Rifamycin sodium

Dose. 0.5 to 1 g of rifamycin sodium daily, by intramuscular injection. 

Fusidic Acid 588.8 Flupenthixol Decanoate 719.8 Rifamycin Sodium... 

Rifamycin sodium used to irrigate a wound has been reported to reduce the serum levels of ciclosporin in a kidney transplant patient. ... 

Difficulties encountered in the separation and stabihty of the individual rifamycins led to studies to increase the yield of individual components of the complex. The addition of sodium diethylbarbitutate to the fermentation medium of N. mediterranei resulted in the formation of rifamycin B as practically the only substance formed (91,92). 

Drugs that may affect tetracyclines include antacids containing aluminum, calcium, or magnesium iron salts zinc salts barbiturates bismuth salts carbamazepine cholestyramine colestipol phenytoin rifamycins urinary alkalinizers (eg, sodium lactate, potassium citrate). 

The rifamycins are ansamycin antibiotics produced by cultures of Amycolatopsis mediterranei (formerly Nocardia mediterranei or Streptomyces mediterranei). The crude antibiotic mixture was found to contain five closely related substances rifamycins A-E, but if the organism was cultured in the presence of sodium diethyl barbiturate (barbitone or barbital), the product was almost entirely rifamycin B (Figure 3.71). Rifamycin B has essentially no antibacterial activity, but on standing in aqueous solution in the presence of air, it is readily transformed by oxidation and intramolecular nucleophilic addition into rifamycin O, which... 

The rifamycins have some remarkable chemical properties. Rifamycin SV can be obtained from the quinone rifamycin S by treating the latter with weak reducing agents such as ascorbic acid. It is fairly stable against oxidation by air and can form a stable sodium salt. This behaviour can be ascribed to the acylamino group in position 2. Unsubstituted naphthoquinone can only be reduced under much more drastic conditions, and once in the hydroquinone form it is very sensitive to oxidation. 

Synonym. Rifamycin SV Sodium Proprietary Name. Rifocin(e)... 

Sodium salt, Chibro-Rifamycin. Orange-red crystals. Soly in water pH 7.2 5 g/100 ml-... 

The British Pharmacopoeia specifies a biological assay for the sodium salt of rifamycin SV [14897-39-5]. It also specifies a spectrophotometric assay for rifampicin (201). The United States Pharmacopeia requires an hplc assay for rifampin (202). 

Although the use of C-labelled acetates and propionates had demonstrated that they were precursors in the formation of rifamycin S it was only by the use of various C-precursors and assignments of the NMR spectra that the labelling pattern from acetate and propionate was established [216]. C-NMR has also been used to establish the biosynthetic pathway of streptovaricin D the use of sodium [l- C]propionate established that the amide carbonyl was derived from the carboxyl group of propionate [217]. The use of methionine ( C-methyl) and sodium [l- C]propionate showed that geldanamycin followed the same biosynthetic pathway as rifamycin and streptovaricin D [218]. 

To prepare rifamycin S, the solution in the organic solvent is extracted again with phosphate buffer, pH 8.0, and sodium persulfate is added, Thus, rifamycin B is oxidized to rifamycin O, which being insoluble in water precipitates and is collected by filtration. The panel is dissolved in tetrahydrofuran, and rifamycin O is hydrolyzed to rifamycin S with sulfuric acid. Water is then added, and rifamycin S is extracted with chloroform. Upon addition of ethanol and concentration under vacuum, rifamycin S crystallizes and is collected by filtration at a high degree of purity. 

Rifamycin S is reduced to rifamycin SV by adding to a methanolic solution an aqueous solution of sodium ascorbate. The solution of rifamycin SV is cleared by filtration, and the sodium salt crystallizes after addition of sodium phosphate solution to... 

A laboratory Scale procedure to obtain rifamycin SV from cultures of strains producing rifamycin S consists of adding ascorbic acid to the fermentation broth. The filtrate is acidified to pH 3 and extracted with ethyl acetate. After evaporation of the solvent, the crude product is absorbed on a silica gel column and eluted with acetone. Fractions containing pure rifamycin SV are combined, and the product can be obtained either as a free acid or its sodium salt (5b). 

The higher concentrations of antibiotic in fermentation broths later obtained allowed simplified procedures of recovery and purification- For example, a filtered broth containing 2.43 g/liter of rifamycin B at alkaline pH was oxidized with a water solution of sodium nitrite. After careful acidification with 10% sulfuric acid, rifamycin O precipitated and was collected by filtration. A 96% yield of the product at 85% purity was obtained (82). 

An early report (79), based on degradation of radioactive rifamycins derived from " C-labeled precursors, suggested the amide-tail direction of biosynthesis for rifamycin. This was reversed later in favor of the amide-head direction when sodium [c(7rZ>a 7- C]propionate, sodium [methylene- C] vo i ondiiQ, sodium propionate sodium [carb-... 

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