Fusidic Acid

Fusidic acid is an antibiotic, which is used to treat various skin infections. Its chemical or molecular formula is C₃₁H₄₈O₆ and it is also known by different names such as fusidine, ramycin, fucithalmic, fucidin acid, and more.

It is obtained from the fungus Fusidium coccineum. It is mainly effective against gram-positive bacteria like species of Staphylococcus, Streptococcus and Corynebacterium. Further, it is a steroid antibiotic obtained from the fermentation broth of Fusidium coccineum. It was developed by Leo Pharma of Denmark and was introduced for clinical use in the 1960s. It is available in the market since 1962.

Fusidic Acid Structure

Its structure is asteroid-type like other antibiotics obtained from fungi. However, it lacks any steroid activity.

Mechanism of Action

It inhibits bacterial protein synthesis by stopping the turnover of elongation factor G (EF-G) from the ribosome. So, it prevents bacterial translation instead of killing the bacteria.

Chemical and Physical Properties of Fusidic acid:

• Its melting point is 192 degrees Celsius.
• Its boiling point is 635 degrees Celsius.
• Its solubility in water is 50 mg/ml
• It is soluble in organic solvents like ethanol, dimethyl formamide, etc. Solubility in ethanol is around 12.5 mg/ml and 14 mg/ml in dimethyl formamide.
• Its molecular weight is 516.7
• Its dissociation constant pKa is 5.35.

Drug Interaction

• Fusidic acid when combined with 1,2-Benzodiazepine can decreases its metabolism.
• Fusidic acid's serum concentration increases when it combines with Abametapir
• Its metabolism increases when it combines with Abatacept.
• Abemaciclib's metabolism decreases when it combines with Fusidic acid.
• When alendronic acid combines with Fusidic acid, the risk of myopathy increases.
• It can decrease the excretion of allopurinol, which may increase the serum level.
• Amiodarone when combined with Fusidic acid can decrease its metabolism.

Dose

The Fusidic acid dosage for adults is 250 mg twice a day or 750 mg three times a day as prescribed by the doctor. It is generally required in smaller doses for skin conditions.

It is available in the form of a tablet and suspension and cream. Its intravenous intake may cause irritation to veins and may result in phlebitis. So, if a patient is able to take it orally, it should not be administered intravenously, even in the treatment of endocarditis (infection of heart chambers).

Side Effects

The intake of Fucidin tablets and suspension that contain sodium fusidate as an active ingredient and the use of creams that contain Fusidic acid may cause the following side effects:

• Liver ailments: Jaundice
• Dark urine
• Redness
• Itching
• Irritation
• Burning sensation at the site of application
• Light colored stools

However, the above symptoms tend to disappear as the patient completes the course of taking Fucidin tablets or suspension. If the symptoms do not disappear over time, one may consult his or her doctor.

Precautions

The pieces of evidence to confirm that it is safe in human pregnancy are not enough. However, according to research done on animals and past clinical experiences, Fusidic acid is not found responsible for birth defects though it can pass through the placental barrier. However, the following precautions should be taken:

• If it is used topically, one should not go near flames as the fabric of dressings, which is in contact with this acid may catch fire and cause severe burns.
• During pregnancy or breastfeeding consult your doctor before taking Fusidic acid.
• Do not apply it in large amounts or use it for a longer duration than prescribed by the doctor as it does not give results quickly, increasing the chances of side effects instead. And, also makes the skin more sensitive to Fusidic acid.
• Further, in case of liver ailments or gallstones, always consult your doctor before taking it.