The active substance in Tuloxxin® Injection is tulathromycin, which belongs to the macrolide group of antibiotics. It differs from many macrolides and other antibiotics as it has a long duration of action, due to its unique chemical structural features (it belongs to the triamilide subclass of macrolides).
A single subcutaneous injection (2.5 mg/tulathromycin per kg bodyweight) is sufficient for the treatment of respiratory diseases in cattle.
Tuloxxin® is a broad-spectrum antibiotic with clinical effects against the main cattle respiratory bacteria pathogens (Mannheimia haemolytica, Histophilus somni, Pasturella multocida, Mycoplasma bovis). These pathogens are involved in the Bovine Respiratory Disease (BRD) Complex, the most common and costly disease affecting beef cattle worldwide.
Sensitivity of bovine respiratory pathogens
Results from a pan-European survey of antimicrobial susceptibility (susceptibility monitoring programs, VetPath, MycoPath) show high sensitivity of bovine respiratory bacteria pathogens against tulathromycin.
The absence or low levels of resistance verify the importance of tulathromycin as one of the antibiotics of choice for treatment against the listed bacteria species.
Pharmacokinetics
Tulathromycin's pharmacokinetic (PK) behaviour is characterized by its rapid release from the injection site, fast distribution to the target tissues (lung, pulmonary epithelial lining fluid (PELF), alveolar macrophages) and high and early concentrations at the sites of pneumonia infection. Tulathromycin's lipophilic nature leads to extensive drug penetration into lung tissue and lung fluids.
Key tulathromycin PK features, allowing single injection therapy in cattle:
- slow release (elimination half-life of approximately 8 days) from the lung
- high lung and pulmonary fluid concentration over several days
- intracellular accumulation in alveolar macrophages over long time periods (15 days)
Pharmacokinetic / Pharmacodynamic relationships
PK / Pharmacodynamic (PD) relationships are an effective tool to predict the efficacy of tulathromycin to inhibit bacterial pathogens in the BRD complex. Figure 1 shows the important role of tulathromycin lung and macrophage concentrations achieved after a single Tuloxxin® injection at a treatment dose of 2.5 mg/kg bodyweight.
Higher tulathromycin concentrations in lung tissue and in macrophages in pulmonary epithelial fluid were determined, more than tulathromycin MIC values for H. somni, P. multocida and M. haemolytica.
The tulathromycin concentrations in the lung and bovine alveolar macrophage cells exceed the MIC90 values for cattle respiratory pathogens for a prolonged time (7 days for lung, 15 days for macrophages) as shown in a cattle PK study (Cox et al., 2010).
Summary
PK characteristics and persistence of high tulathromycin levels over longer periods are the reasons for the excellent clinical response after Tuloxxin® parenteral treatment, shown in clinical studies with natural BRD outbreaks caused by bovine bacterial and mycoplasmal pathogens.
One-shot treatment with Tuloxxin® Injection is the way forward. It is a solution for effective BRD treatment, used to maintain cattle health and welfare in the context of implementation of a responsible antimicrobial stewardship (AMS) policy.
Reference:
Cox, S.R., McLaughlin, C., Fielder, A.E. and Yancey, M.F. (2010). Rapid and prolonged distribution of tulathromycin into lung homogenate and pulmonary epithelial lining fluid of Holstein calves following a single subcutaneous administration of 2.5 mg/kg bodyweight. International Journal of Applied Research in Veterinary Medicine, Vol 8 No. 3. 129-137.
