Efficacy of an oral and tropically stable lipid-based formulation of Amphotericin B (iCo-010) in an experimental mouse model of systemic candidiasis

Development and deployment of a solid oral amphotericin B dosage form to treat visceral leishmaniasis within a pediatric population

Visceral leishmaniasis (VL) is a severe and potentially fatal infection, with over 90% of reported cases occurring in East African countries including Chad, Djibouti, Eritrea, Ethiopia, Kenya, Somalia, South Sudan, Sudan, and Uganda, affecting mainly impoverished individuals, and creating a significant economic burden. Currently, the intravenous single-dose liposomal amphotericin B is the first choice for the treatment of VL. Recently, WHO and DNDi have suggested a combination of intravenous liposomal amphotericin B and oral miltefosine as a potential approach to treat VL. However, miltefosine availability is uncertain, and its side effects frequently cause treatment to be discontinued. Furthermore, due to the difficult route of liposomal amphotericin B administration by intravenous infusion, the lack of formulation's tropical stability, accessibility, injection toxicity, and cost have prevented this injectable formulation of amphotericin B from reaching the most infected populations, particularly the pediatric population. To solve this problem, the development of a solid oral amphotericin B formulation that is cost-effective, safe, tropically stable, and easy to swallow, making it more accessible to children, particularly in rural communities having limited access to medical clinics or trained healthcare professionals is imperative. This viewpoint will discuss the opportunities and challenges of developing an oral amphotericin B formulation for a pediatric population.

Potential lipid-based strategies of amphotericin B designed for oral administration in clinical application

Amphotericin B (AmB) is regarded as a first-line therapy against life-threatening invasive fungal infections. Due to its poor oral bioavailability, AmB is restricted to intravenous administration in clinical practice. As science continues to move forward, two lipid-based formulations are successfully developed for oral AmB administration, currently undergoing phase I clinical trials. Encouragingly, lipid-AmB conjugates with emulsions also exhibit a better bioavailability, which may be another strategy to design oral AmB formulation in clinical practice. Thus, this review mainly focused on the two lipid-based formulations in clinical trials, and discussed the potential perspectives of AmB-lipid conjugation-loaded nanocochleates and emulsions.

Review of Novel Oral Amphotericin B Formulations for the Treatment of Parasitic Infections

Amphotericin B (AmpB) is a polyene macrolide antibiotic used in the treatment of blood-borne parasitic and fungal infections. However, its use, particularly in the developing world, has been limited by dose-dependent kidney toxicity, other systemic-related toxicity issues following injection, the inconvenience of parenteral administration, and accessibility. Oral formulation approaches have focused on the dual problem of solubility and permeability of AmpB, which is poorly water soluble, amphoteric and has extremely low oral bioavailability. Therefore, to enhance oral absorption, researchers have employed micellar formulations, polymeric nanoparticles, cochleates, pro-drugs, and self-emulsifying drug delivery systems (SEDDS). This paper will highlight current uses of AmpB against parasitic infections such as leishmaniasis, preclinical and clinical formulation strategies, applications in veterinary medicine and the importance of developing a cost-effective and safe oral AmpB formulation.

Cochleate formulations of Amphotericin b designed for oral administration using a naturally occurring phospholipid

The purpose of this work was to formulate the poor soluble antifungal and antiparasitic agent Amphotericin B (AmB) in cost-effective lipid-based formulations suitable for oral use in developing countries, overcoming the limitations of poor water solubility, nephrotoxicity and low oral bioavailability. The antifungal agent was formulated, at different molar proportions, in cochleate nanocarriers prepared using an accessible naturally occurring phospholipid rich in phosphatidylserine (Lipoid PSP70). These nanoassemblies were prepared by condensation of negatively charged phospholipid membrane vesicles with divalent cations (Ca²⁺). Small-angle X-ray scattering studies revealed the Ca²⁺-triggered condensation of loosely packed multilamellar vesicles into tightly packed bilayers of strongly dehydrated multilamellar organization characterized by narrow Bragg peaks. Transmission electron microscopy and quasi-elastic light scattering studies demonstrated the formation of nanosized particles. AmB drug loading was above 55% in all formulations. Circular dichroism demonstrated the prevalence of monomeric and complexed forms of AmB over toxic aggregates. The stability of AmB in gastric medium was improved by loading in cochleates and its release in gastrointestinal media was retarded. Confocal microscopy studies revealed the in-vitro interactions of Lipoid PSP70-based cochleates with Caco2 intestinal cell monolayers. The results suggest that the low-cost AmB-loaded cochleates may increase the therapeutic range of this drug.

Development of an Oral Amphotericin B Formulation as an Alternative Approach to Parenteral Amphotericin B Administration in the Treatment of Blood-Borne Fungal Infections

In the Fall of 1999, we presented at medical "Grand Rounds" to a number of Infectious Diseases physicians at Vancouver General Hospital about the co-administration of several antifungal compounds in the treatment of blood-borne fungal infections to patients who were immunocompromised (i.e. cancer patients, patients waiting organ transplantation, HIV/AIDs patients, etc.). During the presentation, a physician from the back of the room called out "can you develop an oral formulation of amphotericin B which could be effective and not have the side-effects associated with the parenteral formulations of the drug". The physician stated that an oral formulation would be a big step forward, improving patient compliance, helping in pre-treatment without admitting patients to the hospital prior to organ transplantation and it would be cost-effective. Initially, I responded to the physician, that it would not be possible to develop an oral amphotericin B formulation that could be absorbed from the gastrointestinal (GI) tract in a high enough concentration to be effective in treating blood-borne fungal infections and yet remains non-toxic due to the physical chemical properties of the drug. However, as I travelled back to my lab from the meeting, it struck me that our understanding of how lipids had been processed and orally absorbed from the GI had advanced to the point the maybe incorporating amphotericin B into such lipids might work. Within several years, our laboratory was able to develop a novel oral amphotericin B formulation that was indeed effective in treating systemic fungal infections without the side-effects associated with the drug in a variety of fungal animal models.

Lipid Systems for the Delivery of Amphotericin B in Antifungal Therapy

Amphotericin B (AmB), a broad-spectrum polyene antibiotic in the clinic for more than fifty years, remains the gold standard in the treatment of life-threatening invasive fungal infections and visceral leishmaniasis. Due to its poor water solubility and membrane permeability, AmB is conventionally formulated with deoxycholate as a micellar suspension for intravenous administration, but severe infusion-related side effects and nephrotoxicity hamper its therapeutic potential. Lipid-based formulations, such as liposomal AmB, have been developed which significantly reduce the toxic side effects of the drug. However, their high cost and the need for parenteral administration limit their widespread use. Therefore, delivery systems that can retain or even enhance antimicrobial efficacy while simultaneously reducing AmB adverse events are an active area of research. Among those, lipid systems have been extensively investigated due to the high affinity of AmB for binding lipids. The development of a safe and cost-effective oral formulation able to improve drug accessibility would be a major breakthrough, and several lipid systems for the oral delivery of AmB are currently under development. This review summarizes recent advances in lipid-based systems for targeted delivery of AmB focusing on non-parenteral nanoparticulate formulations mainly investigated over the last five years and highlighting those that are currently in clinical trials.

The Development of Oral Amphotericin B to Treat Systemic Fungal and Parasitic Infections: Has the Myth Been Finally Realized?

Parenteral amphotericin B has been considered as first-line therapy in the treatment of systemic fungal and parasitic infections, however its use has been associated with a number of limitations including affordability, accessibility, and an array of systemic toxicities. Until very recently, it has been very challenging to develop a bioavailable formulation of amphotericin B due to its physical chemical properties, limited water and lipid solubility, and poor absorption. This perspective reviews several novel oral Amphotericin B formulations under development that are attempting to overcome these limitations.

Design of amphotericin B oral formulation for antifungal therapy

Amphotericin B (AmB) remains the "gold standard" for systemic antifungal therapy, even though new drugs are emerging as the attractive antifungal agents. Since AmB has negligible oral absorption as a consequence of its unfavorable physicochemical characterizations, its use is restricted to parenteral administration which is accompanied by severe side effects. As greater understanding of the gastrointestinal tract has developed, the advanced drug delivery systems are emerging with the potential to overcome the barriers of AmB oral delivery. Much research has demonstrated that oral AmB formulations such as lipid formulations may have beneficial therapeutic efficacy with reduced adverse effects and suitable for clinical application. Here we reviewed the different formulation strategies to enhance oral drug efficacy, and discussed the current trends and future perspectives for AmB oral administration in the treatment of antifungal infections.