Topical treatment of New and Old World cutaneous leishmaniasis in experimental animals

Andrographolide-Soya-L-α-Phosphatidyl Choline Complex Augmented Solubility and Drug Delivery in Leishmania donovani, a Causative Agent for Cutaneous and Visceral Leishmaniasis

The utility of andrographolide (AN) in visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) is limited owing to poor solubility, hindered permeation, and unstable structure under physiological conditions. The present study mainly focuses on synthesizing of andrographolide-Soya-L-α-phosphatidyl choline (ANSPC) complex in ethanol and its characterization using various spectral and analytical techniques. Results from FT-IR, ¹H NMR, ROSEY, and in silico docking techniques suggest ANSPC complex formation due to inter-molecular interaction between the hydrophilic head of SPC and hydroxyl group of AN present at 24th position. ANSPC complex demonstrated the solubility of 113.93 ± 6.66 μg/mL significantly (P < 0.05) greater than 6.39 ± 0.47 μg/mL of AN. The particle size of ANSPC complex was found to be 182.2 ± 2.69 nm. The IC₅₀ value of AN suspension (PBS, pH ~ 7.4) at 24, 48, and 72 h against Leishmania donovani (L. donovani) was noticed to be 32.76 ± 4.53, 20.87 ± 2.37, and 17.71 ± 3.06 μM/mL, respectively. Moreover, augmented aqueous solubility of ANSPC complex led to significant (P < 0.05) reduction in IC₅₀ value, i.e., 25.02 ± 4.35, 11.31 ± 0.60, and 8.33 ± 2.71 μM/mL at 24, 48, and 72 h, respectively. The IC₅₀ values for miltefosine were noted to be 9.84 ± 2.65, 12.13 ± 7.26, and 6.56 ± 0.61 μM/mL at similar time periods. Moreover, ANSPC complex demonstrated augmented cellular uptake at 24 h as compared to 6 h in L. donovani. We suppose that submicron size and phospholipid-mediated complexation might have endorsed the permeation of ANSPC complex across the plasma membrane of L. donovani parasite by transport mechanisms such as P-type ATPase. ANSPC complex warrants further in-depth in vivo studies under a set of stringent parameters for translating the product into a clinically viable form.

Comparative efficacy, toxicity and biodistribution of the liposomal amphotericin B formulations Fungisome® and AmBisome® in murine cutaneous leishmaniasis

Fungisome^® (F), a liposomal amphotericin B (AmB) product, is marketed in India as a safe and effective therapeutic for the parasitic infection visceral leishmaniasis. Its potential in the treatment of cutaneous leishmaniasis (CL), a disfiguring form of the disease affecting the skin, is currently unknown. Here, we report the evaluation of the efficacy of F in the Leishmania major BALB/c murine model of CL, including a head-to-head comparison with the standard liposomal AmB formulation AmBisome^® (A). Upon intravenous administration at dose levels of 5, 10 and 15 mg/kg of body weight (on days 0, 2, 4, 6 and 8), F showed clear signs of toxicity (at 15 mg/kg), while A did not. After complete treatment (day 10), the tolerated doses of 5 and 10 mg/kg F had significant antileishmanial activity (ED₅₀ = 4.0 and 12.8 mg/kg for qPCR-based parasite load and lesion size, respectively), although less than that of A at identical doses (ED₅₀ = 3.0 and 8.8 mg/kg). The efficacy of F was inferior compared to A because lower levels of the active agent AmB accumulated within the infected lesion. In conclusion, despite possibly being less safe and efficacious than A at equivalent doses, the moderate in vivo activity of F could indicate a role in the systemic pharmacotherapy of CL.

Efficacy of Paromomycin-Chloroquine Combination Therapy in Experimental Cutaneous Leishmaniasis

The 4-aminoquinoline chloroquine (CQ) is clinically used in combination with doxycycline to cure chronic Q fever, as it enhances the activity of the antibiotic against the causative bacterium Coxiella burnetii residing within macrophage phagolysosomes. As there is a similar cellular host-pathogen biology for Leishmania parasites, this study aimed to determine whether such an approach could also be the basis for a new, improved treatment for cutaneous leishmaniasis (CL). We have evaluated the in vitro and in vivo activities of combinations of CQ with the standard drugs paromomycin (PM), miltefosine, and amphotericin B against Leishmania major and Leishmania mexicana In 72-h intracellular antileishmanial assays, outcomes were variable for different drugs. Significantly, the addition of 10 μM CQ to PM reduced 50% effective concentrations (EC50s) by over 5-fold against L. major and against normally insensitive L. mexicana parasites. In murine models of L. major and L. mexicana CL, daily coadministration of 50 mg/kg of body weight PM and 25 mg/kg CQ for 10 days resulted in a significant reduction in lesion size but not in parasite load compared to those for mice given the same doses of PM alone. Overall, our data indicate that PM-CQ combination therapy is unlikely to be a potential candidate for further preclinical development.

Chemotherapy of leishmaniasis: present challenges

Cutaneous and visceral leishmaniasis are amongst the most devastating infectious diseases of our time, affecting millions of people worldwide. The treatment of these serious diseases rely on a few chemotherapeutic agents, most of which are of parenteral use and induce severe side-effects. Furthermore, rates of treatment failure are high and have been linked to drug resistance in some areas. Here, we reviewed data on current chemotherapy practice in leishmaniasis. Drug resistance and mechanisms of resistance are described as well as the prospects for applying drug combinations for leishmaniasis chemotherapy. It is clear that efforts for discovering new drugs applicable to leishmaniasis chemotherapy are essential. The main aspects on the various steps of drug discovery in the field are discussed.

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.

Drug resistance in leishmaniasis

The treatment options of leishmaniasis are limited and far from satisfactory. For more than 60 years, treatment of leishmaniasis has centered around pentavalent antimonials (Sb^v). Widespread misuse has led to the emergence of Sb^v resistance in the hyperendemic areas of North Bihar. Other antileishmanials could also face the same fate, especially in the anthroponotic cycle. The HIV/ visceral leishmaniasis (VL) coinfected patients are another potential source for the emergence of drug resistance. At present no molecular markers of resistance are available and the only reliable method for monitoring resistance of isolates is the technically demanding in vitro amastigote-macrophage model. As the armametrium of drugs for leishmaniasis is limited, it is important that effective monitoring of drug use and response should be done to prevent the spread of resistance. Regimens of simultaneous or sequential combinations should be seriously considered to limit the emergence of resistance.

Efeito de uma formulação hidrofílica de paromomicina tópica na leishmaniose cutânea em pacientes com contra-indicações de tratamento com antimonial pentavalente

Descrevem-se o efeito terapêutico e os eventos adversos associados com o uso tópico de paromomicina 10% em gel na leishmaniose cutânea. Quinze pacientes com leishmaniose cutânea cumpriram os critérios de inclusão descritos a seguir: contra-indicação para o uso de antimoniato de meglumina, intradermorreação de Montenegro positiva e até quatro lesões ulceradas. A fórmula foi prescrita duas vezes ao dia por 20 dias. Quatorze pacientes estiveram disponíveis para a avaliação do desfecho terapêutico e a proporção de cura foi de 21,4% (3/14), 50% melhoraram até a epitelização completa e a proporção de falha foi de 28,6%. Nove pacientes que não apresentaram cura inicialmente foram re-tratados. Oito receberam uma nova série de paromomicina tópica e um foi tratado com antimoniato de meglumina. Dois pacientes não receberam novo tratamento e tiveram melhora lenta e contínua. Cinco de oito pacientes retratados com paromomicina tópica alcançaram a cura clínica, e três apresentaram falha, incluindo um paciente que tinha apresentado melhora com o primeiro tratamento. Os eventos adversos foram leves e locais em 53,3% dos pacientes e nunca levaram à suspensão do tratamento.

Drug resistance in leishmaniasis

Leishmaniasis is a complex disease, with visceral and cutaneous manifestations, and is caused by over 15 different species of the protozoan parasite genus Leishmania. There are significant differences in the sensitivity of these species both to the standard drugs, for example, pentavalent antimonials and miltefosine, and those on clinical trial, for example, paromomycin. Over 60% of patients with visceral leishmaniasis in Bihar State, India, do not respond to treatment with pentavalent antimonials. This is now considered to be due to acquired resistance. Although this class of drugs has been used for over 60 years for leishmaniasis treatment, it is only in the past 2 years that the mechanisms of action and resistance have been identified, related to drug metabolism, thiol metabolism, and drug efflux. With the introduction of new therapies, including miltefosine in 2002 and paromomycin in 2005-2006, it is essential that there be a strategy to prevent the emergence of resistance to new drugs; combination therapy, monitoring of therapy, and improved diagnostics could play an essential role in this strategy.

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.

Comparison of the effectiveness of two topical paromomycin treatments versus meglumine antimoniate for New World cutaneous leishmaniasis

The randomized, controlled study compared the therapeutic efficacy and safety of two paromomycin-containing topical preparations with the gold treatment standard, meglumine antimoniate, and with each other in 120 Ecuadorian patients with ulcerated lesions. The two paromomycin treatment comparisons were double-blinded. Group 1 (n = 14) received 15% paromomycin plus 12% methylbenzonium chloride (PR-MBCL) dissolved in a soft white paraffin base, applied twice daily for 30 days. Group 2 (n = 40) was also treated for 30 days with 15% paromomycin plus 10% urea (PR-U) dissolved in the same paraffin base. Group 3 (n = 40) received 20mg/kg/day of IM meglumine antimoniate (MA) for 10 days as per Ecuadorian Ministry of Public Health recommendations at the time of the study. The 10-day treatment was completed by 90% of the MA group compared to 72.5% of the PR-MBCL (X2 = 4.0, P = 0.045) and 75% of the PM-U (X2 = 3.1, P > 0.05) groups whose treatment regime lasted 20 days longer than the MA treatment. Post-treatment lesion burning, redness, inflammation, and soreness were more common in the two paromomycin groups compared to MA group (P < 0.05). The frequency of treatment-related side effects in the two paromomycin groups was similar. Six weeks after the start of treatment, 80.6% of MA subjects were clinically cured compared to 48.3% in the PR-MBCL (X2 = 6.1, P = 0.014) and 40% in the PM-U groups (X2 = 12.6, P = 0.002). By 12 weeks, the proportion of clinically cured subjects in the MA (91.7%) compared to PM-MBCL (79.3%) or PM-U (70%) groups was not significantly different (P > 0.05). MA-treated subjects clinically cured by 12 weeks had a faster mean healing time (29.5 +/- 12.2 days) compared to those in the PM-MBCL (versus 43.1 +/- 14.4 days, t = -3.7, P = 0.001) or PR-U groups (43.5 +/- 17 days; t = -3.2, P = 0.002). During the 48-week post-treatment follow-up period, infection reactivation was observed in 15.2% of the MA subjects compared to 17.4% in the PM-MBCL and 10.5% PM-U of subjects diagnosed as clinically healed by 12 weeks (P > 0.05). The results suggest that although the time required for the clinical healing of ulcerated lesions takes longer, topical paromomycin may be an acceptable therapeutic alternative in endemic areas where meglumine antimoniate is not available, is too costly or medically contraindicated.

Monitoring drug resistance in leishmaniasis

There are many factors that can influence the efficacy of drugs in the treatment of leishmaniasis. These include both an intrinsic variation in the sensitivity of Leishmania species, described for pentavalent antimonials, paromomycin, azoles and other drugs that have reached clinical trials, as well as acquired drug resistance to antimonials. Acquired resistance has been studied in the laboratory for several decades but it is only recently that clinical resistance in L. donovani field isolates has been demonstrated. The monitoring of resistance is problematic due to a reliance on the amastigote-macrophage culture assay to adequately correlate clinical and in vitro resistance and a lack of knowledge about the molecular and biochemical mechanisms of resistance to antileishmanial drugs.

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.

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.

Studies on the topical treatment of experimental cutaneous leishmaniasis: the therapeutic effect of methyl benzethonium chloride and the aminoglycosides, gentamicin and paromomycin

BALB/c mice infected with either Leishmania major or Leishmania mexicana were treated twice a day for 10 days with an ointment containing 15% gentamicin or paromomycin, with or without 12% methylbenzethonium chloride (MBCl). It was found that topical application of either paromomycin or MBCl cured the parasite lesion, and that combined treatment with the two compounds had an additive effect. However, after four days' therapy there was a severe inflammatory response at the treatment site, and in most experiments mice relapsed and renewed lesion growth was observed. It is suggested that a non-specific inflammatory reaction may be an important component of the therapeutic response. In further experiments, L. major infected mice treated with paromomycin and MBCl which had cured but not relapsed 58 days after treatment were challenged with a similar dose of the homologous parasite. Lesions developed 16 days post-infection, and the number of parasites recovered from these lesions was similar to that recovered from lesions in control mice. Therefore no protective immunity had been induced by chemotherapy.

Leishmania major: histopathological responses before and after topical treatment in experimental animals

The cellular response in the cutaneous leishmaniasis lesion (CL), of BALB/c mice treated topically with an ointment composed of 15% paromomycin and 12% methylbenzethonium chloride (PR-ointment) was studied. In the infected, untreated control group, the lesion showed progressive necrosis with an increase in the number of parasites, macrophages, lymphocytes, and polymorphonuclear cells over a period of 18 weeks. In the PR ointment-treated group, complete healing of the lesion was observed 4 weeks after termination of treatment, but total elimination of the parasites from the lesion was observed only 2 weeks later. A marked reduction in the number of macrophages and polymorphonuclear cells was observed during the healing process. A similar phenomenon was observed with mice inoculated intraperitoneally with paromomycin alone, although total elimination of the parasites from the lesions of these mice was not demonstrated over a period of 18 weeks. Neither L3T4 helper T cells nor Ly2 cytotoxic suppressor T cells were detected in the CL lesion, either before or after treatment.