BackgroundCystoisospora suis causes diarrhoeal disease and reduced weight gain in suckling piglets, and a toltrazuril-based oral suspension is available for treatment. Recently a combinatorial product with toltrazuril plus iron has been developed for parenteral application. In this study we compared the efficacy of the injectable product with the oral suspension against experimentally induced piglet cystoisosporosis.MethodsIn a randomised controlled study, three groups of piglets (n = 10–13) were treated either with a fixed dose of 45 mg toltrazuril + 200 mg gleptoferron i.m. per piglet (Forceris®) on the second day of life (study day 2; SD 2) or with 20 mg toltrazuril/kg body weight as an oral suspension (Baycox® 5%) on SD 4 or left untreated (Control group). The Baycox® and the Control group received 200 mg of iron dextran/piglet on SD 2. All piglets were infected with 1000 sporulated C. suis oocysts on SD 3. Faecal samples were taken daily from SD 7 to SD 20 to determine faecal consistency, oocyst shedding and other diarrhoeal pathogens. Body weight was recorded on SD 1 and then weekly until SD 29. Animals were observed daily for general health and after treatment for possible adverse events.ResultsIn the Control group all animals shed oocysts for 3.1 days on average and all animals showed diarrhoea for an average of five days. Excretion peaked on SD 9 (max. 48,618 oocysts per gram of faeces). Treatment with Forceris® completely suppressed oocyst excretion. In the Baycox® group, low levels of excretion could be detected. Diarrhoea was reduced to single piglets in the treated groups. Body weight development was reduced in the Control group compared to the treated groups. Enteropathogenic bacteria (Escherichia coli, Clostridium perfringens) could be detected. All parameters related to oocyst excretion, faecal consistency and weight gain were significantly improved in the treated groups compared to the Control group without significant differences between the treated groups. Both products were safe to use.ConclusionsTreatment with both the injectable (Forceris®) and the oral (Baycox®) formulation of toltrazuril in the prepatent period were safe and highly effective against experimental infection with C. suis in newborn piglets.

There is a real need to develop new therapeutic strategies for African trypanosomiasis infections. In our study, we developed a new drug delivery system of diminazene (DMZ), a trypanocidal drug registered for veterinary use. This drug candidate presents a limited efficacy, a poor affinity for brain tissue and instability. The development of colloidal formulations based on a porous cationic nanoparticle with an oily core ((70)DGNP(+)), has potentially two advantages: stabilization of the drug and potential targeting of the parasite. We analyzed two processes of drug loading: in process (DMZ was added during the preparation of (70)DGNP(+) at 80 °C) and post-loading (DMZ was mixed with a (70)DGNP(+) solution at room temperature). Poor stability of the drug was observed using the in process technique. When using the post-loading technique over 80% drug entrapment efficiency was obtained at a ratio of DMZ:phospholipids (wt:wt) < 5%. Moreover, DMZ loaded into (70)DGNP(+) was found to be protected against oxidation and was stable for at least six months at 4 °C. Finally, in vitro tests on T.b. brucei showed an increased efficacy of DMZ loaded in (70)DGNP(+).

Background Toltrazuril is frequently administered for the metaphylactic control of piglet cystoisosporosis. In a previous study, the efficacy of parenteral toltrazuril (45 mg/piglet, Group Forceris®) applied on the 2nd day of life (dol), and of oral toltrazuril (20 mg/kg of body weight, Group Baycox®) applied on the 4th dol was evaluated in an experimental model with Cystoisospora suis infection on the 3rd dol (late infection, LI). In a follow-up study, efficacy and safety were evaluated against infections with C. suis on the 1st dol (early infection, EI). Parameters included oocyst excretion and faecal consistency, body weight development, bacteriological examinations and animal health. Results All control piglets ( n = 12) shed oocysts and had diarrhoea, while parasite excretion was completely suppressed in both treatment groups ( n = 13 each) and diarrhoea was reduced to a single animal (Forceris® group), resulting in significant differences for these parameters between the treated groups and the controls without significant differences among the treatment groups. No treatment-related adverse events were noted. Body weight gain was reduced in the control group during the acute phase of infection, resulting in significantly lower body weight on the 15th dol. Sows and piglets shed high numbers of Escherichia coli . Clostridium perfringens type A was only detected in low amounts in pooled litter samples. In comparison to the LI study oocyst shedding was more intense in the control animals in EI, while diarrhea was more frequent in LI. In both infection models a high efficacy of toltrazuril in the control of parasitological and clinical outcomes of experimental C. suis infection could be demonstrated. Since in the LI study high numbers of Cl. perfringens type A were detected, it is hypothesized that colonization with these opportunistic pathogens has synergistic effects with C. suis and may explain variable clinical outcomes in untreated animals as well as the sporadic occurrence of diarrhea in toltrazuril-treated piglets. Conclusions Parenteral and oral toltrazuril administered on the 2nd or 4th dol is safe and effective against experimental infections with C. suis on the 1st to 3rd dol. The clinical outcome of experimental infections seems influenced by bacterial coinfections.

Since the 1950s, the chemotherapy of animal African trypanosomosis in cattle has essentially relied on only two compounds: isometamidium chloride (ISM), a phenanthridine, and diminazene aceturate, an aromatic diamidine. The commercial formulations of ISM, including Veridium(®) and Samorin(®), are a mixture of different compounds: ISM is the major component, mixed with the red isomer, blue isomer and disubstituted compound. To investigate the pharmacological effects of these individual compounds ISM, the blue and red isomers and the disubstituted compound were synthesised and purified by HPLC. The activity of each compound was analysed both in vitro, and in mice in vivo. For the in vitro analysis, a drug sensitivity assay was developed in 96-well tissue culture plates to determine the effective concentration which killed 50% of trypanosome population within 48 h of drug exposure (IC50). All compounds tested in vitro possessed trypanocidal activity, and purified ISM was the most active. Veridium(®) and Samorin(®) had similar IC50 values to purified ISM for both Trypanosoma congolense and Trypanosoma brucei brucei. The disubstituted compound had the highest IC50 values whereas intermediate IC50 values were obtained for the blue and red isomers. In vivo, single-dose tests were used to evaluate the trypanocidal and prophylactic activity against T. congolense. Interestingly, the prophylactic effect two months post treatment was as efficient with ISM, Veridium(®), Samorin(®) and the disubstituted compound at the highest dose of 1mg/kg whereas the red and blue isomers both showed much lower prophylactic activity. This study on T. congolense implies that it is necessary to limit the quantity of the blue and red isomers in the commercial mixture. Finally, the in vitro sensitivity assay may be useful for screening new trypanocides but also for the testing and detection of resistant trypanosome isolates.

The design of drug formulations relevant to the treatment of AT must include a combination of very specific properties. In summary, the drug delivery system must be compatible with the physicochemical properties of the drug (charge, lipophilicity and molecular mass) in order to allow high drug payloads while being biocompatible for the patient.