Effects of the newer antifungal agents (bifonazole, ICI 195, 739 and amorolfin) on in vitro phagocytic, lymphocytic and natural-killer cell responses

Amphotericin B and some of the imidazole drugs have been shown to suppress certain neutrophil and lymphocyte functions both in vitro and in vivo. We present here the in vitro effects of: amorolfin, a morpholine derivative; the imidazoles clotrimazole and ketoconazole; the N-substituted imidazole bifonazole and a triazole (ICE 195, 739), on neutrophil and lymphocyte function. All of these drugs inhibited neutrophil random migration, chemotaxis and hexose monophosphate shunt activity. The effects of the drugs on neutrophil adherence, deoxyglucose transport and beta-glucuronidase release were variable while lysozyme release was unaffected. Natural Killer cell cytoxicity was depressed by all drugs tested except for amorolfin. Mitogen-induced lymphocyte blastogenesis was suppressed by all the antifungal drugs tested. Similar results were obtained using the mitogens phytohaemagglutinin, concanavalin A and pokeweed mitogen. The mechanism of action of these drugs on these cell functions remains unknown, there may be a correlation between their effects on fungi and their effects on leukocytes. Clearance of systemic fungal infection is heavily dependent on integrity of the cellular immune system and it is clearly undesirable that antifungal drugs have immunosuppressive properties. Further studies are required to determine the in vivo and clinical relevance of our observations.     

Present state and future direction of topical antifungals]

Topical agents are generally better than oral medicine with respect to systemic side effects. Even if an antifungal drug causes severe systemic side effects, the drug, if it has excellent antifungal activity, can be used for topical treatment. In addition, because most causative fungi in dermatomycosis are usually located in the horny cell layers of the epidermis (superficial layers of the skin), topical antifungals are the first choice of treatment for most dermatomycoses. Many topical antifungals with excellent antifungal activity have recently been developed and once a day topical application is presently possible. In spite of these new agents, however, clinical efficacy and mycological eradication rates have not shown significant improvement and there are still many patients with tinea pedis. One reason that no significant improvement has been observed in the topical antifungal therapy may be due to poor compliance with the treatment. That is, because it is difficult for most patients to continue regular topical application for a long period, most usually stop treatment after clinical symptoms disappear, even though no mycological cure may yet have been achieved. In addition, topical antifungals are not effective for the treatment of hyperkeratotic skin lesions or nail and hair infection. Therefore, the goal of new topical antifungals should be good compliance, which means shortening of the treatment period, high penetration of the drug into horny cell layers, nails, and hair, and high affinity to horny cell layers in order to keep a high concentration of the drug within the lesions.     

New antifungal agents

For more than two decades, amphotericin B has been the single broad-spectrum agent for the treatment of systemic mycoses. Amphotericin B is not always effective, must be given parenterally, and is associated with a host of adverse reactions. Despite amphotericin B toxicity, until recently the systemic mycoses did not rate enough attention to prompt a search for new alternatives. However, three recent events have overcome this inertia: the gradually increasing use of potent immunosuppressive agents and broad-spectrum anti-bacterial drugs; the discovery of the relatively nontoxic azole classes of antifungal drugs in the 1980s and the rapid emergence of AIDS, with its severe accompanying opportunistic fungal infections. In just ten years we have seen the emergence of second-generation imidazole and third-generation triazole antifungal drugs and, most recently, entirely new classes of agents. It is remarkable that so many alternatives are becoming available just at the time when new antifungal drugs have become a major need. This discussion will concentrate on the new antifungal drugs of the past ten years, with the exception of developments in the polyenes and flucytosine, which are covered elsewhere.     

Bronchodilator effects of terbutaline and aminophylline alone and in combination in asthmatic patients.

In 17 patients with moderate to severe asthma, we compared acute bronchodilator effects of the following drugs or drug combinations using a double-blind crossover design: terbutaline, 5; aminophyline 400; terbutaline, 5, plus aminophyline, 400; terbutaline, 2.5; aminophylline, 200; terbutaline, 2.5, plus aminophyline, 200 mg; and placebo. The higher doses of terbutaline and aminophylline alone produced comparable bronchodilation and similarly frequent adverse side effects; low doses of each drug also had comparable effects. The high-dose combination produced significantly (P less than 0.05) greater bronchodilatation than either drug alone. The low dose combination had bronchodilator effects comparable to those produced by the higher dose of either drug alone. These findings suggest therapeutic advantages in combining high doses of theophylline and an oral beta adrenergic agonist (terbutaline) in asthma not well controlled on high doses of either drug alone and in combining these drugs in lower doses in patients experiencing intolerable side effects from a high dose of either drug.     

Allergic bronchopulmonary aspergillosis: A multidisciplinary review

Allergic bronchopulmonary aspergillosis (ABPA) is a rare disease characterized by a complex allergic inflammatory reaction of airways against Aspergillus affecting patients with chronic respiratory diseases (asthma, cystic fibrosis). Exacerbation is often the way to diagnose ABPA and marks its evolution by its recurrent character leading to cortico-requirement or long-term antifungal treatment. Early diagnosis allows treatment of ABPA at an initial stage, preventing recurrence of exacerbations and long-term complications, mainly represented by bronchiectasis. This review of the literature aims to present the current state of the art in terms of diagnosis and treatment of ABPA from a multidisciplinary perspective. As there is no clinical, biological nor radiological specific sign, diagnostic criteria are regularly revised. They are mainly based on the elevation of total and specific IgE against Aspergillus fumigatus and the presence of suggestive CT abnormalities such as mucoid impaction and consolidations. ABPA management includes eviction of mold and pharmacological therapy. Exacerbations are treated in first line with a moderate dose of oral corticosteroids. Azole antifungal agents represent an alternative for the treatment of exacerbations and are the preferential strategy to reduce the future risk of exacerbations and for corticosteroids sparing. Asthma biologics may be of interest; however, their place remains to be determined. Avoiding complications of ABPA while limiting the side effects of systemic drugs remains a major challenge of ABPA management. Several drugs, including new antifungals and asthma biologics, are currently being tested and may be useful in the future.     

Cyclosporine nephrotoxicity

Cyclosporine (CSA) is a new immunosuppressant which has selectivity for the immune system and is without systemic side effects at therapeutic doses. In contrast to the cytotoxic class of immunosuppressants, no myelotoxic, teratogenic, mutagenic, or carcinogenic effects were observed. Nevertheless, overdosage may lead to renal dysfunction, which occurs mainly in rats, and often complicates its clinical use. The experimental data also showed that significant nephrotoxicity was only caused under specific conditions at therapeutic doses. These conditions included ischemia, heminephrectomy, concomitant administration of nephrotoxic drugs, and/or genetic predisposition. Thus, concomitant renal damage is a prerequisite in order to obtain overt nephrotoxicity at therapeutic CSA doses. Since these conditions cannot be avoided in patients, nephrotoxicity often occurs at therapeutic doses in man. The rat might be a suitable experimental model of CSA nephropathy displaying similar morphologic and functional changes as observed in man. This model also allows further investigations on the pathogenic mechanisms which are elusive at the present time.     

Evaluation of a murine model of hepatic candidiasis.

A murine model of focal hepatic candidiasis which we suggest simulates certain conditions of this clinical variant of systemic candidiasis in leukemic patients is described. We have shown that outbred mice inoculated with Candida albicans by the oral-intragastric route as infants (6 days old) and then immunocompromised by cyclophosphamide and cortisone acetate treatment 2 weeks later demonstrate systemic spread of the opportunistic pathogen to the liver, lungs, spleen, and kidneys. Treatment with the immunosuppressive drugs cyclophosphamide and cortisone acetate resulted in alteration of the normal integrity of the mucosal epithelium of the gut as well as in granulocytopenia. Approximately 55% of the animals with C. albicans infections in the liver demonstrated hepatic abscesses. After these same infected, immunocompromised animals were treated with suboptimal dosages of antifungal agents (cilofungin or amphotericin B), either by intraperitoneal or subcutaneous (s.c.) routes, persistent hepatic abscesses were fewer in number and delimited by a distinct outer layer of host tissue but still contained large numbers of the viable pathogen. Blood cell counts indicated that these antifungal drug-treated animals had reestablished approximately the same number of leukocytes per microliter of blood as estimated prior to the immunocompromising drug treatment. Similar conditions in leukemic patients who were in remission and who were undergoing antifungal drug therapy for systemic candidiasis have been reported. Clearance of hepatic infections in mice was accomplished by using appropriate concentrations of amphotericin B administered by daily intraperitoneal or s.c. injection for 5 to 7 days or cilofungin by continuous s.c. infusion for 7 days. However, systemic antifungal therapy did not significantly reduce numbers of C. albicans cells in the stomach and esophagus. Persistent foci of gastrointestinal colonization by C. albicans, especially in the region of the cardial-atrium fold of the stomach of these mice, are reservoirs of the opportunistic pathogen from which reinfection may occur, leading to relapse of systemic candidiasis.     

Potent antifungal agents and use of nanocarriers to improve delivery to the infected site: A systematic review

There are four major classes of antifungals with the predominant mechanism of action being targeting of cell wall or cell membrane. As in other drugs, low solubility of these compounds has led to low bioavailability in target tissues. Enhanced drug dosages have effects such as toxicity, drug–drug interactions, and increased drug resistance by fungi. This article reviews the current state-of-the-art of antifungals, structure, mechanism of action, other usages, and toxic side effects. The emergence of nanoformulations to transport and uniformly release cargo at the target site is a boon in antifungal treatment. The article details research that lead to the development of nanoformulations of antifungals and potential advantages and avoidance of the lacunae characterizing conventional drugs. A range of nanoformulations based on liposomes, polymers are in various stages of research and their potential advantages have been brought out. It could be observed that under similar dosages, test models, and duration, nanoformulations provided enhanced activity, reduced toxicity, higher uptake and higher immunostimulatory effects. In most instances, the mechanism of antifungal activity of nanoformulations was similar to that of regular antifungal. There are possibilities of coupling multiple antifungals on the same nano-platform. Increased activity coupled with multiple mechanisms of action presents for nanoformulations a tremendous opportunity to overcome antifungal resistance. In the years to come, robust methods for the preparation of nanoformulations taking into account the repeatability and reproducibility in action, furthering the studies on nanoformulation toxicity and studies of human models are required before extensive use of nanoformulations as a prescribed drug.     

Immunomodulatory properties of antifungal agents on phagocytic cells

Phagocytic cells, particularly neutrophils and monocytes/macrophages, are the first line and the most effective form of innate host defence against pathogenic fungi. During antifungal therapy these phagocytic cells are also exposed to antifungal agents. In the phagocyte-fungus-antifungal agent interplay, drugs may directly interact with phagocytes through specific pattern recognition receptors, leading to altered antifungal activities. Antifungal agents, through modulation of fungal virulence, may initiate different immune response programs in the phagocytes, leading to antifungal synergism/antagonism or up-regulation of gene expression for a pro-inflammatory response. Additionally, indirect modulation of phagocyte behavior by pretreatment of neutrophils, monocytes, and macrophages with cytokines and exposure to antifungal agents have shown promising findings for combined drug-cytokine therapy that may improve treatment of life-threatening fungal diseases. In this review, we discuss the main in vitro and in vivo immunomodulatory effects of antifungal agents on phagocytes in response to pathogenic fungi, as well as we address underlying immunopharmacologic mechanisms and their potential impact on clinical outcome.     

In vitro and in vivo antifungal activities of FX0685, a novel triazole antifungal agent with potent activity against fluconazole-resistant Candida albicans.

To evaluate the therapeutic potential of FX0685, a new triazole antifungal agent, for the treatment of opportunistic fungal infections, particularly systemic candidiasis and aspergillosis, in vitro and in vivo studies were performed using fluconazole (FLC), itraconazole (ITC) and/or amphotericin B (AMB) as reference drugs. A preliminary in vitro study showed that the antifungal activity of FX0685 against FLC-susceptible Candida albicans, several non-C. albicans Candida species and Cryptococcus neoformans was superior to that of FLC and comparable or superior to those of ITC and AMB, while the anti-Aspergillus fumigatus activity of FX0685 was to varying degrees lower than that of ITC. FX0685 appeared to be comparable to FLC and ITC in the treatment of murine systemic C. albicans and pulmonary A. fumigatus infection, respectively. The biological property of FX0685 was characterized by its potent in vitro and in vivo activity against FLC-resistant C. albicans. Part of this unique property was explained by the finding that it retained potent inhibitory activity against those CYP51 molecules in which amino acid substitutions confer a phenotype of resistance to FLC and some other azole derivatives. All of these results lead to the possibility that FX0685 may be a potential antifungal drug candidate for the treatment of various clinical forms of systemic candidiasis, including those caused by FLC-resistant C. albicans, as well as for the treatment of pulmonary aspergillosis.     

L-carnitine administration in coronary artery disease and cardiomyopathy

Myocardial ischaemia may be defined as a deficiency in cardiac energy supply relative to energy demand. In coronary artery disease (CAD), oxygen supply is limited due to coronary obstruction so energy production is not enough to meet the energy demands for work. Several reports involving about 2500 patients of CAD where carnitine was administered for upto 1 year indicate some beneficial effects. There is reduction in ischaemia showing reduced ST-segment depression and angina, greater effort tolerance and decreased need of cardiac drugs. Carnitine can cause overall improvement in cardiac performance in patients with CAD as well as in cardiomyopathy. More studies are necessary to demonstrate where carnitine can scavenge free radicals apart from its beneficial effect on fatty acid metabolism. Side effects of carnitine are mild nausea and vomiting and dose upto 2 g/day in 3 divided doses may not have any side effects. Intravenous L-carnitine acts rapidly and has no side effects.     

Insights on the anticandidal activity of non-antifungal drugs

The search for new antifungal strategies to overcome Candida infections is essential and a matter of public health, due to the high mortality associated to candidiasis, the increasing incidence of resistance to antifungals and the limited number of drugs available for treatment. Several approaches have been exploited in order to develop new antifungal strategies, e.g. the use of natural products, vaccines, and the combination of an antifungal drug to a non-antifungal substance. Nonetheless, issues related to pharmacokinetic parameters, toxicity and costs have been jeopardizing the discovery of new antifungal drugs. An alternative that could overcome these problems would be treating candidiasis with drugs that have been originally developed to treat other diseases. This strategy, known as drug repositioning or drug repurposing, could diminish the incidence of adverse effects and lower the cost of production, since several steps involved in drug discovery and development have already been accomplished. This review presents a set of known drugs that have been exploited as anticandidal agents, such as antidepressant agents, antiepileptic drugs, statins, among others. These substances affect the growth of Candida spp. in vitro, as well as virulence factors such as morphogenesis and biofilm formation. Moreover, some drugs are able to potentiate the anticandidal activity of known antifungal drugs. Drug repositioning appears as a remarkable alternative to increase the pharmacological arsenal against candidiasis, but further studies must be conducted in order to evaluate the real applicability of known drugs in the treatment of these infections.     

Immunomodulatory Properties of Antifungal Agents on Phagocytic Cells

Phagocytic cells, particularly neutrophils and monocytes/macrophages, are the first line and the most effective form of innate host defence against pathogenic fungi. During antifungal therapy these phagocytic cells are also exposed to antifungal agents. In the phagocyte-fungus-antifungal agent interplay, drugs may directly interact with phagocytes through specific pattern recognition receptors, leading to altered antifungal activities. Antifungal agents, through modulation of fungal virulence, may initiate different immune response programs in the phagocytes, leading to antifungal synergism/antagonism or up-regulation of gene expression for a pro-inflammatory response. Additionally, indirect modulation of phagocyte behavior by pretreatment of neutrophils, monocytes, and macrophages with cytokines and exposure to antifungal agents have shown promising findings for combined drug-cytokine therapy that may improve treatment of life-threatening fungal diseases. In this review, we discuss the main in vitro and in vivo immunomodulatory effects of antifungal agents on phagocytes in response to pathogenic fungi, as well as we address underlying immunopharmacologic mechanisms and their potential impact on clinical outcome.     

New developments in therapy of deep mycoses]

Over the past two decades the incidence of deep mycoses caused by several major groups of fungal pathogens such as Candida spp., aspergilli, Cryptococcus neoformans and zygomycetes has risen steadily. Moreover, opportunistic fungal infections due to Fusarium spp., Trichosporon spp., Pseudallescheria boydii and other emerging pathogens, as well as fluconazole-resistant Candida albicans, all of which are often resistant to existing antifungal drugs, are also encountered more and more frequently. This makes it more difficult for the clinician to achieve successful treatment. Thus there is an urgent need to develop new antifungal agents or formulations with advantages over and/or complimentary to existing drugs. This review focuses on current approaches to antifungal chemotherapy with special reference to the clinical development of new drugs, including (ii) lipid formulations of amphotericin B, (i) second-generation azoles and (iii) antifungal lipopeptides.     

Synergistic effect of deoxyspergualin (DSP) and cyclosporin A (CsA) in the prevention of spontaneous autoimmune diabetes in BB rats

Dose-dependent side effects are frequently observed with immunosuppressive drugs of potential relevance for the immunotherapy of insulin-dependent diabetes mellitus (IDDM), such as CsA and DSP. If CsA and DSP acted synergistically in vivo, their combined use would allow using each compound at lower doses than those required when each drug is given in monotherapy. Consequently, dose-dependent side effects could be reduced and the therapeutic activity maintained or even enforced. Toward this end we studied the effects of combined treatment with CsA and DSP on the course of IDDM in the diabetes-prone (DP)-BB rat. The results show that two ‘low’ doses of CsA (2mg/kg) and DSP (1mg/kg) that are clinically ineffective in suppressing IDDM development in BB rats when administered alone under a prolonged prophylactic regimen (30–105 days old), may successfully prevent, but not cure, the disease when given contemporaneously under the same experimental conditions. The combined treatment was well tolerated, and no side effects were noticed. These data suggest that the combined use of CsA and DSP may deserve consideration for its possible application in the prevention/treatment of human IDDM and other autoimmune diseases.     

Therapeutic monitoring of antidepressant drugs]

Depression is a pathology frequently observed in general medicine (10%). Treatment of depression makes great use of drugs from different pharmacological classes. The optimal posology is difficult to establish, and clinicians prefer to avoid side effects by prescribing low regimen. This study is related to an evaluation of seric antidepressant concentrations in comparison with the daily doses in a large psychiatric population. Side effects of drugs are appreciated by enzymatic determinations.     

Determination of antifungal MICs by a rapid susceptibility assay

A novel microtiter assay for antifungal susceptibility testing was developed. This method has several potential advantages over the M27-A assay of the National Committee for Clinical Laboratory Standards. These include provision of MIC results within 6 to 19 h, graphical display of data, and the availability of objective quantitative endpoints. We refer to the method as the rapid susceptibility assay (RSA). RSA is based on substrate utilization by fungi in the presence of antifungal drugs. Substrate uptake is determined by a colorimetric method, which can be scored by analysis of data obtained from a microplate reader. Variables evaluated in the development of the RSA included inoculum size, incubation period, and efficacy with different classes of antifungal drugs and different yeast isolates. With the rapidly available and quantitative endpoints of the RSA, correlation of MICs and therapeutic drug doses can be evaluated more successfully than they can be evaluated by existing assays.     

Oral candidiasis: clinical features and control

Candidiasis is the most commonly encountered fungal infection, and oral candidiasis is often observed as a local opportunistic infection. Oral candidiasis is clinically divided into three types: acute forms, chronic forms, and Candida-associated lesions. Candida adhesion and multiplication are largely regulated by the local and systemic factors of the host. The local factors include impairment of the oral mucosal integrity, which is usually impaired by hyposalivation, anticancer drugs/radiation for head and neck cancers, denture wearing, a decrease in the oral bacterial population, and poor oral hygiene. Among Candida species, oral candidiasis is mostly caused by Candida albicans (C. albicans), C. glabrata, or C. tropicalis. Oral Candida induces a variety of symptoms, such as oral mucosal inflammation manifesting as an uncomfortable feeling, pain, erythema, erosion, taste abnormalities, and hyperplasia of the oral mucosa. Candida overgrowth in the oral cavity may disseminate to distant organs. Therefore, in order to avoid the sequelae of systemic candidiasis, oral candidiasis should be rapidly controlled. Oral candidiasis is usually treated by the local application of antifungal drugs. However, oral candidiasis occasionally escapes the control of such local treatment due to the development of multi-drug resistant Candida strains and species or due to the suppression of salivation or cellular immune activity. When drug-resistant strains are suspected as the pathogens and when the host is generally compromised, the oral administration of combinations of antifungal drugs, enhancement of cellular immune activity, and improvement of the nutritional condition are recommended.     

Hippocampal alpha 7 and alpha 4 beta 2 nicotinic receptors and working memory

Nicotine and other nicotinic receptor agonists have been found in a variety of studies to improve memory, while nicotinic receptor blockade can impair memory. The critical neural mechanisms for nicotinic involvement with memory are still under investigation. Initial evidence supports the involvement of the ventral hippocampus. Lesions in this area block nicotine-induced memory improvement and mecamylamine-induced impairment. Local ventral hippocampal application of the nicotinic channel blocker mecamylamine impairs memory in the 8-arm radial maze. Both alpha 4 beta 2 and alpha 7 nicotinic receptors seem to be involved. Ventral hippocampal infusions of high doses of the alpha 4 beta 2 nicotinic antagonist dihydro-beta-erythrodine (DH beta E) and the alpha 7 nicotinic antagonist methyllycaconitine (MLA) impair memory performance on the 8-arm radial maze. However, high doses of these drugs may limit specificity and they cause preconvulsant effects, which in themselves may affect memory. The current study used the more challenging 16-arm radial maze to determine the effects of lower doses of these drugs on memory and to differentiate effects on working and reference memory. Adult female Sprague-Dawley rats were trained on a working and reference memory task in the 16-arm radial maze and then were implanted with bilateral chronic guide cannulae directed to the ventral hippocampus. After recovery from surgery, the rats received acute intrahippocampal infusions of dose combinations of DH beta E and MLA. In the first study, DH beta E (0 and 6.75 microg/side) and MLA (0, 6.75, 13.5 and 27 microg/side) were administered in a counter-balanced order. In the second study, lower doses of DH beta E (0, 1.6375, 3.275 and 6.75 microg/side) were administered alone or with MLA (0 and 6.75 microg/side) in a counter-balanced order. In the first study, DH beta E caused a significant increase in both working and reference memory errors. MLA at a dose of 27 microg/side caused a significant increase in working memory errors, but this dose had no significant effect on reference memory errors. Interestingly, no additive effects were seen with combined administration of DH beta E and MLA in this study, and at the doses used, no effects were seen on response latency. In the second study, lower doses of DH beta E did not cause a significant deficit in working memory performance. Co-administration of MLA with these subthreshold doses did precipitate a memory impairment. The current results confirm the specificity of the memory deficits caused by these drugs. These results support the involvement of alpha 4 beta 2 and alpha 7 nicotinic receptors in the ventral hippocampus as being critical for memory function.     

Endothelin antagonist-induced coronary and systemic arteritis in the beagle dog

Two endothelin antagonists, ZD1611 (3-[4-[3-(3-methoxy-5-methylpyrazin-2-ylsulfamoyl)-2-pyridyl]phenyl]-2,2-dimethylpropanoic acid) and ZD2574 (2-(4-isobutylphenyl)-N-(3-methoxy-5-methylpyrazin-2-yl)pyridine-3-sulfonamide), selective for the ET(A) receptor and intended for use in pulmonary hypertension, were tested in Beagle dogs at various doses for periods of up to 4 weeks. These studies included in vivo telemetric hemodynamic assessment, full histopathological and ultrastructural pathological evaluation of coronary arteries. Both drugs produced arteritis in small- and medium-sized coronary arteries after single or multiple doses, some of which were at or below the ED50. The distribution of lesions was predominantly in extramural arteries over the atria and atrioventricular groove of the right side of the heart and consisted of epicardial hemorrhage and arteritis. Systemic arteritis was also present at a lower incidence than the coronary arteritis, was located at different sites and appeared inconsistently. Ultrastructural changes in coronary arteries suggested that damage was the result of mechanical factors. Although these patterns of vascular injury possessed features in common with those induced in dogs by high doses of vasodilating antihypertensive drugs and inotropic agents, they were atypical, as there was no left ventricular myocardial necrosis, papillary muscle damage, or subendocardial hemorrhage suggestive of ischaemia or excessive inotropism. Moreover, physiological monitoring showed no evidence of exaggerated systemic hypotension or reflex tachycardia at doses associated with vascular damage. Consequently, the changes might be the result of a localized pharmacological process such as intense, prolonged vasodilatation in unsupported arteries that are well endowed with endothelin receptors and particularly sensitive to endothelin antagonism.