Tulathromycin

Macrolide antibiotic Triamilide antimicrobial

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog SC or IM 2.5-5 mg/kg Single dose, may repeat in 48-72 hours Duration: Single dose or as needed
Notes: Off-label use; monitor for injection site reactions.
Cat SC or IM 2.5-5 mg/kg Single dose, may repeat in 48-72 hours Duration: Single dose or as needed
Notes: Off-label use; monitor for injection site reactions.
Horse IM 2.5 mg/kg Single dose Duration: Single dose
Notes: Off-label; not approved for horses in many countries; use with caution.
Cattle (beef and non-lactating dairy) SC 2.5 mg/kg Single dose Duration: Single dose
Notes: Administer subcutaneously in the neck. Do not inject more than 10 mL per site.
Swine IM 2.5 mg/kg Single dose Duration: Single dose
Notes: Administer intramuscularly in the neck. Do not inject more than 2 mL per site.
Sheep and Goats SC or IM 2.5 mg/kg Single dose Duration: Single dose
Notes: Off-label; use with caution in lactating animals.
Rabbit SC or IM 2.5-5 mg/kg Single dose, may repeat in 48-72 hours Duration: Single dose or as needed
Notes: Off-label; limited safety data.

Clinical Indications & Species Uses

General Indications
  • Treatment of respiratory tract infections caused by susceptible Gram-positive and Gram-negative bacteria, and Mycoplasma species.
Dog (Canine)
  • Treatment of respiratory tract infections caused by susceptible bacteria (e.g., Bordetella bronchiseptica, Mycoplasma spp.)
  • Skin and soft tissue infections (off-label)
Cat (Feline)
  • Treatment of respiratory tract infections caused by susceptible bacteria (e.g., Chlamydia felis, Mycoplasma spp.)
  • Skin and soft tissue infections (off-label)
Horse (Equine)
  • Treatment of respiratory tract infections caused by susceptible bacteria (e.g., Streptococcus equi, Rhodococcus equi) (off-label)
Cattle (Bovine)
  • Treatment of bovine respiratory disease (BRD) associated with Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis
  • Treatment of infectious bovine keratoconjunctivitis (IBK) associated with Moraxella bovis
  • Treatment of foot rot (interdigital necrobacillosis) associated with Fusobacterium necrophorum and Bacteroides melaninogenicus
Small Ruminants (Sheep / Goat)
  • Treatment of respiratory disease in sheep and goats (off-label)
  • Treatment of foot rot in sheep (off-label)
Rabbit & Small Mammals
  • Treatment of respiratory infections (e.g., Pasteurella multocida) (off-label)

Pharmacology & Mechanism of Action

Drug Class: Macrolide antibiotic | Pharmacological Group: Triamilide antimicrobial

Mechanism of Action: Tulathromycin is a semi-synthetic macrolide antibiotic belonging to the triamilide subclass. It binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis by blocking peptide bond formation and translocation. This action is primarily bacteriostatic but can be bactericidal at higher concentrations. It has a prolonged half-life and high tissue penetration, especially in lung tissue, making it effective against respiratory pathogens.

Pharmacodynamics: Tulathromycin exhibits concentration-dependent and time-dependent killing. It has a post-antibiotic effect (PAE) of several hours. It is active against a broad spectrum of Gram-positive and Gram-negative bacteria, including Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Mycoplasma bovis, and various Mycoplasma species. It also has activity against some anaerobes and intracellular pathogens. Its efficacy is enhanced by its ability to concentrate in phagocytes and be delivered to sites of infection.

⚡ Pharmacokinetics Summary

Absorption: After subcutaneous or intramuscular injection, tulathromycin is rapidly and completely absorbed. Peak plasma concentrations are reached within 30 minutes to 1 hour in cattle and swine. Bioavailability is nearly 100% after parenteral administration.
Distribution: Tulathromycin is extensively distributed throughout the body, with high concentrations in lung tissue, bronchial secretions, and alveolar macrophages. It accumulates in neutrophils and alveolar macrophages, achieving concentrations several-fold higher than in plasma. Volume of distribution is large, indicating extensive tissue penetration.
Metabolism: Tulathromycin undergoes minimal metabolism. It is primarily excreted unchanged in the bile and urine. Some enterohepatic recirculation may occur.
Excretion: Elimination is primarily via biliary excretion into feces, with a smaller amount excreted in urine. The elimination half-life is long, ranging from 2 to 4 days in cattle and swine, allowing for single-dose therapy.
Half-Life: Cattle: ~90 hours; Swine: ~60-90 hours; Dogs: ~24-36 hours (extrapolated)
Bioavailability: Nearly 100% after subcutaneous or intramuscular injection.
Protein Binding: Low to moderate; approximately 30-40% bound to plasma proteins in cattle.

Available Formulations & Strengths

Injectable Solution 100 mg/mL (SC, IM)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to tulathromycin or other macrolides
  • Do not use in animals with known hypersensitivity to macrolide antibiotics
  • Do not use in horses (in some countries) due to risk of fatal colitis
  • Do not use in lactating dairy cattle (in some countries) due to milk withdrawal
  • Do not use in animals with severe hepatic impairment
Warnings & Clinical Precautions:
  • Use with caution in animals with hepatic or renal impairment
  • May cause injection site reactions; administer subcutaneously in cattle, intramuscularly in swine
  • In cattle, do not inject more than 10 mL per site; in swine, do not inject more than 2 mL per site
  • Avoid use in animals with a history of seizures or neurological disorders
  • Use in horses should be avoided due to risk of Clostridium difficile-associated diarrhea and colitis
  • In food animals, observe withdrawal times
  • Not for use in humans; avoid self-injection
  • Use with caution in young animals; safety in neonates not established

Adverse Effects & Reactions

Common:

  • Injection site swelling or pain
  • Transient local inflammation
  • Diarrhea
  • Vomiting (in dogs and cats)
  • Anorexia

Serious / Severe:

  • Anaphylaxis
  • Clostridium difficile-associated diarrhea (especially in horses)
  • Hepatotoxicity
  • Nephrotoxicity
  • Ototoxicity (rare)
  • Neurological signs (ataxia, tremors)

Rare:

  • Bone marrow suppression
  • Cardiac arrhythmias
  • Skin reactions (erythema, urticaria)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Other macrolides or lincosamides Potential additive effects or increased risk of adverse effects Moderate
Chloramphenicol Antagonistic effect on bacterial protein synthesis Moderate
Neuromuscular blocking agents May enhance neuromuscular blockade Mild
Corticosteroids May increase risk of gastrointestinal ulceration Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Gastrointestinal upset (vomiting, diarrhea)
  • Ataxia
  • Tremors
  • Seizures
  • Hepatotoxicity
  • Nephrotoxicity

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce vomiting if recent oral ingestion (not applicable for injectable). Administer activated charcoal if oral. Provide intravenous fluids, monitor liver and kidney function, and manage seizures with diazepam or barbiturates. In severe cases, consider hemodialysis.

Food Animal Withdrawal Times

🥩 Meat: 18 days🥛 Milk: 0 days

For cattle: meat withdrawal is 18 days; milk withdrawal is 0 days (not approved for lactating dairy cattle in some countries, so milk withdrawal may be longer if used off-label). For swine: meat withdrawal is 5 days. For sheep/goats: not established; consult regulatory authorities.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20°C to 25°C (68°F to 77°F), excursions permitted between 15°C and 30°C.

Handling & Special Conditions: Protect from freezing. Keep container tightly closed. Do not use if solution is discolored or contains particulate matter.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in cattle and swine (e.g., Draxxin®). Not approved for other species.

Extra-Label (Off-Label) Use: In the US, tulathromycin is approved for use in cattle and swine. Extra-label use in other species is permitted under AMDUCA with a valid veterinary-client-patient relationship, but requires extended withdrawal times and careful monitoring. In the EU, use in food-producing animals is regulated; check local regulations.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Tulathromycin is a valuable antimicrobial for the treatment of bovine respiratory disease (BRD) and swine respiratory disease due to its long half-life and single-dose convenience. It is particularly effective against Mycoplasma species. In small animals, it is used off-label for respiratory infections, but its use should be reserved for cases where other antibiotics are ineffective or inappropriate. It is not recommended in horses due to the risk of severe colitis. Always adhere to withdrawal times in food animals. Monitor for injection site reactions and adverse effects. Use judiciously to minimize antimicrobial resistance.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)