Comparing cytotoxicity and efficacy of miltefosine and standard antimicrobial agents against Acanthamoeba trophozoites and cyst forms: An in vitro study.

Acanthamoeba keratitis (AK) is an eye disease often occurring in contact lens wearers. AK treatment is prolonged and requires multiple drugs, which can lead to adverse effects. Our study aimed to compare the in vitro activities and safety of Miltefosine with that of conventional antimicrobial agents used to treat AK. Acanthamoeba castellanii genotype T4 was obtained from a patient with keratitis and subjected to in vitro susceptibility testing with various antimicrobial agents, including Chlorhexidine (CHX), Pentamidine isethionate (PI)Polyhexamethylene biguanide (PHMB), and Miltefosine to assess their efficacy against Acanthamoeba trophozoites and cyst. The cytotoxicity of the agents was evaluated in Vero cells, and their selectivity indexes (SI) were calculated. Chlorhexidine exhibited the highest amoebicidal activity with the highest selectivity index against the trophozoite and cyst, ranging from 1.17 to 8.35. The selectivity index of PHMB is slightly comparable to Chlorhexidine, exhibiting significant anti-Acanthamoeba activity. On the other hand, Pentamidine isethionate and Miltefosine displayed low SI among the compounds. Pentamidine isethionate was effective at high concentrations, which was toxic. Miltefosine exhibited the lowest cytotoxicity; nevertheless, due to the lowest anti-Acanthamoeba activity presented a low selectivity against the parasite. Further studies on more clinical samples and prolonged incubation time should be done to investigate the effectiveness and toxicity of drugs in both in vitro and in vivo conditions.

In Vitro Activity of Pentamidine Isethionate against Trophozoite and Cyst of Acanthamoeba.

BACKGROUND: Acanthamoebae are a causative agent of Acanthamoeba keratitis (AK) in immunocompetent individuals. Since access to propamidine isethionate (Brolene®) as a first-line treatment has been limited in recent years, in the current study, we examined the effects of pentamidine isethionate against trophozoite and cyst forms of Acanthamoeba. METHODS: This experimental study was conducted in the Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran, during 2019-2020. Pentamidine isethionate at concentrations of 50, 100, 200, 400, 600, 800, and 1000 µM were tested against trophozoites and cyst stages of T4 genotype, at 24- and 48-hour incubation period, and the viability was determined by trypan blue staining. In addition, the cytotoxic effect of the drug was examined in Vero cells using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The 50% inhibitory concentration (IC50) of pentamidine isethionate on trophozoite after 24 and 48h were 97.4 µM and 60.99 µM. These results on cyst after 24 and 48h were 470 µM and 175.5 µM, respectively. In MTT assay, the drug showed an inhibitory effect on Vero cell growth with IC50 values of 115.4 µM and 87.42 µM after 24h and 48h, respectively. CONCLUSION: Pentamidine isethionate exhibited an inhibitory effect on trophozoite and cyst. Given that the trophozoicidal activity of the drug is in the safe dose, it could be suggested as an alternative in patients with AK; however, further investigation is needed in an animal model to confirm the data.

Good response to pentamidine isethionate in a case of Mucosal Leishmaniasis caused by Leishmania (Viannia) braziliensis that was difficult to treat: Case Report

Abstract In Brazil, meglumine antimoniate is the first drug of choice for mucosal leishmaniasis treatment followed by amphotericin B and pentamidine isethionate. We report the case of a patient with severe mucosal lesions caused by Leishmania (Viannia) braziliensis that were difficult to treat. Over a 14-year period, the patient showed low adherence and three treatment attempts with meglumine antimoniate failed. Additionally, there was an unsatisfactory response to liposomal amphotericin B and nephrotoxicity when using amphotericin B deoxycholate that persisted after new treatment attempt with liposomal amphotericin B. Finally, healing was achieved with pentamidine isethionate and maintained during nine months of monitoring.

Therapeutic response and safety of the topical, sequential use of antiseptic, keratolytic, and pentamidine creams (3-PACK) on Leishmania (Viannia) braziliensis-infected mice

BACKGROUND Topical treatment of New World cutaneous leishmaniasis can be affected by bacterial coinfection, hyperkeratosis, and transdermal drug delivery. OBJECTIVE The aim of this work was to evaluate the therapeutic response and safety of the topical, sequential use of antiseptic, keratolytic, and pentamidine isethionate (PMD) creams (3-PACK kit) on CL-infected BALB/c mice. METHODS A 0.5% chlorhexidine solution (CGH), 10% salicylic acid (SA), and 3% or 6% PMD were used as antiseptic, keratolytic, and antileishmanial drugs, respectively. During the first seven days, antiseptic, followed by 10% SA gel and PMD cream, were applied topically. Subsequently, treatment was performed only with the antiseptic and PMD creams. Skin irritation, reduction of lesion size (mm2), and parasitic load were observed until 30 days of treatment were completed. FINDINGS The 3-PACK treatment using 6% PMD induced a complete lesion reduction in 3/6 mice and a partial reduction in 1/6 mice, with no parasites observed. In contrast, CGH and SA alone, along with the vehicle, were not effective (p < 0.05). Moderate to severe erythema was observed at the application site. MAIN CONCLUSION The topical 3-PACK using 6% PMD was 67% effective in the treatment of CL by Leishmania (Viannia) braziliensis. Currently, work is ongoing to improve PMD isethionate formulation and to determine a dose-response.

Estudo comparativo entre o antimoniato-n-metilglucamina (glucantime) e o isotionato de pentamidina (pentacarinat) em lesões cutâneas da leishmaniose tegumentar / Comparative study of antimony-n-methylglucamine (glucantime) and pentamidine isethionate (Pentacarinat) in skin lesions of cutaneous leishmaniasis

O prognóstico da leishmaniose cutânea (LC) com o uso dos antimoniais pentavalentes (Sb+5) de um modo geral é considerado bom, embora alguns casos tornem-se refratários à terapêutica tradicional. Infelizmente, não existem marcadores de gravidade da doença ou marcadores de resposta terapêutica, limitando a utilização de formas de tratamento mais efetivas. Em alguns casos, porém, existe a necessidade de utilizar outras drogas, como a anfotericina B (desoxocolato) e as pentamidinas (isotionato e mesilato), consideradas como drogas de 2ª escolha no tratamento das leishmanioses, sendo de fundamental importância à busca de novos esquemas terapêuticos. O objetivo do estudo foi comparar a eficácia entre o antimoniato-N-metilglucamina (Glucantime®) e o isotionato de pentamidina (Pentacarinat®) no tratamento da forma cutânea da leishmaniose tegumentar (LT)...

The prognosis of cutaneous leishmaniasis (CL) with the use of pentavalents antimonials (Sb+5) is generally considered good, although in some cases have become refractory to conventional therapy. Unfortunately there are no markers of disease severity or markers of therapeutic response, limiting the use of more effective forms of treatment. In some cases, however, there is a need for other drugs such as amphotericin B (desoxycholate) and pentamidine (isethionate and mesylate), which are considered as the second choice in the treatment of leishmaniasis, since few studies with reduced doses of these drugs demonstrated encouraging results in tegumentary leishmaniasis (TL), which is paramount in the search for new therapeutic regimens using proven antileishmanial drugs. We have compared the effectiveness between the N-methylglucamine antimoniate (Glucantime®) and pentamidine isethionate (Pentacarinat®) in the treatment of CL in an endemic area of tegumentary leishmaniasis (TL)...