawal latency after I.V. KTL prodrug IFEs were significantly higher than that after I.V. KTL-T at 3~4 h. Effective controlling of acute postoperative pain in a longer duration can be achieved by using non-addictive ketorolac derivatives intraveneous emulsions.

Role of diuretics and lipid formulations in the prevention of amphotericin B-induced nephrotoxicity

PURPOSE

To collect available clinical data to define the role of diuretics and lipid formulations in the prevention of amphotericin B (AmB)-induced nephrotoxicity (AIN) in human populations.

METHOD

A literature search was performed in the following databases: Scopus, Medline, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews.

RESULTS AND CONCLUSION

Co-administration of mannitol failed to show any clinically significant benefit in preventing AIN. Potassium-sparing diuretics, such as amiloride and spironolactone, have been shown to have beneficial effects as an alternative or adjunct to oral/parenteral potassium supplements in preventing hypokalemia due to AmB. Lipid-based formulations of AmB are clinically effective and safe in preventing AIN. However, due to their high cost and limited accessibility, these formulations are generally used as second-line antifungal therapy in cases of conventional AmB refractoriness and/or intolerance or pre-existing renal dysfunction. The potential effects of other nephroprotective agents, such as N-acetylcysteine, AIN merit further considerations and investigations.

Amphotericin B Formulations and Drug Targeting

Amphotericin B is a low-soluble polyene antibiotic which is able to self-aggregate. The aggregation state can modify its activity and pharmacokinetical characteristics. In spite of its high toxicity it is still widely employed for the treatment of systemic fungal infections and parasitic disease and different formulations are marketed. Some of these formulations, such as liposomal formulations, can be considered as classical examples of drug targeting. The pharmacokinetics, toxicity and activity are clearly dependent on the type of amphotericin B formulation. New drug delivery systems such as liposomes, nanospheres and microspheres can result in higher concentrations of AMB in the liver and spleen, but lower concentrations in kidney and lungs, so decreasing its toxicity. Moreover, the administration of these drug delivery systems can enhance the drug accessibility to organs and tissues (e.g., bone marrow) otherwise inaccessible to the free drug. During the last few years, new AMB formulations (AmBisome, Abelcet, and Amphotec) with an improved efficacy/toxicity ratio have been marketed. This review compares the different formulations of amphotericin B in terms of pharmacokinetics, toxicity and activity and discusses the possible drug targeting effect of some of these new formulations.

SolEmuls technology: a way to overcome the drawback of parenteral administration of insoluble drugs

In this article, a nanosuspension of AmB was prepared and mixed with the preformed parenteral emulsion Lipofundin and subjected to high-pressure homogenization (SolEmuls technology). Characterization was performed by photon correlation spectroscopy (PCS), laser diffractometry (LD), and zeta potential measurements. Drug incorporation was studied by using light microscopy. The produced emulsions were further investigated by comparing them with the commercially available Fungizone in regard to antifungal efficiency and toxicity. Results suggest that through the SolEmuls process the AmB forms a reservoir, out of which it is released in such a manner that it is more efficient and less toxic than Fungizone.

A patient with progressive multiple myeloma treated successfully with arsenic trioxide after allogeneic bone marrow transplantation

Multiple myeloma (MM) is an incurable progressive disease. Many therapeutic options are available to delay progression, including autologous and allogeneic bone marrow transplantation. At advanced stages, MM is often refractory to treatment. We report a heavily pretreated patient with graft-versus-host disease after bone marrow transplantations, treated at a terminal stage with a modified protocol for arsenic trioxide (ATO). This patient with poor clinical status tolerated the treatment very well. He had a remarkable clinical response and achieved complete remission. The mechanisms of ATO are presented and the potential role of ATO for MM is discussed.

Encapsulation of amphotericin B in poly(ethylene glycol)-block-poly(epsilon-caprolactone-co-trimethylenecarbonate) polymeric micelles

The aim of this work was to evaluate the potential of self-assembling poly(ethyleneglycol)(750)-block-poly(epsilon-caprolactone-co-trimethylenecarbonate)(4500) 50/50 copolymers (PEG-p(CL-co-TMC)) to solubilize amphotericin B in polymeric micelles and to disaggregate the drug to the less toxic monomeric form. Amphotericin B was encapsulated in the micelles upon dilution of a mixture of the liquid polymer and the drug in water. Its solubility was increased by two orders of magnitude depending on polymer concentration. The aggregation state of amphotericin B was decreased by PEG-p(CL-co-TMC). The preparation method and the loading of the polymeric micelles influenced it. The antifungal activity of the drug was reduced by encapsulation in the polymeric micelles whereas the onset of amphotericin B-induced hemolysis was delayed. PEG-p(CL-co-TMC) micelles could be an easy method for amphotericin B encapsulation.

SolEmuls-novel technology for the formulation of i.v. emulsions with poorly soluble drugs

Intravenously injectable o/w emulsions of drugs being poorly soluble in water and simultaneously in oils need to be produced by locating the drug in the interfacial lecithin layer, e.g. amphotericin B. For achieving this, up to now organic solvents were required. The objective was to develop a solvent-free production method for such emulsions. Drug and the pre-formed parenteral emulsion Lipofundin were mixed and subjected to high pressure homogenisation. Drug powder and emulsions were characterised regarding size and physical stability by photon correlation spectroscopy (PCS), laser diffractometry (LD) and zeta potential measurements. Drug incorporation was studied using light microscopy, electron microscopy (EM) and a centrifugation test to separate non-dissolved drug. Amphotericin B and carbamazepine were used as model drugs. The high streaming velocities lead to accelerated drug dissolution and partitioning into the interfacial layer (so-called "solubilisation by emulsification", SolEmuls Technology). The interfacial layer could incorporate (solubilise) a certain amount of drug, revealed by EM pictures. Exceeding this concentration, hybrid dispersions were formed consisting of drug-loaded oil droplets and drug nanocrystals of similar size (approximately 200 nm). Both dispersion types are i.v. injectable opening the opportunity to deliver the drug in a concentrated form at desired low injection volume, e.g. 10 mg/ml.

Solubilizing poorly soluble antimycotic agents by emulsification via a solvent-free process

The purpose of this study was to formulate itraconazole and ketoconazole as oil/water emulsions for parenteral delivery by using a solvent-free homogenization process, namely SolEmuls (solubilization by emulsification) technology. The drugs were incorporated in the commercial emulsion Lipofundin MCT 20%, composed of a medium-chain triglyceride/long-chain triglyceride (MCT/LCT) oil phase (1:1) and stabilized with 1.2% lecithin. Different parameters such as drug-loading capacity, long-term physical stability, and completeness of drug dissolution were investigated. Up to 10.0 mg/mL complete drug dissolution was achieved with itraconazole; at 20 mg/mL hybrid dispersion was obtained. Itraconazole-loaded emulsions were physically stable for 9 months (data up to now). Ketoconazole showed physical instability in the Lipofundin emulsion, which was stabilized with only 1.2% lecithin. Stabilization of ketoconazole-loaded emulsions was achieved using additionally Tween 80 as steric stabilizer. Higher concentrations of ketoconazole (ie, 10.0 mg/mL concentrated ketoconazole emulsions) were also produced with additional 2.0% Tween 80. Ketoconazole-loaded emulsions, 1 mg/mL, which were stabilized with 2.0% Tween 80, were stable for a period of 6 months. It can be concluded, after formulating amphotericin B and carbamazepine with SolEmuls technology, that SolEmuls was also applicable to the antimycotic agents itraconazole and ketoconazole, yielding IV-applicable emulsions with cost-effective production technologies.

Formulation of intravenous carbamazepine emulsions by SolEmuls technology

Oil in water (O/W) emulsions for parenteral nutrition can be employed as intravenous (i.v.) carriers for drugs that are poorly soluble in water and in oil by localising the drug in the interfacial lecithin layer, e.g. Amphotericin B emulsions. By now, the emulsion production required organic solvents. SolEmuls technology localises the drug in the interfacial layer by a solvent-free high-pressure homogenisation process. SolEmuls was applied to produce Carbamazepine emulsions at increasing drug concentrations from 0.5 to 10mg/ml. Drug powder and Lipofundin emulsion were mixed and homogenised at 1500bar. Characterisation of emulsions and short-term stability were performed by photon correlation spectroscopy (PCS) and laser diffractometry. Drug incorporation (absence of non-dissolved drug crystals) was investigated by light microscopy and a centrifugation test. The emulsions were physically stable and complete drug dissolution is possible up to 3mg/ml. Up to 10mg/ml drug hybrid dispersions of emulsion droplets and ultrafine nanocrystals were obtained. Both, emulsions and hybrid dispersions are suitable as i.v. injectables regarding size and stability.

Amphotericin B/emulsion admixture interactions: an approach concerning the reduction of amphotericin B toxicity

Mixing Fungizone with a fat emulsion used for nutritional purpose (Intralipid or Lipofundin ) was reported to decrease Amphotericin B (AmB) toxicity in clinical use. In an effort to understand the reason for this phenomenon, spectral and morphological analyses were done for the Fungizone and Fungizone /Lipofundin admixture (FLmix). The absorption spectra analyses showed that not only Fungizone but also FLmix presented spectra that were concentration dependent. Moreover, the spectra of FLmix remained stable until the concentration of 5 x 10(-7) M, and only at 5 x 10(-8) M did they become similar in shape to the Fungizone spectra. Morphological studies revealed that even though emulsion droplets with or without Fungizone presented the same particle size, the former was less electron dense compared with Lipofundin alone. These results suggest a kind of association between Fungizoneand Lipofundin that remains over the whole range of concentrations. This hypothesis was confirmed by in vitro studies in which FLmix presented an important selectivity against human and fungal cells compared with Fungizone. These findings suggest that parenteral emulsions should be able to reduce the AmB toxicity probably by changing the AmB self-association state by binding it with emulsion droplets.

Can we decrease amphotericin nephrotoxicity?

Amphotericin B (AmB) is considered the drug of choice for the treatment of systemic fungal infections. Nephrotoxicity is a major complication associated with its use, and appears to be related to higher cumulative doses, diuretic use, abnormal serum creatinine at baseline, and the use of concomitant nephrotoxic drugs. The two major hypotheses for the pathogenesis of AmB-related nephrotoxicity are direct effects of the drug on epithelial cell membranes and vasoconstriction. During the last few years, some randomized trials have tested different strategies to reduce AmB-induced renal toxicity. These strategies include sodium supplementation, low-dose dopamine, slower infusion rates, the administration of AmB in lipid emulsions, and in lipid formulations. The results of these trials showed that the lipid formulations of AmB significantly reduce nephrotoxicity. Unfortunately, these agents are costly, restricting their use to patients with a high risk of developing renal failure.

Lyophilized lecithin based oil-water microemulsions as a new and low toxic delivery system for amphotericin B

PURPOSE

To develop and investigate lecithin based oil-water microemulsions as potential amphotericin B (AmB) delivery systems and to evaluate their in vivo acute toxicity.

METHODS

AmB was added to the microemulsion and its location was evaluated by partitioning studies and UV-visible spectrophotometric analysis of the drug. Both, non-lyophilized and reconstituted microemulsions were characterised and assessed for their stability. Single-dose acute toxicity of the AmB microemulsion was studied on male albino Webster-derived CD-1 mice and compared with Fungizone.

RESULTS

The studies performed showed that AmB was intercalated on the oil-water interface of the microemulsion as a complex formed with lecithin molecules. AmB addition did not seem to modify the rheological properties of the original system, but had an effect on its particle size distribution. Lyophilization of the microemulsion led to an oily cake, easily reconstituted and stable at the conditions studied. Single-dose acute toxicity studies proved that the LD50 of AmB microemulsions was of 4 mg kg(-1) of animal weight, compared with 1 mg kg(-1) found for Fungizone.

CONCLUSIONS

Lyophilized lecithin based oil-water microemulsions appear to be valuable systems for the delivery of AmB in terms of easy and low-cost manufacturing, stability and safety compared with the formulations already in market.

Trends in antifungal research

With the increasing use of aggressive immunosuppressive therapies in the management of a variety of patient populations, the continuing presence of the AIDS pandemic and the therapeutic advances employed in critical care settings, an increasing number of serious fungal infections are being encountered by today's practicing clinicians. Traditionally, antifungal drug therapy has been delivered by means of intravenous infusion, oral administration, or topical application. Recently, a number of alternative routes of antifungal drug delivery have been developed and investigated, and the traditional means of antifungal administration have been improved to facilitate the therapeutic use of new and reformulated antifungal agents. Organized based on the route of administration, this chapter reviews these advances in antifungal drug delivery.

Practice guidelines for lipid-based amphotericin B in stem cell transplant recipients

OBJECTIVE

To provide clinicians who practice in the stem cell transplantation (SCT) setting with practical guidelines for the use of lipid-based amphotericin B (AmB) formulations in SCT patients who have documented or probable invasive fungal infections, are experiencing neutropenic fever, or require secondary prophylaxis for fungal infections.

DATA SOURCES

Recommendations are based on the results of a two-day consensus meeting that convened clinicians versed in the management of infectious complications in patients undergoing SCT. This meeting, which was held October 21-23, 1998, in Orlando, Florida, was sponsored by an educational grant from The Liposome Company. In addition, primary articles were identified by MEDLINE search (1980-December 1999) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All of the articles identified from the data sources were evaluated, and all information deemed relevant was included in this review.

DATA SYNTHESIS

Immunocompromised patients, particularly patients undergoing high-dose chemotherapy with SCT, experience a high degree of morbidity and mortality from invasive fungal infections. Historically, treatment for such infections with conventional AmB had been limited primarily by its associated nephrotoxicity. Lipid-based formulations of AmB have helped to advance the management of invasive fungal infections in the SCT population by offering a treatment alternative that allows for administration of adequate amounts of active drug to produce clinical and mycologic responses, compared with conventional AmB, in a delivery system that is less nephrotoxic. Unfortunately, these agents are relatively expensive. Therefore, patients who are candidates for lipid-based products must be selected carefully.

CONCLUSIONS

Practical guidelines are provided for the use of lipid-based AmB formulations in SCT patients who have documented or probable invasive fungal infections, are experiencing neutropenic fever, or require secondary prophylaxis for fungal infections.

[New lipid formulations of amphotericin B. Review of the literature]

INTRODUCTION

Amphotericin B (amB) remains the gold standard for treatment of invasive fungal infections. Lipid formulations of amB have been developed in an attempt to improve both efficacy and tolerability (especially renal toxicity): amB lipid complex (ABLC), liposomal amB (AmBisome), amB colloidal dispersion (ABCD) and amB in lipid emulsion (Intralipid). This review analyzes the data available in the literature.

CURRENT KNOWLEDGE AND KEY POINTS

ABLC, AmBisome and ABCD are effective in various fungal infections, including invasive aspergillosis, systemic candidiasis, cryptococcal meningitis, mucormycosis and fusariosis. These formulations are also effective in persistent febrile neutropenia and in leishmaniosis. The three formulations show little renal toxicity and are safer than conventional amB in this respect. Preliminary data are available on amB in Intralipid: infusion-related adverse effects are reduced, but few data are available on efficacy in documented mycoses.

FUTURE PROSPECTS AND PROJECTS

Large-scale comparative clinical trials may clarify issues of relative efficacy in various forms of fungal infections.

Amphotericin B and its new formulations: pharmacologic characteristics, clinical efficacy, and tolerability

Amphotericin B (amB) remains the gold standard for the treatment of invasive fungal infections. However, the efficacy is limited, with response rates from 10% to 80%. Moreover, amB is toxic, especially for the kidneys. New formulations have been developed in an attempt to improve both efficacy and tolerability. In an attempt to reduce toxicity, a number of investigators have reconstituted amB in a lipid emulsion, but few data are available on efficacy in documented infections. An improvement in immediate and renal tolerance was obtained with equivalent daily dose regimens, but the therapeutic index does not appear to be improved. This approach cannot be recommended at present. Three lipid formulations have been developed and are now available in most countries: amB colloidal dispersion (ABCD), amB lipid complex (ABLC), and liposomal amB (AmBisome). The efficacy of ABCD on various fungal infections has been assessed in open trials, with a response rate of 49% in aspergillosis, 70% in candidiasis, and 67% in mucormycosis. In two randomized trials comparing ABCD with amB in invasive aspergillosis and in persistent febrile neutropenia, the response rates were equivalent. ABCD was less nephrotoxic. In contrast, immediate reactions to ABCD were as frequent and severe as with amB. These immediate effects are more frequent during the first infusions and lessen as treatment continues. The recommended dose is 3-4 mg/kg/day. ABLC appeared to be effective as rescue therapy in various types of invasive mycoses, with a response rate of 42% in aspergillosis, 67% in candidiasis, and 82% in fusariosis. Efficacy identical to that of amB was demonstrated in a comparative randomized trial involving patients with invasive candidiasis. General and renal tolerability is improved compared with amB. The recommended dose regimen is 5 mg/kg/day. Liposomal amB (AmBisome) is the only truly liposomal formulation. The response rates in preliminary trials were 66% in aspergillosis and 81% in candidiasis. Several comparative studies have confirmed that this formulation has similar or superior efficacy relative to amB in various fungal infections and also in the empirical treatment of febrile neutropenia. Renal and general tolerability is excellent. The optimal dosing remains unclear but is generally between 3 and 5 mg/kg/day. A double-blind trial comparing the tolerance of liposomal amB and ABLC demonstrated that both infusion-related events and nephrotoxicity were significantly lower for liposomal amB. In sum, the new lipid formulations of amB are effective in various invasive fungal infections. The three formulations exhibit reduced nephrotoxicity compared with conventional amB. Large-scale comparative clinical trials may clarify issues of relative efficacy in various forms of mycotic infections.

Experimental murine mycotic mastitis: a sensitive and lenient model for studies of antifungal chemotherapy

The murine model of mycotic mastitis was used to study the efficacy of amphotericin B (AmB). Twenty-four BALB/cJ mice at the fifth day of lactation were anesthetized and inoculated through the teat canal (two glands) with 50 microl suspension containing 5.0 x 10(7) cfu ml(-1) Candida albicans blastospores. Mice were randomly divided into two groups: untreated controls and AmB treated. Animals were euthanized 3 and 6 days after infection and treatment (4 mg kg(-1) per day intraperitoneally). The fungal burden of the mammary gland was determined by quantitative cultures. The number of C. albicans cells recovered from mammary gland homogenates were significantly lower in the AmB treated animals (both 3 and 6 days post-infection) than in the untreated controls (P<0.007 and P<0.003, respectively). The mammary glands of all untreated control animals showed marked neutrophilic infiltration, severe necrosis, and presence of blastospores, hyphae and pseudohyphae. In contrast, 10 of 12 animals treated with AmB showed only a mild neutrophilic infiltration which was restricted to alveoli and excretory ducts. All extra-mammary organs were free of infection in both groups. The results demonstrate that the murine mycotic mastitis model is suitable for investigations of new antifungal compounds. In addition, this model is more lenient than the systemic candidiasis models.

A randomized prospective trial of amphotericin B lipid emulsion versus dextrose colloidal solution in critically ill patients

BACKGROUND

Amphotericin B is the agent of choice for most invasive fungal infections in critically ill patients. It is associated with at least a 50% incidence of nephrotoxicity, despite prophylactic measures such as sodium loading. Newer formulations of amphotericin B are available but are costly and have unknown bioavailability in critically ill patients. Previous trials in neutropenic and critically ill patients have demonstrated that mixing amphotericin B with 20% lipid solution (Intralipid; Clintec Nutrition, Deerfield, III) may decrease nephrotoxicity.

METHODS

In this randomized, prospective clinical trial, patients with positive fungal blood cultures, tracheal/sputum cultures or peritoneal cavity cultures were randomized to receive either 0.5 mg/kg per day of amphotericin B dextrose or 1.0 mg/kg per day of amphotericin B lipid emulsion. Duration of therapy was determined by the primary care team. Weekly 24-hour creatinine clearance was measured until 2 weeks after amphotericin B therapy was completed.

RESULTS

The two groups were similar based on age, white blood cell count, serum creatinine, and creatinine clearance at the beginning of therapy. The group receiving amphotericin B lipid emulsion had significantly less decrease in creatinine clearance compared with controls, despite receiving significantly more amphotericin B.

CONCLUSION

Amphotericin B lipid emulsion can be given at a higher total cumulative dose than amphotericin B dextrose with less nephrotoxicity.

Pharmacological parameters of intravenously administered amphotericin B in rats: comparison of the conventional formulation with amphotericin B associated with a triglyceride-rich emulsion

The LD50 determined in rats for the potent antifungal amphotericin B (AB) increased from 4.2 to 12.0 when the conventional AB-deoxycholate (DOC) was compared with AB associated with a triglyceride-rich emulsion (AB-emulsion). The reduction in amphotericin B toxicity is not due to a modification in plasma clearance, as both formulations seem to be removed from plasma at the same rate. Major differences in amphotericin B tissue distribution were not seen for kidney and liver but were seen for the lung. After 24 h administration of a single amphotericin B dose (2.0 mg/kg body weight) 23.78 +/- 11.71 mg/kg tissue was recovered from the lung of animals treated with AB-DOC whereas for AB-emulsion only 5.19 +/- 2.50 mg/kg tissue was recovered. The higher lethality of AB-DOC may be related to the higher concentration of amphotericin B in the lung. The therapeutic efficacy of AB-emulsion was similar to that of AB-DOC as attested by survival curves obtained after treatment of mice infected by Candida albicans. This is highly relevant, as the same is not necessarily found for other less toxic proposed vehicles. The equivalent efficacy and the increment in the LD50 will result in an important improvement in the therapeutic activity of amphotericin B. Furthermore, some data related to storage and stability indicate the clinical utility of this type of drug delivery.

Comparison of the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in fat emulsion in a randomized trial with cancer patients

A multicentric randomized trial was undertaken to compare the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in a fat emulsion (Intralipid) in cancer patients. Group 1 (n = 33) received amphotericin B diluted in 5% dextrose with premedication consisting of promethazine plus an antipyretic. Group 2 (n = 28) received amphotericin B diluted in 20% Intralipid without premedication. Amphotericin B was infused daily at a dose of 1 mg/kg of body weight over a 1-h period to members of both groups for empirical antifungal therapy (in neutropenic patients) or for the treatment of documented fungal infections. The majority of patients (80%) received empirical amphotericin B treatment. The two groups were comparable with regard to age, gender, underlying disease, and the following baseline characteristics: use of other nephrotoxic drugs and serum levels of potassium and creatinine. The median cumulative doses of amphotericin B were 240 mg in group 1 and 245 mg in group 2 (P = 0.73). Acute adverse events occurred in 88% of patients in group 1 and in 71% of those in group 2 (P = 0.11). Forty percent of the infusions in group 1 were associated with fever, compared to 23% in group 2 (P < 0.0001). In addition, patients in group 2 required less meperidine for the control of acute adverse events (P = 0.008), and fewer members of this group presented with hypokalemia (P = 0.004) or rigors (P < 0.0001). There was no difference in the proportions of patients with nephrotoxicity (P = 0.44). The success rates of empirical antifungal treatment were similar in the two groups (P = 0.9). Amphotericin B diluted in a lipid emulsion seems to be associated with a smaller number of acute adverse events and fewer cases of hypokalemia than amphotericin B diluted in 5% dextrose.

Prevention of topical and ocular oxidative stress by positively charged submicron emulsion

A positively charged submicron emulsion with zeta potential values ranging from 35 to 45 mV and mean droplet size around 150-250 nm has recently been developed and characterized. This formulation is based on three surface-active agents, an egg yolk phospholipid mixture, poloxamer 188, and stearylamine, a cationic lipid with a pKa of 10.6. The emulsion toxicity was evaluated in three animal studies. The results of the ocular tolerance study in the rabbit eye indicated that hourly administration of one droplet of the positively charged emulsion vehicle was well tolerated without any toxic or inflammatory response to the ocular surface during the five days of the study. No marked acute toxicity was observed when 0.6 mL of positively charged emulsion was injected intravenously to BALB/c mice. Furthermore, no difference was noted between this group of animals and the group injected with the marketed and clinically well accepted negatively charged Intralipid emulsion. These observations were further confirmed in a four week toxicity study following intravenous administration to rats of 1 mL/kg of the positively charged emulsion as compared to Intralipid. No toxic effect was noted in any of the various organs examined, whereas the results of the hematological and blood chemistry tests remained in the normal range for both emulsions, confirming the preliminary safety study findings. In addition, it was demonstrated by means of a non-invasive technique that alpha-tocopherol positively charged emulsions prevented oxidative damage in rat skin subjected to UVA irradiation. The intrinsic ability of positively charged emulsified oil droplets to protect against reactive oxygen species cannot be excluded, and could act synergistically with the antioxidant alpha-tocopherol itself. The effect of blank and piroxicam positively charged emulsions on rabbit eye following alkali burn was also evaluated. The blank emulsion showed a very rapid healing rate during the first three days with a breakdown in day 14. Complete re-epithelialization was observed in day 28. The same behavior (albeit less pronounced), was noted in piroxicam emulsion, although piroxicam is known to inhibit the epithelial healing process. It can therefore be deduced that the positively charged emulsion vehicle prevented piroxicam from interfering with the epithelial healing process due to the intrinsic free radical scavenger ability of the positively charged submicron emulsion previously demonstrated. Finally, the efficacy of this promising emulsion vehicle containing effective cosmetic ingredients in preventing skin damage and aging following oxidative stress is evaluated.

[Treatment of infantile visceral leishmaniasis]

Visceral leishmaniasis is an endemic disease in the Mediterranean Basin. Children are one of the targets of the infection. Treatment usually requires parenteral injections of pentavalent antimony (Glucantime or Pentostam), but the high frequency of adverse events and the occurrence of primary or secondary resistance cases limit the use of these medications. Diamidines (Pentacarinat) or amphotericin B derivatives are alternatives to antimony. Unfortunately, pharmacokinetics and optimal dosage of diamidines are not well-known, and numerous adverse events are described. Liposomal preparations of amphotericin B enhance its efficiency and tolerance, and the duration of treatment may be reduced to 5 days. Moreover, primary resistance to amphotericin B is not described in immunocompetent children. Allopurinol associated with antimony seems no more efficient than antimony alone. Aminosidine is not evaluated.

Safety and toxicity of amphotericin B in glucose 5% or intralipid 20% in neutropenic patients with pneumonia or fever of unknown origin: randomised study

OBJECTIVE

To compare the feasibility of treatment, safety, and toxicity of intravenous amphotericin B deoxycholate prepared in either glucose or intralipid for empirical antimycotic treatment of neutropenic cancer patients.

DESIGN

Single centre stratified, randomised non-blinded phase II study.

SETTING

University hospital providing tertiary clinical care.

SUBJECTS

51 neutropenic patients (leukaemia (35), lymphoma (11), solid tumours (5)) with refractory fever of unknown origin (24) or pneumonia (27).

INTERVENTIONS

Amphotericin B 0.75 mg/kg/day in 250 ml glucose 5% solution or mixed with 250 ml intralipid 20%, given on eight consecutive days then alternate days, as a 1-4 hour infusion.

MAIN OUTCOME MEASURES

Feasibility of treatment, subjective tolerance (questionnaire), and objective toxicity (common toxicity criteria of the National Cancer Institute).

RESULTS

Study arms were balanced for age, sex, underlying malignancy, renal and liver function, and pre- and concomitant treatment with antibiotics and nephrotoxic agents. No statistically significant or clinically relevant differences were found between the treatment groups for: daily or cumulative dose and duration of treatment with amphotericin B; incidence and time of dose modifications or infusion duration changes related to toxicity; dose or duration of symptomatic support with opiates, antipyretics, or antihistamines; renal function; subjective tolerance; most common toxicity scores; course of infection; and incidence of treatment failures. Patients treated with amphotericin B in intralipid were given fewer diuretics (P<0.05) and therefore had more peripheral oedema (P<0.01) and needed less potassium supplementation (P<0.05) than patients given amphotericin in glucose. Acute respiratory events were more common in the intralipid arm (P<0.05).

CONCLUSIONS

Amphotericin B 0.75 mg/kg/day in intralipid given on eight consecutive days then alternate days provides no benefit and is associated with potential pulmonary side effects possibly because of fat overload or an incompatibility of the two drugs.

A retrospective study on the efficacy and safety of amphotericin B in a lipid emulsion for the treatment of cryptococcal meningitis in AIDS patients

To evaluate the efficacy and safety of Amphotericin B dissolved in dextrose (Amb) or in a lipid emulsion (Intralipid, Amb-IL) in AIDS patients with cryptococcal meningitis, we conducted a retrospective study in 30 AIDS patients with cryptococcal meningitis. A clinical complete resolution was obtained in 11 patients (55%) treated with Amb, and in six patients (60%) treated with Amb-IL. Intralipid did not decrease the infusion-related adverse effects, in particular nephrotoxicity and anaemia. Our results indicate that Amb-IL formulation is useful in the treatment of cryptococcal meningitis in AIDS patients, but it does not reduce the infusion-related adverse events.

Amphotericin B in lipid emulsion: stability, compatibility, and in vitro antifungal activity

Newer formulations of amphotericin B (AmB) complexed with liposomes or lipid suspensions have been developed. Preliminary studies have suggested that AmB in Intralipid (IL) may be as effective as, but less toxic than, conventional formulations of AmB, but few data are available regarding its stability, compatibility, or in vitro antifungal activity. A compatibility study was done to evaluate the effects of AmB concentrations in IL containing either 10 or 20% soybean oil. The effects of temperature, shaking, and AmB and IL concentrations on the stability of AmB-IL suspensions were analyzed by visual inspection and liquid chromatography. The in vitro antifungal activity of AmB-IL, compared to that of AmB alone against reference strains of Candida species was determined by using a broth macrodilution method in accordance with National Committee for Clinical Laboratory Standards guidelines (M27-T). Samples of AmB-IL which were lightly shaken retained more than 90% of the AmB concentration over 21 days when stored at either 4 or 23 degrees C. Varying the AmB concentration did not appear to affect the stability of AmB-IL. However, a precipitate was formed when mixtures with more than 30% lipid as a proportion of the total volume were centrifuged. AmB-IL and AmB alone had similar in vitro antifungal activities against reference strains of yeasts. Further pharmacologic and clinical studies with AmB-IL are warranted, although AmB should not be combined with IL in concentrations capable of producing a precipitate.

Development of liposomal amphotericin B formulation

A considerable effort has been spent in the past three decades to investigate various aspects of liposomes as novel drug delivery systems. In 1990, the first amphotericin B (AmB) liposomal preparation (L-AmB) under the brand name AmBisome was introduced into the market by Vestar. The successful marketing of the product moved liposomes out of the stage of experimental obscurity to the realistic stage of clinical utility. The launch of AmBisome sparked off the introduction of other lipid-based AmB products marketed by Liposome Technology (Amphocil) and The Liposome Co. (Abelcet). The drive behind the development of a modified formulation of AmB was to improve the therapeutic index of this drug with respect to its major drawback associated with both acute and chronic toxic effects. In a 30-year-long experience with AmB, several reports were recorded in the literature of acute adverse effects, such as fever, rigors, vomiting, cardiotoxicity and hypotension occurring during infusion; while long-term therapy was reported to be associated with hypokalemia, renal dysfunction and hematological abnormalities. Another serious problem encountered with the drug had been the poor response obtained in immunocompromised patients like those with AIDS, neutropenia and cancer patients on chemotherapy. The encapsulation of amphotericin B in liposomal vesicles was hence targeted not only to obtain an improvement in the therapeutic index but also to see if it was useful in eradicating deep-seated fungal infections in immunocompromised patients. The liposomal AmB was found to have a better therapeutic index and lower toxicity than the commercial AmB preparations. The LD50 of AmBisome in mouse was 175 mg/kg compared with 3.7 mg/kg for Fungizone, the commercial preparation of AmB. Additionally, L-AmB has prolonged circulation time, and extravasates into the site of infection and delivers the drug directly to the site, with no nephrotoxicity and neurotoxicity as experienced with AmB. This review traces the course of development of L-AmB and discusses the rationale behind the development of its liposomal preparation. The results in in vitro, in vivo and clinical studies, mechanism of action, biodistribution, and formulation considerations of L-AmB are described. The clinical experience with the marketed preparation is reviewed.

Toxicity and efficacy of conventional amphotericin B deoxycholate versus escalating doses of amphotericin B deoxycholate---fat emulsion in HIV-infected patients with oral candidosis

BACKGROUND: Amphotericin B deoxycholate remains the treatment of choice for most systemic fungal infections; however, its clinical use can be limited by infusion-related side effects and nephrotoxicity. New formulations of amphotericin in lipid compounds have been shown to decrease toxicity. We previously showed that a lipid emulsion preparation of amphotericin B deoxycholate was better tolerated than the conventional preparation in dextrose. Therefore, we have now studied the clinical tolerance, renal toxicity and efficacy of higher doses of amphotericin B deoxycholate prepared and infused in a fat emulsion (Intralipid 20%). Thus, this report adds information to the previous publication. METHODS: Forty-two patients infected with HIV and suffering oral candidosis entered the study. The patients received either amphotericin B deoxycholate---glucose 1 mg/kg/day or amphotericin B deoxycholate---lipid emulsion 1 mg/kg/day for 4 days (randomized phase), or amphotericin B deoxycholate---lipid emulsion 2 mg/kg/day or 3 mg/kg/day (escalating-dose phase) for 5 days. Clinical (immediate) side effects and renal (creatinine) tolerance were assessed daily; efficacy against oral candidosis was measured by using a simple clinical score. Serum levels of amphotericin B were also measured. RESULTS: None of the patients receiving amphotericin B deoxycholate---lipid emulsion had treatment interrupted, as compared to four (36%) in the amphotericin B deoxycholate---glucose group (pless-than-or-equal0.01); chills during or after the infusions were significantly less frequent in the amphotericin B deoxycholate---lipid emulsion groups than in the amphotericin B deoxycholate-glucose group (p=0.03). The increase of creatininemia during treatment was significantly higher for patients receiving amphotericin B deoxycholate---glucose than for those receiving amphotericin B deoxycholate---lipid emulsion (p=0.001). The number of patients who had a creatininemia greater-than-or-equal18 mg/L during treatment was significantly higher in both the amphotericin B deoxycholate---glucose group (36%) and in the group receiving the highest dose of amphotericin B deoxycholate---lipid emulsion than in other groups (pless-than-or-equal0.06). The serum concentrations of amphotericin B were lower for the amphotericin B deoxycholate---lipid emulsion regimen than for the amphotericin B deoxycholate---glucose regimen at the same dose of 1 mg/kg/day, but increased with the dose. The change of the oral candidosis score was similar for the same dose of 1 mg/kg/day of amphotericin B deoxycholate infused in either glucose or lipid emulsion; higher doses of amphotericin B deoxycholate---lipid emulsion were more efficacious (p=0.009) and this efficacy seemed to increase with the dose (p=0.06). CONCLUSIONS: The clinical and renal tolerance of amphotericin B deoxycholate are improved when the drug is directly prepared and infused in lipid emulsion (Intrapid) and this preparation allows for greater dosage, up to 3 mg/kg/day, with resultant greater efficacy. This preparation is simple and cost-effective (approximately 7 US $ per 50 mg of amphotercin B) and could be clinically compared to other formulations of amphotericin B.

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.

Effect of amphotericin B associated with a lipid emulsion on the oxidative burst of human polymorphonuclear leukocytes

1. Despite its toxicity, amphotericin B (AB) continues to be the drug of choice for the treatment of systemic fungal infection. The drug acts on several cell types, including polymorphonuclear leukocytes (PMN), where it inhibits the oxidative burst of cells submitted to several stimuli. 2. It was previously shown that the association of AB with a triglyceride-rich emulsion that physiologically mimics chylomicrons reduces toxicity. 3. We found that the association of AB with a triglyceride-rich emulsion reduces the loss of PMN viability produced by the drug. 4. The inhibition of the PMN oxidative burst triggered by phorbol 12-myristate 13-acetate (PMA) and opsonized zymosan (OZ) also was decreased by the association of the drug with this lipid emulsion. 5. Delivery of AB in a lipid emulsion may be of advantage in the treatment of immunosuppressed patients.

Diversity of lipid-based polyene formulations and their behavior in biological systems

Patients with cancer and infectious disease often display dyslipidemias that result in changes in their plasma lipoprotein-lipid composition. It is likely that the interactions of liposomal polyenes with plasma lipoproteins may be responsible for the far different pharmacokinetics and pharmacodynamics of these compounds when they are administered to infected patients rather than to animals or healthy volunteers. Amphotericin B (AmpB) and nystatin are examples of such polyenes. Amphotericin B initially distributes with the high-density lipoprotein (HDL) fraction upon incubation in plasma. Over time, AmpB redistributes from HDLs to low-density lipoproteins (LDLs). This redistribution appears to be regulated by lipid transfer protein. However, when AmpB is incorporated into liposomes composed of negatively or positively charged phospholipids, not only is the capability of LTP to transfer AmpB from HDL to LDL diminished, but AmpB remains retained with only the HDL fraction. However, when liposomal nystatin is incubated in plasma, over 50% of nystatin distributes with HDLs. Over time, nystatin redistributes from HDL to the lipoprotein-deficient plasma fraction, which is composed of mainly aqueous plasma proteins. The lipid composition selected for the drug appears to be a vital constituent in regulating the drug's interaction with biological fluids. Furthermore, liposome (or liposomal particle) size, fluidity, and other physiochemical characteristics also play a role in altering the pharmacokinetics and pharmacological effects of lipid-based drug formulations. Armed with this understanding, a rational approach to clinical development of these formulations could be facilitated.

[Amphotericin B deoxycholate (Fungizone): old drug, new versions]

Amphotericin B-deoxycholate (Fungizone) remains the main treatment of systemic mycoses. However, its toxicity, especially renal impairment, limits its use. The chemical properties of this molecule led to its association with lipidic structures. Among the three so-called liposomal formulations of amphotericin B, only one (AmBisome) is a true liposome. Its tolerance is good, along with high blood concentrations. The two others formulations, either in disk or ribbon form, are not true liposomes and these formulations are not as well tolerated as the former. These three forms of amphotericin are very expensive, thus limiting their use. The association of amphotericin B with other lipidic structures is of great interest. The direct solubilization of Fungizone in an emulsion (Intralipid 20%) is inexpensive and easily prepared extemporaneously; this preparation of Fungizone leads to a strong reduction of side effects and its efficacy is at least equivalent to conventional Fungizone. In the future, the association with triglycerides or lecithins is probable: possibly providing promising formulations.

Carrier effects on biological activity of amphotericin B

Amphotericin B (AmB), the drug of choice for the treatment of most systemic fungal infections, is marketed under the trademark Fungizone, as an AmB-deoxycholate complex suitable for intravenous administration. The association between AmB and deoxycholate is relatively weak; therefore, dissociation occurs in the blood. The drug itself interacts with both mammalian and fungal cell membranes to damage cells, but the greater susceptibility of fungal cells to its effects forms the basis for its clinical usefulness. The ability of the drug to form stable complexes with lipids has allowed the development of new formulations of AmB based on this property. Several lipid-based formulations of the drug which are more selective in damaging fungal or parasitic cells than mammalian cells and some of which also have a better therapeutic index than Fungizone have been developed. In vitro investigations have led to the conclusion that the increase in selectivity observed is due to the selective transfer of AmB from lipid complexes to fungal cells or to the higher thermodynamic stability of lipid formulations. Association with lipids modulates AmB binding to lipoproteins in vivo, thus influencing tissue distribution and toxicity. For example, lipid complexes of AmB can be internalized by macrophages, and the macrophages then serve as a reservoir for the drug. Furthermore, stable AmB-lipid complexes are much less toxic to the host than Fungizone and can therefore be administered in higher doses. Experimentally, the efficacy of AmB-lipid formulations compared with Fungizone depends on the animal model used. Improved therapeutic indices for AmB-lipid formations have been demonstrated in clinical trials, but the definitive trials leading to the selection of an optimal formulation and therapeutic regimen have not been done.

Administration of amphotericin B in lipid emulsion decreases nephrotoxicity: results of a prospective, randomized, controlled study in critically ill patients

OBJECTIVES

To evaluate the differences in efficacy and in clinical and biochemical tolerance to amphotericin B administered in a lipid emulsion compared with amphotericin B administered in 5% dextrose in water in the treatment of Candida albicans infection in intensive care unit (ICU) patients.

DESIGN

Prospective, controlled, randomized study, conducted during a 2.5-yr period, comparing the two treatment protocols.

SETTING

General ICU of a university-affiliated municipal hospital.

PATIENTS

Sixty consecutive critically ill patients with confirmed or suspected Candida infection.

INTERVENTIONS

Patients received amphotericin B (1 mg/kg/24 hrs), administered randomly in 5% dextrose in water (group A), or in lipid emulsion (20% intralipid) (group B).

MEASUREMENTS AND MAIN RESULTS

Clinical tolerance (fever, chills, hemodynamics), hepatorenal tolerance, and biological tolerance (serum electrolytes and coagulation profile) were evaluated. Patients receiving amphotericin B in lipid emulsion experienced a lower frequency rate of drug-associated fever (61.4% vs. 5.8%, p < .003) rigors (54% vs. 8.5%, p < .004), hypotension (17% vs. 0%), and nephrotoxicity (increase of serum creatinine concentration 66.7% vs. 20%, p < .0002). Significant (264,500 +/- 71,460 to 163,570 +/- 34,450 mm3, p < .01) thrombocytopenia, not associated with active bleeding, occurred in patients receiving amphotericin B lipid in emulsion but not in patients receiving the drug in dextrose.

CONCLUSIONS

Treatment with amphotericin B in a lipid emulsion when given to critically ill patients with Candida sepsis seems to be safer and as effective as the conventional mode of administration.

Pharmacologic influence on nutrition support therapy: use of propofol in a patient receiving combined enteral and parenteral nutrition support

Propofol is a lipid-based sedative that provides 1.1 kcal/mL. Because propofol has rapid onset and quick recovery, it is becoming used widely in critical care units. A 15-year-old critically ill pregnant patient received specialized nutrition support concomitantly with propofol infusion for sedation. A serum triglyceride concentration obtained on day 6 of the propofol infusion was 1100 mg/dL with no previous history of hyperlipidemia. Caloric intakes from propofol averaged 1275 kcal/d (range 445 to 2354 kcal/d) over a 5-day period. Infusion of propofol or any other lipid-based drug must be monitored closely when given in conjunction with enteral or parenteral nutrition to avoid the pitfalls of overfeeding and hypertriglyceridemia. Enteral and parenteral formulas must be manipulated to provide optimal nutrient intakes while not overfeeding with fat when using increased amounts of lipid-based drugs.

Pharmacokinetics of conventional formulation versus fat emulsion formulation of amphotericin B in a group of patients with neutropenia

The pharmacokinetics of amphotericin B administered in a conventional 5% dextrose (glucose) (5% D) solution and in a 20% fat emulsion formulation (Intralipid; 20% IL) were compared in 16 patients (mean age, 42 years [range, 18 to 70 years]) who had been hospitalized for hematological malignancies and with proven or suspected fungal infections. All of the patients received 50 mg (approximately 1 mg/kg of body weight per day) of amphotericin B daily in random order, either as a 50-ml lipid emulsion (20% IL) (group I) or in 500 ml of 5% D (group II). Five serum samples were taken during the 24 h after drug administration, and the levels of amphotericin B were measured by high-pressure liquid chromatography. Serum amphotericin B concentrations declined rapidly during the first 6 h, and subsequent measurements revealed a slow terminal elimination phase in both groups. The maximum serum amphotericin B concentration was significantly lower when the drug was administered in 20% IL (1.46 +/- 0.61 versus 2.83 +/- 1.17 micrograms/ml; P = 0.02). The area under the concentration-time curve from 0 to 24 h was also much lower in group I (17.22 +/- 11.15 versus 28.98 +/- 15.46 micrograms.h/ml). The half-life of the distribution phase was approximately three times longer in group I (2.92 +/- 2.34 h versus 0.64 +/- 0.24 h; P = 0.011). Conversely, the half-lives of the elimination phase were approximately equal in the two groups (11.44 +/- 5.18 versus 15.23 +/- 5.25 h). The mean residence times were also similar in both groups (19.41 +/- 11.13 versus 19.65 +/- 7.86 h). The clearance and the steady-state volume of distribution of amphotericin B in group I were about twice as great as those in group II (62.97 +/- 35.51 versus 33.01 +/- 14.33 ml/kg/h and 1,043.92 +/- 512.10 versus 562.32 +/- 152.05 ml/kg [P = 0.034], respectively). Finally, the volume of distribution in the central compartment was greater in group I than in group II (618.17 +/- 231.80 versus 328.19 +/- 151.71 ml/kg; P = 0.013), but there were no differences in the volume of distribution in the peripheral compartment (425.75 +/- 352.87 versus 234.14 +/- 75.92 ml/kg). These results suggest that amphotericin B has a different pharmacokinetic profile when it is administered in 20% IL than when it is administered in the standard 5% D form and that the main difference is due to a clear-cut difference in the steady-state volume of distribution, especially that in the central compartment.

Administration of lipid-emulsion versus conventional amphotericin B in patients with neutropenia

OBJECTIVE

To evaluate the usefulness of a 20% lipid emulsion as a delivery system for amphotericin B (1 mg/mL) administered over 1 hour to patients with neutropenia with hematologic malignancies compared with amphotericin B (0.1 mg/mL) administered in dextrose 5% solution over the same time.

DESIGN

A prospective, comparative, randomized, labeled study.

SETTING

Hematology unit, pharmacy service, university general hospital.

PARTICIPANTS

Twenty patients with neutropenia with hematologic malignancies and proven or suspected fungal infections, 10 in the fat emulsion group (group 1) and 10 in the dextrose 5% group (group 2).

MAIN OUTCOME MEASURES

Clinical tolerance (i.e., fever, shaking chills, nausea, blood pressure, pulse rate) and biologic tolerance (i.e., urea, creatinine, sodium, potassium).

RESULTS

Clinical tolerance was comparable in both groups although amphotericin B in fat emulsion was better tolerated. Medication for symptoms related to the administration of amphotericin B was given in 6 cases in group 1 and in 8 cases in group 2. There was a statistically significant difference in the urea concentrations between the 2 groups (p = 0.023); there was an observed increase between the initial and the final serum urea (56.8 mg/d in group 1, 79.8 mg/dL in group 2). Statistically significant differences in creatinine serum concentrations (84.9 mumol/L in group 1, 123.8 mumol/L in group 2) (p = 0.047) were found. No differences were found in the antifungal efficacy of the treatment. However, as amphotericin B was started in the majority of cases (75%) as empiric treatment for fever unresponsive to antibiotic therapy, it is difficult to compare the efficacy of both preparations.

CONCLUSIONS

The clinical tolerance of lipid-emulsion infusions is similar to that of conventionally administered amphotericin B therapy. Renal toxicity appears to be decreased when the drug is administered in a fat emulsion. This type of preparation permits the reduction of the volume and the time of administration for amphotericin B therapy.

Population pharmacokinetics and renal function-sparing effects of amphotericin B colloidal dispersion in patients receiving bone marrow transplants

The purpose of this study was to evaluate the pharmacokinetics of amphotericin B colloidal dispersion and its effect on creatinine clearance in bone marrow transplant patients with systemic fungal infections. Seventy-five patients (42 females and 33 males) with a median age of 34.5 years and a median weight of 70.0 kg were enrolled in the study. Patients received 1 of 15 dose levels (range, 0.5 to 8.0 mg/kg of body weight) daily for a mean duration of 28 days and a mean cumulative dose amount of 8 g. Plasma samples for amphotericin B determination (median number, 4; range, 2 to 30) and daily serum creatinine values were obtained for each patient. Iterative two-stage analysis, one of several approaches to population pharmacokinetic and pharmacodynamic modelling, was employed for the pharmacokinetic analysis. The plasma data were available for 51 of 75 patients and were best described by a two-compartment model. Both plasma clearance and volume of distribution increased with escalating doses; the overall average terminal elimination half-life was 29 h. Of the covariates studied, only body weight and dose size were significant. Serum creatinine values over the duration of therapy were available for 59 of 75 patients. Overall, there was no net change in renal function over the duration of therapy; 12 patients had > 30% increases in creatinine clearance, whereas 13 had > 30% decreases. No measure of amphotericin B colloidal dispersion exposure, demographic values, or concomitant treatment with other medications was related to changes in the creatinine clearance.