Source: Medicines and Medical Devices Safety Authority (NZ) Revision Year: 2019 Publisher: LEO Pharma Ltd, Auckland, New Zealand, Ph: 0800 497 456
Pharmacotherapeutic group: Corticosteroids, potent, combinations with antibiotics, dermatological preparations
ATC code: D07CC01
Fucicort cream is a combination preparation containing the corticosteroid betamethasone valerate and the antibiotic, fusidic acid.
Betamethasone belongs to the group of potent corticosteroid (class III) and exerts its effect by suppressing local immunoreactions, including vasodilatation, swelling and soreness.
Fusidic acid inhibits bacterial protein synthesis. Fusidic acid binds to elongation factor G (EF-G), preventing release of the EF-G-guanosine diphosphate complex, which stall the protein synthesis. Fusidic acid has bacteriostatic activity at low concentrations but bactericidal activity at high concentrations.
Fusidic acid is primarily active against Gram-positive bacteria, in particular S. aureus including MRSA.
Fusidic acid is also active against Streptococcus spp., Corynebacterium minutissimum, some Neisseria spp., and certain Clostridium spp.
In S. aureus two main types of resistance mechanisms have been characterized. The first is caused by mutations in the fusidic acid binding site of EF-G (fusA) and the other involves horizontal acquisition of determinants encoding FusB –type resistance determinants (fusB and fusC) that binds to EF-G.
Due to its unique molecular structure and distinct mode of action, target specific crossresistance with other classes of antibacterial agents has not been detected.
Most gram negative bacteria (including Haemophilus influenza, Enterobactericeae such as Escherichia coli and Klebsiella pneumonia and Pseudomonas spp.) are inherently resistant to fusidic acid.
There are no data that accurately define the pharmacokinetics of Fucicort following topical administration in human.
In vivo and in vitro studies suggest that there is only negligible systemic absorption of topically administered fusidic acid. In vitro studies show that fusidic acid can penetrate intact human skin. The degree of penetration depends on factors such as the duration of exposure to fusidic acid and the condition of the skin. Fusidic acid is excreted mainly in the bile with little excreted in the urine.
The concentration of fusidic acid achieved in the skin is well above the minimum inhibitory concentration (MIC) required for sensitive S. aureus strains.
As there is only negligible systemic absorption of topically administered fusidic acid, the amount of fusidic acid likely to be distributed, biotransformed and eliminated from the systemic circulation following appropriate topical application is therefore of little clinical significance.
Betamethasone valerate is absorbed following topical administration. The degree of absorption is dependent on various factors including skin condition and site of application. Occlusion of the treated area under plastic material strongly increases the absorption. The amount absorbed is metabolized in the liver and excreted in the urine.
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