Estimation of sodium fusidate levels in human serum, aqueous humour, and vitreous body

Fusidic acid pharmacology, pharmacokinetics and pharmacodynamics

Fusidic acid comes in a variety of formulations for oral, intravenous and topical use. After oral administration of 500 mg Cmax values range from 14.5-3.3 mg/l and an elimination half-life of 8.9-11.0 h. Similar values are obtained with intravenous administration of the sodium salt, although peaks tend to be higher. Bioavailability for the new film-coated tablet is approximately 91% while that of the suspension formulation appears to be much lower. Repeated dosing results in substantial drug accumulation when given 8-hourly, and to a variable extent depending on dose when administered 12-hourly. One study has demonstrated a modest dose-dependency for pharmacokinetics, with decreased clearance at higher doses. Fusidic acid is primarily eliminated by non-renal mechanisms, and a proportion of the drug is metabolised to seven or more breakdown products that can be detected in bile. Hypoalbuminaemia increases fusidic acid clearance, while clearance is decreased in the presence of severe cholestasis, and essentially unchanged in renal failure. Fusidic acid is highly protein-bound (91-98S), but has good penetration to a number of tissues including skin blisters, burns, infected bone and joints. Topical application of fusidic acid results in poor penetration through skin but good penetration into aqueous and vitreous humour. Little is known about the pharmacodynamics of fusidic acid, apart from the fact that it is slowly bactericidal against Staphylococcus aureus, and produces moderate post-antibiotic effects in vitro.

Gas gangrene panophthalmitis. A case from Greenland

A case of clostridium perfringens gas gangrene panophthalmitis developed after a penetrating eye injury. The affected eye became amaurotic, but the panophthalmitis was controlled by minimal surgical debridement and systemic antibiotic therapy with penicillin, fucidic acid and metronidazole. Elective enucleation was performed 15 days after the trauma for cosmetic reasons. The enucleated eye was examined histopathologically and showed massive retinal necrosis but no signs of bacteriae.

Topical antibiotic prophylaxis for cataract surgery: a controlled trial of fusidic acid and chloramphenicol

The effectiveness of topical fusidic acid 1%, in a viscous drop base, to reduce or eliminate ocular microflora in patients undergoing cataract surgery has been studied. Forty-two patients received fusidic acid on a double-blind basis and for comparison 21 patients were similarly assessed with topical chloramphenicol. A further 17 patients received no treatment other than subconjunctival cephazolin administered to all operated eyes at the time of surgery. Quantitative bacterial counts from the conjunctivae and lash lines of each patient were made 24 hours before surgery, on the morning of operation and again 48 hours after surgery. With a regimen of five administrations on the day prior to surgery, neither topical fusidic acid 1.0% nor chloramphenicol 0.5% produced clinically or statistically significant reductions of the ocular microflora. In contrast perioperative subconjunctival cephazolin effectively reduced or eliminated lid and conjunctival microflora following surgery. This study indicates that the effectiveness of a topical antibiotic preparation for overt ocular infection cannot be directly extrapolated to the effect on resident ocular microflora, at least with short-term use for presurgical prophylaxis.

High-performance liquid chromatographic determination of fusidic acid in plasma

Fusidic acid was determined in plasma by a high-performance liquid chromatographic method. Fusidic acid was extracted from plasma with acetonitrile that was salted out with ammonium sulfate. Prior to salting out cadmium sulfate was mixed with the acetonitrile-plasma mixture to help remove interfering constituents. A 150 mm X 4.6 mm column packed with 5-microns cyanopropyl stationary phase was used for chromatography. The mobile phase was acetonitrile-20 mM sodium dihydrogenphosphate (pH 3.50) (39:61, v/v). An ultraviolet-visible detector was set at 204 nm. The presence of water in the injection solvent had a significant effect on the fusidic acid peak height. A number of clinically important acquired immunodeficiency syndrome drugs did not interfere with the fusidic acid determination. The relative standard deviation varied between 0.99 and 7.8%. A limit of detection of 200 ng/ml was obtained for a 80-microliters injection.

Metastatic Staphylococcus aureus endophthalmitis: a case report

A case of bilateral metastatic Staphylococcus aureus endophthalmitis is presented. It evolved over a two-week period, causing some diagnostic confusion. Treatment with fusidic acid and benzylpenicillin resulted in the retention of useful vision in one eye and good vision in the other.

Intraocular penetration of fusidic acid with topical Fucithalmic

Fucithalmic is a newly developed 1% microcrystalline suspension of the antistaphylococcal antibiotic fusidic acid. Penetration into the eye was investigated in twenty patients about to undergo cataract extraction. A single dose produced median antibiotic levels in the aqueous humour of 0.3 mcg/ml, maintained for at least 12 hours. Repeated doses produced significantly higher levels, median 0.8 mcg/ml, indicating some cumulative effect. The results show that fusidic acid passes the corneal aqueous barrier, and twice daily administration of Fucithalmic gives aqueous concentrations comparable with or higher than those seen after recommended systemic administration.

Determination of sodium fusidate and fusidic acid in dosage forms by high-performance liquid chromatography and a microbiological method

A new High-performance liquid chromatographic (HPLC) method for the assay of sodium fusidate (I) or fusidic acid in dosage forms was developed and compared to a microbiological assay. A linear relationship was obtained between absolute peak area and amount of I(r = 0.99+) in the 50-1000-microgram/ml range. In the microbiological assay, Staphylococcus aureus (NCTC 6571) was the test organism, using an agar diffusion technique. With five test levels of the standard, potencies were interpolated from standard curve using a log transformation straight-line method with least-squares fitting (r = 0.99+). Both methods were applied to assay I (or fusidic acid) in tablets, a suspension, and an ointment. Excellent agreement was observed between results of the two methods.

Fusidic acid: new opportunities with an old antibiotic

The extensive foreign experience with fusidic acid prior to its belated introduction to Canada is reviewed. Fusidic acid is a steroid antibiotic with minimal toxic and hormonal effects that is mainly excreted through the liver. It has a predominantly bactericidal action and does not shown cross-resistance with other antibiotics. Since organisms resistant to this drug form easily in vitro when exposed to low concentrations, complementary treatment with another antibiotic may be required in some clinical situations. Although fusidic acid is active in vitro against a number of organisms, to date it has mainly been used to treat serious infections due to Staphylococcus aureus. The agent appears to be particularly valuable in the treatment of bone and joint infections and in pediatric practice. Fusidic acid will soon be available in Canada for both oral and intravenous administration. Attainable antibiotic levels in many tissues and body fluids greatly exceed the minimum inhibitory concentrations.

Comparison of susceptibility of Neisseria meningitidis to sodium sulphadiazine and sodium fusidate in vitro

Out of 100 strains of meningococci examined 62 were resistant to 1 mg/l or more of sodium sulphadiazine, including 82% of group W135 strains and 69% of group B strains. All strains were sensitive in vitro to 0.5 mg/l of sodium fusidate. Sodium fusidate should be considered as a chemoprophylactic agent for those who may be at risk of meningococcal disease.

Interaction of albumin and fusidic acid

1. By combining the agar plate diffusion technique for determination of antibiotic activity and zone microelectrophoresis in agar gel, the activity of fusidic acid in individual serum proteins of blood and pus obtained from patients given sodium fusidate revealed albumin to be responsible for the protein binding of this antibiotic.2. Based on the assumption that only free fusidic acid is microbiologically active, the relationship between the concentration of albumin and the ratio of free to total fusidic acid was determined at four concentrations of free fusidic acid, using as test organisms four differently sensitive variants of a Staphylococcus aureus strain. At each concentration an increasing amount of albumin (0-40 mg/ml culture medium) decreased the activity of fusidic acid as determined in serial dilutions (IC50).3. The law of mass action expressed as Langmuir's adsorption isotherm was valid if a correction for the influence of albumin on the sensitivity of the strain of Staph. aureus was introduced. For other test organisms no correction is necessary. The constant in Langmuir's adsorption isotherm was K=78400+/-8200 l./mol and n=3.15 (95% confidence limits: 2.09-5.52).4. The mean blood concentration was 20.8 mug/ml and the mean pus concentration 17.2 mug/ml in nineteen sets of blood and pus samples. The ratio of pus to blood corresponds to the ratio of published values for the protein concentrations in serum and in inflammatory oedema.5. It is concluded that for albumin bound drugs the ;storage depot' of the organism also includes the fluid of the tissue spaces including the inflammatory oedema. As recent studies have revealed an extravascular albumin pool similar in size to the plasma pool, this ;storage depot' should not be neglected.