News briefing： Florfenicol, also known as florfenicol, is a chemically synthesized new generation of animal-specific chloramphenicol (also known as amide alcohol) broad-spectrum antibiotics, which has antibacterial activity against a variety of bacteria and does not for

Catalog:

1.pharmacology>

2.Drug interaction>

3.side effects and side effects>

4.indications and clinical applications>

5.main preparations, usage and dosage>

6.guidelines for clinical medication and points for attention>

Florfenicol, also known as florfenicol, is a chemically synthesized new generation of animal-specific chloramphenicol (also known as amide alcohol) broad-spectrum antibiotics, which has antibacterial activity against a variety of bacteria and does not form with human drugs. Cross-resistance. It is characterized by wide antibacterial spectrum, good antibacterial effect, rapid absorption by oral or injection, wide distribution of various organs in the body, blood-brain barrier, and no cross-resistance with other commonly used antibacterial drugs. In particular, there is no potential for aplastic anemia, which is relatively safe.

Because chloramphenicol is highly toxic, it can seriously inhibit the hematopoietic function of animal bone marrow,which can cause leukocytosis and thrombocytopenia, or lead to irreversible aplastic anemia, and has immunosuppressive effect. At present, florfenicol has become the main alternative to chloramphenicol after banning, and plays an important role in veterinary clinic. How to use florfenicol correctly and reasonably has become the focus of attention in pig production and clinical application.

1.pharmacology

(1) The pharmacodynamic structure of florfenicol is similar to that of chloramphenicol. It is a single fluorine derivative of thiamphenicol. Its antimicrobial spectrum, antimicrobial activity, antimicrobial mechanism and indications are the same as those of chloramphenicol.

As the para-nitro group of chloromycetin benzene ring is substituted by thionyl group, the toxicity and side effects are reduced, but there is still dose-dependent reversible inhibition of bone marrow hematopoietic function. Its mechanism is that it can bind to the 50S subunit of 70S ribosome of bacteria, block the peptide acyltransferase, inhibit the extension of the peptide chain, thereby interfering with the synthesis of bacterial protein and producing antimicrobial effect.

This product is a broad-spectrum quick-acting bacteriostatic agent. Its antimicrobial activity is slightly better than that of chloramphenicol and thiamphenicol. Its drug resistance and drug residue are low. It has strong antimicrobial activity to many kinds of Gram-positive bacteria, Gram-negative bacteria and mycoplasma, especially to gram-negative bacteria, which is superior to gram-positive bacteria, but less effective to gram-positive cocci than penicillin and tetracycline. It is highly sensitive to hemolytic Pasteurella multocida, Pasteurella multocida (*), Actinobacillus pleuropneumoniae (Contagious Pleuropneumonia), and is sensitive to most gram negative Enterobacteriaceae, including paratyphoid, Klebsiella, Escherichia coli, Salmonella and Brucella. The sensitive Gram-positive bacteria are Streptococcus, Cryptococcus pyogenes, Listeria, Pneumococcus, Staphylococcus and so on. It has a certain effect on leptospirosis, chlamydia and Rickettsia. It can also enter cells smoothly, and it is also effective for pathogens in various cells. It also plays an important role in various anaerobic bacteria, such as Clostridium tetanus and actinomycetes.

In addition, the general dose of florfenicol has bacteriostatic effect, and it can kill bacteria at high concentration or when it acts on bacteria highly sensitive to the product. Bacteria can acquire resistance to the product. Escherichia coli is easy to produce and cross-resistant with thiamphenicol. This product is ineffective against Pseudomonas aeruginosa, fungi and viruses.

(2) pharmacokinetics of pig * s intake is relatively complete, and its bioavailability is high. Even under feeding conditions, it can absorb 80% to 90%. Because florfenicol does not bind to glucuronic acid in the liver, it has higher antimicrobial activity in vivo, which is 2.5-5 times stronger than chloramphenicol. Oral administration and intramuscular injection absorb rapidly, with high blood concentration and wide distribution of drugs. They can infiltrate into various tissues and body fluids, and also have high concentration in the viscera. It can pass the blood-brain barrier smoothly, and ascites and pleural effusion can also infiltrate. The half-life is long and the effective concentration is maintained for a long time.

2.Drug interaction

(1) In most cases, florfenicol should not be used in combination with macrolides (such as tylosin, erythromycin, telmicosin, getamycin, etc.), lincomycins (such as lincomycin) and diterpene semisynthetic antibiotics - tamicin (mycoplasma), which can produce antagonism when used. Because they have the same mechanism of action, they all bind to the 50S subunit of bacterial ribosome, and the latter three antibiotics can replace or prevent the combination of florfenicol and the 50S subunit of bacterial ribosome, that is to say, because of the competitive action site, the effect is reduced.

(2) Flufenicol should not be used in combination with beta-lactone amines (such as penicillins and cephalosporins) and fluoroquinolones (such as enrofloxacin and ofloxacin) because it is a quick-acting inhibitor of bacterial protein synthesis, and the latter is a fast-acting fungicide in reproductive period. Under the action of the former, the speed of protein synthesis of bacteria is inhibited, and bacteria stop growing and multiplying, which weakens the bactericidal effect of the latter. Therefore, it can not be used at the same time when treating diseases that need quick sterilization.

(3) Flufenicol can be used in combination with tetracyclines (such as doxycycline, chlortetracycline, etc.) and myxobacterium, showing an additive effect, because the mechanism of action is different and the position of action is not competitive. It can also be used in combination with aminoglycosides to treat septicemia and pulmonary infection caused by mixed infection of aerobic and anaerobic bacteria.

3.side effects and side effects

(1) Although the side effects and adverse reactions of florfenicol are less than those of chloramphenicol, it will not cause irreversible bone marrow aplastic anemia, but it can cause dose-related hematopoietic system damage, and the reversible inhibition of bone marrow erythropoiesis is more common than that of chloramphenicol. The clinical manifestation is anemia or leukocyte and thrombocytopenia due to inhibition of erythrocyte production.

(2) The strong immunosuppressive effect of florfenicol is about 6 times stronger than that of chloramphenicol. Because of the inhibition of antibody synthesis, it is forbidden to use florfenicol during vaccination or for those with severe immune deficiency.

(3) * embryo sows are used cautiously during pregnancy and lactation. In addition, large dose of florfenicol can cause peripheral circulatory failure in * * newborn piglets, so the newborn piglets should be avoided.

(4) long term oral administration can cause digestive disorders, vitamin deficiency symptoms, mild vomiting and diarrhea.

(5) Dual infection can cause pulmonary, gastrointestinal and urinary tract infections such as Pseudomonas aeruginosa, Staphylococcus aureus and fungi.

4.indications and clinical applications

(1) Mainly used for the treatment of various infections caused by sensitive bacteria and secondary infections and complications caused by various causes, especially for respiratory diseases. Recommended as Pasteurellosis (swine fever), * * contagious pleuropneumonia and Haemophilus Haemophilus disease, it is especially suitable for treating bacterial infections with fluoroquinolones and other antibacterial agents, especially for moderate infections. It can also be used for the treatment of Streptococcus (Fei Yan), Bordetella bronchi * (atrophic rhinitis), respiratory diseases caused by Mycoplasma pneumoniae (hog *), and porcine eporyocytic disease caused by Mycoplasma Haemophilus (Fei Yan). * the sick pigs showed elevated body temperature, no food, shortness of breath, cough, asthma, some mouth breathing, nasal fluid frothy liquid, sometimes mixed with blood, skin congestion and small bleeding points; some joints swelling, ears and nose cyanosis (blue purple).

(2) Salmonellosis (piglet paratyphoid fever), colibacillosis (piglet yellow diarrhea, piglet white diarrhea, piglet edema) and enteritis caused by other susceptible bacteria are characterized by increased body temperature, mental retardation, loss of appetite or non-feeding, constipation or diarrhea, and sometimes vomiting.

(3) Streptococcus suis, staphylococcal disease, exudative dermatitis * (fat pig) and other systemic infectious diseases, such as mastitis, hystertis, cystitis, postpartum fever, no food, postpartum lactation syndrome (PPDS), etc.

(4) Bacterial meningitis and brain abscess with unknown pathogens, especially caused by ampicillin-resistant Streptococcus pneumoniae.

(5) urinary tract infection caused by E. coli and * Actinobacillus. Because the drug is not inactivated by metabolism in the liver, but excreted from the kidney, the active concentration in urine is high and the curative effect is good.

(6) dysentery caused by * * disease caused by Treponema dysentery.

(7) * * weaning multisystemic wasting syndrome (PWMS) or porcine respiratory disease syndrome (PRDC) and dermatitis nephrotic syndrome (PDNS).

(8) abdominal cavity infection. The combination of aminoglycosides is often needed to control the mixed infection of aerobic bacteria and anaerobic bacteria.

(9) other infections. Such as anaerobic bacteria, chlamydia infection, brucellosis and so on.

5.main preparations, usage and dosage

(1) Florfenicol injection (specification: 10mL: 1g; 100ml: 30g) intramuscular injection (calculated by florfenicol): one dose, 20mg/kg body weight, twice a day, for 3-5 days.

(2) Florfenicol injection powder (specification: 50g: 5g) for oral administration (based on florfenicol): one dose of 20-30mg/kg body weight, twice a day, for 3-5 days.

(3) Premixtures of florfenicol (specifications: 100g: 20g; 100g: 10g; 100g: 5g; 100g: 2g) for the treatment of infections caused by susceptible bacteria, 40 g per ton of feed was added for 7 days.

6.guidelines for clinical medication and points for attention

(1) Although the toxicity and side effects of florfenicol are lower than those of chloramphenicol and there is no irreversible aplastic anemia, it still has hematological toxicity. It can also cause reversible inhibition of cell formation and reduction of white blood cells and platelets, and has stronger immunosuppressive effect than chloramphenicol. Therefore, the indications should be strictly controlled and should not be used for mild sensation. It should not be used as a preventive drug for infection, but only when some severe infections or low toxicity drugs are ineffective. The duration of the treatment should be continued until cure and prevent recurrence. However, excessive dosage or repeated treatment should be avoided to prevent the possibility of reversible bone marrow suppression toxicity.

(2) Due to the embryotoxicity of high dosage of florfenicol and peripheral circulatory failure of premature piglets or newborn piglets, pregnant sows, especially in late pregnancy and newborn piglets, should avoid using florfenicol.

(3) florfenicol can not be mixed with sulfadiazine sodium intramuscular injection. Avoid oral or intramuscular injection when combined with alkaline drugs, so as to avoid decomposition failure. It should not be mixed with tetracycline hydrochloride, kanamycin, gentamicin, adenosine triphosphate and coenzyme A. In order to avoid precipitation and reduce efficiency.

(4) Intravenous injection is forbidden. Muscle degeneration and necrosis may occur after intramuscular injection. Therefore, alternate injection of deep muscles of neck and buttock can be used.

(5) treatment of pig farms * contagious pleuropneumonia, Haemophilus influenzae, swine plague and Streptococcus suis. At the beginning of the disease, when the sick pigs had better appetite, the dosage could be increased when mixed feeding, and the feed was added to florfenicol (titer) 60 to 80g, preferably with doxycycline (200g). For 7 days, it has a good effect. For fever, cough and asthma caused by infectious diseases, antibiotics alone can be used without adding other antipyretic analgesics, cough and asthma drugs. If a sick pig develops * high fever and does not eat, it should be isolated and treated with intramuscular injection of florfenicol. If the body temperature exceeds 41 degrees, it can be used in combination with antipyretic analgesics and dexamethasone, and the effect is better.

(6) In the prevention and treatment of respiratory syndrome (PRDC), some manufacturers recommend the combination of florfenicol with amoxicillin or tylosin or tamicin. The author believes that this method is inappropriate. Because from the pharmacological point of view, the two can not be used together.

(7) The official "Guidelines for the Use of Veterinary Drugs" and the instructions of many manufacturers indicate that the product is injected intramuscularly every 48 hours, twice for a course of treatment. The result of the trial is not ideal, but according to the weight of 20-30 mg/kg, twice a day, for 3-5 days, the effect is better. It is suggested that you get your own experience through practice.

(8) In the prevention and treatment of swine diseases, care should be taken to administer the drugs in accordance with the prescribed dosage and course of treatment, and abuse should not be allowed to avoid adverse consequences.