Absorption and Distribution of Toltrazuril and Toltrazuril Sulfone in Plasma, Intestinal Tissues and Content of Piglets after Oral or Intramuscular Administration

Comparison of an injectable toltrazuril-gleptoferron and an oral toltrazuril + injectable gleptoferron in piglets: Hematinic activities and pharmacokinetics

Iron deficiency anemia (IDA) and cystoisosporosis are the most common clinical conditions of fast-growing piglets. Until now, IDA and cystoisosporosis have been managed by intramuscular injection of iron complexes (such as dextran or gleptoferron) and oral administration of toltrazuril. Recently, a new combination product containing toltrazuril and gleptoferron for intramuscular application (Forceris®) has been registered. The objective of this study was to compare the pharmacokinetic profiles of toltrazuril and its main metabolite, toltrazuril sulfone, following a single oral (Baycox®) or intramuscular (Forceris®, a toltrazuril-iron combination product) administration at 20 mg/kg to young suckling piglets. The orally treated piglets were also supplemented with iron (Gleptosil®), and the hematinic activities were compared. Piglets in both groups received comparable doses. The peak concentration (Cmax) of toltrazuril after intramuscular administration was 11% lower than that after oral administration (p = .376). However, the exposure to toltrazuril (AUC) was significantly increased (40% higher) when toltrazuril was administered intramuscularly (p = .036). The Cmax and AUC values of the active metabolite, toltrazuril sulfone were 39% and 34% higher, respectively, after intramuscular administration (p = .007 and 0.008, respectively). Piglets in both groups were properly protected against IDA. In conclusion, a higher relative bioavailability of toltrazuril is observed when toltrazuril is administered intramuscularly.

Metaphylactic strategies using toltrazuril against coccidiosis in goat kids

Goat coccidiosis compromises animal welfare, reduces productivity and may cause mortality and delayed growth rates in goat kids around the weaning period worldwide. This field study was conducted to evaluate the efficacy of metaphylactic treatments with two doses of toltrazuril (20 or 40 mg/kg body weight - BW, p. o.), at different timing, in kids naturally infected with Eimeria spp. A total of 97 healthy goat kids (Majorera milk aptitude breed) were divided into five groups, depending on the age of treatment (2 or 7 weeks). One group remained untreated as a negative control until the end of the study. Faecal oocyst shedding, faecal consistency, and body weight of the animals were monitored at day 0 and at weekly intervals. Counts of oocysts per gram of faeces (OPG) were determined by a modified McMaster technique. Morphometric identification of Eimeria species was carried out on individual faecal samples from each experimental group after oocyst sporulation. Goat kids treated at two weeks of age maintained OPG values close to zero during the 5 weeks post-treatment and, overall, had lower faecal oocyst counts than untreated control animals. No significant differences were observed between the two doses of toltrazuril used in two-week-old treated animals. By contrast, when treatment was carried out at seven weeks of age, the dose of 40 mg/kg BW of toltrazuril reduced oocyst levels for longer and to a greater extent than the 20 mg/kg dose. Irrespectively of the treatment and dose, toltrazuril delayed the appearance of pathogenic Eimeria species, i. e. Eimeria ninakohlyakimovae and Eimeria arloingi. As a whole, Eimeria christenseni, with a rather moderate pathogenicity, was highly predominant throughout the study period, including the untreated control group, which was probably the reason why clinical signs of coccidiosis were barely observed throughout the experiment. Under these circumstances, the positive effect of toltrazuril on body weight condition observed in some treated groups was difficult to correlate to the timing and doses. Metaphylactic treatments with 20 mg/kg BW toltrazuril given at two weeks of age are sufficient to control oocyst excretion in goat kids; whereas if administered later in 7-week-old animals, thereby coinciding with the frequently observed peak of oocyst elimination in goat kids under field conditions, a higher dose might be advisable to prevent environmental contamination with infectious oocysts.

On the efficacy of preventive toltrazuril treatments and the diagnosis of Cystoisospora suis infections in intensively raised piglets in farms from southeast Spain

This study investigated the presence and abundance of Cystoisospora suis oocysts in faecal samples from 131 one- to three-week-old pig litters belonging to eight intensively raised, indoor herds in Spain. Seven herds used preventive anticoccidial toltrazuril treatments administered orally or by intramuscular injection, and one did not use preventive anticoccidial treatments. The diagnosis was performed using two oocyst flotation-concentration methods, Bailenger's method in every herd and the more recent Joachim's method in four herds. Oocysts were detected in every farm, the proportion of oocyst-positive samples was higher with Bailenger's technique, and the estimated overall prevalence (95% confidence interval) was 40 (32-49)%, including 47 (29-65)% in non-medicated litters, 52 (38-67)% in orally medicated litters and 28 (16-40)% in intramuscularly medicated litters (p < 0.05). However, mixed logistic regression models indicated that the risk of infection was not significantly associated with preventive anticoccidial treatments (p > 0.05), and increased with age, was higher in herds with partially compared to fully slatted dung floors in farrowing pens and in litters with pigs with diarrhoea (p < 0.05). The median (range) oocysts per gram of faeces (OpG) in infected litters by Bailenger's method was 623 (35-49048) and mixed negative binomial models revealed no significant association between infection intensity in positive litters and pen's floor type and piglets age, faecal consistency and treatment status (p > 0.05). The apparent low efficacy of Toltrazuril suggests treatment administration failures, reduced residual efficacy or low susceptibility of C. suis strains in study farms and needs further investigation.

Pharmacokinetics of toltrazuril and its metabolite, toltrazuril sulfone, in suckling piglets following oral and intramuscular administrations

Toltrazuril (TZR) is currently the only registered chemotherapeutic drug in the European Union for the treatment of Cystoisospora suis. This study investigated the comparative pharmacokinetics and tissue concentration-time profiles of TZR and its active metabolite, toltrazuril sulfone (TZR-SO2 ), after oral (per os, p.o.) and intramuscular (i.m.) administration to suckling piglets. Following a single administration of TZR orally at 50 mg/piglet or intramuscularly at 45 mg/piglet, higher concentrations of TZR and TZR-SO2 were observed in all three investigated tissues after p.o. administration. The mean TZR concentration in serum peaked at 14 μg/mL (34.03 h) and 5.36 μg/mL (120 h), while TZR-SO2 peaked at 14.12 μg/mL (246 h) and 9.92 μg/mL (330 h) after p.o. and i.m. administration, respectively. TZR was undetectable in the liver after p.o. administration (18 days) and in the jejunum (24 days) after i.m. injection, while TZR-SO2 was still detectable in all three tissues after 36 days regardless of administration routes. This study showed that p.o. formulation exhibited faster absorption and higher serum/tissue TZR/TZR-SO2 concentrations than i.m. formulation. Both formulations generated sufficient therapeutic concentrations in the serum and jejunum, and sustained enough time to protect against Cystoisospora suis infection in the piglets.

Pharmacokinetics, bioavailability, and excretion of ponazuril in piglets

Ponazuril is a triazine anticoccidial drug which is the main metabolite of toltrazuril in animals, it has excellent activity against many protozoa, including Cystoisospora suis, and has broad application prospects in the control of swine coccidiosis. To evaluate the pharmacokinetic and excretion characteristics of ponazuril, 12 healthy piglets aged 10-14 days were divided into 2 groups for pharmacokinetic studies, which were given 20 mg/kg body weight ponazuril orally and intravenously, respectively. And 6 other piglets were housed individually in metabolic cages and given the same oral dose of ponazuril. After administration, the concentration of ponazuril in plasma, fecal, and urine samples collected was determined using high-performance liquid chromatography (HPLC). The plasma concentration profiles of ponazuril obtained after intravenous and oral administration were analyzed simultaneously by the nonlinear mixed-effects (NLME) model. Following the results, the pharmacokinetics of ponazuril exhibited a Michaelis-Menten elimination with Michaelis-Menten constant K_m and maximum metabolic rate V_m of 10.8 μg/mL and 0.083 mg/kg/h. The apparent volume of distribution was calculated to be 735 mL/kg, and the final estimated oral bioavailability was 81%. Besides, cumulatively 86.42 ± 2.96% of ponazuril was recovered from feces and 0.31% ± 0.08% from urine during 0-1,020 h after oral administration. These findings indicated a good oral absorption of ponazuril in piglets with nonlinear disposition and slow excretion largely via feces, implying sustained drug concentration in vivo and long-lasting anticoccidial effects.

Cystoisospora suis infection in suckling piglets in Brazil: Prevalence and associated factors

Piglet coccidiosis is a parasitic disease caused by the protozoan Cystoisospora suis, which is regarded as the most prevalent gastrointestinal parasite in intensive pig farms. Despite the availability of highly effective chemo-metaphylaxis (toltrazuril), coccidiosis is still prevalent in European and other countries. We conducted a cross-sectional study on swine farms in Brazil, to assess the prevalence of Cystoisospora suis in fecal samples and determined the associated factors. In total, 666 litters from 50 farms were sampled twice within one week between samplings (mean age at sampling: 10.75 and 17.7 days). Of 666 litters, 225 (33.8%) were positive at least once, and the expected within farm prevalence of C. suis oocysts was 32.9% (25.4-41.3%; 95% confidence interval). Oocysts were more prevalent in fecal samples collected from farms with diarrhea (odds ratio = 6.75). The room temperature was also positively associated with oocyst detection; a one-degree increase in room temperature increased the chance of a litter being positive by 23.2%. Up-to-date, this is the most comprehensive technical evidence of factors associated with C. suis infection in Brazilian industrial piglet farms.