Tylvalosin (brand name Aivlosin®) is a macrolide antibiotic most commonly used to treat respiratory and enteric bacterial infections from Mycoplasma spp., Brachyspira pilosicoli, Brachyspira hyodysenteriae, Clostridium spp., and Bacteroides spp. in pigs and poultry.
It has antibacterial activity against Gram-positive bacteria some Gram-negative fastidious bacteria, and mycoplasma. It has no activity against the naturally resistant Enterobacteriaceae including Escherichia coli and Salmonella spp. Typically, macrolides achieve higher concentrations in tissues than in plasma.
Gram-positive bacteria that Tylvalosin has antibacterial activity against include Staphylococcus, Micrococcus, Microbacterium, Bacillus, Corynebacterium, Aerococcus, Arthrobacter and Streptococcus, Campylobacter, Enterococcus, and Clostridia.
Tylvalosin's solubility and absorption can be significantly influenced by administration route, dosage level, species, and formulation differences. This affects its bioavailability and therapeutic efficacy.
A study in 2025 by Z Wen et al revealed that when given orally, the drug reached its peak concentration within 3 hours. The absolute bioavailability of tylvalosin was relatively low in chickens, with values of 5.92%, 3.56%, and 3.04% for the doses of 5, 10, and 25 mg/kg, respectively. Dosing intervals greater than 6 hours failed to achieve therapeutic concentrations.
A recent study by Salman et al in 2025 discovered that Tylvalosin causes damage to lungs, hepatic and renal tissues when given to chickens at 25 mg/Kg of body weight.
This is in conflict with a previous study by A Salman in 2021 which determined the drug can be used safely in chickens at a dose of 25 mg/kg of body weight without affecting liver and kidney functions. This conclusion was made based on blood chemistry evaluation of ALT, AST, Alkaline phosphatase, Albumin and Urea, Uric acid, and total protein and bilirubin in sampled chickens. Blood parameters showed a decrease in WBCs following treatment.
Egg withdrawal period: This drug is not supposed to be given to birds that lay eggs intended for human consumption.
Storage: Store in a cool dry place at or below 25°C (77°F).
