Role of mitochondria in the differential action of sodium deoxycholate and ursodeoxycholic acid on rat duodenum.

Sodium deoxycholate (NaDOC) inhibits the intestinal Ca2+ absorption and ursodeoxycholic acid (UDCA) stimulates it. The aim of this study was to determine whether NaDOC and UDCA produce differential effects on the redox state of duodenal mitochondria altering the Krebs cycle and the electron transport chain (ETC) functioning, which could lead to perturbations in the mitochondrial dynamics and biogenesis. Rat intestinal mitochondria were isolated from untreated and treated animals with either NaDOC, UDCA, or both. Krebs cycle enzymes, ETC components, ATP synthase, and mitochondrial dynamics and biogenesis markers were determined. NaDOC decreased isocitrate dehydrogenase (ICDH) and malate dehydrogenase activities affecting the ETC and ATP synthesis. NaDOC also induced oxidative stress and increased the superoxide dismutase activity and impaired the mitochondrial biogenesis and functionality. UDCA increased the activities of ICDH and complex II of ETC. The combination of both bile acids conserved the functional activities of Krebs cycle enzymes, ETC components, oxidative phosphorylation, and mitochondrial biogenesis. In conclusion, the inhibitory effect of NaDOC on intestinal Ca2+ absorption is mediated by mitochondrial dysfunction, which is avoided by UDCA. The stimulatory effect of UDCA alone is associated with amelioration of mitochondrial functioning. This knowledge could improve treatment of diseases that affect the intestinal Ca2+ absorption.

Minimum concentration of Amphotericin B in serum according to the formulation, dose, and daily or prolonged intermittent therapeutic regimen.

INTRODUCTION: The therapeutic efficacy of daily amphotericin B infusion is related to its maximum concentration in blood; however, trough levels may be useful in intermittent regimens of this antifungal drug. METHODS: : High performance liquid chromatography (HPLC) was used to determine the minimum concentration (Cmin) of amphotericin B in the serum of patients receiving deoxycholate (D-Amph) or liposomal amphotericin B (L-AmB) for the treatment of cryptococcal meningitis (n=28), histoplasmosis (n=8), paracoccidioidomycosis (n=1), and leishmaniasis (n=1). RESULTS: Daily use of D-Amph 30 to 50 mg or L-AmB 50 mg resulted in a similar Cmin, but a significant increase ocurred with L-AmB 100 mg/day. The geometric mean Cmin tended to decrease with a reduction in the dose and frequency of intermittent L-AmB infusions: 357 ng/mL (100 mg 4 to 5 times/week) > 263 ng/mL (50 mg 4 to 5 times/week) > 227 ng/mL (50 mg 1 to 3 times/week). The impact on Cmin was variable in patients whose dose or therapeutic scheme was changed, especially when administered the intermittent infusion of amphotericin B. The mean Cmin for each L-AmB schedule of intermittent therapy was equal or higher than the minimum inhibitory concentration of amphotericin B against Cryptococcus isolates from 10/12 patients. The Cmin of amphotericin B in patients with cryptococcal meningitis was comparable between those that survived or died. CONCLUSIONS: By evaluating the Cmin of amphotericin B, we demonstrated the therapeutic potential of its intermittent use including in the consolidation phase of neurocryptococcosis treatment, despite the great variability in serum levels among patients.

Minimum concentration of Amphotericin B in serum according to the formulation, dose, and daily or prolonged intermittent therapeutic regimen

Abstract INTRODUCTION: The therapeutic efficacy of daily amphotericin B infusion is related to its maximum concentration in blood; however, trough levels may be useful in intermittent regimens of this antifungal drug. METHODS : High performance liquid chromatography (HPLC) was used to determine the minimum concentration (Cmin) of amphotericin B in the serum of patients receiving deoxycholate (D-Amph) or liposomal amphotericin B (L-AmB) for the treatment of cryptococcal meningitis (n=28), histoplasmosis (n=8), paracoccidioidomycosis (n=1), and leishmaniasis (n=1). RESULTS: Daily use of D-Amph 30 to 50 mg or L-AmB 50 mg resulted in a similar Cmin, but a significant increase ocurred with L-AmB 100 mg/day. The geometric mean Cmin tended to decrease with a reduction in the dose and frequency of intermittent L-AmB infusions: 357 ng/mL (100 mg 4 to 5 times/week) > 263 ng/mL (50 mg 4 to 5 times/week) > 227 ng/mL (50 mg 1 to 3 times/week). The impact on Cmin was variable in patients whose dose or therapeutic scheme was changed, especially when administered the intermittent infusion of amphotericin B. The mean Cmin for each L-AmB schedule of intermittent therapy was equal or higher than the minimum inhibitory concentration of amphotericin B against Cryptococcus isolates from 10/12 patients. The Cmin of amphotericin B in patients with cryptococcal meningitis was comparable between those that survived or died. CONCLUSIONS: By evaluating the Cmin of amphotericin B, we demonstrated the therapeutic potential of its intermittent use including in the consolidation phase of neurocryptococcosis treatment, despite the great variability in serum levels among patients.

Novel and safe single-dose treatment of cutaneous leishmaniasis with implantable amphotericin B-loaded microparticles.

The development of an effective amphotericin B (AmB) topical formulation to replace the systemically toxic injections currently used in cutaneous leishmaniasis (CL) treatment is challenging due to poor absorption through the skin. Aiming at an effective local chemotherapy, we designed PLGA (poly(lactide-co-glycolide acid) microparticles loaded with deoxycholate amphotericin B (d-AmB) for both macrophage intracellular targeting and sustained extracellular release. For that, d-AmB/PLGA microparticles with sizes ranging from 0.5 µm to 20 µm were synthesized and tested both in vitro and in vivo. In vitro, d-AmB/PLGA was more selectively active against intracellular amastigotes of Leishmania amazonensis than free d-AmB (selectivity index = 50 and 25, respectively). In vivo, the efficacy of a single intralesional (i.l) injection with d-AmB/PLGA was determined in early and established BALB/c mouse ear lesions. In early lesions, a single injection given on day 10 of infection was more effective in controlling parasite growth than eight i.l. injections with free d-AmB, as measured on day 120. Such d-AmB/PLGA injection was also effective in established lesions (day 30), leading to 97% parasite burden reduction, as compared with d-AmB or liposomal AmB (Ambisome®) i.l. injection containing the same AmB dose. Pharmacokinetic studies showed that following d-AmB/PLGA injection, AmB leaked slower from non-infected than infected ears, yet remaining in the ear tissue for as long as 30 days. Of interest, AmB was not detectable in the circulating plasma for at least two weeks of d-AmB/PLGA injection, contrasting with the rapid and durable (2 days) detection after free d-AmB injection. Despite the transient ear swelling and local cell infiltration, no alterations in AST, ALT and creatinine serum levels was induced by d-AmB/PLGA. For its approved components, local efficacy, and single-dose applicability, this novel and safe AmB microparticle depot formulation has strong potential as a new therapy for human CL.

Novel steroid derivatives: synthesis, antileishmanial activity, mechanism of action, and in silico physicochemical and pharmacokinetics studies.

The search for new drugs for the treatment of leishmaniasis is an important strategy for improving the current therapeutic arsenal for the disease. There are several limitations to the available drugs including high toxicity, low efficacy, prolonged parenteral administration, and high costs. Steroids are a diverse group of compounds with various applications in pharmacology. However, the antileishmanial activity of this class of molecules has not yet been explored. Therefore, in the present study, we investigated the antileishmanial activity and cytotoxicity of novel steroids against murine macrophages with a focus on the derivatives of cholesterol (CD), cholic acid (CA), and deoxycholic acid (DA). Furthermore, the mechanism of action of the best compound was assessed, and in silico studies to evaluate the physicochemical and pharmacokinetic properties were also conducted. Among the sixteen derivatives, schiffbase2, CD2 and deoxycholic acid derivatives (DOCADs) were effective against promastigotes of Leishmania species. Despite their low toxicity to macrophages, the majority of DOCADs were active against intracellular amastigotes of L. amazonensis, and DOCAD5 exhibited the best biological effect against these parasitic stages (IC50 = 15.34 µM). Neither the CA derivatives (CAD) nor DA alone inhibited the intracellular parasites. Thus, the absence of hydroxyl in the C-7 position of the steroid nucleus, as well as the modification of the acid group in DOCADs were considered important for antileishmanial activity. The treatment of L. amazonensis promastigote forms with DOCAD5 induced biochemical changes such as depolarization of the mitochondrial membrane potential, increased ROS production and cell cycle arrest. No alterations in parasite plasma membrane integrity were observed. In silico physicochemical and pharmacokinetic studies suggest that DOCAD5 could be a good candidate for an oral drug. The data demonstrate the potential antileishmanial effect of certain steroid derivatives and encourage new in vivo studies.

Continuous infusion of amphotericin B deoxycholate: an innovative, low-cost strategy in antifungal treatment.

The combination of amphotericin B and sodium deoxycholate is the formulation most used in clinical practice. The development of new agents such as amphotericin with lipid formulations, caspofungin, voriconazole and other azolic derivatives, promoted alternatives to amphotericin B deoxycholate. However, because of the high cost of these new drugs, their use is difficult in a scenario of limited resources. A few strategies have been devised to make the use of amphotericin B deoxycholate less toxic. In this review, we seek to describe the accumulated knowledge about this molecule, with focus on its use in continuous infusion, which appears to be an alternative to reduce toxicity, while maintaining its clinical efficacy.

Pharmacological parameters of intravenously administered amphotericin B in rats: comparison of the conventional formulation with amphotericin B associated with a triglyceride-rich emulsion.

The LD50 determined in rats for the potent antifungal amphotericin B (AB) increased from 4.2 to 12.0 when the conventional AB-deoxycholate (DOC) was compared with AB associated with a triglyceride-rich emulsion (AB-emulsion). The reduction in amphotericin B toxicity is not due to a modification in plasma clearance, as both formulations seem to be removed from plasma at the same rate. Major differences in amphotericin B tissue distribution were not seen for kidney and liver but were seen for the lung. After 24 h administration of a single amphotericin B dose (2.0 mg/kg body weight) 23.78 +/- 11.71 mg/kg tissue was recovered from the lung of animals treated with AB-DOC whereas for AB-emulsion only 5.19 +/- 2.50 mg/kg tissue was recovered. The higher lethality of AB-DOC may be related to the higher concentration of amphotericin B in the lung. The therapeutic efficacy of AB-emulsion was similar to that of AB-DOC as attested by survival curves obtained after treatment of mice infected by Candida albicans. This is highly relevant, as the same is not necessarily found for other less toxic proposed vehicles. The equivalent efficacy and the increment in the LD50 will result in an important improvement in the therapeutic activity of amphotericin B. Furthermore, some data related to storage and stability indicate the clinical utility of this type of drug delivery.