Topical treatment of cutaneous leishmaniasis

Review of Leishmaniasis Treatment: Can We See the Forest through the Trees?

There are three known clinical syndromes of leishmaniasis: cutaneous (CL), mucocutaneous (MCL), and visceral disease (VL). In MCL and VL, treatment must be systemic (either oral or intravenous), while CL treatment options vary and include observation-only localized/topical treatment, oral medications, or parenteral drugs. Leishmaniasis treatment is difficult, with several factors to be considered. First, the efficacy of treatments varies among different species of parasites prevalent in different areas on the globe, with each species having a unique clinical presentation and resistance profile. Furthermore, leishmaniasis is a neglected tropical disease (NTD), resulting in a lack of evidence-based knowledge regarding treatment. Therefore, physicians often rely on case reports or case series studies, in the absence of randomized controlled trials (RCT), to assess treatment efficacy. Second, defining cure, especially in CL and MCL, may be difficult, as death of the parasite can be achieved in most cases, while the aesthetic result (e.g., scars) is hard to predict. This is a result of the biological nature of the disease, often diagnosed late in the course of disease (with possible keloid formation, etc.). Third, physicians must consider treatment ease of use and the safety profile of possible treatments. Thus, topical or oral treatments (for CL) are desirable and promote adherence. Fourth, the cost of the treatment is an important consideration. In this review, we aim to describe the diverse treatment options for different clinical manifestations of leishmaniasis. For each currently available treatment, we will discuss the various considerations mentioned above (efficacy, ease of use, safety, and cost).

Amine-Linked Flavonoids as Agents Against Cutaneous Leishmaniasis

We have designed, synthesized, and characterized a library of 38 novel flavonoid compounds linked with amines. Some of these amine-linked flavonoids have potent in vitro activity against parasites that cause cutaneous leishmaniasis, a tropical disease endemic in 80 countries worldwide. The most promising candidate, FM09h, was highly active with IC₅₀ of 0.3 μM against L. amazonensis, L. tropica and L. braziliensis amastigotes. It was metabolically stable (39% and 66% of FM09h remaining after 30-minute incubation with human and rat liver microsomes respectively). In L. amazonensis LV78 cutaneous leishmaniasis mouse model, intralesional injection of FM09h (10 mg/kg, once every 4 days for 8 times) demonstrated promising effect in reducing the footpad lesion thickness by 72%, displaying an efficacy comparable to SSG (63%).

Therapeutic advances in the topical treatment of cutaneous leishmaniasis: A review

Cutaneous leishmaniasis has been endemic since decades. Millions of cases are reported worldwide specially in developing and underdeveloped countries. There are 2 major types of cutaneous leishmaniasis based on the causating species found in different regions of the world. These include New and Old World cutaneous leishmaniasis, which are self-healing, but if not treated, these may cause severe scars and many other complications like mucosal involvement. The conventional gold standard treatment for both types is mainly intralesional or parenteral administration of antimonial. Lately, a great deal of research has been done on development of topical treatment based on single agent or combination therapy. This review summarizes the current state of literature regarding therapeutic outcome of topical treatment against cutaneous leishmaniasis caused by different species in different regions.

Development and Characterization of a Semi-Solid Dosage Form of Meglumine Antimoniate for Topical Treatment of Cutaneous Leishmaniasis

Cutaneous leishmaniasis (CL) is treated with painful intralesional injections of meglumine antimoniate (MA). With the aim of developing an alternative topical treatment for CL, a gel-based formulation with 30% MA was prepared and its physicochemical properties, stability and rheological behavior were studied. The following were assessed: drug release on propylene hydrophilic membranes ex vivo human skin permeation, tolerance in healthy volunteers, cytotoxicity in three cell lines and anti-leishmanial activity against Leishmania infantum promastigotes and amastigotes. The MA gel formulation was found to have suitable pH, and good spreadability and stability. Low quantities of pentavalent antimony (Sb^V) were observed in release and permeation tests, whereas retention was high in both non-damaged and damaged skin (71,043.69 ± 10,641.57 and 10,728 ± 2254.61 µg/g/cm² of Sb^V, respectively). The formulation did not have a toxic effect on the cell lines, and presented lower Sb^V IC₅₀ values against amastigotes (15.76 ± 4.81 µg/mL) in comparison with the MA solution. The high amount of drug retained in the skin and the Sb^V IC₅₀ values obtained suggest that this semi-solid dosage form has potential as an alternative treatment of CL.

Exploiting knowledge on pharmacodynamics-pharmacokinetics for accelerated anti-leishmanial drug discovery/development

Introduction: Being on the top list of neglected tropical diseases, leishmaniasis has been marked for elimination by 2020. In the light of small armamentarium of drugs and their associated drawbacks, the understanding of pharmacodynamics and/or pharmacokinetics becomes a priority to achieve and sustain disease elimination. Areas covered: The authors have looked into pharmacological aspects of existing and emerging drugs for treatment of leishmaniasis. An in-depth understanding of pharmacodynamics and pharmacokinetics (PKPD) provides a rationale for drug designing and optimizing the treatment strategies. It forms a key to prevent drug resistance and avoid drug-associated adverse effects. The authors have compiled the researches on the PKPD of different anti-leishmanial formulations that have the potential for improved and/or effective disease intervention. Expert opinion: Understanding the pharmacological aspects of drugs forms the basis for the clinical application of novel drugs. Tailoring drug dosage and individualized treatment can avoid the adverse events and bridge gap between the in vitro models and their clinical application. An integrated approach, with pragmatic use of technological advances can improve phenotypic screening and physiochemical properties of novel drugs. Concomitantly, this can serve to improve clinical efficacies, reduce the incidence of relapse and accelerate the drug discovery/development process for leishmaniasis elimination.

Development and evaluation of zinc phthalocyanine nanoemulsions for use in photodynamic therapy for Leishmania spp

Photodynamic therapy (PDT) combines light with photosensitizers (PS) for production of reactive oxygen species (ROS) that can kill infectious microorganisms such as bacteria, fungi and protozoa. The application of nanotechnology has enabled the advancement of PDT because many PS are insoluble in water, necessitating a nanocarrier as a physiologically acceptable carrier. Nanoemulsions are efficient nanocarriers for solubilizing liposoluble drugs, like the PS, in water. Cutaneous (CL) and mucocutaneous leishmaniasis (ML) are caused by different species of the genus Leishmania, transmitted to humans by sandfly bites. Parasites are hosted in skin macrophages producing ulcerative lesions. Thus, a topical treatment, effective and inexpensive, for CL and ML is preferable to systemic interventions. There are topical treatments like paromomycin and amphotericin B, but they have many local side effects or a very high cost, limiting their use. This work aimed to develop a zinc phthalocyanine (photosensitizer) oil-in-water nanoemulsion, essential clove oil and polymeric surfactant (Pluronic^® F127) for the formulation of a topical delivery system for use in PDT against Leishmania amazonensis and Leishmania infantum. The nanoemulsion was produced by a high-energy method and characterized by size, polydispersity, morphology, pH, content and stability studies. The toxicity in the dark and the photobiological activity of the formulations were evaluated in vitro for Leishmania and macrophages. The formulation presented was pH compatible with topical use, approximately 30 nm in size, with a polydispersity index ≤0.1 and remained stable at room and refrigerator temperature during the stability study (60 days). The zinc phthalocyanine nanoemulsion is effective in PDT against Leishmania spp.; use against skin infections can be a future application of this topical formulation, avoiding the use of oral or injectable medications, decreasing systemic adverse effects.

Diagnosis and Treatment of Leishmaniasis: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH)

It is important to realize that leishmaniasis guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. The IDSA and ASTMH consider adherence to these guidelines to be voluntary, with the ultimate determinations regarding their application to be made by the physician in the light of each patient's individual circumstances.

Combined suboptimal schedules of topical paromomycin, meglumine antimoniate and miltefosine to treat experimental infection caused by Leishmania (Viannia) braziliensis

OBJECTIVES

This study aimed to evaluate the efficacy of binary combinations of suboptimal schedules of drugs with different administration routes (topical paromomycin, intramuscular meglumine antimoniate and oral miltefosine) to treat animals infected with Leishmania (Viannia) braziliensis.

METHODS

Hamsters were inoculated with L. (V.) braziliensis and after ulceration of lesions, divided into seven groups: untreated control, paromomycin, miltefosine, meglumine antimoniate, meglumine antimoniate + paromomycin, miltefosine + paromomycin and meglumine antimoniate + miltefosine. Meglumine antimoniate and miltefosine were administered at low doses and topical paromomycin at a single daily application regimen. The animals were treated for 20 consecutive days (meglumine antimoniate and/or paromomycin) and/or 10 alternate days (miltefosine). Lesion sizes were determined weekly. Upon completion of treatment, parasites were recovered from skin lesions and spleens and evaluated by limiting dilution assay.

RESULTS

The combinations of a once daily application of paromomycin with low doses of miltefosine or meglumine antimoniate yielded higher efficacies in reducing the parasite load as well as lesion size when compared with any of these drugs administered as monotherapy regimens at the same suboptimal schedules.

CONCLUSIONS

Considering the parameters evaluated, the combinations of a systemic therapy with topical treatment were more effective than monotherapy with each of these drugs. These combinations may represent an alternative combination strategy for the treatment of leishmaniasis caused by L. (V.) braziliensis.

Rapid healing of cutaneous leishmaniasis by high-frequency electrocauterization and hydrogel wound care with or without DAC N-055: a randomized controlled phase IIa trial in Kabul

Background

Anthroponotic cutaneous leishmaniasis (CL) due to Leishmania (L.) tropica infection is a chronic, frequently disfiguring skin disease with limited therapeutic options. In endemic countries healing of ulcerative lesions is often delayed by bacterial and/or fungal infections. Here, we studied a novel therapeutic concept to prevent superinfections, accelerate wound closure, and improve the cosmetic outcome of ACL.

Methodology/Principal Findings

From 2004 to 2008 we performed a two-armed, randomized, double-blinded, phase IIa trial in Kabul, Afghanistan, with patients suffering from L. tropica CL. The skin lesions were treated with bipolar high-frequency electrocauterization (EC) followed by daily moist-wound-treatment (MWT) with polyacrylate hydrogel with (group I) or without (group II) pharmaceutical sodium chlorite (DAC N-055). Patients below age 5, with facial lesions, pregnancy, or serious comorbidities were excluded. The primary, photodocumented outcome was the time needed for complete lesion epithelialization. Biopsies for parasitological and (immuno)histopathological analyses were taken prior to EC (1^st), after wound closure (2^nd) and after 6 months (3^rd). The mean duration for complete wound closure was short and indifferent in group I (59 patients, 43.1 d) and II (54 patients, 42 d; p = 0.83). In patients with Leishmania-positive 2^nd biopsies DAC N-055 caused a more rapid wound epithelialization (37.2 d vs. 58.3 d; p = 0.08). Superinfections occurred in both groups at the same rate (8.8%). Except for one patient, reulcerations (10.2% in group I, 18.5% in group II; p = 0.158) were confined to cases with persistent high parasite loads after healing. In vitro, DAC N-055 showed a leishmanicidal effect on pro- and amastigotes.

Conclusions/Significance

Compared to previous results with intralesional antimony injections, the EC plus MWT protocol led to more rapid wound closure. The tentatively lower rate of relapses and the acceleration of wound closure in a subgroup of patients with parasite persistence warrant future studies on the activity of DAC N-055.

Trial Registration

ClinicalTrails.gov NCT00947362

In many countries of the Middle East such as Afghanistan, cutaneous leishmaniasis is a highly prevalent, chronic and stigmatizing skin disease. Poor hygiene conditions frequently aggravate the lesions due to bacterial and fungal superinfections. Classical treatments with injections of pentavalent antimony are hampered by costs, side effects, resistance development, supply and manufactural quality problems. In the present study on Afghan patients with Leishmania tropica-induced skin lesions we evaluated the clinical effect of an initial removal of lesion tissue by electrocoagulation using a bipolar high-frequency electrosurgery instrument, followed by daily moist wound treatment with or without a preparation of pharmaceutical sodium chlorite (DAC N-055). DAC N-055 is a compound with anti-infective, immunomodulatory and tissue repair-promoting effects. Our analysis revealed that the carefully performed moist wound treatment led to a rapid healing of the wounds within an average period of 6 weeks, even in the absence of the sodium chlorite preparation. This is considerably faster than the time spans previously reported for local or systemic antimony treatment. We believe that the current standard for local care of chronic wounds should also be applied to Leishmania skin lesions. If combined with an initial single high-frequency electrocoagulation, it is a highly effective, inexpensive and well-tolerated treatment option for cutaneous leishmaniasis.

Efficacy of paromomycin ointment in the treatment of cutaneous leishmaniasis: results of a double-blind, randomized trial in Isfahan, Iran

Although pentavalent antimonials are often used in the first-line treatment of cutaneous leishmaniasis (CL), they have several adverse effects. Intralesional administration of antimonials and other antileishmanial drugs can be painful. In the present, double-blind, randomized study, to determine if topical treatment with paromomycin is effective in the treatment of CL, 35 cases of CL were treated, twice daily for 30 days, with a commercial skin-care lotion containing 10% urea (the placebo) and another 30 were similarly treated with the same lotion to which paromomycin sulphate had been added (to give a concentration of 15%). Each case was assessed clinically 7, 14, 21 and 30 days after treatment began, and parasitologically 30 and 60 days after the initiation of treatment. Five (17%) and five (17%) of the cases treated with paromomycin showed complete healing, with the apparent clearance of amastigotes from their lesions, 30 and 60 days after treatment began, respectively. At the same time-points, however, the lesions on six (17%) and seven (20%) of the cases in the placebo group, respectively, also appeared to have healed completely. Ointment containing 15% paromomycin therefore appears ineffective in the treatment of CL, at least when applied twice daily for 30 days to the lesions of cases from an endemic area of Isfahan, Iran.

Topical paromomycin with or without gentamicin for cutaneous leishmaniasis

BACKGROUND

There is a need for a simple and efficacious treatment for cutaneous leishmaniasis with an acceptable side-effect profile.

METHODS

We conducted a randomized, vehicle-controlled phase 3 trial of topical treatments containing 15% paromomycin, with and without 0.5% gentamicin, for cutaneous leishmaniasis caused by Leishmania major in Tunisia. We randomly assigned 375 patients with one to five ulcerative lesions from cutaneous leishmaniasis to receive a cream containing 15% paromomycin-0.5% gentamicin (called WR 279,396), 15% paromomycin alone, or vehicle control (with the same base as the other two creams but containing neither paromomycin nor gentamicin). Each lesion was treated once daily for 20 days. The primary end point was the cure of the index lesion. Cure was defined as at least 50% reduction in the size of the index lesion by 42 days, complete reepithelialization by 98 days, and absence of relapse by the end of the trial (168 days). Any withdrawal from the trial was considered a treatment failure.

RESULTS

The rate of cure of the index lesion was 81% (95% confidence interval [CI], 73 to 87) for paromomycin-gentamicin, 82% (95% CI, 74 to 87) for paromomycin alone, and 58% (95% CI, 50 to 67) for vehicle control (P<0.001 for each treatment group vs. the vehicle-control group). Cure of the index lesion was accompanied by cure of all other lesions except in five patients, one in each of the paromomycin groups and three in the vehicle-control group. Mild-to-moderate application-site reactions were more frequent in the paromomycin groups than in the vehicle-control group.

CONCLUSIONS

This trial provides evidence of the efficacy of paromomycin-gentamicin and paromomycin alone for ulcerative L. major disease. (Funded by the Department of the Army; ClinicalTrials.gov number, NCT00606580.).

Drug delivery systems for the topical treatment of cutaneous leishmaniasis

INTRODUCTION

The parenteral administration of pentavalent antimonials for the treatment of all forms of leishmaniasis, including cutaneous leishamniasis (CL), has several limitations. Therapy is long, requiring repeated doses and the adverse reactions are frequent. Topical treatment is an attractive alternative for CL, offering significant advantages over systemic therapy: fewer adverse effects, ease of administration, and lower costs.

AREAS COVERED

This review covers, from 1984 to the present, the progress achieved for the development of topical treatment for CL, using different drugs such as paromomycin (PA), imiquimod, amphotericin B (AmB), miltefosine, and buparvaquone. PA is the most commonly studied drug, followed by AmB and Imiquimod. These drugs were incorporated in conventional dosage forms or loaded in lipid nanocarries, which have been used mainly for improved skin delivery and antileishmanial activity.

EXPERT OPINION

Developing an effective topical treatment for CL using these antileishmanial drugs still remains a great challenge. Insights into the most promising delivery strategies to improve treatment of CL with PA and AmB using conventional dosage forms, lipid nanocarriers, and combined therapy are presented and discussed. The results obtained with combined therapy and alternative delivery systems are promising perspectives for improving topical treatment of CL.

Topical buparvaquone formulations for the treatment of cutaneous leishmaniasis

As the part of a study to develop buparvaquone (BPQ) formulations for the treatment of cutaneous leishmaniasis, the topical delivery of BPQ and one of its prodrugs from a range of formulations was evaluated. In previous studies, BPQ and its prodrugs were shown to be potent antileishmanials in-vitro, with ED50 values in the nanomolar range. 3-Phosphono-oxymethyl-buparvaquone (3-POM-BPQ) was the most potent antileishmanial and was chosen, together with the parent drug, for further investigation. The ability of the parent and prodrug formulations to cross human and murine skin was tested in-vitro using the Franz diffusion cells. Formulations intended for topical application containing either BPQ or 3-POM-BPQ were developed using excipients that were either acceptable for topical use (GRAS or FDA inactive ingredients) or currently going through the regulatory process. BPQ was shown to penetrate both human epidermal membranes and full thickness BALB/c skin from a range of formulations (gels, emulsions). Similarly, 3-POM-BPQ penetrated full-thickness BALB/c skin from several gel formulations. In-vitro binding studies showed that BPQ bound melanin in a dose-dependent manner and preferably bound to delipidized skin over untreated BALB/c skin (on a weight to weight basis). The results confirm that BPQ and its prodrug 3-POM-BPQ can penetrate the skin from several formulations, making them potentially interesting candidates for further investigation of topical formulations using in-vivo models of cutaneous leishmaniasis.

WR279,396, a third generation aminoglycoside ointment for the treatment of Leishmania major cutaneous leishmaniasis: a phase 2, randomized, double blind, placebo controlled study

Background

Cutaneous leishmaniasis (CL) is a disfiguring disease that confronts clinicians with a quandary: leave patients untreated or engage in a complex or toxic treatment. Topical treatment of CL offers a practical and safe option. Accordingly, the treatment of CL with WR279,396, a formulation of paromomycin and gentamicin in a hydrophilic base, was investigated in a phase 2 clinical study in Tunisia and France.

Methods

A phase 2, randomized, double blind, vehicle-controlled study was conducted to assess the safety and efficacy of topical WR279,396 when applied twice a day for 20 days as treatment for parasitologically confirmed CL. The study protocol established the primary efficacy end point as complete clinical response (CCR) defined as 50% or greater reduction in the ulceration size of an index lesion by day 50 (D50) followed by complete re-epithelialization by D100, and no relapse through D180.

Results

Ninety-two subjects were randomized. Leishmania major was identified in 66 of 68 isolates typed (97%). In the intent-to-treat population, 47 of 50 WR279,396 treated participants (94%) met the definition of CCR, compared with 30 of 42 vehicle-placebo participants (71%) [p = 0.0045]. Erythema occurred in 30% and 24% of participants receiving WR279,396 and placebo, respectively [p = 0.64]. There was no clinical or laboratory evidence of systemic toxicity.

Conclusion

Application of WR279,396 for 20 days was found to be safe and effective in treating L. major CL, and offers great potential as a new, simple, easily applicable, and inexpensive topical therapy for this neglected disease.

Trial Registration

ClinicalTrials.gov NCT00703924

Cutaneous leishmaniasis is due to a small parasite (Leishmania) that creates disfiguring sores, and affects more than one million persons (mainly children) each year. Treating lesions with a cream—instead of with injections as currently done—would greatly improve the well-being of affected patients. No cream formulation that would be efficient and would not create important skin irritation has been identified yet. Here, we tested a new cream formulation (WR279,396) containing paromomycin and gentamicin, two members of a well-known family of antibacterial antibiotics (aminoglycosides). Injectable paromomycin is efficient in other forms of the disease (visceral leishmaniasis). This was a carefully monitored study (phase 2) involving mainly children in Tunisia and France. The cream was applied twice a day for 20 days. The proportion of patients treated with the paromomycin-containing cream (active formulation) that cured (94%) was higher than that observed (71%) in patients treated with a cream that did not contain the active product (placebo formulation). Local irritation affected less than one-third of the patients and was usually mild. This new cream formulation was safe and effective in treating cutaneous leishmaniasis, thereby providing a new, simple, easily applicable, and inexpensive treatment for this neglected disease.

Is paromomycin an effective and safe treatment against cutaneous leishmaniasis? A meta-analysis of 14 randomized controlled trials

Background

High cost, poor compliance, and systemic toxicity have limited the use of pentavalent antimony compounds (SbV), the treatment of choice for cutaneous leishmaniasis (CL). Paromomycin (PR) has been developed as an alternative to SbV, but existing data are conflicting.

Methodology/Principal Findings

We searched PubMed, Scopus, and Cochrane Central Register of Controlled Trials, without language restriction, through August 2007, to identify randomized controlled trials that compared the efficacy or safety between PR and placebo or SbV. Primary outcome was clinical cure, defined as complete healing, disappearance, or reepithelialization of all lesions. Data were extracted independently by two investigators, and pooled using a random-effects model. Fourteen trials including 1,221 patients were included. In placebo-controlled trials, topical PR appeared to have therapeutic activity against the old world and new world CL, with increased local reactions, when used with methylbenzethonium chloride (MBCL) compared to when used alone (risk ratio [RR] for clinical cure, 2.58 versus 1.01: RR for local reactions, 1.60 versus 1.07). In SbV-controlled trials, the efficacy of topical PR was not significantly different from that of intralesional SbV in the old world CL (RR, 0.70; 95% confidence interval, 0.26–1.89), whereas topical PR was inferior to parenteral SbV in treating the new world CL (0.67; 0.54–0.82). No significant difference in efficacy was found between parenteral PR and parenteral SbV in the new world CL (0.88; 0.56–1.38). Systemic side effects were fewer with topical or parenteral PR than parenteral SbV.

Conclusions/Significance

Topical PR with MBCL could be a therapeutic alternative to SbV in selected cases of the old world CL. Development of new formulations with better efficacy and tolerability remains to be an area of future research.

Millions of people worldwide are suffering from cutaneous leishmaniasis that is caused by parasites of the genus Leishmania. Although pentavalent antimony compounds are the treatment of choice, their use is limited by high cost, poor compliance, and systemic toxicity. Paromomycin was developed to overcome such limitations. However, there is no consensus on its efficacy. This meta-analysis assessed the efficacy and safety of paromomycin compared with placebo and pentavalent antimony compounds. Fourteen randomized controlled trials, including 1,221 patients, met our selection criteria. Topical paromomycin appeared to have therapeutic activity against the old world and new world cutaneous leishmaniasis, with increased local reactions, when combined with methylbenzethonium chloride. Topical paromomycin was not significantly different from intralesional pentavalent antimony compounds in treating the old world form, whereas it was inferior to parenteral pentavalent antimony compounds in treating the new world form. However, a similar efficacy was found between parenteral paromomycin and pentavalent antimony compounds in treating the new world form. Fewer systemic side effects were observed with topical and parenteral paromomycin than pentavalent antimony compounds. These results suggest that topical paromomycin with methylbenzethonium chloride could be a therapeutic alternative to pentavalent antimony compounds for selected cases of the old world cutaneous leishmaniasis.

A review of photodynamic therapy in cutaneous leishmaniasis

We present a review of six clinical studies investigating the use of photodynamic therapy (PDT) using porphyrin precursors for the treatment of Old World cutaneous leishmaniasis (CL). Thirty-nine patients with a total of 77 lesions received PDT using a range of treatment schedules following topical application of aminolevulinic acid (ALA) or methyl-aminolevulinate (MAL). The tissue response to PDT is accompanied by a mild burning sensation, erythema and reversible hypo- and hyperpigmentation. Few mechanistic studies have addressed the principles underlying the use of PDT for CL. All six reviewed papers suggest that PDT with porphyrin precursors is relatively effective in treating CL. Data are still limited, and PDT cannot at this point be recommended in routine clinical practice. The mechanism of action of this promising therapeutic modality needs to investigated further and additional controlled trials need to be performed.

Optimization of topical therapy for Leishmania major localized cutaneous leishmaniasis using a reliable C57BL/6 Model

Background

Because topical therapy is easy and usually painless, it is an attractive first-line option for the treatment of localized cutaneous leishmaniasis (LCL). Promising ointments are in the final stages of development. One main objective was to help optimize the treatment modalities of human LCL with WR279396, a topical formulation of aminoglycosides that was recently proven to be efficient and safe for use in humans.

Methodology/Principal Findings

C57BL/6 mice were inoculated in the ear with luciferase transgenic L. major and then treated with WR279396. The treatment period spanned lesion onset, and the evolution of clinical signs and bioluminescent parasite loads could be followed for several months without killing the mice. As judged by clinical healing and a 1.5-3 log parasite load decrease in less than 2 weeks, the 94% efficacy of 10 daily applications of WR279396 in mice was very similar to what had been previously observed in clinical trials. When WR279396 was applied with an occlusive dressing, parasitological and clinical efficacy was significantly increased and no rebound of parasite load was observed. In addition, 5 applications under occlusion were more efficient when done every other day for 10 days than daily for 5 days, showing that length of therapy is a more important determinant of treatment efficacy than the total dose topically applied.

Conclusions/Significance

Occlusion has a significant adjuvant effect on aminoglycoside ointment therapy of experimental cutaneaous leishmaniasis (CL), a concept that might apply to other antileishmanial or antimicrobial ointments. Generated in a laboratory mouse-based model that closely mimics the course of LCL in humans, our results support a schedule based on discontinuous applications for a few weeks rather than several daily applications for a few days.

When initiating the cutaneous disease named cutaneous leishmaniasis (CL), Leishmania parasites develop within the parasitophorous vacuoles of phagocytes residing in and/or recruited to the dermis, a process leading to more or less chronic dermis and epidermis-damaging inflammatory processes. Topical treatment of CL could be a mainstay in its management. Any improvements of topicals, such as new vehicles and shorter optimal contact regimes, could facilitate their use as an ambulatory treatment. Recently, WR279396, a third-generation aminoglycoside ointment, was designed with the aim to provide stability and optimal bioavailability for the molecules expected to target intracellular Leishmania. Two endpoints were expected to be reached: i) accelerated clearance of the maximal number of parasites, and ii) accelerated and stable repair processes without scars. A mouse model of CL was designed: it relies on the intradermal inoculation of luciferase-expressing Leishmania, allowing for in vivo bioluminescence imaging of the parasite load fluctuation, which can then be quantified simultaneously with the onset and resolution of clinical signs. These quantitative readout assays, deployed in real time, provide robust methods to rapidly assess efficacy of drugs/compounds i) to screen treatment modalities and ii) allow standardized comparison of different therapeutic agents.

Cutaneous leishmaniasis: Clinical report of two cases and review of the recent literature

With 1-1.5 million cases reported every year cutaneous leishmaniasis represents an increasing health problem. The course of cutaneous leishmaniasis varies from a single self-healing ulcer to a persistent ulcer or progressive mucosal disease with nasopharyngeal destruction. An enormous array of topical and systemic treatment modalities has been endorsed. The response to treatment depends on the species of parasite as well as the host's immunological and genetic status. Species-specific treatment guidelines based on evidence from controlled studies are highly desirable. We present two cases of cutaneous leishmaniasis, one in a child and one during pregnancy, reviewing various diagnostic and therapeutic measures with special attention to problems in young and pregnant patients.

Cutaneous leishmaniasis in the returning traveler

Infection with protozoan parasites of the genus Leishmania leads to a wide variety of clinical disease syndromes called leishmaniasis, or more appropriately the leishmaniases. The three major clinical syndromes are cutaneous leishmaniasis, mucosal leishmaniasis, and visceral leishmaniasis. All three of these syndromes have been documented in returning travelers. This article focuses on cutaneous leishmaniasis with some comment on mucosal leishmaniasis.

Topical chemotherapy of cutaneous Leishmaniasis

Cutaneous leishmaniasis (CL) is one of the most important causes of chronic ulcerative skin lesions. The disease is endemic in many parts of the world, presenting a range of clinical forms - acute, chronic, recurrent and diffuse(1). Several species of Leishmania are involved, including L. major, L. tropica and L. aethiopica in the Old World, and several members of the L. braziliensis and L. mexicana complexes in the New World. Some forms of the disease produce only mild, self-limited lesions, while at the other extreme are the destructive mucocutaneous forms caused by L. braziliensis and L. panamensis(1-7). In all cases, chemotherapy tends to be difficult - often requiring prolonged parenteral administration of toxic drugs such as pentavalent antimonials or amphotericin B. Such drugs are also expensive and relatively inefficient in the sense that much of the active ingredient is excreted by the patient before reaching its target. Consequently, there is renewed interest in the development of active formulations suitable for topical application directly onto the lesions.

Leishmaniasis cutánea

Leishmaniases are diseases caused by infection by protozoa of the genus Leishmania. Cutaneous leishmaniasis caused by Leishmania infantum is frequent in Spain, especially in certain geographic areas. Diagnosis of cutaneous leishmaniasis is difficult because of the varied symptoms and because making cultures of this parasite is complicated. There are also different therapeutic, medical and surgical options, none of which is fully satisfactory. We review the most significant agents of cutaneous leishmaniasis in Spain.

Challenges and new discoveries in the treatment of leishmaniasis

Leishmaniasis is a parasitic disease caused by a hemoflagellate, Leishmania spp. The parasite is transmitted by the bite of an infected female phlebotomine sandfly. The disease is prevalent throughout the world and in at least 88 countries. Human leishmanial infections may manifest in any of the four most common forms. Depending on the causative species, it can manifest as cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), diffused cutaneous leishmaniasis (DCL), or visceral leishmaniasis (VL). Although there are nearly 25 compounds having antileishmanial effects, only a few are used for humans and most of these are parenteral. The oldest was urea stibamine, developed in India in 1922. The original drug had severe toxic effects, and later on its pentavalent compounds were prepared, which remained the sole treatment modality for several decades and saved millions of lives. However, reports of unresponsiveness to pentavalent sodium antimony gluconate (SAG) started in the 1970s, and in some parts of India about a quarter of kala-azar cases are reported to have developed resistance even to its higher doses. This development led to successful clinical trials of pentamidine and amphotericine B. The latter, an antifungal compound, was also found to be highly nephrotoxic, and to minimize these side effects various colloidal and lipid formulations have been prepared. These preparations are comparatively safe but are exorbitantly costly. In the past two decades, more focus has been given to finding oral drugs to minimize injection-associated complications, including blood-borne infection. Various drugs were reported effective, including antifungal ketoconazole. However, the most promising drug found is an anticancer compound, miltefosine, that belongs to the alkylphosphocholine group. The drug has undergone experimental and clinical trials and found to be 94%-97% effective. However, the drug cannot be given during pregnancy and shows severe gastrointestinal side effects. Moreover, its cost will be another limiting factor. Other drugs such as paromomycin, allopurinol, and sitamaquine have been reported with variable cure rates. Because of these limitations, a combination therapy, preferably coupled with specific parasite enzyme inhibitors, is the only hope.

Delivery strategies for antiparasitics

Optimisation of drug carrier systems and drug delivery strategies that take into account the peculiarities of individual infectious agents and diseases are key elements of modern drug development. In the following, different aspects of a rational design for antiparasitic drug formulation will be reviewed, covering delivery systems such as nano- and microparticles, liposomes, emulsions and microemulsions, cochleates and bioadhesive macromolecules. Functional properties for each carrier system will be discussed as well as their therapeutic efficacy for parasitic diseases, including leishmaniasis, human African trypanosomiasis, human cryptosporidiosis, malaria and schistosomiasis. Critical issues for the application of drug carrier systems will be discussed, focusing on biopharmaceutical and pathophysiological parameters such as routes of application, improvement of body distribution and targeting intracellularly persisting pathogens.

Non-ulcerative cutaneous leishmaniasis in Honduras fails to respond to topical paromomycin

A double-'blind', placebo-controlled trial of topical therapy with 15% paromomycin (aminosidine) and 10% urea in white paraffin was carried out on 53 patients with non-ulcerating cutaneous leishmaniasis in Honduras. Although the treatment was not effective, several unexpected findings emerged from the trial. Leishmania mexicana was found to be the cause of many of the skin lesions in one of the 2 study sites. These lesions were clinically indistinguishable from those caused by L. chagasi, the aetiologic agent previously found for this form of leishmaniasis. This is the first documented report of L. mexicana in Honduras.

Treatment of New World cutaneous and mucosal leishmaniases

The most extensive investigations of treatment of New World cutaneous leishmaniasis have been performed against L. panamensis disease in Colombia, and the relative value of regimens shown there may be instructive for disease from other areas. In Colombia, a 90-95% cure rate was achieved with three different drug regimens: The standard regimen of pentavalent antimony (20 mg/ kg/day for 20 days parenterally) A short course of pentamidine (3 mg/kg every other day for four injections intramuscularly The marketed combination of topical paromomycin (15%)-MBCl (12%) for 10 days, plus antimony (20 mg/kg/day parenterally) for 7 days. My view is that all these regimens could be chosen as first-line therapy for cutaneous disease in Colombia. The antimony regimen has the advantage of established use; the disadvantages are cost, requirement for injections each day for 20 days, and considerable morbidity in the last two weeks of therapy. The pentamidine regimen has the advantage of a short time course; the disadvantages are lack of experience with this new regimen and frequent, although moderate, morbidity. The combined topical-parenteral regimen has the advantage of requiring few and nontoxic injections; the primary disadvantage is that the regimen is novel and its efficacy has not been confirmed. It would be expected that cases of lesions in other areas caused by L. braziliensis complex would respond in a similar manner to these regimens. To date, however, only the efficacy of the standard antimonial regimen has been confirmed. In certain regions of Central America, other regimens may be effective. Thus, ketoconazole appears to be effective for the more rapidly self-curing forms of disease (cutaneous disease caused by L. mexicana and L. panamensis from Central America), and a short course of antimony may be effective against L. braziliensis in Guatemala.

Treatment of cutaneous leishmaniasis

The World Health Organization estimates that approximately 400,000 new cases of leishmaniasis occur worldwide each year. Cutaneous leishmaniasis is being encountered more frequently in the United States because of increasing travel and immigration from endemic areas. The indications for treatment and recommended treatment regimens reported in the infectious disease and dermatology literature vary widely. We examine both classic and newly developed therapeutic agents and modalities for cutaneous leishmaniasis. Proper therapy depends on species identification. New World leishmaniasis, in general, requires more aggressive therapy; parenteral antimonials are the drugs of choice. Physical modalities may suffice in most cases of Old World leishmaniasis because of its strong tendency toward spontaneous resolution.

Limited efficacy of injectable aminosidine as single-agent therapy for Colombian cutaneous leishmaniasis

Ninety military patients with cutaneous leishmaniasis in Colombia were randomly allocated to 3 treatment regimens of parenteral aminosidine sulphate: (i) 12 mg aminosidine base/kg/d for 7 d, (ii) 12 mg/kg/d for 14 d, and (iii) 18 mg/kg/d for 14 d. With the 89 evaluable patients, the cure rates 12 months after the end of treatment were 10%, 45%, and 50%, respectively. Fifty-eight of the 66 patients who were not cured had lesions that enlarged or were unchanged by 1.5 months after treatment follow up. The other 8 patients had lesions that relapsed between 3 and 12 months after therapy. Even in group (iii) the cure rate was inferior to that (> 90%) with antimony or pentamidine previously reported in this patient population. This study indicates that parenteral aminosidine alone is less likely to be successful in the treatment of cutaneous lesihmaniasis than visceral leishmaniasis, for which a 74% cure rate has been reported. Further trials might consider the combination of aminosidine with other antileishmanial drugs.

Treatment of 'Old World' cutaneous leishmaniasis with aminosidine ointment: results of an open study in London

Five preparations of ointment containing aminosidine were used to treat lesions of 'Old World' cutaneous leishmaniasis. A preparation containing 12-15% aminosidine with 10% urea in white soft paraffin was nontoxic. 23 of 27 patients treated healed in a mean of 6.7 weeks, the ointment being applied daily for up to 12 weeks.

Topical treatment of American cutaneous leishmaniasis with paramomycin and methylbenzethonium chloride: a clinical study under field conditions in Ecuador

Fifty-two patients with American cutaneous leishmaniasis (ACL) from the Pacific coast of Ecuador were treated topically with an ointment containing 15% paramomycin (PR) and 12% methylbenzethonium chloride (MBCL) in vaselinum album (white soft paraffin; white petrolatum). After 20 applications (over 10 or 20 d) all lesions showed complete epithelialization within the first 100 d. Five patients developed new lesions during the one year observation period; 2 of these were probably reinfections. Considering all 5 cases as treatment failures, the healing rates were: 72% after 50 d, 90% after 100 d, and 85% after 360 d. In a separate study in the same area, a group of 23 patients was left without treatment for 3 months. Only 9% of the untreated patients healed spontaneously after 50 d. Growth of the lesion, inflammation and pain were observed at the beginning of treatment. After treatment, most lesions healed rapidly without scars. The drug was well accepted by the patients and was easy to administer under tropical field conditions.

Topical treatment of New World cutaneous leishmaniasis in Belize: a clinical study

BACKGROUND

Many studies have been performed during the past decade to find an effective topical therapy for cutaneous leishmaniasis (CL).

OBJECTIVE

Our purpose was to evaluate the effect of paromomycin ointment (P-ointment) containing 15% paromomycin sulfate and 12% methylbenzethonium chloride on Belizean patients with New World CL.

METHODS

Fifty-three patients were treated twice daily for 14 to 21 days with P-ointment.

RESULTS

Sixty-eight percent of the patients healed, 6% had a delayed cure, and 26% did not respond. No toxic effects from the ointment were observed.

CONCLUSION

Topical paromomycin is as efficacious in the treatment of New World CL as other currently accepted modalities that are potentially more toxic.

Intralesional treatment of cutaneous leishmaniasis with sodium stibogluconate antimony

BACKGROUND

Cutaneous leishmaniasis represents a difficult disease to manage in endemic areas. Systemic treatment is hampered by both expense and compliance. Side effects may play a major role in this aspect as well.

METHODS

The effectiveness of intralesional treatment of leishmaniasis was investigated. Seven hundred and ten patients were treated with injections of sodium stibogluconate intralesionally. The clinical diagnosis was confirmed by demonstrating the parasite in the smears obtained from the lesion. Fine insulin needle was used to infiltrate the lesion with sodium stibogluconate (0.5 to 1.0 mL).

RESULTS

Generally eight injections were sufficient, but some of the complicated lesions needed up to 24 injections. Sixty-two percent of patients were men. The majority of the study population (64%) were children below 15 years of age. The results showed that 72% of lesions healed completely, 23.9% showed some improvement, while 4.1% showed some deterioration. Lesions of the lips, cheeks, chin, and neck healed faster than lesions in other parts of the body. Side effects were mild and limited to pain at the site of the injection and hyperpigmentation in those who were treated by folk medicine.

CONCLUSIONS

Intralesional treatment is as effective as the standard systemic antimonials. It offers a less expensive alternative and a low side effects profile. Our findings confirmed the findings of earlier workers. It is recommended for treatment of cutaneous leishmaniasis in endemic areas.

Herbicides to curb human parasitic infections: in vitro and in vivo effects of trifluralin on the trypanosomatid protozoans

Leishmaniasis is a major tropical disease for which current chemotherapies, pentavalent antimonials, are inadequate and cause severe side effects. It has been reported that trifluralin, a microtubule-disrupting herbicide, is inhibitory to Leishmania amazonensis. In this study, the in vitro effect of trifluralin on different species of trypanosomatid protozoans was determined. In addition to L. amazonensis, trifluralin is effective against Leishmania major and Leishmania tropica, which cause cutaneous infections, Leishmania donovani, which causes visceral disease, Leishmania panamensis, which may cause mucocutaneous infection, and Trypanosoma brucei, an important human and veterinary pathogen. Moreover, most encouragingly, trifluralin is effective in vivo as a topical ointment against L. major and Leishmania mexicana murine cutaneous leishmaniasis. Thus, trifluralin is a promising lead drug for several related, prevalent tropical diseases: leishmaniasis, trypanosomiasis of animals, and, possibly, African trypanosomiasis in humans.

Effect of topical paromomycin on cell-mediated immunity during cutaneous leishmaniasis

BACKGROUND

The aim of this study was to evaluate the effect of topical paromomycin treatment on the development of immunity during cutaneous leishmaniasis.

METHODS

Three parameters of immunity were measured in the course of the disease: leishmanicidal effector activity, lymphocyte proliferation (cell-mediated immunity), and antibody levels (humoral immunity). Peripheral blood specimens of 55 treated and 36 untreated patients were tested.

RESULTS

The main results of this study showed that there was a significant delay in the development of leishmanicidal effector activity and to a lesser extent also a delay in the development of antigen-specific proliferative response in the treated compared with the untreated group. No difference was observed between the groups regarding the values achieved in the various tests.

CONCLUSIONS

These results suggest that topical paromomycin treatment delays the development of cell-mediated immunity but does not affect the levels of immunity that are eventually achieved.

An in vitro model for screening antileishmanial drugs: the human leukaemia monocyte cell line, THP-1

Standard anti-leishmanial drugs were tested for their ability to inhibit the growth of intracellular amastigotes of Leishmania aethiopica, L. donovani and L. infantum in the human leukemia monocyte THP-1 cell line. Sodium stibogluconate and meglumine antimoniate were active against L. donovani with ED50 values of 8.9 micrograms SbV/ml and 2.9 micrograms SbV/ml, respectively. L. aethiopica was less sensitive to sodium stibogluconate with an ED50 value of 25.3 micrograms SbV/ml while pentamidine had an ED50 value of 0.6 microM. Both L. donovani (ED50, 9.3 microM), and L. aethiopica (ED50, 6.4 microM), were sensitive to aminosidine sulphate. An L. infantum isolate, clinically resistant to meglumine antimoniate treatment, had an ED50 of 22.2 micrograms SbV/ml. The toxic level of drugs on host cells was determined by colorimetric Methyl Tetrazolium (MTT) assay prior to activity tests. The results obtained with the THP-1 in vitro drug screening model were similar to those obtained in the mouse peritoneal macrophage model.

Current treatment recommendations for leishmaniasis

OBJECTIVE

To review the epidemiology, clinical presentation, risk factors for transmission, and pathogenesis of leishmaniasis, as well as current treatment options for this disease. DATA SOURCES/DATA SELECTION: We reviewed unclassified medical-threat briefing material, subject-matter reviews, and case reports from the world's infectious disease literature. We concentrated on literature pertaining to the pathogenesis and management of leishmaniasis indigenous to Southwest Asia.

DATA EXTRACTION

Data from subject reviews published in the English language were evaluated. Case reports and clinical trials provided supplemental data on evolving theories and management options.

DATA SYNTHESIS

The clinical presentation of leishmaniasis is highly variable. Management relies heavily upon the use of parenteral antimonial drugs. Although these agents are effective in most cases, toxicity and the emergence of resistance limit the usefulness of standard therapies. Alternative treatment modalities include heat, surgical curettage, ketoconazole, metronidazole, pentamidine, rifampin, amphotericin B, aminoglycosides, allopurinol, and immunotherapy.

CONCLUSIONS

Although the number of reported cases of leishmaniasis in the US has generally been low, there is a possibility that more cases may be reported in the future because of the large number of military personnel returning to this country from endemic areas. Medical personnel, particularly those working in governmental institutions, should be familiar with the pathogenesis of this unusual infection as well as potential treatment options.