Macrolides

Macrolides
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
ND
Tilmicosin
20 mg/kg
20 mg/kg
ND

 

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 or parenteral administration to laying hens. 8 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.