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erythromycin

[hóng méi sù]

drugs

Erythromycin is an organic compound with chemical formula C thirty-seven H sixty-seven NO thirteen , a macrolide antibiotic, is mainly used in tonsillitis caused by streptococcus Scarlatina Diphtheria and carrier, gonorrhea, listeriosis, lower respiratory tract infection of Streptococcus pneumoniae (the above applies to penicillin resistant patients. For Legionella pneumonia and Mycoplasma pneumonia, this product can be used as the first choice.) It can also be used for upper respiratory tract infection caused by influenza bacilli, Staphylococcus aureus skin and soft tissue infection, syphilis, intestinal amebiasis, etc.

Drug name: erythromycin
Foreign name: Erythromycin^[2]^[5]
Prescription medicine or not: yes
Main indications: Streptococcus induced tonsillitis Scarlatina Diphtheria and carrier, gonorrhea, listeriosis, lower respiratory tract infection caused by Streptococcus pneumoniae
Main drug contraindications: Erythromycin can penetrate the placental barrier and enter breast milk. Pregnant women and lactating women should use it with caution. Allergies to macrolides
Dosage form: Ointment, oral constant release dosage form, injection (sterile powder for injection), eye ointment, intestinal solvent (tablet, capsule)^[3-6]
Whether included in medical insurance: yes

Drug type: Antiinfectives^[3-4]
chemical formula: C thirty-seven H sixty-seven NO thirteen
molecular weight: seven hundred and thirty-three point nine four
CAS login number: 114-07-8
Melting point: 138 to 140 ℃
Boiling point: 818.4 ℃
Density: 1.2 g/cm ³
Appearance: White or milky white crystalline powder
Flash point: 448.8 ℃
Security description: S24； S37； S45
Hazard symbol: Xn
Hazard description: R42/43

catalog

fifteen Assay
sixteen Storage
seventeen Safety terminology
eighteen Risk terminology

Action category

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Macrolide antibiotics.

indication

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1. Acute tonsillitis, acute pharyngitis and sinusitis caused by hemolytic streptococcus and pneumonia streptococcus.

2. Scarlet fever and cellulitis caused by hemolytic streptococcus.

3. Mycoplasma pneumoniae pneumonia, chlamydia pneumoniae pneumonia.

4. Gas gangrene, anthrax, tetanus.

5. Diphtheria (adjuvant treatment) and diphtheria carrier.

6. Chlamydia trachomatis conjunctivitis.

7. Urogenital infection caused by Chlamydia and Mycoplasma.

8. Listeria disease.

9. Legionella pneumonia (Legionellosis).

10. Gonococcal infection.

11. Campylobacter jejuni enteritis.

12. Oral infection caused by anaerobic bacteria.

13. Whooping cough.

14. Actinomycosis.

15. Dermatology is mainly used for non gonococcal urethritis (cervicitis), gonorrhea, syphilis, chancroid, chlamydial lymphogranuloma (venereal lymphogranuloma), acne, staphylococcal skin infection, scarlatina, etc.

taboo

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Erythromycin can penetrate the placental barrier and enter breast milk. Pregnant women and lactating women should use it with caution. Allergies to macrolides.

character

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This product is white or almost white crystal or powder, odorless, slightly hygroscopic.

This product is easily soluble in methanol, ethanol or acetone, and very slightly soluble in water.

Specific curl

Take this product, weigh it precisely, add absolute ethanol to dissolve it and dilute it quantitatively to make a solution containing about 20mg per 1mL, place it for 30 minutes, and then measure it according to the law (general rule 0621), with the specific rotation of - 71 ° to - 78 °.

Specifications

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Enteric coated (tablet, capsule), (ethyl succinate);

Tablets and capsules: 0.125g (125000 units), 0.25g (250000 units);

Sterile powder for injection: 0.25g (250000 units), 0.3g (300000 units);

Ointment: 1%;

Eye ointment: 0.5%^[5-6]

Usage and dosage

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1. (1) ① Common oral dose: 1~2g per day, divided into 3~4 times. ② Legionellosis: The daily dose can be increased to 2-4g, which can be taken four times. (2) Local administration: treat trachoma, conjunctivitis and keratitis, and apply proper amount of eye ointment to the eyelid several times a day. (3) Dose for renal insufficiency: generally, patients with renal insufficiency do not need to reduce the dosage.

2. Children: (1) Oral administration: 30~50mg/kg per day, divided into 3~4 times. (2) Local administration: trachoma, conjunctivitis, keratitis, apply proper amount of eye ointment to the eyelid several times a day.

3. Intravenous drip: (1) Adult: ① General dosage: 1-2 g per day, divided into 2-4 times. ② Legionnaires' disease: 3~4g per day, four times. The high dose shall not exceed 4g. (2) Children: 20~40mg/kg, 2~4 times a day.

Adverse reactions

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1. Gastrointestinal symptoms such as diarrhea, nausea, vomiting, middle and upper abdominal pain, anorexia and so on may occur after medication, and the incidence is related to the dosage.

2. Some hepatotoxicity, such as fatigue, jaundice and abnormal liver function, may occur occasionally after treatment.

3. Ototoxicity may be caused by high-dose (≥ 4g per day) administration or by patients with liver and kidney diseases or elderly patients. The main manifestation is hearing loss. It may be related to the high blood concentration (>12mg/L), and most of them can return to normal after drug withdrawal.

4. Drug fever, rash, eosinophilia and other allergic reactions may occasionally occur after medication, with an incidence of 0.5%~1%.

5. A few patients occasionally have arrhythmia, oral or vaginal candidiasis, etc.

6. Venous irritation or phlebitis may occasionally occur in some patients after intravenous administration.

Drug interaction

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1. Erythromycin and carbamazepine 、 Valproic acid When used together with other antiepileptic drugs, the metabolism of carbamazepine and valproic acid can be inhibited, leading to the increase of the blood concentration of the latter and toxic reaction. Moreover, carbamazepine can reduce erythromycin efficacy through liver microsomal oxidase.

2. Erythromycin and Cyclosporine Combined use can promote the absorption of cyclosporine and interfere with its metabolism. Its clinical manifestations are abdominal pain, hypertension and liver dysfunction.

3. Erythromycin and Xanthines（ Dihydroxypropyltheophylline Except) the same use can reduce the liver clearance of aminophylline, and lead to the increase of serum aminophylline concentration and (or) the increase of toxic reaction. This phenomenon is more likely to occur after 6 days of the same use, and the reduction of aminophylline clearance is proportional to the peak value of erythromycin serum.

4. Erythromycin and digoxin When used together, it can clear the bacteria in the intestinal tract that can inactivate digoxin, thus leading to the intestinal liver circulation of digoxin, raising the blood concentration of digoxin and causing toxic reactions.

5. Erythromycin and Lovastatin When combined, it can inhibit the metabolism of lovastatin and increase its blood concentration, which may cause rhabdomyolysis.

6. Erythromycin and Midazolam When combined with triazolam, midazolam and triazolam can reduce the clearance rate of midazolam and triazolam and enhance their effect.

7. Erythromycin and Alfentanil Combined use can inhibit the metabolism of alfentanil and prolong its action time.

8. Erythromycin combined with other hepatotoxic drugs may enhance hepatotoxicity.

9. High dose erythromycin and Ototoxic drugs Combined use may increase ototoxicity; The patients with renal dysfunction are particularly prone to occur.

10. Erythromycin and Astemizole 、 Terfenadine Combined use of antihistamines can increase cardiac toxicity and cause arrhythmia.

11. Erythromycin and Ergotamine tartrate Combined use can cause acute ergot poisoning (such as peripheral vasospasm).

12. Long term use warfarin The use of erythromycin can lead to prolonged prothrombin time in 30% of patients, thus increasing the risk of bleeding.

13. Erythromycin and chloramphenicol It has antagonistic effect when used in combination with lincomycin.

14. Erythromycin and β- Lactam Antibacterial activity of the two drugs could be reduced by combined use.

15. Erythromycin and acyeterion When taken together, it can block the intestinal and hepatic circulation of sex hormones and reduce the efficacy of the contraceptive pill.

Pharmacology and toxicology

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pharmacology

Erythromycin is an alkaline antibiotic produced by Streptomyces erythrius, which belongs to macrolides. Erythromycin is an antibacterial agent, but it also has bactericidal effect on highly sensitive bacteria at high concentrations. Its mechanism of action is that it can bind reversibly to the 50S subunit of the bacterial ribosome near the donor ("P" position) through the bacterial cell membrane, block the binding of transfer ribonucleic acid (tRNA) to the "P" position, and also block the migration of polypeptide chain from the receptor ("A" position) to the "P" position, so that the bacterial protein synthesis is inhibited, thus playing an antibacterial role. Erythromycin is only effective against actively dividing bacteria. Erythromycin has a wide antibacterial spectrum and is effective against most gram-positive bacteria, some gram-negative bacteria and some atypical pathogens. Erythromycin has strong antibacterial activity against Staphylococcus (including enzyme producing strains), streptococcus, pneumococcus, anthrax, clostridium tetanus, diphtheria, gonococcus, meningococcus, influenza bacillus, pertussis bacillus, campylobacter jejuni, legionella, listeria, and Israel actinomycetes; For Treponema pallidum, Mycoplasma pneumoniae, Leptospira, Rickettsia; Chlamydia also has a good inhibitory effect. Erythromycin lactate is the lactouronate of erythromycin. Erythromycin lactate is absorbed and hydrolyzed to release the active ingredient erythromycin. Erythromycin can bind reversibly to the bacterial ribosome near the donor site ("P" position) through the bacterial cell membrane, block the binding of transfer ribonucleic acid (tRNA) to the "P" position, and also block the displacement of polypeptide chain from the receptor site ("A" position) to the "P" position, so that the bacterial cell protein synthesis is inhibited, thus playing an antibacterial role. Erythromycin Lactate is effective against most gram-positive bacteria, some gram-negative bacteria and some atypical pathogens.

Toxicology

The antibacterial spectrum of erythromycin is similar to that of penicillin. It has a strong inhibitory effect on gram-positive bacteria, and also has a considerable inhibitory effect on gram-negative bacteria. It is used to inhibit mycoplasma, actinomycetes, spirochetes, rickettsia, chlamydia, nocardia, a few mycobacteria and amoeba protozoa. It is often a substitute for patients with penicillin allergy. The oral absorption is poor, 18%~45%; the plasma protein binding rate is 73%; the half-life is 1.5h; it can be extended to 6h without urine; the volume distribution is 0.72L/kg. The normal dosage for adults is 1~2g/d, divided into 3~4 times. It can also be made into eye ointment to treat trachoma, conjunctivitis and keratitis, and applied to the eyelid.

clinical manifestation

1. The common adverse reactions were gastrointestinal reactions, nausea, vomiting, stomachache, diarrhea, tongue pain, anorexia, etc. The incidence is related to the dose. It can induce pseudomembranous enteritis.

2. Allergic reaction: various rashes, drug fever, eosinophilia, etc. One case of anaphylactoid purpura and renal failure was reported. Esterified erythromycin can cause cholestatic liver damage.

3. Large dose of erythromycin may occasionally cause tinnitus and temporary hearing impairment.

4. Intravenous drip is easy to cause phlebitis.

5. It was reported that one case of myasthenia gravis occurred after 1.5g of this drug, and disappeared after stopping the drug.

treatment

1. In case of toxic reaction, the drug shall be stopped, and intravenous infusion shall be used to promote excretion.

2. When severe jaundice occurs, glucocorticoid treatment is given.

3. In case of allergic reaction, anti allergic treatment shall be given.

Pharmacokinetics

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Erythromycin 200 ～ 250mg orally, and the blood concentration reaches the peak value after 2 ～ 3h, generally lower than 1 μ g/mL。 After drug absorption, it is widely distributed in all tissues and body fluids except cerebrospinal fluid and brain tissue, especially in liver, bile and spleen (the concentration in bile can reach 10~40 times of the concentration in blood). The concentration of the drug in kidney, lung and other tissues can be several times higher than that of the bleeding drug; It also has high concentration in subcutaneous tissue, sputum and bronchial secretions (the concentration in sputum is close to that in blood); The concentration in pleural and peritoneal effusion and pus can reach the effective bacteriostatic concentration. Erythromycin can enter the prostate and seminal vesicles in a certain amount (about 33% of the blood concentration), but it is not easy to penetrate the blood cerebrospinal fluid barrier. When the meninges are inflamed, the concentration in the cerebrospinal fluid is only about 10% of the blood concentration. Erythromycin can enter the fetal blood circulation and breast milk. The fetal blood concentration is 5%~20% of the maternal blood concentration, and the breast milk concentration can reach more than 50% of the blood concentration. After oral administration of erythromycin with different salts, the bioavailability is about 30%~65%. The apparent distribution volume is 0.9L/kg. The protein binding rate was 70%~90%. The half-life is about 1.4~2.0h, and the half-life of anuria patients can be extended to 4.8~6.0h. Free erythromycin is metabolized in the liver, mainly concentrated in the liver and discharged from bile. About 2%~5% of the oral dosage and 10%~15% of the injected dosage are discharged from the glomerular filtration with urine in the original form. The concentration in urine can reach 10~100 μ g/mL。 In addition, there is a certain amount of medicine in the feces. Peritoneal dialysis and hemodialysis can not effectively remove erythromycin. Erythromycin lactate is a water-soluble erythromycin lactouronate, which reaches the peak of blood concentration after intravenous drip. Intravenous infusion of 2g within 24h, the average blood concentration was 2.3 ～ 6.8mg/L. After absorption, the drug is widely distributed in all tissues and body fluids except cerebrospinal fluid and brain tissue, especially in liver, bile and spleen. The concentration of the drug in kidney, lung and other tissues can be several times higher than that of the bleeding drug; It also has high concentration in subcutaneous tissue, sputum and bronchial secretions (the concentration in sputum is close to that in blood); The concentration in pleural and peritoneal effusion and pus can reach the effective bacteriostatic concentration. Erythromycin can enter the fetal blood circulation and breast milk, but it is not easy to penetrate the blood cerebrospinal fluid barrier. Free erythromycin is mainly metabolized in the liver, concentrated in the liver, excreted with bile, and carries out enterohepatic circulation. About 10%~15% of the injected volume is filtered from the glomerulus in the original form and discharged with urine. The concentration in urine can reach 10~100mg/L. In addition, there is a certain amount of medicine in the feces. Peritoneal dialysis and hemodialysis can not effectively remove erythromycin.

matters needing attention

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1. Erythromycin is an antibacterial drug, which should be administered at certain intervals to maintain the drug concentration in the body and facilitate the function.

2. Erythromycin tablets should be swallowed as a whole. If the powder is taken, it will be damaged by stomach acid and have a negative effect. Young children can take erythromycin esterified, which is acid stable.

3. Intravenous infusion is easy to cause phlebitis, and the infusion speed should be slow.

4. Erythromycin can destroy and reduce the effect in acid infusion. Generally, it should not be compatible with low pH glucose infusion. In 500 mL of 5%~10% glucose infusion, add vitamin C injection (1 g of sodium ascorbate) or 0.5 mL of 5% sodium bicarbonate injection to raise the pH above 5, and add erythromycin lactose to help stabilize.

Compound Introduction

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essential information

Chemical formula: C thirty-seven H sixty-seven NO thirteen

Molecular weight: 733.927

CAS No.: 114-07-8

EINECS No. 204-040-1

Physical and chemical properties

Density: 1.2g/cm three

Melting point: 138-140 º C

Boiling point: 818.4 º C

Flash point: 448.8 º C

Appearance: white or milky white crystalline powder

Storage condition: 0-6 º C

Solubility: soluble in ethanol, methanol, chloroform, insoluble in water^[1]

Molecular structure data

Molar refractive index: 198.16

Molar volume (cm three /mol）：607.1

Isotonic specific volume (90.2K): 1625.9

Surface tension (dyne/cm): 51.4

Polarization (10 -24 cm three ）：74.99^[1]

Calculate chemical data

Reference value for drainage parameter calculation (XlogP): 2.7

Number of hydrogen bond donors: 5

Number of hydrogen bond receptors: 14

Number of rotatable chemical bonds: 7

Number of tautomers: 3

Topological molecule polar surface area (TPSA): 194

Number of heavy atoms: 51

Surface charge: 0

Complexity: 1180

Number of isotope atoms: 0

Determine the number of atomic structure centers: 18

Number of uncertain atomic structure centers: 0

Determine the number of chemical bond structure centers: 0

Number of uncertain chemical bond structure centers: 0

Number of covalent bond units: 1^[1]

purpose

The product is a macrolide antibiotic with an antibacterial spectrum similar to that of penicillin. It has a strong inhibitory effect on gram-positive bacteria, such as staphylococcus, streptococcus pyogenes, green streptococcus, streptococcus pneumoniae, fecal streptococcus, hemolytic streptococcus, clostridium, diphtheria, and anthrax. It also has a certain inhibitory effect on gram-negative bacteria, such as gonococcus, helicobacter, pertussis bacillus, brucella, legionella, meningococcus, Haemophilus influenzae, Bacteroides, some dysentery bacilli and Escherichia coli. In addition, it can inhibit mycoplasma, actinomycetes, spirochetes, rickettsia, chlamydia, nocardia, a few mycobacteria and amoeba protozoa. Staphylococcus aureus and other staphylococcus and streptococcus bacteria are easily resistant to the product. It is characterized by the strain that is resistant to penicillin and is sensitive to the product. The mechanism of action is mainly to combine with the 50S subunit of ribonucleosomes, inhibit peptide acyltransferase, affect the migration process of ribonucleosomes, hinder the growth of peptide chains, inhibit the synthesis of bacterial proteins, and act as an bacteriostatic agent.

identify

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1. In the chromatogram recorded under the erythromycin group, the retention time of the main peak of the test solution should be consistent with that of the standard solution.

2. The infrared absorption spectrum of this product should be consistent with the control spectrum (spectrum set 167 figure). In case of any discrepancy, take an appropriate amount of this product and the standard product, add a small amount of chloroform to dissolve them, evaporate them in a water bath, dry them in a phosphorus pentoxide dryer under reduced pressure, and then measure them, except for 1980cm -1 To 2050 cm -1 Outside the wavelength range, it should be consistent with the chromatogram of the reference substance.

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alkalinity

Take 0.1g of this product, add 150mL of water, shake, and measure according to the law (general rule 0631). The pH value should be 8.0~10.5.

Related substances

Determine according to the method of high performance liquid chromatography (general rule 0512).

PH8.0 phosphate solution: take 11.5g of dipotassium hydrogen phosphate, add 900mL of water to dissolve it, adjust the pH value to 8.0 with 10% phosphoric acid solution, and dilute it with water to 1000mL.

Test solution: Take about 40mg of this product, place it in a 10mL measuring flask, add 4mL of methanol to dissolve it, dilute it with pH8.0 phosphate solution to the scale, and shake it up.

Control solution: precisely measure 1mL of the test solution, place it in a 100mL measuring flask, dilute it to the scale with pH8.0 phosphate solution methanol (3:2), and shake it well.

System suitability solution (1): Take about 40mg of erythromycin standard, place it in a 10mL measuring flask, add 4mL of methanol to dissolve it, dilute it to the scale with pH8.0 phosphate solution, and shake it well.

System suitability solution (2): Take 40mg of erythromycin system suitability reference substance, place it in a 10mL measuring flask, add 4mL of methanol to dissolve it, dilute it to the scale with pH8.0 phosphate solution, and shake it well.

Sensitivity solution: precisely measure an appropriate amount of the control solution, and dilute it quantitatively with pH8.0 phosphate solution methanol (3:2) to prepare a solution containing about 4 µ g per 1mL.

Chromatographic conditions: octadecyl silane bonded silica gel is used as filler (XTerraRP C18 column, 4.6mm × 250mm, 3.5 µ m or equivalent chromatographic column), acetonitrile - 0.2mol/L dipotassium hydrogen phosphate solution (adjust pH to 7.0 with phosphoric acid) - water (35:5:60) is used as mobile phase A, acetonitrile - 0.2mol/L dipotassium hydrogen phosphate solution (adjust pH to 7.0 with phosphoric acid) - water (50:5:45) is used as mobile phase B, First, use mobile phase A to elute equivalently. After the elution of erythromycin B is completed, perform linear gradient elution as per the following table. The flow rate is 1.0mL per minute, the column temperature is 65 ℃, the detection wavelength is 210nm, and the injection volume is 100 µ L.

Time (minutes)	Mobile phase A (%)	Mobile phase B (%)
zero	one hundred	zero
t g	one hundred	zero
t g +2	zero	one hundred
t g +9	zero	one hundred
t g +10	one hundred	zero
t g +20	one hundred	zero

Note: t g Is the retention time of erythromycin B

System suitability requirements: In the chromatogram of system suitability solution (1), the tailing factor of erythromycin A peak should not be greater than 2.0. The chromatogram of system suitability solution (2) should be consistent with the standard chromatogram of erythromycin system suitability reference substance. The retention time of erythromycin A peak is about 23 minutes, the relative retention times of impurity A, impurity B, impurity C, impurity D, impurity E and impurity F are about 0.4, 0.5, 0.9, 1.6, 2.3 and 1.8 respectively, and the relative retention times of erythromycin B and erythromycin C are about 1.7 and 0.55 respectively, The resolution between impurity B peak and erythromycin C peak, erythromycin B peak and impurity F peak should not be less than 1.2, and the resolution between impurity C peak and erythromycin A peak should meet the requirements. In the sensitivity solution chromatogram, the signal to noise ratio of the peak height of the main component should be greater than 10.

Determination method: Precisely measure the test solution and the reference solution, respectively inject them into the liquid chromatograph, and record the chromatogram.

Limit: if there is an impurity peak in the chromatogram of the test solution, the peak area of impurity C shall not be more than 3 times (3.0%) of the main peak area of the reference solution, the corrected peak areas of impurity E and impurity F (multiplied by the correction factor 0.08) shall not be more than 2 times (2.0%) of the main peak area of the reference solution, and the corrected peak area of impurity D (multiplied by the correction factor 2) The peak area of Impurity A, Impurity B and other single impurities shall not be greater than 2 times (2.0%) of the main peak area of the reference solution. The sum of the corrected peak areas of all impurities shall not be greater than 7 times (7.0%) of the main peak area of the reference solution. The peaks smaller than the main peak area of the sensitivity solution shall be ignored.

Thiocyanate

It is determined by ultraviolet visible spectrophotometry (general rule 0401).

Test solution: take about 0.1g of this product, weigh it accurately, put it into a 50mL brown bottle, add 20mL of methanol to dissolve it, add 1mL of ferric chloride test solution, dilute it with methanol to the scale, and shake it up.

Reference solution: take two portions of potassium thiocyanate dried at 105 ° C for one hour, each about 0.1g, weigh accurately, put them into two 50mL measuring flasks, add 20mL methanol to dissolve and dilute to the scale, shake up, precisely measure 5mL, put them into a 50mL measuring flask, dilute to the scale with methanol, shake up, precisely measure 5mL, put them into a 50mL brown bottle, add 1mL ferric chloride test solution, dilute to the scale with methanol, shake up.

Blank solution: measure 1mL of ferric chloride test solution, place it in a 50mL brown bottle, and dilute it to the scale with methanol.

Determination method: Take the test solution, the reference solution and the blank solution, and measure the absorbance respectively at the wavelength of 492nm (all should be measured within 30 minutes). The ratio of absorbance per unit weight of the two reference solutions should be 0.985~1.015.

Limit: The content of thiocyanate shall not exceed 0.3%, and the molecular weights of thiocyanate and potassium thiocyanate are 58.08 and 97.18 respectively.

water content

Take about 0.2g of this product, add 10% imidazole anhydrous methanol solution to dissolve it, and determine it according to the moisture determination method (General Rule 0832, Method 1). The moisture content should not exceed 6.0%.

Ignition residue

It shall not exceed 0.2% (general rule 0841).

Erythromycin component

Determine according to the method of high performance liquid chromatography (general rule 0512).

Test solution: Take about 40mg of this product, weigh it accurately, put it into a 10mL measuring bottle, add 4mL of methanol to dissolve it, dilute it with pH8.0 phosphate solution to the scale, and shake it well.

Standard solution (1): Take about 40mg of erythromycin standard, weigh it precisely, put it into a 10mL measuring bottle, add 4mL methanol to dissolve it, dilute it with pH8.0 phosphate solution to the scale, and shake it well.

Standard solution (2): precisely measure 1mL of standard solution (1), place it in a 100mL measuring flask, dilute it to the scale with pH8.0 phosphate solution methanol (3:2), and shake it well.

PH8.0 phosphate solution, system suitability solution (1), system suitability solution (2), chromatographic conditions: see related substances.

System suitability requirements: in addition to the sensitivity requirements, see related substances.

Determination method: Precisely measure the test solution, standard solution (1) and standard solution (2), inject them into the liquid chromatograph, and record the chromatogram.

Limit: calculate the content of erythromycin A in the test sample according to the peak area of erythromycin A in the standard solution (1) by the external standard method, which shall not be less than 93.0% if it is anhydrous; calculate the content of erythromycin B and erythromycin C in the test sample according to the peak area of erythromycin A in the standard solution (2) by the external standard method, which shall not exceed 3.0% if it is anhydrous.

Assay

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Accurately weigh an appropriate amount of this product, add ethanol (10mg plus 1mL of ethanol) to dissolve it, dilute it quantitatively with sterile water to make a solution containing about 1000 units per 1mL. According to the method of microbial assay of antibiotics (general rule 1201), the confidence limit rate should not be more than 7%, and 1000 erythromycin units are equivalent to 1mg of C thirty-seven H sixty-seven NO thirteen 。