Azithromycin (CAS No.: 83905-01-5) - Broad-Spectrum Macrolide Antibacterial for Respiratory, Skin & STI Infections
As a professional supplier of pharmaceutical-grade and veterinary-grade antibacterial active ingredients, we provide high-purity Azithromycin that strictly complies with global pharmacopoeia standards (USP, EP, BP, CP). A second-generation semi-synthetic macrolide antibiotic derived from erythromycin, it offers enhanced potency, a broader spectrum, and a unique once-daily, short-course dosing regimen. It is widely used in human medicine for treating respiratory, skin, and sexually transmitted infections (STIs)-especially in patients with poor adherence to long-term therapy-and in veterinary practice for livestock and companion animals, serving as a critical agent against drug-resistant Gram-positive and atypical pathogens.
Product Basic Information
| Item | Details |
|---|---|
| Product Name | Azithromycin |
| CAS No. | 83905-01-5 |
| Synonyms | (2R,3S,4R,5R,8R,10R,11R,12S,13S,14R)-13-[(2,6-Dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-2-ethyl-3,4,10-trihydroxy-3,5,6,8,10,12,14-heptamethyl-11-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-1-oxa-6-azacyclopentadecan-15-one |
| Molecular Formula | C₃₈H₇₂N₂O₁₂ |
| Molecular Weight | 748.98 |
| Appearance | White to off-white crystalline powder; Odorless or with a slight characteristic odor |
| Specification | - Pharmaceutical Grade: Purity ≥98.0% (HPLC); Assay 950–1050 μg/mg (anhydrous basis); Loss on drying ≤2.0%; Heavy metals (Pb≤5ppm, Hg≤1ppm, Cd≤1ppm); Residual solvents (methanol ≤300ppm, acetone ≤500ppm)- Veterinary Grade: Purity ≥95.0% (HPLC); Assay 900–1100 μg/mg; Heavy metals ≤10ppm |
| Melting Point | 113–115°C (with slight decomposition) |
| Solubility | Practically insoluble in water (≈0.25 g/L at 25°C); Soluble in methanol (≈100 g/L), ethanol (≈50 g/L), chloroform (≈200 g/L); Slightly soluble in acetone |
| Storage Conditions | Store in a cool (15–25°C), dry, light-protected container; Sealed to prevent moisture absorption and degradation (stable under neutral pH, sensitive to strong acid/alkali); Avoid contact with oxidizing agents; Shelf life: 36 months for pharmaceutical grade, 24 months for veterinary grade |
Core Functions & Mechanism of Action
Azithromycin exerts a bacteriostatic effect (bactericidal at high doses against susceptible strains) by targeting the bacterial ribosome, disrupting protein synthesis-with key advantages over first-generation macrolides (e.g., erythromycin):
Ribosome Binding: Azithromycin binds reversibly to the 50S subunit of the bacterial ribosome (specifically the 23S rRNA), with 10–100 times higher affinity than erythromycin. This binding blocks the translocation step of protein synthesis, halting peptide chain elongation.
Unique Pharmacokinetics: It exhibits concentration-dependent activity and a long half-life (~68 hours), allowing for once-daily dosing and short courses (3–5 days). It also accumulates in leukocytes and tissues (e.g., lung, skin, genital tract) at concentrations 10–100 times higher than in plasma-critical for treating intracellular pathogens.
Broad Spectrum:
Gram-Positive: Active against Staphylococcus aureus (MSSA), Streptococcus pneumoniae (including some macrolide-sensitive strains), and Streptococcus pyogenes.
Gram-Negative: Inhibits Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, and Neisseria meningitidis.
Atypical Pathogens: Highly effective against intracellular microbes like Mycoplasma pneumoniae, Chlamydophila pneumoniae, Chlamydia trachomatis, and Legionella pneumophila.
Core Applications
Azithromycin is administered orally (tablets, capsules, suspensions) or intravenously (IV) for severe infections; oral formulations are preferred due to excellent bioavailability (~37%) and tolerability. It is not active against viral infections (e.g., cold/flu) or Gram-negative rods (e.g., E. coli, Klebsiella).
1. Human Pharmaceutical Field
1.1 Respiratory Tract Infections
Community-Acquired Pneumonia (CAP): First-line therapy for CAP caused by Mycoplasma pneumoniae, Chlamydophila pneumoniae, or Haemophilus influenzae. Oral dose: 500 mg on Day 1, followed by 250 mg once daily on Days 2–5 (total 1.5 g); IV dose: 500 mg once daily for 2–3 days, then switch to oral.
Acute Pharyngitis/Tonsillitis: For Streptococcus pyogenes infections (alternative to penicillin). Oral dose: 500 mg once daily for 3 days (or 1.5 g single dose in some regions).
Acute Bronchitis Exacerbation: Treats bacterial superinfection in patients with COPD. Oral dose: 500 mg on Day 1, 250 mg Days 2–5.
1.2 Skin & Soft Tissue Infections
Cellulitis & Impetigo: For Staphylococcus aureus (MSSA) or Streptococcus pyogenes infections. Oral dose: 500 mg on Day 1, 250 mg Days 2–5 (or 1 g once weekly for 2 weeks for severe cases).
Folliculitis: Topical formulations (1% gel) for mild cases; oral dose for widespread infection.
1.3 Sexually Transmitted Infections (STIs)
Chlamydia Trachomatis Infections: First-line therapy for urethritis, cervicitis, or pelvic inflammatory disease (PID). Oral dose: 1 g single dose (high compliance due to one-time administration).
Gonorrhea: Alternative therapy for Neisseria gonorrhoeae (combined with ceftriaxone to combat resistance). Oral dose: 1 g single dose + ceftriaxone 250 mg IM.
Syphilis: Second-line therapy for early syphilis (penicillin-allergic patients). Oral dose: 500 mg twice daily for 14 days.
1.4 Other Infections
Legionnaires' Disease: Effective against Legionella pneumophila. IV/oral dose: 500 mg once daily for 10–14 days.
Mycobacterium Avium Complex (MAC): Prophylaxis and treatment for MAC in immunocompromised patients (e.g., HIV-positive). Oral dose: 1.2 g once weekly.
2. Veterinary Field (Livestock & Companion Animals)
Azithromycin is used to treat bacterial infections in cattle, pigs, chickens, dogs, and cats-especially for intracellular pathogens like Mycoplasma:
Bovine Respiratory Disease (BRD): Caused by Mycoplasma bovis or Mannheimia haemolytica. IM/oral dose: 10 mg/kg body weight once daily for 3 days.
Porcine Respiratory Disease Complex (PRDC): For Mycoplasma hyopneumoniae or Actinobacillus pleuropneumoniae. Oral dose: 5–10 mg/kg once daily for 3–5 days.
Poultry Chronic Respiratory Disease (CRD): Treats Mycoplasma gallisepticum in chickens. Oral dose: 10–20 mg/kg drinking water for 3–5 days.
Canine/Feline Skin & Ear Infections: For Staphylococcus pseudintermedius (skin) or Mycoplasma spp. (ears). Oral dose: 5–10 mg/kg once daily for 5–7 days.
Contraindications: Avoid use in horses (colitis risk) or animals with pre-existing hepatic impairment; not approved for dairy cattle producing milk for human consumption.
Quality & Safety Assurance
As a widely used macrolide with a low side effect profile, Azithromycin requires strict quality control to ensure potency, purity, and safety-especially given emerging resistance in some pathogens:
1. Manufacturing & Purity Control
Production: Produced via semi-synthetic modification of erythromycin (introduction of a methyl-substituted nitrogen into the macrolide ring), followed by purification (chromatography) and crystallization. The process ensures:
Minimal impurities (e.g., degradation products, related macrolides) ≤1.0% (pharmaceutical grade);
Consistent potency (950–1050 μg/mg) for reliable therapeutic effect.
GMP Compliance: Pharmaceutical-grade Azithromycin is manufactured in Grade D cleanrooms (per ICH Q7 guidelines); veterinary grade complies with GMP for animal pharmaceuticals.
2. Comprehensive Testing Protocol
| Test Item | Method | Acceptance Criterion |
|---|---|---|
| Purity & Assay | HPLC (C18 column, 210 nm detection) | Pharmaceutical grade: ≥98.0% purity; Assay 950–1050 μg/mg |
| Related Substances | HPLC (gradient elution) | Single impurity ≤0.5%; Total impurities ≤1.0% (pharmaceutical grade) |
| Heavy Metals | ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) | Pharmaceutical grade: Pb≤5ppm; Veterinary grade: ≤10ppm |
| Residual Solvents | GC (headspace sampling, FID detector) | Class 2 solvents ≤500ppm; Class 1 solvents not detected |
| Loss on Drying | Gravimetric method (105°C for 2 hours) | ≤2.0% (pharmaceutical grade) |
| Identification | IR Spectroscopy & HPLC Retention Time | Matches reference standard spectrum; Retention time consistent with standard |
3. Safety Reminders
Human Use:
Contraindications: Hypersensitivity to macrolide antibiotics; history of QT interval prolongation (avoid with antiarrhythmics like sotalol); severe hepatic impairment.
Adverse Effects: Mild and rare: gastrointestinal upset (nausea, diarrhea), headache, and rash; rare but serious: hepatotoxicity (reversible upon discontinuation) and torsades de pointes (in patients with electrolyte abnormalities).
Drug Interactions: Minimal compared to erythromycin (weak CYP3A4 inhibitor); avoid concurrent use with digoxin (increased serum digoxin levels) or warfarin (monitor INR).
Veterinary Use:
Withdrawal Periods: Cattle: 28 days (meat); Pigs: 14 days (meat); Chickens: 7 days (meat/eggs); Dogs/Cats: No withdrawal period (non-food animals).
Residue Warning: Prohibited in dairy cattle (milk residues) and laying hens (egg residues) beyond the withdrawal period.
Cooperation & Contact
We supply Azithromycin in grades and forms tailored to human and veterinary applications:
Pharmaceutical Grade: Fine powder or film-coated granules (1kg–100kg per order, sealed aluminum foil bags with desiccants) for oral/IV formulations.
Veterinary Grade: Powder for livestock oral premixes or injectables (10kg–500kg per order; monthly production capacity of 2000kg).
Value-added services include:
Providing DMF (Drug Master File) and CEP (Certificate of Suitability) for pharmaceutical-grade products to support EU/US/Asia registration.
Technical support for pediatric suspensions (improving palatability) and veterinary formulation stability testing.
Batch-specific COA with purity, assay, and residual solvent results to ensure regulatory compliance.
If you are a pharmaceutical manufacturer, generic drug company, or veterinary drug enterprise, please contact us for detailed cooperation:
Contact Information:
Email: sales@huarongpharma.com
Phone/WhatsApp: +86 13751168070
We adhere to the principles of "broad-spectrum efficacy, safety compliance, and dosing convenience" and look forward to partnering with global healthcare and animal health industries!
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