Azithromycin is a semi-synthetic macrolide antibiotic structurally derived from erythromycin, and a member of a subclass of macrolide antibiotics with bacteriocidal and bacteriostatic activities. It has been used in the treatment of Mycobacterium avium intracellular infections, toxoplasmosis, and cryptosporidiosis. Azithromycin reversibly binds to the 50S ribosomal subunit of the 70S ribosome of sensitive microorganisms, thereby inhibiting the translocation step of protein synthesis, wherein a newly synthesized peptidyl tRNA molecule moves from the acceptor site on the ribosome to the peptidyl (donor) site, and consequently inhibiting RNA-dependent protein synthesis leading to cell growth inhibition and cell death. Azithromycin is an antibiotic useful for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumonia, traveler’s diarrhea, and certain other intestinal infections. It may also be used for a number of sexually transmitted infections including chlamydia and gonorrhea infections.
Mechanism of Action of Azithromycin
Indications of Azithromycin
- Acute bacterial sinusitis (adequately diagnosed)
- Acute bacterial otitis media (adequately diagnosed)
- Pharyngitis, tonsillitis
- Acute exacerbation of chronic bronchitis (adequately diagnosed)
- Mild to moderately severe community-acquired pneumonia
- Skin and soft tissue infections
- Uncomplicated Chlamydia trachomatis urethritis and cervicitis
- Legionella Pneumonia
- Mycoplasma Pneumonia
- Pneumonia
- Tonsillitis/Pharyngitis
- Sinusitis
- Skin and Structure Infection
- Gonococcal Infection – Uncomplicated
- Nongonococcal Urethritis
- Chlamydia Infection
- Cervicitis
- Chancroid
- Pelvic Inflammatory Disease
- Chronic Obstructive Pulmonary Disease
- Bronchitis
- Mycobacterium avium-intracellular
- Granuloma Inguinale
- STD Prophylaxis
- Pertussis Prophylaxis
- Pertussis
- Lyme Disease – Erythema Chronicum Migrans
- Babesiosis
- Bacterial Endocarditis Prophylaxis
- Toxoplasmosis
- Campylobacter Gastroenteritis
- Upper Respiratory Tract Infection
Contraindication of Azithromycin
- History of severe hypersensitivity (e.g. anaphylactic reaction) to any other type of betalactam antibacterial agent (penicillins, monobactams and carbapenems).
- Hemolytic anemia
- Liver problems
- Interstitial nephritis
- Subacute cutaneous lupus erythematosus
- Systemic lupus erythematosus
- Allergies macl& betalactams
- Known hypersensitivity to azithromycin, erythromycin, any macrolide or ketolide antibiotic. Coadministration w/ pimozide. History of cholestatic jaundice/hepatic dysfunction associated w/ prior use of azithromycin.
Dosage of Azithromycin
Strengths: 250 mg, 500 mg, 600 mg; 1 g; 2 g; 2.5 g I.V; 100 mg/5 mL; 200 mg/5 mL Suspension
Chronic Obstructive Pulmonary Disease
Immediate-release
- 500 mg orally once a day for 3 days OR 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5
Pneumonia
Immediate-release
- 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5
Extended-release
- 2 g orally once as a single dose
- Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy
Upper Respiratory Tract Infection
ASBMT and IDSA Recommendations
Bacterial infections within the first 100 days of HCT
Immediate-release
- Alternative treatment: 250 mg orally once a day
- Prevention of bacterial infections for HCT patients with anticipated neutropenic periods of at least 7 days
Tonsillitis/Pharyngitis
Immediate-release
- 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5
IDSA Recommendations
Immediate-release
- Individuals with penicillin allergy: 12 mg/kg orally once a day
- Maximum dose: 500 mg/day
- Duration of therapy: 5 days
Skin and Structure Infection
Immediate-release
- 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5
IDSA and NIH Recommendations
Immediate-release
- Patients greater than 45 kg: 500 mg orally on day 1, then 250 mg orally once a day on days 2 through 5
- Patients less than 45 kg: 10 mg/kg orally on day 1, then 5 mg/kg orally once a day for 4 additional days
- Alternative therapy for Bartonella infections (not endocarditis or central nervous system infections): 500 mg orally once a day for at least 3 months
Community-acquired pneumonia
Immediate-release
- 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5
Extended-release
- 2 g orally once as a single dose
- Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy
Sinusitis
Immediate-release
- 500 mg orally once a day for 3 days
Extended-release
- 2 g orally once as a single dose
Pelvic Inflammatory Disease
- 500 mg IV once a day for 1 or 2 days, followed by 250 mg (immediate-release formulation) orally once a day to complete a 7-day course of therapy.
Pediatric Pneumonia
6 months and older
Immediate-release
- 10 mg/kg (maximum: 500 mg/dose) orally on day 1, followed by 5 mg/kg (250 mg/dose) orally once a day on days 2 to 5
Extended-release
- Patients less than 34 kg: 60 mg/kg (maximum dose: 2 g/dose) orally as a single dose
- Patients 34 kg or greater: 2 g orally as a single dose
16 years and older
- Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy
IDSA and Pediatric Infectious Disease Society (PIDS) Recommendations
3 months to less than 5 years
- Parenteral: 10 mg/kg on days 1 and 2 of treatment, transitioning to oral treatment when possible
- Oral: 10 mg/kg orally on day 1, then 5 mg/kg/day orally once a day on days 2 to 5
5 years and older
- Oral: 10 mg/kg (maximum: 500 mg/day) orally on day 1, followed by 5 mg/kg/day
- maximum: 250 mg/day orally on days 2 to 5
Pediatric Mycoplasma Pneumonia
6 months and older
Immediate-release
- 10 mg/kg (maximum: 500 mg/dose) orally on day 1, followed by 5 mg/kg (250 mg/dose) orally once a day on days 2 to 5
Extended-release
- Patients less than 34 kg: 60 mg/kg (maximum dose: 2 g/dose) orally as a single dose
- Patients 34 kg or greater: 2 g orally as a single dose
16 years and older
- Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy
IDSA and Pediatric Infectious Disease Society (PIDS) Recommendations
3 months to less than 5 years
- Parenteral: 10 mg/kg on days 1 and 2 of treatment, transitioning to oral treatment when possible
- Oral: 10 mg/kg orally on day 1, then 5 mg/kg/day orally once a day on days 2 to 5
5 years and older
- Oral: 10 mg/kg (maximum: 500 mg/day) orally on day 1, followed by 5 mg/kg/day
- maximum: 250 mg/day orally on days 2 to 5
Tonsillitis/Pharyngitis
2 years and older
- Immediate-release: 12 mg/kg (maximum: 500 mg/dose) orally once a day for 5 days
Pediatric, Bacterial Infection
American Academy of Pediatrics (AAP) Recommendations
Immediate-release, Less than 1 month
- IV: 10 mg/kg IV every 24 hours
- Oral: 10 to 20 mg/kg orally every 24 hours
1 month or older
- Mild to moderate infections: 5 to 12 mg/kg orally once a day
- Severe infections: 10 mg/kg IV once a day
Skin and Structure Infection
IDSA Recommendations,
Immediate-release
- Patients greater than 45 kg: 500 mg orally on day 1, then 250 mg orally once a day on days 2 through 5
- Patients less than 45 kg: 10 mg/kg orally on day 1, then 5 mg/kg orally once a day for 4 additional days
Side Effects of Azithromycin
Most common
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- leukopenia/leukemia
- hemolytic anemia
- serum sickness
- agranulocytosis
- pain, swelling, irritation where injected
- stomach upset
- sweating
- skin color change, mild diarrhea
- mild nausea
- loss of appetite
- vaginal discharge and itching
- swelling of feet or legs
- chest pain
- constipation
- cough
- diarrhea or loose stools
- difficulty with breathing
- dizziness
- heartburn
- There are no adequate data on the use of azithromycin in pregnant women. In reproduction toxicity studies in animals, azithromycin was shown to pass the placenta, but no teratogenic effects were observed. The safety of azithromycin has not been confirmed with regard to the use of the active substance during pregnancy. Therefore azithromycin should only be used during pregnancy if the benefit outweighs the risk.
Lactation
- Azithromycin has been reported to be secreted into human breast milk, but there are no adequate and well-controlled clinical studies in nursing women that have characterized the pharmacokinetics of azithromycin excretion into human breast milk. In infertility studies conducted on the rat, reduced pregnancy rates were noted following administration of azithromycin. The relevance of this finding to humans is unknown.
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