Effects of amorphous and polymorphs of PF1022A, a new antinematode drug, on Angiostrongylus costaricensis in mice

Propofol: Current Updates, Challenges, and Strategies for Improved Self-Nanoemulsifying Formulation

Propofol, commonly used as an intravenous (IV) anesthetic and sedative, requires strict aseptic handling to prevent microbial contamination. There have been alarming reports of bloodborne pathogen transmission due to unsafe injection practices and the reuse of single-use propofol vials. Additionally, managing pain during anesthesia induction and determining the correct dose for sedation pose significant challenges with IV propofol. Despite its effectiveness, propofol's limited water solubility and poor oral bioavailability restrict its use outside of anesthesia. Understanding how propofol works remains complex. Advances in nanotechnology have significantly improved the bioavailability of hydrophobic drugs through self-nanoemulsifying drug delivery systems (SNEDDS). These lipid-based formulations create nanoscale emulsions upon contact with gastrointestinal fluids, enhancing drug solubilization and absorption. For instance, studies have shown that SNEDDS can improve bioavailability by 2- to 3-fold compared to traditional formulations, as demonstrated with drugs such as propofol, whose poor water solubility limits its therapeutic efficiency. This review delves into propofol's chemical properties, pharmacokinetics, and pharmacodynamics, evaluating the potential of SNEDDS to address its formulation challenges and discussing promising candidates in clinical trials. Furthermore, it examines the potential of using SNEDDS to improve propofol's bioavailability through nonintravenous routes. This review highlights the potential of SNEDDS to enhance propofol's therapeutic effectiveness beyond its traditional use in anesthesia, opening new avenues for its application.

Natural products as anthelmintics: safeguarding animal health

Covering literature to December 2022This review provides a comprehensive account of all natural products (500 compounds, including 17 semi-synthetic derivatives) described in the primary literature up to December 2022, reported to be capable of inhibiting the egg hatching, motility, larval development and/or the survival of helminths (i.e., nematodes, flukes and tapeworms). These parasitic worms infect and compromise the health and welfare, productivity and lives of commercial livestock (i.e., sheep, cattle, horses, pigs, poultry and fish), companion animals (i.e., dogs and cats) and other high value, endangered and/or exotic animals. Attention is given to chemical structures, as well as source organisms and anthelmintic properties, including the nature of bioassay target species, in vivo animal hosts, and measures of potency.

Development of emodepside as a possible adulticidal treatment for human onchocerciasis-The fruit of a successful industrial-academic collaboration

Current mass drug administration (MDA) programs for the treatment of human river blindness (onchocerciasis) caused by the filarial worm Onchocerca volvulus rely on ivermectin, an anthelmintic originally developed for animal health. These treatments are primarily directed against migrating microfilariae and also suppress fecundity for several months, but fail to eliminate adult O. volvulus. Therefore, elimination programs need time frames of decades, well exceeding the life span of adult worms. The situation is worsened by decreased ivermectin efficacy after long-term therapy. To improve treatment options against onchocerciasis, a drug development candidate should ideally kill or irreversibly sterilize adult worms. Emodepside is a broad-spectrum anthelmintic used for the treatment of parasitic nematodes in cats and dogs (Profender and Procox). Our current knowledge of the pharmacology of emodepside is the result of more than 2 decades of intensive collaborative research between academia and the pharmaceutical industry. Emodepside has a novel mode of action with a broad spectrum of activity, including against extraintestinal nematode stages such as migrating larvae or macrofilariae. Therefore, emodepside is considered to be among the most promising candidates for evaluation as an adulticide treatment against onchocerciasis. Consequently, in 2014, Bayer and the Drugs for Neglected Diseases initiative (DNDi) started a collaboration to develop emodepside for the treatment of patients suffering from the disease. Macrofilaricidal activity has been demonstrated in various models, including Onchocerca ochengi in cattle, the parasite most closely related to O. volvulus. Emodepside has now successfully passed Phase I clinical trials, and a Phase II study is planned. This Bayer–DNDi partnership is an outstanding example of “One World Health,” in which experience gained in veterinary science and drug development is translated to human health and leads to improved tools to combat neglected tropical diseases (NTDs) and shorten development pathways and timelines in an otherwise neglected area.

Onchocerca volvulus is the causative agent of human river blindness, and current elimination programs rely on the use of ivermectin to kill microfilariae. Since no adulticidal drug is available and adult worms have a life span of up to 15 years, elimination programs need to be sustained over several decades. Emodepside is an anthelmintic that is licensed as a dewormer for cats and dogs. Due to its ability to eliminate nematodes located in various extraintestinal host tissues, including migrating larvae and adult filarial worms, it is considered to be an excellent candidate for the treatment of onchocerciasis. Intense collaboration between academia and the pharmaceutical industry has led to a deep understanding of the novel mode of action of the drug and of its parasite target spectrum. Phase I clinical trials with emodepside have demonstrated its safety and adulticide activity against the closely related cattle parasite Onchocerca ochengi. Currently, Phase II clinical trials are planned to confirm that emodepside, developed initially to improve animal health, has also the potential to improve human health by tackling a very important neglected tropical disease (NTD).

Efficacy evaluation of anthelmintic products against an infection with the canine hookworm (Ancylostoma caninum) isolate Worthy 4.1F3P in dogs

Ancylostoma caninum is the most prevalent intestinal nematode of dogs, and has a zoonotic potential. Multiple-drug resistance (MDR) has been confirmed in a number of A. caninum isolates, including isolate Worthy 4.1F3P, against all anthelmintic drug classes approved for hookworm treatment in dogs in the United States (US). The cyclooctadepsipeptide emodepside is not registered to use in dogs in the US, but in a number of other countries/regions. The objective of this study was to evaluate the efficacy of emodepside + praziquantel, as well as three commercial products that are commonly used in the US for treatment of hookworms, against a suspected (subsequently confirmed) MDR A. caninum isolate Worthy 4.1F3P. 40 dogs infected on study day (SD) 0 with 300 third-stage larvae, were randomly allocated to one of five treatment groups with eight dogs each: pyrantel pamoate (Nemex®-2), fenbendazole (Panacur® C), milbemycin oxime (Interceptor®), emodepside + praziquantel tablets and non-treated control. Fecal egg counts (FEC) were performed on SDs 19, 20, 22, 27, 31 and 34. All treatments were administered as per label requirements on SD 24 to dogs in Groups 1 through 4. Two additional treatments were administered on SDs 25 and 26 to dogs in Group 2 as per label requirements. Dogs were necropsied on SD 34 and the digestive tract was removed/processed for worm recovery and enumeration. The geometric mean (GM) worm counts for the control group was 97.4, and for the pyrantel pamoate, fenbendazole, milbemycin oxime, and emodepside + praziquantel groups were 74.8, 72.0, 88.9, and 0.4, respectively. These yielded efficacies of 23.2%, 26.1%, and 8.8%, and 99.6%, respectively. These data support previous findings of the MDR status of Worthy 4.1F3P as treatments with pyrantel pamoate, fenbendazole and milbemycin oxime lacked efficacy. In sharp contrast, Worthy 4.1F3P was highly susceptible to treatment with emodepside + praziquantel.

Synthesis and anthelmintic activity of substituted (R)-phenyllactic acid containing cyclohexadepsipeptides

The substituted (R)-phenyllactic acid containing cyclohexadepsipeptides (CHDPs) represent novel enniatin derivatives with strong in vivo activities against the parasitic nematode Haemonchus contortus Rudolphi in sheep. 2D NMR spectroscopic analysis revealed for the substituted (R)-phenyllactic acid containing CHDPs one major conformer with an unsymmetrically folded conformation lacking a cis-amide bond. A correlation between the substitution pattern and its anthelmintic activity was found. Here we report on a simple total synthetic pathway of the precursor for this particular type of CHDPs and an efficient modification of the benzylic side chain (R-PhLac(2)).

Drug trials for treatment of human angiostrongyliasis

Abdominal and cerebral angiostrongyliasis are two important infections produced by metastrongylid worms, the former occurring in Central and South America and the later in Asia and Pacific Islands. Drug treatment is a challenge since the worms and its evolving larvae live or migrate inside vessels and efficient killing of the parasites may produce more severe lesions. Larvicidal effect of certain drugs appears to be more easily accomplished but this outcome is not useful in abdominal angiostrongyliasis since clinical manifestations appear to result from sexual maturation of the worms. We review the drug trials in murine experimental models and conclude that most of them could not be considered good candidates for treatment of human infection, except for PF1022A, pyrantel and flubendazole.

Conformational color polymorphism and control of crystallization of 5-methyl-2-[(4-methyl-2-nitrophenyl)amino]-3-thiophenecarbonitrile

5-Methyl-2-[(4-methyl-2-nitrophenyl)amino]-3-thiophenecarbonitrile is an example of conformational and color polymorphism. The compound crystallizes in red (R), dark red (DR), light red (LR), and orange (O) modifications. There are two specific goals for this study. One is to characterize the complex thermodynamic relationship among these four known forms, and the other is to use the knowledge of the thermodynamic relationship to control the crystallization of these forms. The different forms were characterized by X-ray powder diffractometry as well as Fourier-transform infrared (FT-IR) and Raman spectroscopy; their complex thermodynamic relationships were determined by thermal analysis, solubility measurements, and slurry conversion studies. According to the solubility results, all forms are enantiotropically related: R is the thermodynamically most stable form above 60 degrees C, O is the most stable form between room temperature and 60 degrees C, LR is the most stable form below -15 degrees C, and DR is metastable throughout the entire temperature range. DR, LR, and O have very similar free energy at ambient temperature, which is the reason for the complex transition behavior. Finally, a schematic energy-temperature diagram was constructed that combines all experimental data in a comprehensive thermodynamic picture and provides insights into how to control the crystallization of the individual forms.

Frontiers in anthelmintic pharmacology

Research in anthelmintic pharmacology faces a grim future. The parent field of veterinary parasitology has seemingly been devalued by governments, universities and the animal industry in general. Primarily due to the success of the macrocyclic lactone anthelmintics in cattle, problems caused by helminth infections are widely perceived to be unimportant. The market for anthelmintics in other host species that are plagued by resistance, such as sheep and horses, is thought to be too small to sustain a discovery program in the animal health pharmaceutical industry. These attitudes are both alarming and foolish. The recent history of resistance to antibiotics provides more than adequate warning that complacency about the continued efficacy of any class of drugs for the chemotherapy of an infectious disease is folly. Parasitology remains a dominant feature of veterinary medicine and of the animal health industry. Investment into research on the basic and clinical pharmacology of anthelmintics is essential to ensure chemotherapeutic control of these organisms into the 21st century. In this article, we propose a set of questions that should receive priority for research funding in order to bring this field into the modern era. While the specific questions are open for revision, we believe that organized support of a prioritized list of research objectives could stimulate a renaissance in research in veterinary helminthology. To accept the status quo is to surrender.