Description:
A group of organic compounds that contain a macrocyclic lactone ring linked glycosidically to one or more sugar moieties.
Mechanism of action:
Binding to the 50S subunit of the bacterial ribosome and inhibiting translocation of peptidyl-tRNA from the A site to the P site. The result of this inhibition is that bacteria are not able to complete proteins that are essential for life. Macrolides are bacteriostatic.
Source
Tylosin: Streptomyces fradiae
Tilmicosin: Produced semisynthetically by chemical modifications of desmycosin.
Chemistry:
Tylosin consists primarily of tylosin factor A with small amounts of three minor factors, desmycosin (factor B), macrocin (factor C) and relomycin (factor D). Tylosin factor A has the highest microbiological potency.
Indications: Mycoplasmosis, Necrotic enteritis, Ornithobacterium rhinotracheale.
| Dosage: |
Chickens:
|
Turkeys:
|
Pigeons:
|
|
Tylosin
|
50 mg/Kg
|
50 mg/kg
|
25mg/kg IM SID; 50mg/kg PO SID*
|
|
Tilmicosin
|
20 mg/kg
|
20 mg/kg
|
ND
|
*SID= Once daily
Drug interactions: Florfenicol and lincosamides have mechanisms of action similar to the macrolides; they may be prevented from binding, or prevent a macrolide from binding to the 50 S subunit of bacterial ribosomes.
Residues
Tylosin: Residue in tissues is very rare. It is eliminated from the body upon withdrawal of the drug. Eggs: Persistent macrolide residues can be deposited in eggs following oral administration to laying hens. 3 days.
Tilmicosin: Liver should be the target tissue for tilmicosin residues in broiler chickens. The recommended withdrawal time is 10 days.
Pharmacokinetics: Protein binding: chickens - 30%
TYLOSIN
|
Animal
Species
|
Mg/kg
PO
|
Tmax
(Hr)
|
t 1/2
(Hr)
|
F(%)
|
| Chickens |
10 |
1.5 |
2.07 |
30-34 |
TILMICOSIN
|
Animal
Species
|
Mg/kg
PO
|
Tmax
(Hr)
|
t 1/2
(Hr)
|
Cmax
(microg/ml)
|
| Chickens |
30 |
3.99±0.84
|
47.4±9.32
|
2.09±0/37
|
Tilmicosin is rapidly absorbed and slowly eliminated after oral administration.
Comments: 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. Tilmicosin has a stronger antimicrobial activity than tylosin against G. anatis, P. multocida and Mycoplasma.