Pharmacotherapeutic group: Otologicals, corticosteroids and anti-infectives in combination, dexamethasone and anti-infectives.
ATCvet code: QS02CA06
Marbofloxacin, a synthetic bactericidal agent belonging to the fluoroquinolone family that acts by inhibiting DNA gyrase. It exhibits a broad spectrum of activity against Gram-positive bacteria (e.g. Staphylococcus intermedius) and against Gram-negative organisms (Pseudomonas aeruginosa, Escherichia coli and Proteus mirabilis). In the European literature susceptibility data (MIC50 values) for canine and feline otitis pathogens are presented:
Microorganism MIC50 (µg/ml)
Ps. aeruginosa 0.5
S. (pseudo)intermedius 0.25
S. aureus 0.25
Susceptibility breakpoints have been determined as ≤ 1 µg/ml for sensitive, 2 µg/ml for intermediate and ≥ 4 µg/ml for resistant bacterial strains.
Marbofloxacin is not active against anaerobes. Resistance to fluoroquinolones occurs by chromosomal mutation with three mechanisms: decrease of the bacterial wall permeability, expression of efflux pump or mutation of enzymes responsible for molecule binding.
Clotrimazole, an anti-fungal agent that belongs to the imidazole family and which acts by causing changes in membrane permeability, allowing intracellular compounds to leak from the cell and thus inhibiting cellular molecular synthesis. It exhibits a wide spectrum of activity and is aimed, in particular, at Malassezia pachydermatis.
Pharmacokinetics studies in dogs at the therapeutic dosage have shown that:
Marbofloxacin plasma concentrations peak at 0.06 µg/ml on the 14th day of treatment. Marbofloxacin bonds weakly to plasma proteins (< 10% in dogs) and is eliminated slowly, mainly in the active form, predominantly in urine (2/3) and in faeces (1/3). Clotrimazole absorption is extremely poor (plasma concentration < 0.04 µg/ml).
Dexamethasone acetate plasma concentration reaches 1.25 ng/ml on the 14th day of treatment. Dexamethasone resorption is not increased by the inflammatory process induced by otitis.