Pharmacotherapeutic group: Intestinal antiinfectives, antibiotics.
ATCvet code: QA07AA92.
Apramycin is a broad-spectrum bactericidal aminoglycoside antibiotic whose action results from the binding to the 30S subunit of the ribosome, preventing protein synthesis and disrupting the membrane permeability of bacteria. Apramycin is effective against Gram-negative bacteria (Salmonella and Escherichia coli).
Resistance mechanisms: Different aminoglycoside 3-N acetyltransferase enzymes (AAC-3) have been related with resistance to apramycin. These enzymes confer different cross-resistance against other aminoglycosides. Some strains of Salmonella Typhimurium DT104 in addition to resistance against beta-lactams, streptomycin, tetracyclines and sulphonamides carry a conjugative resistance plasmid against apramycin. Apramycin resistance can be influenced by co-selection (resistance to apramycin has been described to be located in the same mobile genetic element that other resistant determinants in Enterobacteriaceae) and cross resistance (e. g. with gentamicin).
Resistance developed by chromosomal resistance is minimal for most of the aminoglycosides.
The oral administration of apramycin is intended for antimicrobial activity within the gut; apramycin is poorly absorbed, but absorption may be increased in young animals and in animals with disrupted intestinal barrier.
Absorption may be high in new-born animals but rapidly decreases in the first weeks of life.
Calves. Serum levels peak at approximately 6 hours with a value of 2.4 μg/ml following oral administration of 40 mg apramycin/kg of bodyweight.
Distribution, biotransformation and excretion:
Apramycin is mainly excreted through faeces, under active form, and only a small quantity is excreted in the urine.
Pigs. Very little metabolism of apramycin takes place in the animal.
Dosing 10 kg pigs with 14C apramycin resulted in approximately 83% being recovered from the faeces, and 4% from the urine, as 14C apramycin.