Chemistry - A macrolide antibiotic related structurally to erythromycin, tylosin is produced from Streptomyces fradiae. It occurs as an almost white to buff-colored powder with a pKa of 7.1. It is slightly soluble in water and soluble in alcohol. Tylosin is considered to be highly lipid soluble. The tartrate salt is soluble in water. The injectable form of the drug (as the base) is in a 50% propylene glycol solution.
Storage/Stability/Compatibility - Unless otherwise instructed by the manufacturer, injectable tylosin should be stored in well-closed containers at room temperature. Tylosin, like erythromycin, is unstable in acidic (pH <4) media. It is not recommended to mix the parenteral injection with other drugs.
Pharmacology - Tylosin is thought to have the same mechanism of action as erythromycin (binds to 50S ribosome and inhibits protein synthesis) and exhibits a similar spectrum of activity. It is a bacteriostatic antibiotic. For more specific information on organisms that tylosin is usually active against, refer to the erythromycin monograph just prior to this one. Cross resistance with erythromycin occurs.
Uses/Indications - Although the injectable form of tylosin is approved for use in dogs and cats, it is rarely used parenterally in those species. Oral tylosin is sometimes recommended for the treatment of chronic colitis in small animals (see Doses), but controlled studies documenting its efficacy have not been performed. Tylosin is also used in clinically in cattle and swine for infections caused by susceptible organisms.
Pharmacokinetics - Tylosin tartrate is well absorbed from the GI tract, primarily from the intestine. The phosphate salt is less well absorbed after oral administration. Tylosin base injected SQ or IM is reportedly rapidly absorbed.
Like erythromycin, tylosin is well distributed in the body after systemic absorption, with the exception of penetration into the CSF. The volume of distribution of tylosin is reportedly 1.7 L/kg in small animals. Tylosin enters milk in concentrations of approximately 20% of those found in serum.
Tylosin is eliminated in the urine and bile apparently as unchanged drug. The elimination half life of tylosin is reportedly 54 minutes in small animals, 139 minutes in newborn calves and 64 minutes in calves 2 months of age or older.
Contraindications/Precautions/Reproductive Safety - Tylosin is contraindicated in patients hypersensitive to it or other macrolide antibiotics (e.g., erythromycin). Most clinicians feel that tylosin is contraindicated in horses, as severe and sometimes fatal diarrheas may result from its use in that species. No information was located with regards to the reproductive safety of tylosin, but it is unlikely to have serious teratogenic potential.
Adverse Effects/Warnings - Most likely adverse effects with tylosin are pain and local reactions at intramuscular injection sites, and mild GI upset (anorexia, and diarrhea). Tylosin may induce severe diarrheas if administered orally to ruminants or by any route to horses. In swine, adverse effects reported include edema of rectal mucosa and mild anal protrusion with pruritis, erythema, and diarrhea.
Overdosage/Acute Toxicity - Tylosin is relatively safe in most overdose situations. The LD50 in pigs is greater than 5 g/kg orally, and approximately 1 g/kg IM. Dogs are reported to tolerate oral doses of 800 mg/kg. Long-term (2 year) oral administration of up to 400 mg/kg produced no organ toxicity in dogs. Shock and death have been reported in baby pigs overdosed with tylosin, however.
Drug Interactions - Drug interactions with tylosin have not been well documented. It has been suggested that it may increase digitalis glycoside blood levels with resultant toxicity. It is suggested to refer to the erythromycin monograph for more information on potential interactions.
Drug/Laboratory Interactions - Macrolide antibiotics may cause falsely elevated values of AST (SGOT), and ALT (SGPT) when using colorimetric assays. Fluorometric determinations of urinary catecholamines can be altered by concomitant macrolide administration.
For susceptible infections:
a) 17.6 mg/kg IM once daily. Continue treatment for 24 hours after symptoms have stopped, not to exceed 5 days. Do not inject more than 10 ml per site. Use the 50 mg/ml formulation in calves weighing less than 200 pounds. (Package insert; Tylosin Injection—TechAmerica)
b) For bronchopneumonia and fibrinous pneumonia in cattle associated with penicillin G-refractory C. pyogenes infections or other bacteria sensitive to tylosin and resistant to sulfas, penicillin G and tetracyclines: using Tylosin 200 mg/ml : 44 mg/kg IM q24h. Recommend a 21 day slaughter withdrawal at this dosage. (Hjerpe 1986)
c) 5 - 10 mg/kg IM or slow IV once daily; not to exceed 5 days. (Huber 1988a)
d) Tylosin base injectable: 10 mg/kg IM initially, then 6 mg/kg IM q8h (q8-12h in calves). (Baggot 1983)
a) 12 mg/kg /day IM for 5 days to treat acute mycoplasma infections ( Schmidt, 1986).
a) Schmidt, M: Elephants (Proboscidea). In: Fowler, M.E. (ed): Zoo and Wild Animal Medicine. 1986. Saunders, Philadelphia. pp.911-912.
Monitoring Parameters -
1) Clinical efficacy
2) Adverse effects
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Tylosin Injection 50 mg/ml, 200 mg/ml; Tylan® (Elanco), generic; (OTC) Approved for use in nonlactating dairy cattle, beef cattle, swine, dogs, and cats. Slaughter withdrawal = cattle 21 days; swine 14 days.
(Note: Although this author was unable to locate parenteral products approved for use in lactating dairy animals, one source (Huber 1988a) states that tylosin has a 72 hour milk withdrawal for dairy cattle, and 48 hour milk withdrawal in dairy goats and sheep.)
Tylosin tartrate (approximately 4000 mg/teaspoonsful) in 100 g bottles; Tylan®Soluble (Elanco); (OTC) Approved for use in turkeys (not layers), chickens (not layers) and swine. Slaughter withdrawal swine = 2 days; chickens = 1 day; turkeys = 5 days.
There are many approved tylosin products for addition to feed or water for use in beef cattle, swine, and poultry. Many of these products also have other active ingredients included in their formulations.
Human-Approved Products: None.
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