Thiamphenicol

Description

Thiamphenicol is a broad-spectrum antibiotic chloramphenicol, which is more effective to the gram-negative bacteria than the gram-positive bacteria. At room temperature, it is a white to off-white crystalline powder or crystal, which can be quickly and completely absorped by oral adminstration, as well as it is excreted mainly in the prototype from the urine for metabolism. It is clinically applied for the treatment of respiratory, urinary tract, liver and gallbladder, typhoid and other intestinal surgery, gynecology and ENT infections. Especially in the mild infections it is more effective. It has the similar chemical structure with the chloramphenicol. Its methyl sulfone substituted the nitro of chloramphenicol, which reduced its toxicity, and in vivo its antibacterial activity is 2.5-5 times stronger than chloramphenicol. For gram-positive bacteria, such as streptococcus pneumoniae and hemolytic streptococcus, it has very strong antibacterial effect, while for gram-negative bacteria, such as Neisseria gonorrhoeae, meningococcus, lung Bacteroides, E. coli, Vibrio cholerae, Shigella and influenza bacillus, it also has strong antibacterial effect. For anaerobic bacteria, Rickettsia and amoeba, it has antibacterial effect in some extent. It has the same antimicrobial mechanism with chloramphenicol, which mainly inhibits the synthesis of bacterial protein. This drug is absorped quickly by oral administration, which reaches peak blood concentration within two hours. Its half-life is 5 hours, that is more longer than chloramphenicol. The bacteria have complete cross resistance to it and chloramphenicol, while the bacteria have some cross-resistance phenomenon to it and tetracycline.
Thiamphenicol also has strong immunosuppressive effects, which is an excellent immunosuppressant. Its mechanism of action have significantly different with other immunosuppressive agents. The immunosuppressive effect is several times higher than the chloramphenicol. It can be as the effective extender for transplantation reaction and surgically allogeneic transplantation.

Chemical Properties

White to off-white crystalline powder or crystal. Melting point (℃) 178-180 (swirled), 164-166 (right-handed).

Uses

It is applied for the treatment of respiratory, urinary tract, liver and gallbladder, typhoid and other intestinal surgery, gynecology and ENT infections. Especially in the mild infections it is more effective.

Chemical Properties

Off-White Solid

Originator

Thiophenicol,Clin Midy,France,1967

Uses

chelating agent, antiseborrheic

Uses

Antimicrobial

Uses

Thiamphenicol is a semi-synthetic chloramphenicol prepared by total synthesis from thiophenol in which the nitro moiety of chloramphenicol is replaced by a methylsulphone, first synthesised at Sterling Winthrop in 1952. Thiamphenicol is a broad spectrum antibiotic with good activity against Gram negative and anaerobic bacteria. Thiamphenicol acts by binding to the 23S sub-unit of the 50S ribosome inhibiting protein synthesis. Thiamphenicol has been extensively studied with over 800 literature citations.

Uses

Thiamphenicol is an antibiotic. Thiamphenicol is the methyl-sulfonyl analogue of chloramphenicol and has a similar spectrum of activity, but is 2.5 to 5 times as potent. Thiamphenicol is used particul arly for the treatment of sexually transmitted infections and pelvic inflammatory disease.

Definition

ChEBI: Thiamphenicol is a sulfone and a monocarboxylic acid amide. It has a role as an immunosuppressive agent and an antimicrobial agent.

Manufacturing Process

A mixture of 50 parts by weight of racemic 2-acetylamino-1-(4- methylmercaptophenyl)-1,3-propanediol, 100 parts by weight of concentrated hydrochloric acid, and 500 parts by weight of water was warmed on a steam bath for thirty minutes. The resulting solution was cooled to about 40°C and was then made strongly alkaline by addition of 35% aqueous sodium hydroxide solution. The alkaline solution was then refrigerated. The white solid which separated from the cooled solution was collected on a filter. There was thus obtained 27 parts by weight of 2-amino-1-(4-methylmercaptophenyl)- 1,3-propanediol. This product melted at 130.7°C to 131.9°C after recrystallization from methanol.
This compound was converted to the tartrate and the optical isomers were resolved.
A mixture of 1.1 g of 2-amino-1-(4-methylmercaptophenyl)-1,3-propanediol, obtained as described above and 1.6 ml of ethyl dichloroacetate was heated on a steam bath for three hours. The resulting viscous yellow oil was dissolved in 25 ml of ethylene chloride and filtered hot with charcoal, and the filtrate was allowed to cool to about 25°C. From the filtrate there separated 0.92 g of tiny white leaflets which were collected on a filter. Recrystallization of this product, which was a dextro-rotary form of 2-dichloroacetylamino-1-(4- methylmercaptophenyl)-1,3-propanediol from nitroethane yielded the pure product, which melted at 111.6°C to 112.6°C.
7 g of the 2-dichloroacetylamino-1-(4-methylmercaptophenyl)-1,3-propanediol obtained as described above was dissolved in 30 ml of acetone. To this solution there was added dropwise with stirring 10 ml of 40% peracetic acid. The temperature during the reaction was maintained at 39°C to 45°C by cooling the reaction vessel. After stirring the mixture for two hours, it was diluted with 100 ml of water and the solution allowed to stand over the weekend in the refrigerator. The solid which separated from solution was collected on a filter, washed several times with ice water, and dried overnight at 70°C.

Therapeutic Function

Antibacterial

Antimicrobial activity

It is generally less active than chloramphenicol, but is equally active against Str. pyogenes, Str. pneumoniae, H. influenzae and N. meningitidis, including some strains resistant to chloramphenicol. It is more actively bactericidal against Haemophilus and Neisseria spp.

Acquired resistance

There is complete cross-resistance with chloramphenicol in those bacteria which elaborate acetyltransferase, although the affinity of the enzyme for thiamphenicol is lower. Organisms that owe their resistance to other mechanisms may be susceptible.

Pharmacokinetics

An oral dose of 500 mg produces a peak plasma level of 3–6 mg/L after about 2 h. The plasma half-life is 2.6–3.5 h. It is said to reach the bronchial lumen in concentrations sufficient to exert a bactericidal effect on H. influenzae. Unlike chloramphenicol it is not a substrate for hepatic glucuronyl transferase; it is not eliminated by conjugation, and its half-life is not affected by phenobarbital induction.
About 50% of the dose can be recovered in an active form in the urine within 8 h and 70% over 24 h. The drug is correspondingly retained in the presence of renal failure, and in anuric patients the plasma half-life has been reported to be 9 h, a value not significantly affected by peritoneal dialysis. Biliary excretion is believed to account for removal of the antibiotic in anuric patients. The plasma concentration is elevated and half-life prolonged in patients with hepatitis or cirrhosis.

Clinical Use

Similar to that of chloramphenicol.

Side effects

There are no reports of irreversible bone-marrow toxicity. This has been related to the absence of the nitro group, and hence its reduction products, and differences in the biochemical effects of thiamphenicol and chloramphenicol on mammalian cells. It exerts a greater dose-dependent reversible depression of hemopoiesis and immunogenesis than chloramphenicol, and has been used for its immunosuppressive effect. Therapeutic doses (1–1.5 g) are likely to depress erythropoiesis in the elderly or others with impaired renal function.

Purification Methods

Recrystallise thiamphenicol from H2O or CHCl3. The UV has max at 224, 266 and 274nm ( 13,700, 800 and 700) in 95% EtOH. The 1S,2S-isomer [1478651-7] has m 164.3-166.3o (from H2O/EtOAc/pet ether) and [] D 25 -12.6o (c 1, EtOH); and the racemate 1RS,2RS-Racefenical [847-25-6] has m 181-183o (dec) from CHCl3/EtOAc/pet ether. [Cutler et al. J Am Chem Soc 74 5475, 5482 1952, UV: Nachod & Cutler J Am Chem Soc 74 1291 1952, Suter et al. J Am Chem Soc 75 4330 1953, Cutler et al. J Am Pharm Assoc 43 687 1954, Beilstein 13 IV 2957.]