Lipid formulations of amphotericin B. Less toxicity but at what economic cost?

Liposome composition in drug delivery design, synthesis, characterization, and clinical application

Liposomal drug delivery represents a highly adaptable therapeutic platform for treating a wide range of diseases. Natural and synthetic lipids, as well as surfactants, are commonly utilized in the synthesis of liposomal drug delivery vehicles. The molecular diversity in the composition of liposomes enables drug delivery with unique physiological functions, such as pH response, prolonged blood circulation, and reduced systemic toxicity. Herein, we discuss the impact of composition on liposome synthesis, function, and clinical utility.

Burden of acute kidney injury in HIV patients under deoxycholate amphotericin B therapy for cryptococcal meningitis and cost-minimization analysis of amphotericin B lipid complex

Deoxycholate amphotericin B (d-AMB) has a higher rate of acute kidney injury (AKI) in comparison of lipid formulations. However, lipid amphotericin B has high costs in developing countries. The aim of this study is to assemble a model of cost-minimization of amphotericin B lipid complex (ABLC) in patients with cryptococcal meningitis. This is a retrospective study done in a cohort of patients with cryptococcal meningitis to study the economic impact of its use in developing countries. Cost analysis were based on direct cost of different antifungal therapies, chronic dialysis after discharge, and survival of patients based on a retrospective cohort of 102 patients infected with human immunodeficiency virus with confirmed diagnosis of cryptococcal meningitis. From 102 patients treated with d-AMB, 60.78% developed any grade of AKI and 10.78% developed AKI demanding hemodialysis. The percentage of patients with meningeal cryptococcosis treated with d-AMB that requeired chronic HD was 2.39%. The same model was performed for patient that would be treated with ABLC, which resulted in 0.20% of patients demanding chronic HD due to its lower nephrotoxicity. When the model is applied in 100 patients, the total costs with d-AMB would be US$ 184,543 and with ABLC would be US$ 1,640,109 in 5 years. Treatment with ABLC would be cost saving in comparison to d-AMB treatment, if early switch of treatment occurred in patients presenting AKI. The change should be as soon as possible to avoid further complication, like dialysis, which is associated with a lower life expectancy.

Efficacy and safety of amphotericin B formulations: a network meta-analysis and a multicriteria decision analysis

Objectives

Despite its broad spectrum, conventional amphotericin B (AB) is associated with serious adverse events. Lipid-based formulations may offer safer options. We aimed to synthesize the evidence of efficacy and safety of AB formulations.

Methods

We performed a systematic review and network meta-analysis (NMA) to compare all available formulations: conventional AB; lipid complex or ABLC; colloidal dispersion or ABCD; liposomal or LAB; AB in Intralipid. Randomized controlled trials were searched in four databases. Cure, fever, chills, nephrotoxicity, death and drug discontinuation were assessed. NMA was based on Bayesian methods accounting for direct and indirect comparisons. Probability ranks estimating the best formulation were built for each outcome. The relative benefit–risk of formulations was assessed with stochastic multicriteria acceptability analyses (SMAA).

Key findings

We identified 25 trials (n = 2996). No significant differences among drugs were observed for cure or death. All lipid-based formulations were safer than conventional AB for nephrotoxicity. AB-Intralipid was more tolerable than conventional AB and caused less chills than ABCD. AB-Intralipid was the best therapy (>60%) regarding nephrotoxicity, fever, chills and discontinuation. The scenario from SMAA favoured AB-Intralipid (81% acceptability). Conventional AB was secondary to all lipid-based formulations.

Conclusions

Amphotericin B-Intralipid was identified as safer, cost-saving treatment in comparison with other formulations.

Liposomes as nanomedical devices

Since their discovery in the 1960s, liposomes have been studied in depth, and they continue to constitute a field of intense research. Liposomes are valued for their biological and technological advantages, and are considered to be the most successful drug-carrier system known to date. Notable progress has been made, and several biomedical applications of liposomes are either in clinical trials, are about to be put on the market, or have already been approved for public use. In this review, we briefly analyze how the efficacy of liposomes depends on the nature of their components and their size, surface charge, and lipidic organization. Moreover, we discuss the influence of the physicochemical properties of liposomes on their interaction with cells, half-life, ability to enter tissues, and final fate in vivo. Finally, we describe some strategies developed to overcome limitations of the “first-generation” liposomes, and liposome-based drugs on the market and in clinical trials.

Management of fungal infections following allogeneic stem cell transplantation

Fungal infection remains an important complication in allogeneic stem cell transplantation (allo-SCT). Since the prognosis of fungal infection is poor, prophylaxis is critical for its management; owing to recent progression in allo-SCT management and widespread use of reduced-intensity regimens, the strategy of infectious prophylaxis has also changed. Various antifungals have recently been developed and applied to clinical use. A major change in antifungal management will probably occur in the next few years.

Leczenie grzybic górnych dróg oddechowych i ucha

Fungi, in comparison with other pathogenic factors, have high pathogenicity. The number of fungal species which are able to infect people is over 500. The upper respiratory tract and ear have permanent contact with external environment which makes their ontocenoses open to continuous exchange of microorganisms of which they consist. In etiology of inflammatory processes 21 species which belonging to 3 genera (Zygomycota, Ascomycota, Basidiomycota) of fungi play important role. Administration of antifungal drugs can be: prophylactic, empiric preemptive and therapeutic. Physicians may prescribe antibiotics (mainly pollens: amphotericin B, natamycin and nystatin) and chemiotherapeutics (mainly azoles and fluorpirymidins, pigments, chlorhexidine and chlorquinaldol). In ENT practice topical and systemic drugs can be administrated. Topical lozenges include amphotericin B, clotrimazole, chlorhexidine or chlorquinaldol and oral gels: nystatin and miconazole. Some of drugs are in the form of suspension/solution, which can be used for inhalation, into the sinus, for swabbing or for lavage: amphotericin B, natamycin, nystatin, clotrimazol, flucytosine, miconazole, fluconazole, vorykonazole, caspofungin. It should be underlined that only a few of dugs can be absorbed from the digestive tract: flucytosine, fluconazole, itraconazole, ketoconazole, miconazole, vorykonazole.

Antifungal prophylaxis following reduced-intensity stem cell transplantation

Reduced-intensity stem cell transplantation (RIST) has been developed to be a novel curative option for advanced hematologic diseases. Its minimal toxicity allows for transplantation in patients with advanced age or with organ dysfunction. Young patients without comorbidity can undergo RIST as outpatients. However, fungal infection remains an important complication in RIST. Given the poor prognosis of fungal infection, prophylaxis is critical in its management. The prophylactic strategy is recently changing with the development of RIST. Hospital equipment is important for fungal prophylaxis; however, the median day for the development of fungal infection is day 100, when most RIST patients are followed as outpatients. The focus of fungal management after RIST needs to shift from in-hospital equipment to oral antifungals. Various antifungals have recently been developed and introduced for clinical use. A major change in antifungal management will probably occur within several years.

[Fungal infection following reduced-intensity stem cell transplantation (RIST)]

Hematopoietic stem cell transplantation has been established as a curative treatment for advanced hematologic malignancies. Transplantation with a reduced-intensity conditioning regimen has been developed, and the minimal toxicity of reduced-intensity stem cell transplantation (RIST) has made this procedure available for patients of advanced age or with organ dysfunction. The response of malignant lymphoma and some solid tumors to RIST has been observed. RIST with unrelated donors and umbilical cord blood has been studied. Fungal infection is an important complication of RIST. Since the prognosis of fungal infection is poor, the management has been focused on its prophylaxis. Given recent progression in RIST management, the strategy of infectious prophylaxis has also changed. Equipment in the hospital is important for fungal infection; however, the median day of the development of fungal infection is day 100, when most patients are followed as outpatients. The focus of fungal management after RIST is oral antifungal agents rather than in-hospital equipment. Various antifungal agents have recently been developed and applied for clinical use, and many of these have been developed simultaneously for the first time. A major change in antifungal management will probably occur in the next several years.

Treatment Costs and Survival in Patients with Grades III-IV Acute Graft-Versus-Host Disease after Allogenic Hematopoietic Stem Cell Transplantation During Three Decades

To determine development of treatment, costs, and survival for patients with grades III/IV acute graft-versus-host disease (GVHD), data from 88 patients with grades III/IV acute GVHD were collected. The patients were divided into three groups: patients who received transplants from 1977 through 1989 (group A), 1990 through 1999 (group B), and 2000 through 2004 (group C). The costs for treatment, enumerated to year 2003 costs, were calculated. An increased 1-year survival rate was found in group C, at 21% versus 9% and 8% for groups A and B, respectively (P=0.02). Death by acute GVHD was increased by repeat transplantation (P<0.001), grade IV acute GVHD (P<0.001), human leukocyte antigen mismatch (P=0.009), and transplantation before 2000 (P=0.015). Transplantation after 1990 (P=0.003) and grade IV acute GVHD (P=0.03) were associated with higher treatment costs. It was found that the time the patients had GVHD did not differ among the three groups. In conclusion, the costs and survival rates associated with severe acute GVHD has increased in recent years.

Economic Evaluation of Intravenous Itraconazole for Presumed Systemic Fungal Infections in Neutropenic Patients in Korea

Systemic fungal infections remain a major clinical problem in immunocompromised patients. Presumed systemic fungal infections (PSFI) are treated empirically with an intravenous antifungal agent to reduce the occurrence of documented infections and associated mortality. The objective of this study was to compare the cost-effectiveness of intravenous itraconazole (IVitra) treatment with the current first-line empirical treatment of PSFI with conventional amphotericin B (CAB) in cases of neutropenic cancer and bone marrow transplantation (BMT). Cost-effectiveness was expressed as cost per additional "responder" (defined as a patient without fever or major toxicity). We developed a medical decision analytical tree that included probabilities of toxicity, response and pathogen documentation, and second-line treatments. Clinical data were obtained from randomized clinical trials, and resource use data were obtained from a panel of clinical experts. The total cost of treating PSFI per neutropenic cancer patient was lower for IVitra than for CAB, and this lower cost resulted from a reduced need for second-line antifungals. In a cost-effectiveness analysis, IVitra treatment was superior to CAB treatment. Compared with current treatment with CAB, IVitra therapy was shown to be a cost-effective and cost-saving empirical treatment for PSFI in neutropenic cancer patients and BMT patients.

Comparison of the effect of amphotericin B desoxycholate and amphotericin B colloidal dispersion on renal functions and renal morphology in rats

BACKGROUND AND AIM

Amphotericin B (AmB) desoxycholate remains as one of the most efficacious agents currently available for the treatment of systemic fungal infections; however, amphotericin B colloidal dispersion (ABCD) has been developed because of AmB desoxycholate nephrotoxicity. The goal of our study was to compare the effect of administration of AmB desoxycholate and ABCD on renal functions and renal morphology in rats.

RESULTS

Amophotericin B desoxycholate as well as ABCD causes damage to renal tubuli and polyuria. Amophotericin desoxycholate causes considerably more severe damage to tubuli than ABCD, but the morphological damage to renal glomeruli is minimal in both formulas. In tubular cells, AmB desoxycholate causes severe damage to mitochondria, vacuolation of cytoplasm, and increased values of volume density of peroxisomes.

CONCLUSION

None of these formulas causes a decrease in glomerular filtration in rats when animals are properly hydrated.

Liposomal amphotericin B (AmBisome) for fungal infections in immunocompromised adults and children

Invasive fungal infections are rare but life-threatening infections, most often occurring in immunocompromised patients. For a long time, Amphotericin B has been the best choice for treatment, because it is fungicidal with a broad antifungal spectrum and minimal risk of resistance development. The therapeutic use of amphotericin B has, however, been limited by its toxicity-both acute as well as chronic. To counter this, amphotericin B has been encapsulated in liposomes, which reduces its toxicity and allows higher doses to be given. Ambisome is a true, spherical, small unilamellar liposome with a median size of 80 nm. The pharmacokinetic profile was changed, and the maximum concentration and AUC of amphotericin B after AmBisome treatment were greater than those found with the conventional drug. The highest tissue concentrations of AmBisome were found in the liver and spleen, and less than 1% of the administered dose was recovered in other organs. At Huddinge University Hospital, we were the first to use and report on the experience of AmBisome. We now have more than 12 years' experience in transplant recipients, with a good safety profile, improved rate of curing mycological proven infections and reduced mortality in fungal infections. In two placebo-controlled prophylactic trials, we found that AmBisome was effective for preventing fungal colonization and invasive fungal infections, respectively, in allogeneic stem cell and liver transplantation. In uncontrolled and, more recently, in randomized controlled studies at other centers, AmBisome has revealed less toxicity and an efficacy equal or superior to that of the conventional drug in treating neutropenia-associated fever and proven invasive fungal infections in both adults as well as in children. Although investigators tend to increase the dose used, the optimal dose for probable or proven infection is still under debate. Based on our own experience in using AmBisome and the experience at other centers, we can conclude that AmBisome represents a major breakthrough in the treatment of invasive fungal infections, especially in immunocompromised patients.

Pulmonary reactions during treatment with amphotericin B: review of published cases and guidelines for management

Acute respiratory events occasionally have been observed during the infusion of amphotericin B. Herein we analyze the 21 cases that have been reported, including a fatal reaction observed by us. Some useful guidelines are provided that likely will allow treatment to be continued safely for patients who have experienced such reactions.

The cost of treating systemic fungal infections

The increasing incidence of systemic fungal infections and rising medical costs have highlighted the need for an economic appraisal of antifungal agents to determine the most cost-effective therapeutic option. Cost savings derived from the prophylactic or empirical use of antifungal agents have been difficult to estimate because of the lack of information on the costs of systemic fungal infections. Fluconazole is effective in prophylaxis and represents a direct cost saving compared with polyenes. However, itraconazole oral solution, an effective and widely used antifungal prophylactic agent, has not been analysed for cost effectiveness. In empirical therapy, the development of new formulations of existing agents has prompted a number of cost comparisons. In particular, the cost of treatment with conventional amphotericin-B has been compared with the costs of the new lipid-associated formulations of amphotericin-B or the new intravenous (IV) formulation of itraconazole. The acquisition costs of lipid-associated amphotericin-B and IV itraconazole are higher than the cost of conventional amphotericin-B; however, these costs appear to be offset by reductions with both these agents in the cost for increased length of hospital stay and treating adverse events seen with conventional amphotericin-B. In neutropenic patients and bone marrow transplant recipients, IV itraconazole may be the most cost-effective option for empirical therapy.

Comparison of amphotericin B lipid complex (ABLC) vs. ambisome in the treatment of suspected or documented fungal infections in patients with leukemia

Fungal infections remain a major cause of treatment failure and death in acute leukemia. New liposomal preparations of amphotericin B are now available. While less toxic, their comparative efficacy and toxicity profiles are unknown. In this study the comparative efficacy and safety of ABLC vs. AmBisome was evaluated in seventy-five patients with leukemia who developed 82 episodes of suspected or documented mycosis, and were treated (1:1) with either ABLC (n=43) or AmBisome (n=39). Both drugs were dosed accordingly from 3 to 5 mg/kg/day. Using an intent-to-treat analysis, the overall response to therapy was 27/43 (63%) for ABLC and 15/39 (39%) for AmBisome (p=0.03). Median dose and duration of treatment was 10 days at 3 mg/kg for ABLC and 15 days at 4 mg/kg for AmBisome. Acute, not dose-limiting infusion side effects were seen in 70% vs. 36% (p=0.002), ABLC vs. AmBisome. Increase of bilirubin > 1.5 times from baseline was 38% vs. 59%, ABLC vs. AmBisome (p=0.05). ABLC and AmBisome were equally effective for the treatment of suspected or documented fungal infections. While, acute infusion-toxicity was greater with ABLC, infusion toxicity requiring discontinuation was similar for both drugs. AmBisome was better tolerated than ABLC but was associated with mild abnormalities in liver function tests at the end of therapy.

Aspergillosis in bone marrow transplant recipients

Invasive aspergillosis in bone marrow transplant recipient is associated with a high mortality. Diagnosis is often delayed because the inflammatory response is blunted by immunosuppression. The gold standard of tissue biopsy is often considered too in invasive as the procedure is often complicated by bleeding and secondary infection. Recent finding on non-invasive tests such as serial measurement of peripheral blood galactomannan antigen or DNA appears to be promising. However, the limited availability of such tests and requirement for expertise are still hampering their use in routine clinical management. More often than not, initiation of antifungal therapy is empirical and based on suggestive radiological changes. Amphotericin B remains the gold standard of therapy but liposconal preparation may prove to be less nephrotoxic and equally effective. Treatment outcome depends more on the acceleration of the recovery of the immune system and the reduction of anti-GVHD therapy than the antifungal agent followed by surgical resection. The efficacy of many reported anti-aspergillosis prophylactic regimen has not been proved in randomized control trials. Despite the absence of data, such policy should still be considered in transplant units with high incidence of aspergillus or undergoing renovation.

Comparison of the efficacy of free and non-ionic-surfactant vesicular formulations of paromomycin in a murine model of visceral leishmaniasis

Non-ionic-surfactant vesicular (NIV) formulations of paromomycin have been tested in-vitro and in-vivo for their activity against Leishmania donovani. Production of NIV was dependent both on the surfactant used and on the concentration of paromomycin; only two of the surfactants studied formed vesicles at the highest paromomycin concentration (9 mg mL(-1)). At surfactant-lipid concentrations > or = 1.5 mM, suspensions of NIV (drug- or glucose-loaded) were cytotoxic to macrophages infected with L. donovani; high levels of nitrite were produced in cell supernatants. At surfactant-lipid concentrations < 1.5 mM, drug-loaded NIV were more effective than the same dose of free drug, in terms of the percentage of cells infected and the number of parasites/cell. At surfactant-lipid concentrations < or = 0.15 mM, drug-loaded NIV were ineffective in-vitro. In-vivo, treatment with decaethylene glycol mono n-hexadecyl ether paromomycin NIV was more effective than hexaethylene glycol mono n-hexadecyl ether paromomycin NIV, in terms of suppression of liver and spleen parasite burdens. Against liver parasites, both types of paromomycin-loaded NIV were more effective than free drug. Neither the NIV nor free forms of paromomycin caused significant suppression of bone-marrow parasites. The study shows that entrapment of paromomycin in NIV can be used to increase its antileishmanial activity in-vitro and in-vivo.

A comparative analysis of lipid-complexed and liposomal amphotericin B preparations in haematological oncology

No comparative clinical information on the properties of lipid-associated amphotericin preparations is presently available. In this single-centre retrospective analysis over a 5-year period the indications, efficacy and toxicity of true liposomal amphotericin (AmBisome) were compared with a lipid complexed preparation (Abelcet). In a novel approach APACHE III scores were used in addition to neutrophil counts, disease status and additional immunosuppression to accurately assess the severity of illness in both groups and enable valid comparison. Overall, AmBisome at a median dose of 1.9 mg/kg/d was found to have similar clinical outcome to Abelcet at a median dose of 4.8 mg/kg/d. Nephrotoxicity and electrolyte abnormalities were similar in both groups. Rigors and febrile episodes were more common with Abelcet. Prospective randomized comparative trials are required to clarify the optimum dosages and therapeutic and economic issues associated with these agents.

The covalent coupling of Arg-Gly-Asp-containing peptides to liposomes: purification and biochemical function of the lipopeptide

With the advent of liposomes as drug carriers, there arises a need for efficient targeted delivery in vivo. Proteins coupled to liposomes usually yield heterogeneous products that are ill-defined both chemically and in terms of spatial orientation. We now report on the disulfide linkage to the surface of intact liposomes of a peptide representing one-half of a ligand-receptor pair. An RGD-motif-containing peptide was coupled to the phospholipid PDP-DOPE of the liposomes by a thiol-disulfide exchange. The resulting lipopeptides were amenable to definition by TLC, HPLC, and MS and found to be in a functional orientation allowing biochemical interaction with their receptor, the integrin glycoprotein IIb-IIIa.

Liposomal amphotericin B (AmBisome) compared with amphotericin B both followed by oral fluconazole in the treatment of AIDS-associated cryptococcal meningitis

OBJECTIVE

Amphotericin B deoxycholate initial therapy and fluconazole maintenance therapy is the treatment of choice for AIDS-associated cryptococcal meningitis. However, the administration of amphotericin B is associated with considerable toxicity. A potential strategy for reducing the toxicity and increasing the therapeutic index of amphotericin B is the use of lipid formulations of this drug.

DESIGN AND METHODS

HIV-infected patients with cryptococcal meningitis were randomized to treatment with either liposomal amphotericin B (AmBisome) 4 mg/kg daily or standard amphotericin B 0.7 mg/kg daily for 3 weeks, each followed by fluconazole 400 mg daily for 7 weeks. During the first 3 weeks, clinical efficacy was assessed daily. Mycological response was primarily evaluated by cerebrospinal fluid (CSF) cultures at days 7, 14, 21 and 70.

RESULTS

Of the 28 evaluable patients, 15 were assigned to receive AmBisome and 13 to receive amphotericin B. Baseline characteristics were comparable. The time to and the rate of clinical response were the same in both arms. AmBisome therapy resulted in a CSF culture conversion within 7 days in six out of 15 patients versus one out of 12 amphotericin B-treated patients (P = 0.09), within 14 days in 10 out of 15 AmBisome patients versus one out of nine amphotericin B patients (P = 0.01), and within 21 days in 11 out of 15 AmBisome patients versus three out of eight amphotericin B patients (P = 0.19). When Kaplan-Meier estimates were used to compare time to CSF culture conversion, AmBisome was more effective (P < 0.05; median time between 7 and 14 days for AmBisome versus > 21 days for amphotericin B). AmBisome was significantly less nephrotoxic.

CONCLUSIONS

A 3-week course of 4 mg/kg AmBisome resulted in a significantly earlier CSF culture conversion than 0.7 mg/kg amphotericin B, had equal clinical efficacy and was significantly less nephrotoxic when used for the treatment of primary episodes of AIDS-associated cryptococcal meningitis.

Comparison of the efficacies of various formulations of amphotericin B against murine visceral leishmaniasis

The antileishmanial efficacies of four proprietary amphotericin B (AmB) formulations (Fungizone, AmBisome, Abelcet, and Amphocil) and an experimental nonionic surfactant vesicle (NIV) formulation were compared in a murine model of acute visceral leishmaniasis. By a multiple-dosing regimen, groups of Leishmania donovani-infected BALB/c mice were treated (2.5 mg of AmB per kg of body weight) on days 7 to 11 postinfection with one of the AmB formulations, and parasite burdens were determined on day 18 postinfection. All of the formulations caused significant suppression parasite burdens in spleens (P < 0.01 to 0.0005) and livers (P < 0.0005) compared with those in the spleens and livers of the controls. In addition, a significant suppression of parasite burdens in bone marrow (P < 0.0005) compared to the burdens in the bone marrow of the controls was obtained for all the formulations except Abelcet, which was inactive at this site. On the basis of their overall efficacies (activity against liver, spleen, and bone marrow parasites), the formulations could be ranked as follows: Amphocil = AmBisome > AmB-NIV > Abelcet >> Fungizone. On the basis of spectrophotometric measurements, AmB was shown to exist in a predominantly aggregated state in all of the formulations. Although incubation in 50% serum altered the degree of aggregation, the AmB remained predominantly aggregated, indicating that the AMB-lipid complex in all of the formulations was physically stable. The results of the study showed that antiparasitic efficacy is associated positively with the degree of AmB aggregation in the presence of serum.

Bone marrow transplantation using unrelated donors for haematological malignancies

Bone marrow transplantation from unrelated donors is increasingly used to treat haematological malignancies. There are almost 4 million volunteer donors now available. Therefore, it is possible to find an HLA-A, -B and -DR-identical donor for around 70% of the patients. The major obstacles to unrelated bone marrow transplantations have been rejection, severe acute graft-versus-host disease (GVHD) and prolonged immune recovery leading to frequent infections and a high transplant-related mortality. However, with improved tissue typing using DNA techniques, immunosuppression using T-cell depletion in vitro or in vivo, the frequency of acute GVHD is acceptable and the results approach those obtained with HLA-identical siblings. For patients with chronic myeloid leukaemia, the worldwide 3-year survival is around 40%. Other indications for bone marrow transplantation with unrelated marrow include acute leukaemia and myelodysplastic syndromes with high-risk features. Unrelated cord blood cells and unrelated peripheral blood progenitor cells will be increasingly used as alternative haematopoietic stem cell sources to bone marrow. Improved immunosuppression, more accurate tissue typing, growth factors and better management of infections is expected to improve outcome using unrelated haematopoietic stem cells for transplantation in the near future.

Do variations in molecular structure affect the clinical efficacy and safety of lipid-based amphotericin B preparations?

While amphotericin B is the drug of choice in the treatment of most fungal infections, systemic adverse reactions and dose-dependent nephrotoxicity associated with its use frequently render the conventional preparation of amphotericin unsuitable. A number of lipid-based formulations of amphotericin have been developed to overcome the limitations of the parent compound. These preparations, amphotericin B lipid complex (ABLC), amphotericin B colloid dispersion (ABCD) and liposomal amphotericin differ from one another significantly in their molecular structure. They are also considerably more expensive than the parent compound. Clinical data on their appropriate use are limited. This review looks at the differences in molecular structure of these preparations, and at the available clinical safety and efficacy data.

Advanced and controlled drug delivery systems in clinical disease management

Advanced and controlled drug delivery systems are important for clinical disease management. In this review the most important new systems which have reached clinical application are highlighted. Microbiologically controlled drug delivery is important for gastrointestinal diseases like ulcerative colitis and distally localized Crohn's disease. In cardiology the more classic controlled release systems have improved patient compliance and decreased side effects. In the treatment of intractable pain the spinal and transdermal route is well documented. In neurology the flattened peak-through levels of antiepileptic drugs and anti Parkinson's drugs represents a more predictable kinetic profile. Tracheal delivery of corticosteroids and sympaticomimetics in asthma and Chronic Obstructive Pulmonary Disease is fully accepted in clinical practice: delivery by this route results in better efficacy and a better safety profile. In gynaecology the delivery of pulsatile hormones (LHRH) is used for pregnancy induction, while transdermal oestrogens are promising in the prevention of osteoporosis. In surgical practice the use of antibiotic impregnated bone cement and antibiotic impregnated biodegradable collagens is well established. To prevent infections intravascular catheters coated with heparin or antibiotics are used. In ophthalmology the Ocusert systems provide a controlled release of different drugs in the eye. Most spectacular is the clinical introduction of the first liposomal drugs; amfotericine B and daunorubicine. Liposomal formulations of these drugs have enhanced activity and decreased toxicity compared to conventional formulations.