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Pharmacological particulars
Pharmacotherapeutic group: intestinal antiinfectives, antibiotics.
ATCvet code: QA07AA92
Pharmacodynamic properties
As an aminoglycoside antibiotic apramycin binds to the 30S ribosomal subunit and interferes with the protein synthesis. Through mechanisms not yet completely elucidated, it acts on the cell wall and is bactericidal. The overall spectrum includes many aerobic or facultative anaerobic Gram-negative bacteria, including Enterobacteriaceae. It has no activity against anaerobic bacteria or under anaerobic conditions.
Susceptibility of the E. coli strains from pigs to apramycin can vary geographically and over time.
The most important mechanism of resistance against apramycin is the production of modifying enzymes that are usually encoded by resistance genes derived from plasmids. Depending on their spectrum, these enzymes may cause cross-resistance between aminoglycosides. Resistance may also be caused by a change of the ribosomal attachment sites, or the conveying system allowing the penetration of the cell.
Until harmonised international interpretative criteria relevant for susceptibility testing are available for apramycin, nationally approved and validated methods should be followed.
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. 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.
Pharmacokinetic properties
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.
Apramycin is excreted in its active form via the kidney.