What Factors Affect a Sufficient Nitrofurantoin Dose?

Furantoin, aliases furantan, furantan, nitrofurantoin, nitrofurantoin. This product is a bright yellow crystalline powder. It is odorless, bitter, and darker when exposed to light. This product is soluble in dimethylformamide, slightly soluble in acetone, very slightly soluble in ethanol, and almost insoluble in water or chloroform. It is mainly used for urinary system infection caused by sensitive bacteria.

Drug Name: Furantoin
Alias: Furantantidine
Foreign name: Furadantin, Furantoin
Whether prescription drugs: Non-prescription drugs

Main indications: Urinary system infection caused by sensitive bacteria
Dosage: Oral: 0.1g / time for adults, 4 times / day
Dosage form: tablet
Athletes use with caution: Use with caution
Whether to include health insurance: Incorporate

Furantoin compounds

Furantoin Basic Information

Chinese name: furantoin

Chinese alias: Furantoin; Nitrofurantoin; Furantan; Nifuratoin; Furantozine;

English name: nitrofurantoin

English alias: Furadatine; 5-Nitrofurantoin; Nitrofurantoine; Furadoine; 2,4-Imidazolidinedione, 1-[[((5-nitro-2-furanyl) methylene] amino]-;

CAS number: 67-20-9

Molecular formula: C ₈ H ₆ N ₄ O ₅

Molecular weight: 238.16

Exact mass: 238.03400

PSA: 120.73000

LogP: 0.86340 ^[1]

Furotoin physical and chemical properties

Melting point: 268 ° C ^[2]

Refractive index: 1.52 (20 C)

Flash point: 43

Density: 0.915 g / cm ³ (20 C)

Water solubility: <0.01 g / 100 mL at 19 ºC

Appearance: Lemon yellow crystalline powder

Furantoin Safety Information

Symbol: GHS07 GHS08

Signal Word: Danger

Hazard statement: H302; H317; H334

Cautionary statements: P261; P280; P342 + P311

Packing level: III

Hazard category: 6.1 (b)

Customs code: 2933990090

Dangerous Goods Transport Code: 2811

WGK Germany: 3

Danger category code: R22; R42 / 43

Safety instructions: S22-S36 / 37-S45

RTECS number: MU2800000

Dangerous goods mark: Xn ^[1]

Furantoin production method

Aminohydantoin can be made from hydrazine hydrate and urea, and then obtained by condensation with nitrofuran diethyl ester.

Furantoin use

Organic synthesis and biochemical research. medicine. This product is an excellent antibacterial drug with a broad antibacterial spectrum. It is absorbed quickly and completely after oral administration, and excreted quickly. It can be excreted in the urine up to 40-50%. It is often used to treat various urinary tracts caused by sensitive bacteria. infection. It has an effect on both Gram-negative and positive bacteria. It is mainly used for urinary tract infections caused by sensitive bacteria, especially for acute urinary tract infections caused by E. coli and Proteus. It is clinically used for urinary system infections caused by sensitive bacteria, such as pyelonephritis, urinary tract infections, cystitis and prostatitis, etc. ^[1] .

Furantoin Pharmacopoeia Standard

Furantoin source (name), content (potency)

This product is 1-[(5-nitrofuran methylene) amino] hydantoin. Calculated on dry basis, containing C8H6N4O5 should be 98.0% to 102.0%.

Furantoin traits

This product is a yellow crystalline powder; odorless, bitter taste; dark color gradient when encountering light.

This product is soluble in dimethylformamide, slightly soluble in acetone, very slightly soluble in ethanol, and almost insoluble in water or chloroform.

Furantoin identification

(1) Take about 5mg of this product, add 5ml each of water and sodium hydroxide test solution to dissolve, the solution is dark orange red.

(2) Take about 5mg of this product, add 5ml of water and 0.2ml of ammonia test solution to dissolve, and add 5ml of silver nitrate test solution to form a yellow precipitate (different from furacillin and furazolidone).

(3) The infrared light absorption spectrum of this product should be the same as that of the control ("Infrared Spectra of Drugs" 181).

Furantoin test

acidity

Take 0.50g of this product, add 50ml of water, shake for 10 minutes, filter, take the filtrate, and measure it according to law (Appendix VIH of the second edition of the Pharmacopoeia of 2010 Edition), the pH value should be 5.5 7.0.

relative substance

Protect from light. Take 0.25g of this product, put it in a 10ml measuring bottle, add 5ml of dimethylformamide to dissolve it, and dilute it to the mark with acetone as the test solution; take 1ml of precise amount, place it in a 100ml measuring bottle, and dilute to the mark with acetone , As a control solution. According to the thin-layer chromatography (2010 Appendix B Pharmacopoeia Part II) test, draw 3 l of each of the two solutions above, and pip the same silica gel GF254 thin-layer plate, using nitromethane-methanol (9: 1) as the developing agent, and develop , Air-dry, dry at 105 ° C for 5 minutes, inspect under UV light (254nm), and spray with phenylhydrazine hydrochloride solution (take 0.75g of phenylhydrazine hydrochloride, add 50ml of water to dissolve, decolorize with activated carbon, filter, and take all Add 25 ml of hydrochloric acid and 200 ml of water to the filtrate, and heat at 105 ° C for 10 minutes. If the test solution shows obvious spots of impurities, it must not be deeper than the main spots of the control solution.

Furacillin

Protect from light. Take about 100mg of this product, weigh it accurately, place it in a 25ml measuring bottle, add 2ml of dimethylformamide precisely to dissolve, add 20ml of water precisely, shake well, leave it for 15 minutes to form a precipitate, filter through the membrane, and take the filtrate As a test solution; take an appropriate amount of furancillin reference substance, accurately weigh, add dimethylformamide to dissolve and quantitatively dilute to make a solution containing 5 g per 1 ml, take 2 ml precisely, place in a 25 ml measuring bottle, and add water precisely 20ml, shake well as the reference solution. Another 1 ml of the reference solution and the test solution were mixed and used as a system suitability test solution. According to the high performance liquid chromatography (2010 edition Pharmacopoeia Part II Appendix V D) test, use octadecylsilane bonded silica as a filler; phosphate buffer solution (take 6.8 g of potassium dihydrogen phosphate, add 500 ml of water to dissolve, use 1.0mol / L sodium hydroxide solution was used to adjust the pH to 7.0, and diluted with water to 1000ml)-tetrahydrofuran (90:10) as the mobile phase; the detection wavelength was 375nm. Take the system suitability test solution: 100 l, inject it into the liquid chromatograph, and record the chromatogram. The resolution between the furantoin peak and the furacillin peak should be greater than 4.0. Precisely measure 100 l each of the test solution and the reference solution, inject them into the liquid chromatograph, and record the chromatogram. For the chromatogram of the test solution, if there are chromatographic peaks consistent with the retention time of furacicillin, the peak area calculated according to the external standard method shall not exceed 0.01%.

Loss on drying

Take this product and dry it at 105 to constant weight, and the weight loss shall not exceed 1.0% (Appendix L of Part Two of the Pharmacopoeia of 2010 Edition).

Residue on ignition

Must not exceed 0.1% (Appendix N of Part Two of the 2010 Pharmacopoeia).

Determination of furantoin

Protect from light. It was determined by high performance liquid chromatography (Appendix D, Part Two of the Pharmacopoeia, 2010 Edition).

1 Chromatographic conditions and system suitability tests

Use octadecylsilane bonded silica as a filler; use phosphate buffer solution (take 6.8 g of potassium dihydrogen phosphate, dissolve in 500 ml of water, adjust the pH to 7.0 with 1 mol / L sodium hydroxide solution, and dilute to 1000 ml with water )-Acetonitrile (88:12) is the mobile phase; the detection wavelength is 254nm. Take an appropriate amount of acetanilide, dissolve and dilute with water to make a solution containing 1mg per 1ml, take an appropriate amount of furantoin, add dimethylformamide to dissolve and dilute to make a solution containing 0.5mg per 1ml, take the above two solutions Each 10ml was mixed, and as a system suitability test solution, 10 l was injected into a liquid chromatograph, and the chromatogram was recorded. The resolution between the furantoin peak and the acetanilide peak should be greater than 3.0.

2 Assay

Take about 20mg of this product, accurately weigh it, put it in a 100ml measuring bottle, add 40ml of dimethylformamide to dissolve, dilute with water to the mark, shake well, take a precise amount of 10l, inject the liquid chromatograph and record the chromatogram Furantoin reference substance was taken and determined in the same way. Calculate the peak area according to the external standard method, and get ^[3] .

Furantoin Categories

Antibacterials.

Furantoin storage

Shaded and sealed.

Furantoin

Furantoin enteric-coated tablets

Furantoin laboratory analysis

Method name: Furantoin API-Determination of Furantoin-Spectrophotometry.

Scope of application: This method uses spectrophotometry to determine the content of furantoin in raw materials of furantoin.

This method is suitable for furantoin drug substance.

Principle of the method: The test sample was dissolved in dimethylformamide and diluted with water to prepare a test solution. The test solution was placed in an ultraviolet-visible spectrophotometer, and the absorbance was measured at a wavelength of 367 nm to calculate its content.

Reagent: dimethylformamide

Equipment: UV-visible spectrophotometer

Sample preparation: 1. Preparation of test solution

Precisely weigh about 40mg of the test product, put it into a 600mL beaker, add 10mL of dimethylformamide to dissolve, immediately add 400mL of water, stir well (if the precipitate is precipitated, slightly warm, the solution can still be clarified), move to a 500mL brown measuring flask Add a small amount of water to wash the beaker, wash the liquid into the measuring flask, dilute with water to the mark, shake well, accurately measure 10mL and place in a 100mL brown measuring bottle, dilute to the mark with water, and shake to obtain the test solution.

Note: "Precision weighing" means that the weighing weight should be accurate to one thousandth of the weighing weight. "Precision measurement" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in national standards.

Operation steps: Test the solution of the test product within 1 hour by UV spectrophotometry, measure the absorbance at a wavelength of 367nm, and calculate the absorption coefficient (E1% 1cm) of C8H6N4O5 as 766, that is, it is obtained.

Note: The spectrophotometric method should be based on the same batch of solvent prepared as the test product, using a 1cm quartz absorption cell. The wavelength with the highest absorbance is used as the measurement wavelength. Generally, the error of the absorbance reading of the test product is between 0.3 and 0.7. The slit band width of the instrument should be less than half the width of the absorption band of the test product, otherwise the measured absorbance is low. The selection of the slit width should be based on reducing the absorption of the test article when the slit width is reduced. Because the absorption cell and the solvent may have blank absorption, the blank reading should be subtracted after measuring the absorbance of the test product, and then the content is calculated ^[4] .

Furantoin Drug Description

Furantoin pharmacological effects

Pharmacodynamics

Central nervous system The mechanism of action of this product is not very clear, and may be related to interference with bacterial enzymes and bacterial metabolism disorders. Depending on the concentration, furantoin may have antibacterial or bactericidal effects.

Pharmacokinetics

The microcrystalline form of the product is quickly and completely absorbed in the small intestine, the absorption of the large crystalline form is slower, and the gastrointestinal irritation caused by the product is also stronger. Drug concentrations in serum are very low, high concentrations occur in the urine, and drug concentrations in the kidney may also be higher. The product can also enter the fetal circulation through the placenta. The protein binding rate is 60%, part of it is inactivated by various tissues (including liver), and T1 / 2 is 0.3 to 1 hour. Glomerular filtration is the main excretion pathway, and a small amount is secreted and reabsorbed from the renal tubules. 30 to 40% are excreted from the urine quickly in the original form, and the excretion of the large crystalline form is more severe ^[5] .

Furantoin indications

Urinary tract infections caused by sensitive E. coli, pneumococcus, aerobacterium, and proteus; prevention of urinary tract infections. The antibacterial activity of this product is not affected by pus and tissue decomposition products, and it has strong activity in acid urine ^[5] .

Furantoin dosage

Candida Adults take 50 to 100 mg every 6 hours, and preventive application is 50 to 100 mg per night.

Pediatric infants are disabled within one month; children over one month once every 6 hours, according to the weight of 1.25 ~ 1.75mg / kg; preventive application once every night before bedtime, according to the weight of 1 ~ 2mg / kg.

[Formulations and specifications] Furantoin tablets 50mg

Oral, 0.1g once, 3 to 4 times a day. Should not be used for more than two weeks.

[Preparation] Enteric-coated tablets; 0.05g each; 0.1g.

Furantoin is contraindicated

chlorpheniramine (1) Patients who are allergic to one furan drug may also have cross-allergies to other furans.

(2) Since furantoin can penetrate the placenta and the fetal enzyme system is not fully developed, it should not be taken by pregnant women in term to avoid the possibility of hemolytic anemia in the fetus.

(3) A small amount of furantoin can enter breast milk, and its advantages and disadvantages must be considered when applying to lactating women.

(4) The following conditions should be used with caution: glucose-6-phosphate dehydrogenase (G6PD) deficiency; peripheral neuropathy; lung disease; renal failure.

This drug should be contraindicated in newborns, because the enzyme system is not fully developed and there is a risk of hemolytic anemia ^[5] .

Furantoin precautions

stomach (1) Furantoin should be taken with food to reduce gastrointestinal irritation; although absorption is delayed, total absorption is increased (the peak concentration of large crystals can be increased), and the retention time of therapeutic concentration in urine is also See extension.

(2) The course of treatment should be at least 7 days, or continue to take the medicine for more than 3 days after the removal of urinary bacteria.

(3) The daily dose of those who use long-term suppression therapy should be reduced.

(4) This product is not effective for patients with creatinine clearance of 30ml / min. This product should not be used in patients with renal insufficiency (creatinine clearance <50ml / min), as its accumulation of metabolites can cause toxic reactions.

It can be absorbed quickly when fasting and has high curative effect. Application of enteric-coated tablets can reduce gastrointestinal reactions ^[5] .

Furantoin adverse reactions

(1) The more common ones are: chest pain, chills, cough, fever, and difficulty breathing (pneumonia).

(2) Less common: dizziness, drowsiness, headache (neurotoxicity), numbness of the face or mouth, tingling or burning, pale skin (hemolytic anemia), abnormal tiredness or weakness (neurotoxicity, polyneuropathy, hemolysis Anemia); yellow staining of the skin and sclera (hepatitis).

Leukopenia. Can cause gastrointestinal reactions: nausea, vomiting, loss of appetite, bloating, diarrhea. Taken after meals can reduce the response. Allergic rash, fever, chest tightness, asthma, and shock can also occur. Peripheral neuritis, hallucinations, etc. Individual cases can cause liver and kidney damage. Use with caution in patients with liver dysfunction. Can cause changes in hemogram and hemolytic anemia. Collection of medical education network

Cardiovascular System

Occasionally repolarization abnormalities appear on the ECG during drug fever or acute lung reactions.

Respiratory system

In Finland and Sweden, this reaction accounts for 40 to 85% of the total adverse reactions of furantoin. It is mainly found in women, especially those between 40 and 50 years old, and is rare in children. This response is independent of dose. Symptoms such as acute severe dyspnea, tachycardia, dry cough, high fever (often accompanied by chills), cyanosis, chest pain, occasional joint pain, Back pain or headache, vomiting, rash, collapse, and anaphylactic shock may occur. What is seen in the lungs is a rough twist sound at the base of the lungs or fine wet rales. Wheezing is rare. X-ray examination, in 80 to 90% of patients, common light or small nodular shadows at the bottom of the lung are common, dense dense shadows are rare. Occasionally there is fluid on both sides of the chest. White blood cell count is normal or neutral and lymphocytosis. Eosinophilia is common in the late stages. After discontinuation of the drug, fever and clinical symptoms often resolve rapidly within a few hours. Acute lung reactions are often accompanied by rashes, rare liver reactions with granulomatous hepatitis, and some only show elevated serum transaminase. Delayed acute lung response is often accompanied by liver response to chronic active hepatitis. These diseases are often accompanied by a broad-spectrum serum innate immune response (lupus-like syndrome).

The cause of acute lung reaction is undoubtedly the allergy mechanism, which may be type III of the Coombs and Gell classification. Skin tests are sometimes positive, but most are negative. Lymphocyte metastasis tests are often positive.

The chronic lung response is 10-20 times less than the acute response. In long-term medication, dyspnea worsens and often has a dry cough without fever or acute symptoms. Rales are often heard at the bottom of the lungs. Mild pulmonary insufficiency is common. X-ray showed interstitial infiltration of the middle lobe and basal base, occasionally fibrotic hyperplasia and alveolar exudation. The clinical symptoms recovered quickly after stopping the drug, but the X-ray recovery was slow, and almost half of the patients recovered incompletely. It is rare to fail due to significant fibrous hyperplasia. Individual cases have died of cardiopulmonary failure.

Bronchial asthma caused by this product has been reported in only a few cases. Patients with a history of asthma may be associated with bronchial asthma when an acute lung reaction occurs.

nervous system

Urinary system Since the 1960s, hundreds of cases of polyneuropathy have been reported. The mechanism is toxic and related to dose, tissue concentration and renal function. Long-term medication and the elderly can also occur. The earliest symptoms appear 3 days after administration (usually 9 to 45 days). Neuropathy mainly invades the limbs, starting from the apex, and most severely distal. It initially manifests as loss of sensation, often accompanied by severe muscle atrophy. It can be fully or partially recovered after discontinuation. But severe lesions are irreversible. Recovery from exercise loss is slower and less complete than felt. Some patients' symptoms occur after the end of a course of treatment, which is inconsistent with some reports suggesting that the symptoms no longer progress after discontinuation. Posterior optic neuritis can also occur. Irritability, euphoria, or even mental symptoms are present at the same time, but it is rare. Children can also develop multiple neuropathy. Nerve damage is degeneration of myelin sheath of nerves and nerve roots, and corresponding degeneration of anterior horn cells and muscle fibers. The etiology is unknown, it is considered that glutathione reductase is insufficiency. Even for healthy people, using this product every day for 2 weeks can cause a significant extension of motor nerve conduction time. If renal insufficiency is noted, and the product is used with caution, the risk of polyneuritis can be reduced. Early detection of paresthesia symptoms and timely withdrawal and treatment can basically prevent the occurrence of severe lesions.

Digestive system

Gastrointestinal symptoms are the most common adverse effects of this drug, but are usually not harmful and are dose-related. Of the 737 patients treated with this drug, 38 were nausea and loss of appetite, and 28 were vomiting. The patient's daily dosage was below 4 mg / kg, and the incidence of adverse reactions was 1.6%, such as 23.6% above 7 mg / kg. Recently reported 8917 patients with acute and 1555 chronic urinary tract infections, after treatment with this product, 3.8% of patients need to stop medication due to adverse gastrointestinal reactions. Abdominal pain and diarrhea are rare, and gastric bleeding is even more rare.

Hepatotoxicity caused by this product is rare. Jaundice often occurs in bile accumulating hepatitis. Few days before the onset of jaundice, fever and rash are often seen, and eosinophilia is increased. Some patients use this drug again Jaundice can recur. Clinical symptoms improved after discontinuation, while histological changes lasted longer. About 30 cases of chronic active hepatitis causing jaundice (or jaundice-free) have been reported, and their aminotransferases, lactate dehydrogenases, and clonal gamma globulin have increased.

Hematopoietic system

In some cases, even children, megaloblastic anemia can occur. This is due to the disorder of folate metabolism. Individual cases have hemoglobinemia, but no hemolytic anemia, one of which is a newborn. A case of severe hemorrhagic disease with a deficiency of coagulation factor and has been reported, which may be caused by liver damage caused by this drug. A few cases have proven to be allergic granulocytopenia.

Allergic reaction

lung Allergic skin reactions are less common, reported at about 1.9%, and often occur concurrently with other reactions such as drug fever, lung or liver reactions. They manifest as pruritus, pimples, maculopapular urticaria, or angioedema. Exudative polymorphic erythema or Lyell's syndrome is rare. A few cases have experienced transient hair loss.

Transient sperm cell reduction occurs in about one-third of male patients taking large doses because sperm maturity stops. Other scholars have found that the therapeutic amount of this drug can reduce the number of spermatozoa, sperm motility, and ejaculation ^[5] .

Furantoin Drug Interactions

(1) Drugs that can cause hemolysis are combined with furantoin, which tends to increase the hemolytic response.

(2) Both probenecid or benzofurone can inhibit the renal tubular secretion of furantoin, which leads to an increase in the plasma concentration and / or half-life of the latter, while a decrease in urine concentration and a decrease in efficacy. The probenecid dose should be adjusted.

This product is used in combination with antacids to reduce the absorption of this medicine. This product can reduce the antibacterial effect of nalidixic acid, so the two cannot be used together.

It should not be combined with nalidixic acid, because they have antagonistic effects.

Furantoin manufacturer

Beijing Shuanghe Pharmaceutical Co., Ltd., Shanghai Xinyi Pharmaceutical Co., Ltd., Dandong Medical Innovation Pharmaceutical Co., Ltd., East Pharmaceutical Group Corporation Shenyang Keda Co., Ltd., Qilianshan Pharmaceutical Factory in Gansu Province, Xinjiang Guanlin Pharmaceutical Co., Ltd., Xi'an Li Jun Pharmaceutical Co., Ltd., Wuhan Jiu'an Pharmaceutical Co., Ltd., Henan Plain Pharmaceutical Factory, Jiangxi Gannan Pharmaceutical Factory, Shandong Jintai Group Co., Ltd., Jinan Jinda Pharmaceutical Co., Ltd., Shandong Jintai Pharmaceutical Factory, Huainan Zhonglian Pharmaceutical Industry Co., Ltd., Jiangsu Sihuan Biological Co., Ltd., Zhenjiang Second Pharmaceutical Factory, Zhenjiang Pharmaceutical Co., Ltd., Jiangsu Jibel Pharmaceutical Co., Ltd., Ningbo Pharmaceutical Factory, Shanxi Linfen Biochemical Pharmaceutical Factory, Chifeng Weikang Biochemical Pharmaceutical Co., Ltd. , Chaoyang Pharmaceutical Factory, Linfen Jianmin Pharmaceutical Factory, Shanxi Fenhe Pharmaceutical Factory, Inner Mongolia Jilantai Salinization Group, Taiyuan Huawei Pharmaceutical Co., Ltd., Zhangjiakou Dongfeng Pharmaceutical Factory.

2 Can cause hemolytic anemia, jaundice and peripheral neuritis ^[5] .

Furantoin tablets

Pharmacological action

Kinetics This product is antibacterial. Escherichia coli is most sensitive to this product, and some strains of Enterobacteriaceae bacteria such as Enterobacter aerogenes, Enterobacter cloacae, Proteus, Klebsiella are sensitive to this product. Pseudomonas aeruginosa is usually Product resistance. This product has antibacterial effect on Gram-positive bacteria such as Enterococcus. The antibacterial activity of the product is not affected by pus and tissue decomposition products, and has strong activity in acid urine. The antibacterial action mechanism is to interfere with the oxidoreductase system in bacteria, thereby blocking its metabolic process. This product is an enteric sugar-coated tablet, which is yellow after removal of the coating.

The microcrystalline form of the product is quickly and completely absorbed in the small intestine, and the large crystalline form is absorbed more slowly. Taken with food can increase the bioavailability of two crystalline forms. Drug concentrations are very low in serum and higher in urine. The product can penetrate the placenta and blood-cerebrospinal fluid barrier. The serum protein binding rate was 60%. The blood elimination half-life (T1 / 2a) is 0.3 to 1 hour. Glomerular filtration is the main excretion pathway, and a small amount is secreted and reabsorbed from the renal tubules. 30% to 40% are rapidly excreted in the original form through the urine, and the large crystalline form is excreted more slowly. The product can also be excreted by bile and cleared by dialysis.

Indication

It is used for acute simple lower urinary tract infections caused by E. coli, Enterococcus, Staphylococcus, Klebsiella, Enterobacter and other bacteria, and can also be used for the prevention of urinary tract infections.

Dosage

Adults take 50 to 100 mg once orally, 3 to 4 times a day. Low dose for simple lower urinary tract infections; children over 1 month should be taken 4 times a day at a weight of 5 to 7 mg / kg. The course of treatment is at least 1 week, or at least 3 days after the urine culture turns negative. For the prevention of repeated episodes of urinary tract infection, the product is 50-100 mg daily for adults, 1 mg / kg daily for children.

Adverse reactions

1. Nausea, vomiting, anorexia, and diarrhea are common gastrointestinal reactions.

2. Allergic reactions such as rash, drug fever, granulocytopenia, and hepatitis can also occur. Hemolytic anemia can still occur in those with glucose-6-phosphate dehydrogenase deficiency.

3. Headache, dizziness, drowsiness, myalgia, nystagmus and other adverse reactions of the nervous system can occur occasionally, most of which are reversible. Peripheral neuritis can occur in severe cases, and patients with original renal dysfunction or long-term use of this product are prone to occur.

4. Furantoin can cause fever, cough, chest pain, pulmonary infiltration, and eosinophilia and other acute pneumonia manifestations. It can disappear quickly after stopping the treatment. The use of corticosteroids in severe patients may reduce symptoms; patients who have been taking it for more than 6 months, Occasionally can cause interstitial pneumonia or pulmonary fibrosis, should be stopped early and appropriate treatment measures should be taken.

Taboo

Newborns, term pregnant women, renal dysfunction, and patients with allergies to furans are contraindicated.

Precautions

1. Furantoin should be taken with food to reduce gastrointestinal irritation.

2. The course of treatment should be at least 7 days, or continue medication until the urine bacteria are cleared for more than 3 days.

3. Long-term application of the product for more than 6 months may cause diffuse interstitial pneumonia or pulmonary fibrosis. It should be closely observed, detected early, and discontinued in time. Therefore, those who use this product for long-term prevention need to weigh the advantages and disadvantages.

4. Use with caution in patients with glucose-6-phosphate dehydrogenase deficiency, peripheral neuropathy, and lung disease.

5. Interference with laboratory test indicators: This product can interfere with the determination of urine glucose, because its metabolites in the urine can cause false positive reactions to the copper sulfate reagent. Newborns within 1 month are disabled.

6. Furantoin can pass through the placental barrier and the fetal enzyme system is not fully developed. Therefore, it should not be used by pregnant women in late pregnancy. It is forbidden for term pregnant women to avoid the possibility of hemolytic anemia in the fetus.

7. A small amount of furantoin can enter the milk and induce hemolytic anemia in the infants, especially those who lack glucose-6-phosphate dehydrogenase, and should stop breastfeeding when taking this product. Elderly patients should be used with caution, and the dosage should be adjusted according to renal function.

Overdose

The main manifestation of this product is vomiting. This product has no specific antidote for overdose. It is necessary to further induce vomiting, and to give a lot of fluid to ensure that the drug is excreted with urine. The product can also be removed by dialysis.

interaction

1. When combined with furanotoin, drugs that can cause hemolysis may increase the hemolytic response.

2. Combination with hepatotoxic drugs may increase liver toxicity; combined with neurotoxic drugs may increase neurotoxicity.

3. Both probenecid and benzofurone can inhibit the renal tubular secretion of furantoin, leading to an increase in the plasma concentration of the latter and / or an increase in serum half-life, while a decrease in urine concentration and a decrease in the curative effect. The dose should be adjusted ^[5] .

Furantoin clinical application

Nephritis treatment

In a random survey, researchers used radioisotope-labeled dimercaptobutanediol (DMSA) scintigraphy to track intravenously administered cefatriaxone for children with pyelonephritis for 3 and 10 days and found long-term results. Medication does not have an advantage over short course medication in reducing renal scarring.

The study was led by Dr. Benador and was carried out by a research team at Cantonal University Hospital in Geneva, Switzerland and the Children's Hospital at the University of Zurich in Switzerland. The results were published in the March issue of the Journal of Children's Diseases.

At present, the best treatment for pediatric pyelonephritis is still controversial. The purpose is to study whether prolonged dosing time can prove to reduce the occurrence of kidney scars.

A total of 220 children, ranging in age from three months to 16 years, were randomly divided into two groups of 110 patients. Urinary cultures were positive in all children, and DMSA scans after 3 to 4 days confirmed acute kidney inflammation. One group was given furantoin 50 mg / kg for 3 days, intravenously once a day; the other group was given the same dose for 10 days. In both groups, cefixime was administered orally until the 15th day after the intravenous medication was stopped. A follow-up DMSA scan was performed in the third month after hospitalization.

Dr. Benador's team found that the incidence of kidney scars was similar in the two groups, with 36% in the 3-day group and 33% in the 10-day group, with no significant difference. The incidence of scarring in older children over 1 year is 42%, compared with 24% in infants. After weighting the age difference, gender, pre-treatment fever period, inflammatory intensity found during the scan, and ureteral reflux, there was no significant difference in the incidence of scars between the two groups.

The research team did find that the size of the inflammatory damage determines the possibility of scarring-9% of small lesions and 46% of large lesions can cause scarring, but at any level of inflammation, the formation of scars is independent of treatment. In addition, the recurrence of urinary tract inflammation in the children was also monitored. Relapses occurred in 15 children, and there was no difference between the two groups.

Mentioning an earlier study using DMSA scans, Benador et al. Pointed out that the incidence of scarring was lower (9.6%) in children in this study after receiving oral or intravenous injections with oral antibiotics for 14 days. Because the study object is only 1 to 24 months old children, and the disease is not serious.

It is pointed out that although the experimental study found that the damage of kidney tissue depends on the inflammatory response, and the duration of the inflammatory response determines the degree of scar formation, the study did not find a relationship between the duration of fever before treatment and scar formation.

Although oral medications can reduce the cost of treating pyelonephritis, the use of oral therapies in young children is still discouraged because vomiting can cause inadequate administration and oral medications have a poor effect on bacteremia. Benador et al. Believe that since the duration of intravenous antibiotics does not affect the formation of scars, research should focus on the use of anti-inflammatory drugs other than antibiotics in order to slow the acute inflammation and the scar formation caused by it.

1 case of allergies

Suffering from a female, 62 years old. The patient self-administered enteric-coated furantoin 0.1 g, tid due to frequent urination and dysuria before 40 days. She developed asthma 4 weeks after taking it, and continued to take medicine without further treatment. Her condition became progressively worse. Admission examination: T37.0 , R20 times / min, P80 times / min, BP18.0 / 12.0kPa. The breath sounds of both lungs were clear, and no dry or wet rales were heard. The heart rate was 80 beats / min, the law was uniform, the liver and spleen were not enlarged, and the urine test was normal. There was no abnormal change on chest X-ray. Diagnosis: Furantoin-induced allergic reactions. He was given B vitamins and neurotrophic agents and healed after 2 weeks.

The usual dosage of furantoin is 0.1g, qid, and continuous taking of the drug should generally not exceed 2 weeks. If used in large amounts or for a long time, peripheral neuritis may occur and occasional allergic reactions such as asthma. The patient had not been consulted before taking the drug and was taken for 4 weeks, resulting in asthma.

Have lung toxicity

According to the Australian Bulletin of Adverse Drug Reactions Issue 4 this year, the Australian Council of Adverse Drug Reactions (ADRAC) has so far received 576 reports of suspicious pulmonary adverse reactions with furanotoin, including 46 cases since 1995. Of these, 40 were related to long-term use of furantoin. The most common symptoms were dyspnea or coughing, but some people had allergic reactions, such as fever, itching, rash, or eosinophilia; patients had chest X-rays, CT scans, and biopsies. Or autopsy confirmed pulmonary fibrosis or interstitial pneumonia.

Most of the reports are elderly women, with a female to male ratio of 7.1, and a median age of 70 years (47 to 90 years). The dose of furantoin is 50 to 300 mg / d (the recommended daily preventive dose is 50 to 100 mg). In some patients, severe lung reactions occurred with low-dose furantoin (50 mg / d) for 8 months, and the longest onset time was 16 years. By the time of the report, 12 patients had recovered, but some patients had sustained lung injury, and 2 patients died of pulmonary toxicity.

ADRAC cautions that when using furantoin for treatment of 6 months, attention should be paid to its lung toxicity, especially in the elderly. Patients should also be aware of the potential for lung toxicity, and should seek medical attention promptly if adverse pulmonary reactions (such as dyspnea or persistent cough) occur, and immediately stop using furatoin.

Helicobacter pylori experiment

Experimental background

Antibiotic resistance is increasingly recognized as the main cause of ineffective treatment for H. pylori infection. New treatments for metronidazole or erythromycin-clarithromycin-resistant Helicobacter infections are currently clinically needed.

Purpose

Investigate the efficacy of furantoin quadruple therapy for Helicobacter pylori infection.

experimental method

Patients diagnosed with Helicobacter pylori infection receive furantoin (100 mg three times daily), omeprazole (20 mg twice daily), Pepto-Bismol (2 tablets three times daily), tetracycline (500 mg three times daily) Four-drug combination treatment for 14 days. Four or more weeks after the end of treatment, patients were reviewed for endoscopic histological examination and tissue culture, or urea breath test.

Experimental results

Thirty patients were selected for the experiment, including 25 males and 5 females, with an average age of 54.9 years. The most common diagnoses are duodenal ulcers (23%) and gastroesophageal reflux disease (18%). The target cure rate was 70% (95% CI: 50.6-85%). The effect of tetrafuranotocin on metronidazole-sensitive strains (88%; 15/17) was higher than that of metronidazole-resistant strains (33%; 3/9; P = 0.008). Two of the patients who failed treatment were sensitive to metronidazole before treatment and became resistant to the drug after treatment.