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• Description

  Chloramphenicol, also known as chlornitromycin, is a broad-spectrum, bacteriostatic antibiotic derived from Streptomyces venezuelae. It is first isolated from cultures of Streptomyces venequelae in 1947 but now produced synthetically. The synthetic product is racemic, also called synthomycin. Syntomycin is a mixture of chloramphenicol L-isomer and d-isomer. Because of dextroisomer antibacterial effect, the effect of synthomycin is only half of the natural products. It has a relatively simple structure and was the first broad-spectrum antibiotic to be discovered. It is effective against several gram-positive and gram-negative bacteria and commonly used in researching protein synthesis and to select for chloramphenicol-resistant transformed cells or the bacterial CAT gene.
  Chloramphenicol is a semisynthetic, broad-spectrum antibiotic derived from Streptomyces venequelae with primarily bacteriostatic activity. Chloramphenicol diffuses through the bacterial cell wall and reversibly binds to the bacterial 50S ribosomal subunit. The binding interferes with peptidyl transferase activity, thereby prevents transfer of amino acids to the growing peptide chains and blocks peptide bond formation. As a result bacterial protein synthesis is blocked and impede bacterial cell proliferation. ;

• Chemical Properties

  It is white or yellowish green needle like crystals. The melting point is 150.5-151.5℃ (149.7-150.7℃). Under the high vacuum it can be sublimated, slightly soluble in water (2.5mg/ml at 25℃), slightly soluble in propylene glycol (150.8mg/ml), soluble in methanol, ethanol, butanol, ethyl acetate, acetone, insoluble in ether, benzene, petroleum ether, vegetable oil. Taste is very bitter. ;

• Antimicrobial Spectrum

  Chloramphenicol is bacteriostatic and a broad-spectrum antibiotic active against both gram-positive and gram-negative bacteria including rickettsia (cause of rocky-mountain spotted fever) and chlamydia. It is also found effective against Haemophilus influenzae causing meningitis.
  1. Gram-positive: Streptococcus spp., Staphylococcus spp., Enterococcus spp., Bacillus anthracis, Listeria monocytogenes.
  2. Gram-negative: Hemophilus influenzae, M. catarrhalis, N. meningitides, E. coli, P. mirabilis, Salmonella spp., Shigella spp., Stenotrophomonas maltophilia.
  ;

• Uses

  1. Chloramphenicol is used for the treatment caused by typhoid bacillus, dysentery bacillus, Escherichia coli, bacillus, influenza and pneumococcal infections such as brucellosis.
  2. Chloramphenicol is used in the treatment of infections caused by bacteria. It works by killing bacteria or preventing their growth.
  3. Chloramphenicol is used to treat serious infections in different parts of the body. It is sometimes given with other antibiotics. However, chloramphenicol should not be used for colds, flu, other virus infections, sore throats or other minor infections, or to prevent infections.
  4. Chloramphenicol should only be used for serious infections in which other medicines do not work. This medicine may cause some serious side effects, including blood problems and eye problems. Symptoms of the blood problems include pale skin, sore throat and fever, unusual bleeding or bruising, and unusual tiredness or weakness.
  You and your doctor should talk about the good this medicine will do as well as the risks of taking it .
  Chloramphenicol is available only with your doctor's prescription. ;

• Mechanism of action

  Inhibition of protein synthesis, Chloramphenicol irreversibly binds to a receptor site on the 50S subunit of the bacterial ribosome, inhibiting peptidyl transferase. This inhibition consequently results to the prevention of amino acid transfer to growing peptide chains, ultimately leading to inhibition of protein formation. ;

• Pharmacokinetics

  After oral administration, it is rapidly and completely absorbed, can be widely distributed in body tissues and body fluids. In the cerebrospinal fluid concentration distribution were higher than other antibiotics, oral bioavailability was 75%~90%. After oral half hour of in the blood can reach the effective concentration, It can reach the peak in 2 to 3 hours. Take oral 0.5g, 1g and 2g, blood drug concentration was 4mg/L, 8~10mg/L and 16~21mg/L in 2 hours, 1~2g, 4 times a day, can make the blood to maintain long-term effective concentration of 10mg/L~5. After intravenous injection, the average is similarity with oral blood drug concentration of the same dose. After intramuscular absorption is slow and irregular, blood concentration is only oral amounts of 50%, but the maintenance time is long. The plasma protein binding rate is 50%~60%., the half-life of 2 to 3 hours, the half-life of newborns was significantly higher than that of adults, under the age of 2 is about 24 hours, 2 to 4 years is about 12 hours. This product is absorbed and widely distributed in the body each Reduce the concentrations of blood concentration in the blood to body fluids and tissues of liver and kidney was the highest, followed by the lung, spleen, heart, intestine and brain. Bile content is low, about 20%~50%, but also can enter the pleural effusion and ascites, milk, fetal circulation and ocular tissue. Through the blood brain barrier to reach the cerebrospinal fluid (CSF), in normal cerebrospinal fluid (CSF) in concentrations is up to 20%~50%, inflammation is up to 50%~100%. It is mainly in the liver metabolism, binding with glucuronic acid to inactivation, about 75%~90% of the metabolites in 24 hours urine, of which 5%~15% for the prototype drug. 1 g orally, urine concentration is 70~150mg/L. serious liver disease patients, the half-life may be extended due to hepatic metabolism and poisoning caused by accumulation. ;

• Indications

  This product is fat soluble, synthetic peptide can inhibit the formation and prevent protein. Is a bacteriostatic agent, high concentration or effect highly sensitive to the bacteria to this product showed bactericidal action. This product is applicable to the general application of typhoid and paratyphoid salmonella, and other Bacteroides fragilis.
  1. Chloramphenicol is the preferred treatment of typhoid and paratyphoid fever, and can be used for typhoid Salmonella infections.
  2. Used for pneumococcal in patients allergic to penicillin, ampicillin B Hib meningitis or tolerance, meningococcal meningitis, sensitive to the change of gram negative bacilli meningitis.
  3. Used for aerobic and anaerobic bacteria mixed infection of otogenic brain abscess.
  4. Used for serious anaerobic infections, such as Bacteroides fragilis infection.
  5. Used as aminoglycoside drugs in the treatment of infection caused by sensitive bacteria and other microorganisms, such as influenza bacillus, Salmonella and other gram negative bacilli to sepsis, pulmonary infection.
  6. Used for the local treatment of flu from Escherichia coli, bacillus, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus and eye, ear superficial infection.
  7. It is effective for Rickettsia, mycoplasma, and infection.
  8. Coli and Serratia of Pseudomonas aeruginosa is infections.
  9. Chloramphenicol eye drops for the treatment of infections caused by sensitive bacteria caused by the eye, such as trachoma, conjunctivitis, keratitis, blepharitis etc..
  10. This medicine local ear drops can be used for treating sensitive bacteria infections caused by otitis externa, acute and chronic otitis media, the drug ear plugs can also be for inflammation of the ear canal and radical mastoidectomy postoperative oozing pus. ;

• resistance

  Drug resistance of gram negative bacilli on chloramphenicol acetyltransferase, mostly due to drug inactivation, the enzyme is mediated by the R factor. Drug resistance of gram positive bacteria, may also be due to similar mechanisms, but not fully clear. Some strains of Pseudomonas aeruginosa and Proteus, Klebsiella, are another way to generate drug resistance, which prompted the permeability change, and chloramphenicol cannot enter the cell.
  Bacterial resistance to chloramphenicol resistant strains both in vitro and in vivo, increased gradually in recent years. Escherichia coli, Salmonella and other gram negative bacilli can be due to drug resistance factor factor (R) transfer and acquire resistance. It has been proven that with R factor of Escherichia coli can produce acetyl transferase, chloramphenicol acetylation of failure; chloramphenicol resistant Staphylococcus aureus can also produce some inducible enzyme, under the participation of acetyl CoA, the acetylation of chloramphenicol. ;

• Drug interactions

  Chloramphenicol inhibits hepatic microsomal enzyme of phenytoin and tolbutamide (Jia Tangning) and chlorpropamide and dicoumarol (and possibly other drug metabolism, and the prolonged in vivo half-life, increased concentrations of serum. Poisoning aggravate that death is also reported. On the other side, phenobarbital, phenytoin, rifampin (are, 1985) can decrease the serum concentration of chloramphenicol, which was estimated to be due to the inductive effect of drugs on the liver enzymes. Therefore, at the same time, the application effect of chloramphenicol pharmacokinetics of drugs, should be paid attention to the monitoring of serum concentration of chloramphenicol.
  Chloramphenicol can delay the iron, folic acid and vitamin B12 on anemia treatment response. It can interfere with the host to tetanus toxoid anamnestic response. Therefore, at the same time, the application situation chloramphenicol and active immune agents should be avoided.
  Antagonistic effects of chloramphenicol on penicillin bactericidal effect, which is verified in vitro and animal experiments, but its clinical significance is not clear. This kind of combination, only in the proof of such treatment is benefit, began to be used. ;

• Adverse reactions and precautions

  1. Inhibition of bone marrow hematopoietic function: for the most serious toxicity of chloramphenicol, such as red blood cells, granulocyte and platelet reduce. There are two types: one is the reversible inhibition, manifested as neutropenia and thrombocytopenia, and anemia, related to dose and duration can be gradually recovered after drug withdrawal; Second is irreversible aplastic anemia, with dosage and duration without direct relationship, low incidence, once often occur difficult to reverse, high mortality rate and a few survivors can development for granulocytic leukemia, women, children, and liver and kidney function not entire occurrence rate is high. This is the main reason to limit the clinical application.
  2. In the liver, metabolism rate of this product is very high, on the function of the liver, it has impaired the appropriate quantity (adult day not more than 1 g) or not as much as possible.
  3. Chloramphenicol is only 5%~10% prototype drug discharge from the kidney, it is not appropriate for the treatment of urinary tract infection.
  4. Premature infants and neonatal as much as possible.
  5. I see the spirit of neurological symptoms, should be promptly discontinued.
  6. During late pregnancy and lactation are not suitable for this application, because this product in vivo is conjugated with glucuronic acid and detoxification, conjugates excreted by the kidneys. And this product can be through the placenta to the fetus, fetal and neonatal, due to not perfect of enzyme system in the liver, glucuronic acid combined with the ability is poor and excretory function of the kidney is weak. Therefore, it is very easy to cause drug accumulation, the newborn gray baby syndromes. Gray cyanosis, dyspnea, vomiting, abdominal distension and circulatory failure with unique performance, high fatality rate. In addition, this product can damage the hematopoietic system, can make the pregnant women aplastic anemia, neonatal thrombocytopenia and other consequences. ;

• Methods of production

  Methods for producing countries in the world to chloramphenicol had a lot of research, summed up: (1) p-nitroacetophenone method; (2) styrene method; (3) Cinnamyl alcohol method; (4) The nitro cinnamic alcohol method; (5) P-nitrobenzaldehyde method. China use p-nitroacetophenone method, the method is by ethylbenzene via nitration, oxidation, bromide, salt, hydrolysis, acetylation, addition, reduction, decomposition, split second chloride acetylation and chloramphenicol. ;

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