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Pharmacological particulars
Pharmacotherapeutic group: Corticosteroids, combinations with antibiotics.
ATCvet code: QD07CC01
Pharmacodynamic properties
Betamethasone valerate is a potent corticosteroid that possesses anti-inflammatory and anti‑pruritic properties.
Fusidic acid has a steroidal structure but does not possess any steroid-like effects. It belongs to the class of antibiotics called Fusidanes. Fusidic acid acts by prohibiting the protein synthesis of bacteria when it binds to elongation factor G (required for translocation on the bacterial ribosome after peptide bond formation during protein synthesis).
Its action is largely bacteriostatic, but at high concentrations (2-32-fold higher than the MIC) the effect may be bactericidal. Fusidic acid has activity against Gram‑positive bacteria, namely Staphylococcus spp. (particularly S.pseudintermedius) including penicillinase producing species. It is also active against streptococci.
Pathogenic bacteria
Fusidic acid Sensitive/Resistant
Fusidic acid MIC
Gram-positive bacteria
Staphylococcus pseudintermedius
MIC90 ~ 0.25-4 µg/ml
Streptococcus spp.
MIC90 ~ 8-16 µg/ml
Corynebacteria spp.
MIC90 ~ 0.04-12.5 µg/ml
Gram-negative bacteria
Pseudomonas spp.
>128 µg/ml
>128 µg/ml
Data based on studies conducted mainly in Europe but also in North America between 2002 and 2011.
Two major mechanisms of resistance to fusidic acid have been reported in S. aureus – the alteration of the drug target site which is due to chromosomal mutations in FusA (encoding elongation factor EF-G) or FusE encoding ribosome protein L6, and the protection of the drug target site by FusB family proteins, including fusB, fusC, and fusD. The fusB determinant originally was found on the plasmid in S. aureus but has also been found on a transposon-like element or in a staphylococcal pathogenicity. No cross-resistance between fusidic acid and other antibiotics that are in clinical use has been identified.
Pharmacokinetic properties
In vitro data obtained from a study on dog skin indicates that 17 % of the applied dose of betamethasone and 2.5 % of the applied dose of fusidic acid are absorbed over 48 hours after the administration of the product to the skin. Absorption after administration to inflamed skin is likely to be greater.