Draxxin 25: Product Information (Page 2 of 4)
Swine
Following intramuscular (IM) administration to feeder pigs at a dosage of 2.5 mg/kg BW, tulathromycin is nearly completely absorbed, with peak plasma concentrations achieved within ~0.25 hr. The volume of distribution exceeds 15 L/kg, which is consistent with extensive tissue binding. This large distribution volume results in a long terminal elimination half- life (60 to 90 hours) despite a rapid systemic free drug clearance (187 mL/kg/hr). There are no gender differences in swine tulathromycin pharmacokinetics.
Comparative Bioavailability Summary
Despite slightly lower peak concentrations with DRAXXIN 25 Injectable Solution, a single IM dose of 2.5 mg tulathromycin/kg BW of either DRAXXIN Injectable Solution (100 mg/mL) or DRAXXIN 25 Injectable Solution (25 mg/mL) resulted in comparable tulathromycin total systemic exposure. Therefore, DRAXXIN 25 Injectable Solution is considered to be therapeutically equivalent to DRAXXIN Injectable Solution when administered to swine by IM injection at a dose of 2.5 mg tulathromycin/kg BW.
Calves
Following subcutaneous (SC) administration into the neck of feeder calves at a dosage of 2.5 mg/kg BW, tulathromycin is nearly completely absorbed, with peak plasma concentrations achieved within ~0.25 hr. The volume of distribution exceeds 11 L/kg4, which is consistent with extensive tissue binding. This large distribution volume results in a long terminal elimination half- life of more than 100 hours, despite a rapid systemic free drug clearance (170 mL/kg/hr). No pharmacokinetic differences are observed in castrated male versus female calves.
Comparative Bioavailability Summary
Despite lower peak concentrations with DRAXXIN 25 Injectable Solution, a single SC dose of 2.5 mg tulathromycin/kg BW of either DRAXXIN Injectable Solution (100 mg/mL) or DRAXXIN 25 Injectable Solution (25 mg/mL) resulted in comparable total systemic tulathromycin exposure. Therefore, DRAXXIN 25 Injectable Solution is considered to be therapeutically equivalent to DRAXXIN Injectable Solution when administered to calves by SC injection at a dose of 2.5 mg tulathromycin/kg BW.
4 Clearance and volume estimates are based on intersubject comparisons of 2.5 mg/kg BW administered by either subcutaneous or intravenous injection.
MICROBIOLOGY
Swine
Tulathromycin has demonstrated in vitro activity against A. pleuropneumoniae , P. multocida , B. bronchiseptica , H. parasuis , and M. hyopneumoniae. The MICs of tulathromycin against indicated pathogens collected from field studies were determined using methods recommended by the Clinical and Laboratory Standards Institute (CLSI, M31-A and M31-A3). MICs for H. parasuis were determined using Veterinary Fastidious Medium and were incubated up to 48 hours at 35 to 37°C in a CO2-enriched atmosphere. These values are represented in Table 3, below.
Indicated pathogen | Date isolated | No. of isolates | MIC50 †(μg/mL) | MIC90 †(μg/mL) | MIC range (μg/mL) |
---|---|---|---|---|---|
Actinobacillus pleuropneumoniae | 2000-20022007-2008 | 13588 | 1616 | 3216 | 16 to 324 to 32 |
Haemophilus parasuis | 2000-2002 | 31 | 1 | 2 | 0.25 to > 64 |
Pasteurella multocida | 2000-20022007-2008 | 5540 | 11 | 22 | 0.5 to > 64≤ 0.03 to 2 |
Bordetella bronchiseptica | 2000-2002 | 42 | 4 | 8 | 2 to 8 |
*The correlation between in vitro susceptibility data and clinical effectiveness is unknown.
** The lowest MIC to encompass 50% and 90% of the most susceptible isolates, respectively
Calves
Tulathromycin has demonstrated in vitro activity against M. haemolytica , P. multocida , H. somni , and M. bovis , four pathogens associated with BRD. The MICs of tulathromycin against indicated pathogens collected from field studies using DRAXXIN Injectable Solution (100 mg/mL) were determined using methods recommended by the CLSI (M31-A2). These values are represented in Table 4, below.
Indicated pathogen | Date isolated | No. of isolates | MIC50 †(μg/mL) | MIC90 †(μg/mL) | MIC range (μg/mL) |
---|---|---|---|---|---|
Manneheimia haemolytica | 1999 | 642 | 2 | 2 | 0.5 to 64 |
Pasteurella multocida | 1999 | 221 | 0.5 | 1 | 0.25 to 64 |
Histophilus somni | 1999 | 36 | 4 | 4 | 1 to 4 |
Mycoplasma bovis | 1999 | 43 | 0.125 | 1 | ≤0.063 to > 64 |
* The correlation between in vitro susceptibility data and clinical effectiveness is unknown.
** The lowest MIC to encompass 50% and 90% of the most susceptible isolates, respectively.
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