Plasma pharmacokinetics of clorsulon following administration of a single subcutaneous or intravenous injection to cattle.

The benzenedisulfonamide derivative clorsulon is a potent fasciolicide which is marketed in fixed combination injectables, typically combined with the macrocyclic lactone ivermectin. In the presented pharmacokinetic study, the plasma profile of clorsulon in 32 healthy, young Brown Swiss cattle was administered a single intravenous dose at 3 mg/kg body weight or subcutaneously at 3, 6 or 12 mg/kg body weight (4 intact male and 4 female animals per treatment) as a 30% w/v clorsulon injection formulation. Serial blood samples were collected up to 24 days after administration to establish the pharmacokinetics, bioavailability and dose proportionality of clorsulon. Following a single intravenous injection of clorsulon at 3 mg/kg body weight, the area under the concentration versus time curve from the start of dose administration to the time of the last quantifiable concentration (AUClast ) was 4830 ± 941 day*ng/mL, and half-live was 2.37 ± 0.98 days. The back extrapolated concentration at time 0 was 38,500 ± 6070 ng/mL. The volume of distribution at steady state and clearance were 685 ± 107 mL/kg and 664 ± 127 mL/day/kg, respectively. In the groups dosed at 3, 6 or 12 mg/kg body weight by subcutaneous injection, clorsulon plasma concentrations rose to maximum within 0.5 day and decreased to the last sample point. For these groups, the maximum plasma clorsulon concentrations were 3100 ± 838, 5250 ± 1220 and 10,800 ± 1730 ng/mL, respectively, and the AUClast was 5330 ± 925, 9630 ± 1300 and 21,500 ± 3320 day*ng/mL, respectively. Half-lives, 2.01 ± 0.62, 3.84 ± 1.42 and 5.36 ± 0.60 days, respectively, increased significantly with dose, likely related to increasing dose volume. Clorsulon was well absorbed and fully bioavailable (103%-114%) after subcutaneous injection. No gender-related difference in systemic exposure was observed. Assessment of Cmax and AUClast demonstrated a proportional increase in systemic exposure to the clorsulon subcutaneous doses over the range of 3-12 mg/kg body weight.

Gamithromycin in sheep: Pharmacokinetics and clinical evaluation against ovine footrot.

In the context of a development program to obtain the market authorization of injectable gamithromycin 15% w/v solution (Zactran®, Boehringer Ingelheim) for use in sheep against footrot, the pharmacokinetic profile of gamithromycin was established and the safety and efficacy of the treatment were confirmed in a multicenter field study in Europe. The basic pharmacokinetic parameters established in healthy young Merino sheep administered gamithromycin at 6 mg/kg body weight based on the analysis of plasma samples which were collected in intervals up to 12 days after subcutaneous injection were: area under the curve until last quantifiable concentration, 8.88 ± 2.33 µg*h/mL; maximum plasma concentration, 448 ± 180 ng/mL; terminal half-life, 42.5 ± 5.25 h. The safety and clinical efficacy against footrot of gamithromycin 15% w/v solution were evaluated in comparison to tilmicosin 30% w/v solution (Micotil®, Elanco) treatment in 364 sheep of various breeds, sex and age from commercial farms in the United Kingdom (2 sites), Germany (3 sites) and France (1 site). Animals were enrolled based on lesions characteristic of footrot and lameness associated with the presence of footrot-related bacterial pathogens and were randomly allocated and treated in a 1:1 ratio with a single subcutaneous dose of gamithromycin or tilmicosin at label dosage (6 or 10 mg/kg body weight, respectively). Lameness and footrot lesions were evaluated at five and 21 days after treatment; the injection site in all animals was examined the day after treatment and followed up daily in the animals with injection site reaction until complete injection site reaction resolution. Samples of 310 and 120 animals tested positive for Dichelobacter nodosus and Fusobacterium necrophorum, respectively, at inclusion, and data of 359 animals were included into the combined analyses (5 animals excluded for unintentional overdosing [1], lack of follow-up [1], concurrent antibiotic medication for non-footrot conditions [3]). Lameness scores at 21 days after treatment demonstrated a significantly (p = 0.0396) better success for the gamithromycin treatment compared to the tilmicosin treatment (97.8% vs. 93.3%). Post-dosing footrot lesion scores followed similar trends of rapid and marked decrease (improvement) for both treatments with similar (p = 0.127) treatment success for the gamithromycin and tilmicosin treatments (97.8% and 96.0%, respectively). Both treatments were safe; injection site reactions noted in 19 gamithromycin- and 25 tilmicosin-treated animals resolved within five days or six days of treatment, respectively. Gamithromycin 15% w/v solution administered once to sheep by subcutaneous injection at 6 mg/kg body weight demonstrated a pharmacokinetic profile similar to that reported previously in sheep and cattle and was confirmed to be a safe and efficacious treatment for naturally occurring ovine footrot in a multicenter clinical field study conducted in Europe.

Pour-on administration of eprinomectin to lactating dairy goats: Pharmacokinetics and anthelmintic efficacy.

Lactation is discussed as a physiological covariate which may influence the exposure characteristics of systemically acting drugs including macrocyclic lactones and potentially alter their pharmacological response. This study characterizes for the first time in the same study, the plasma profile and therapeutic anthelmintic efficacy of eprinomectin 5 mg/ml solution (EPRINEX® Multi, Boehringer Ingelheim) administered as a pour-on at 1 mg per kg body weight to lactating dairy goats. The study was conducted in compliance with VICH GCP and anthelmintic efficacy evaluation guidelines and included 20 goats harboring induced adult gastrointestinal and pulmonary nematode infections. The goats were blocked on pre-treatment body weight and randomly allocated either to remain untreated (control) or to be eprinomectin-treated. Plasma samples to determine the plasma disposition kinetics of eprinomectin (B1a component) were obtained at intervals up to 14 days following treatment when the animals were necropsied for parasite enumeration and identification. Basic pharmacokinetic parameters of eprinomectin determined in the ten eprinomectin-treated goats were as follows: AUClast , 23.8 ± 9.7 day*ng/ml and Cmax , 5.35 ± 2.27 ng/ml; individual maximum plasma concentrations were observed from 8 to 48 h after treatment (median Tmax , 0.5 days). Topical eprinomectin treatment efficacy, based on significant (p < .01) worm burden reductions in eprinomectin-treated animals relative to untreated controls, was ≥97% to 100% against adult Dictyocaulus filaria, Haemonchus contortus, Teladorsagia circumcincta(pinnata/trifurcata), Trichostrongylus axei, T. colubriformis, Cooperia curticei, Nematodirus battus, and Oesophagostomum venulosum. Both pharmacokinetic parameters and anthelmintic activity in lactating dairy goats were similar to those observed in parasitized young growing and adult female non-lactating dairy goats treated with eprinomectin administered as a pour-on.

Gamithromycin in swine: Pharmacokinetics and clinical evaluation against swine respiratory disease.

The pharmacokinetics of gamithromycin were evaluated in 26 male castrated and female crossbred swine administered gamithromycin 15% w/v (Zactran®, Boehringer Ingelheim) intravenously at 6 mg/kg bodyweight or intramuscularly at 3, 6 or 12 mg/kg bodyweight. Blood samples were collected up to Day 10 to establish the plasma profile of gamithromycin, bioavailability and dose proportionality. When administered by intramuscular injection at 6 mg/kg BWT, pharmacokinetic parameters were as follows: area under the curve until last quantifiable plasma concentration, 5.13 ± 0.957 µg*hours/ml; maximum plasma concentration, 960 ± 153 ng/ml at 5 to 15 min; terminal half-life of 94.1 ± 20.4 hr. Absolute bioavailability was 92.2%. Increase in systemic exposure was proportional to the gamithromycin dose level over the range 3-12 mg/kg BWT. No gender-related statistically significant difference in exposure was observed. For clinical evaluation of Zactran® against swine respiratory disease, 305 pigs from six commercial farms in three countries in Europe with signs associated with Actinobacillus pleuropneumoniae and/or Haemophilus parasuis and/or Pasteurella multocida and/or Bordetella bronchiseptica were used. At each site, animals were treated once in a 1:1 ratio with a single intramuscular dose of Zactran® (6 mg gamithromycin/kg bodyweight) or Zuprevo® (4% w/v tildipirosin at 4 mg/kg bodyweight; MSD Animal Health) at the recommended dose respectively. Animals were observed and scored daily for 10 consecutive days for signs of swine respiratory disease (depression, respiration and rectal temperature), and animals presenting signs of clinical swine respiratory disease (Depression Score 3 and/or Respiratory Score 3 associated with Rectal Temperature > 40.0°C) were removed from the study and considered as treatment failure. Animals which remained in the study were individually assessed for 'treatment success' or 'treatment failure' (Depression Score ≥ 1 and Rectal Temperature > 40.0°C or Respiratory Score ≥ 1 and Rectal Temperature > 40.0°C). Using a non-inferiority hypothesis test (non-inferiority margin = 0.10), the proportion of treatment successes in the Zactran® group (97%) was equivalent to or better than that in the Zuprevo® group (93%).

Eprinomectin pour-on (EPRINEX® Pour-on, Merial): efficacy against gastrointestinal and pulmonary nematodes and pharmacokinetics in sheep.

BACKGROUND: The anthelmintic efficacy of the 0.5% w/v topical formulation of eprinomectin (EPN), EPRINEX® Pour-on (Merial) when administered at 1 mg/kg body weight was evaluated in sheep in two dose confirmation laboratory studies and one multicenter field study. In addition, the pharmacokinetics of EPN when administered at that dosage to adult sheep was determined. RESULTS: In the two dose confirmation studies, which included 10 sheep each, sheep treated with topical EPN had significantly (p < 0.05) fewer of the following nematodes than the untreated sheep with overall reduction of nematode counts by >99%: adult Dictyocaulus filaria, Haemonchus contortus, Teladorsagia circumcincta(pinnata/trifurcata), Trichostrongylus axei, T. colubriformis, T. vitrinus, Cooperia curticei, Nematodirus battus, Strongyloides papillosus, Chabertia ovina and Oesophagostomum venulosum, and inhibited fourth-stage Teladorsagia larvae. A total of 196 sheep harboring naturally acquired gastrointestinal nematode infections were included in the field efficacy study at two sites each in Germany (48 Merino x Ile de France lambs, 52 adult Merino females) and in Italy (adult male and female Bagnolese, Lacaune, Lacaune x Bagnolese, Bagnolese x Sarda sheep; 48 animals per site). Animals were blocked on pre-treatment body weight and within each block, one animal was randomly assigned to the control (untreated) group and three animals were randomly assigned to be treated with topical EPN. Examination of feces 14 days after treatment demonstrated that, relative to the controls, topical EPN-treated sheep had significantly (p < 0.0001) lower strongylid egg counts. Reduction was ≥97% at each site and 98.6% across all sites. Pharmacokinetics of EPN following single treatment with topical EPN were determined in eight ~4.5 year old female Merino cross sheep based on the analysis of plasma samples which were collected from two hours to 21 days following treatment. The main pharmacokinetic parameters were: Cmax 6.20 ± 1.71 ng/mL, AUClast 48.8 ± 19.2 day*ng/mL, Tmax 3.13 ± 2.99 days and T1/2 6.40 ± 2.95 days. No treatment-related health problems or adverse drug events were observed in any study. CONCLUSION: These studies demonstrated 0.5% w/v EPN administered topically at 1 mg/kg body weight to be highly efficacious against a broad range of ovine gastrointestinal nematodes and D. filaria lungworms and well tolerated by sheep of different ages, breeds, gender and physiological status.

Gamithromycin plasma and skin pharmacokinetics in sheep.

This study assessed the plasma kinetics and skin/plasma concentration ratio of the azalide antibiotic gamithromycin (ZACTRAN(®), Merial) in sheep after a single subcutaneous administration at 6 mg/kg bodyweight. Gamithromycin concentrations in plasma samples collected at various intervals up to 21 days following treatment and metacarpal skin obtained from animals at two, five and ten days after treatment were determined by liquid chromatography-tandem mass spectrometry methods. After administration, gamithromycin was rapidly absorbed, and individual maximum plasma concentrations were observed within 6 hours post-dose. Plasma peak concentration was 573 ± 168 ng/ml. The mean area under the plasma concentration versus time curve extrapolated to infinity was 8.00 ± 1.41 µg · hr/ml, and the mean terminal half-life was 34.5 ± 5.4 hours. Gamithromycin skin concentrations were much higher than the plasma concentrations resulting in skin/plasma concentration ratios of approximately 21, 58, and 138 at two, five and ten days post-dose, respectively, demonstrating extensive distribution to skin tissue.

Pharmacokinetics and anthelmintic efficacy of topical eprinomectin in goats prevented from grooming.

Pharmacokinetics and anthelmintic activity of topical eprinomectin in goats prevented from physical contact to others and self-grooming were studied. Sixteen approximately 7 months old male castrated German White Noble goats harbouring induced infections of gastrointestinal nematode parasites were included in the study. They were blocked based on pre-treatment body weight (range 22.4 to 36.4 kg) and then randomly allocated to the untreated control group or the group treated with topical 0.5% w/v eprinomectin (EPRINEX Pour-on, Merial) at 1 mg/kg body weight. Plasma samples were collected prior to and at intervals up to 14 days following treatment and analyzed to determine the concentrations of eprinomectin (B1a component). Parasites were recovered, identified, and counted following necropsy 14 days after treatment. Goats treated with topical eprinomectin had significantly fewer (≥99% reduction, p < 0.01) adult Cooperia curticei, Haemonchus contortus, Nematodirus battus, Oesophagostomum venulosum, Ostertagia circumcincta, and Trichostrongylus colubriformis than the untreated controls. Basic pharmacokinetic parameters for eprinomectin B1a were AUCinfinity, 37.1 ± 15.2 day ng/mL; T½, 5.11 ± 2.83 days; and Cmax, 5.93 ± 1.87 ng/mL; individual maximal concentrations were observed 1 or 2 days after treatment. Results of this study indicate that oral ingestion is not required to achieve adequate exposure for excellent anthelmintic efficacy following topical administration of eprinomectin at 1 mg/kg body weight to goats.

Pharmacokinetics and metabolism of eprinomectin in cats when administered in a novel topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel.

Four studies were conducted to determine the pharmacokinetic characteristics and in vitro metabolism of eprinomectin, a semi-synthetic avermectin, in cats. Pharmacokinetic parameters including bioavailability of eprinomectin were determined in a parallel study design comprised of one group of eight cats which were treated once topically at 0.12 mL/kg bodyweight with BROADLINE(®), a novel combination product (fipronil 8.3% (w/v), (S)-methoprene 10% (w/v), eprinomectin 0.4% (w/v) and praziquantel 8.3% (w/v)), delivering a dose of 0.5mg eprinomectin per kg body weight, and a group of six cats which received 0.4% (w/v) eprinomectin at 0.4 mg/kg bodyweight once by intravenous injection. For cats treated by topical application, the average eprinomectin (B1a component) maximum plasma concentration (Cmax) was 20 ng/mL. The maximum concentrations were reached 24h after dosing in the majority of the animals (six of eight cats). The average terminal half-life was 114 h due to slow absorption ('flip-flop' kinetics). Following intravenous administration the average Cmax was 503 ng/mL at 5 min post-dose, and the mean elimination half-life was 23 h. Eprinomectin was widely distributed with a mean volume of distribution of 2,390 mL/kg, and the clearance rate was 81 mL/h/kg. Mean areas under the plasma concentration versus time curves extrapolated to infinity were 2,100 ngh/mL and 5,160 ngh/mL for the topical and intravenous doses, respectively. Topical eprinomectin was absorbed with an average absolute bioavailability of 31%. In a second parallel design study, the dose proportionality of eprinomectin after single topical administration of BROADLINE(®) was studied. Four groups of eight cats each were treated once topically with 0.5, 1, 2 or 5 times the minimum recommended dose of the combination, 0.12 mL/kg bodyweight. Based on comparison of areas under the plasma concentration versus time curves from the time of dosing to the last time point at which eprinomectin B1a was quantified, and Cmax, dose proportionality was established. In addition, the metabolic pathway of eprinomectin using cat liver microsomes, and plasma protein binding using cat, rat, and dog plasma were studied in vitro. Results of the analyses of eprinomectin B1a described here showed that it is metabolically stable and highly protein bound (>99%), and thus likely to be, as with other species, excreted mainly as unchanged parent drug in the feces of cats.

Reevaluation of efficacy against nematode parasites and pharmacokinetics of topical eprinomectin in cattle.

A study was conducted to confirm the efficacy of topical eprinomectin against nematodes and to evaluate the pharmacokinetics in cattle prevented from having physical contact with other cattle and from self-grooming. Sixteen male Brown Swiss calves were infected with larvae of recently isolated nematode parasites. Inoculation was scheduled so that the nematodes were expected to be adults at the time of treatment. Animals were blocked based on pretreatment body weight and randomly allocated to the untreated control group or the group treated with EPRINEX® Pour-On (Merial; 0.5 mg eprinomectin per kilogram body weight). Plasma samples were collected prior to and between 1 and 21 days following treatment and analysed for eprinomectin (B1a component) concentrations. For parasite recovery, identification and counting, animals were humanely euthanized 21 days after treatment. Calves treated with eprinomectin had significantly (p < 0.05) fewer (>99 % reduction) adult Dictyocaulus viviparus, Bunostomum phlebotomum, Cooperia oncophora, Cooperia surnabada, Cooperia punctata, Nematodirus helvetianus, Oesophagostomum radiatum, Ostertagia ostertagi, Ostertagia lyrata, and Trichostrongylus axei and inhibited fourth-stage Nematodirus and Ostertagia larvae than the controls. The main pharmacokinetic parameters of eprinomectin B1a were: AUC(inf), 124 ± 24 day ng/mL; T (1/2), 5.2 ± 0.9 days; and C (max), 9.7 ± 2.2 ng/mL. Individual maximal concentrations were observed 3-7 days after treatment. This study confirmed the continued high level of efficacy of topically administered eprinomectin against a wide range of recently isolated nematodes. In addition, this study demonstrates that oral ingestion is not required to achieve adequate exposure for efficacy following topical administration of eprinomectin.

Using the Mehran risk scoring tool to predict risk for contrast medium-induced nephropathy in patients undergoing percutaneous angiography.

BACKGROUND: Patients who have radiological imaging with contrast material are at risk for contrast medium-induced nephropathy, reduced renal function, longer hospitalizations, and renal failure requiring dialysis. OBJECTIVE: To determine whether the Mehran risk scoring tool can be used to predict changes in hospitalized patients who had percutaneous angiography. METHODS: Data on 196 patients admitted for cardiac angiography who had Mehran risk scores higher than 6 were analyzed retrospectively. Creatinine levels, used as predictors of contrast medium-induced nephropathy, were evaluated at day 2, day 3, and day 4 through day 7. RESULTS: Creatinine levels were significantly higher in patients with a Mehran risk score of 11 or higher than in patients with a risk score of 6 to 10 at all times. CONCLUSIONS: The Mehran risk scoring tool provides reliable data before patients have percutaneous angiography.

Congressional Careers, Committee Assignments, and Seniority Randomization in the U.S. House of Representatives.

This paper estimates the effects of initial committee seniority on the career histories of Democratic members of the House of Representatives from 1949 to 2006. When more than one freshman representative is assigned to a committee, positions in the seniority queue are established by lottery. Randomization ensures that queue positions are uncorrelated in expectation with other legislator characteristics within these groups. This natural experiment allows us to estimate the causal effect of seniority on a variety of career outcomes. Lower ranked committee members are less likely to serve as subcommittee chairs on their initial committee, are more likely to transfer to other committees, and have fewer sponsored bills passed in the jurisdiction of their initial committee. On the other hand, there is little evidence that the seniority randomization has a net effect on reelection outcomes or non-committee bills passed.

Pyrene binding to persistent micelles formed from a dendro-calixarene.

The formation of micelles of an amphiphilic dendro-calixarene (1) was studied using pyrene as a guest molecule. Steady-state fluorescence experiments were performed, which showed that pyrene is readily solubilized in the micelles and senses an environment with a moderate polarity. Time-resolved fluorescence measurements showed that pyrene in the micelles have two lifetimes, suggesting some compartmentalization of the guest within the micelles. Pyrene bound to the micelles is completely protected from the interaction with anionic species in the aqueous phase, due to the repulsion between the anions and the negatively charged micelles. Compared to conventional micelles, such as those formed with sodium dodecyl sulfate, micelles of 1 form at much lower concentrations of monomer.