Azithromycin

General

• Type: Macrolide
• Dosage Forms: powder for solution, suspension reconstituted, packet, tablet
• Dosage Strengths: powder for solution: 500mg, 2.5g; suspension reconstituted: 100, 200mg/5mL; packet: 1g; tablet: 250, 500, 600mg
• Routes of Administration: PO, IV
• Common Trade Names: Zithromax, Z-Pak, Zmax

Adult Dosing

COPD exacerbation

• 500mg PO x1 on day 1, then 250mg PO q24h x4 days
• Alt: 500mg PO q24h x3 days

PID

• 500mg IV q24h x1-2 days, then 250mg PO q24h x5-6 days

Urethritis, non-gonococcal initial infection

• 1 g PO x1

Chancroid

• 1 g PO x1

MAC

• Disseminated: 500-600mg PO q24h (not 1st-line agent; use with ethambutol)
• Primary prophylaxis: 1200mg PO qwk Alt: 600mg PO 2x/wk
• Secondary prophylaxis: 500-600mg PO q24h (not 1st-line agent; use with ethambutol)

Salmonella

• 1 g PO q24h x1 day, then 500mg PO q24h x2-6 days

Indications by Disease

Disease	Dose	Context
Acute diarrhea	500mg PO once daily x 5 days	Campylobacter
Acute diarrhea	500mg PO daily x 5 days	Shigella
Acute diarrhea	20mg/kg (1g) PO once	Vibrio cholerae
Babesiosis	500-1000mg day 1 then 250-1000mg daily x 10 days	Mild parasitemia less than 4 percent option 1 with Atovaquone
Bacterial conjunctivitis	1% ophthalmic solution 1 drop BID for 2 days THEN 1 drop daily for 5 days	Bacterial Conjunctivitis, Topical
COPD exacerbation	500mg PO x1 on day 1, then 250mg PO q24h x4 days; Alt: 500mg PO q24h x3 days	COPD exacerbation
Cervicitis	1 g PO x 1	GC/Chlamydia, Pregnant
Chancroid	1 g PO x1	Chancroid
Endocarditis	500mg (15mg/kg) PO	Dental Procedure Prophylaxis
Gonorrheal conjunctivitis	1g (20mg/kg) PO one time dose	Chlamydial Conjunctivitis
Gonorrheal conjunctivitis	1g PO one dose	Gonococcal Conjunctivitis
Infectious tenosynovitis	1g PO once	Gonococcal
Lymphogranuloma venereum	1g PO weekly for 3 weeks	Pregnancy Alternative
Mastitis	500mg PO x1 day 1, then 250mg PO daily days 2-5	PCN allergy alternative
Mycobacterium avium complex	1200mg PO weekly (Alt: 600mg PO twice weekly)	Primary prophylaxis
Mycobacterium avium complex	500-600mg PO daily (use with ethambutol; not 1st-line)	Treatment, disseminated
Mycobacterium avium complex	500-600mg PO daily (use with ethambutol; not 1st-line)	Secondary prophylaxis
Pelvic inflammatory disease	500mg IV q24h x1-2 days, then 250mg PO q24h x5-6 days	PID
Pertussis	500mg PO once daily for day #1 then 250mg PO once daily for days #2-5	Adults
Pneumonia (main)	500mg IV daily	ICU, Risk of Pseudomonas
Pneumonia (main)	500mg IV	ICU, Low Risk
Pneumonia (main)	500 mg daily	Inpatient, CAP Non-ICU
Pneumonia (main)	500 mg on first day then 250 mg daily	Outpatient, Unhealthy
Pneumonia (main)	500 mg on first day then 250 mg daily	Outpatient, Healthy
Salmonella	1 g PO q24h x1 day, then 500mg PO q24h x2-6 days	Salmonella
Streptococcal pharyngitis	12 mg/kg PO once (maximum = 500 mg), then 6 mg/kg (max=250 mg) once daily for the next 4 days	Penicillin Allergy (anaphylaxis)
Toxoplasmosis	1200mg PO q24hrs	Immunosuppressed alt
Traveler's diarrhea	500mg PO q24h x 3 days OR 1000mg PO x 1	Traveler's Diarrhea
Typhoid fever	1 g PO daily x 5 days	Quinolone Resistant, Oral
Urethritis in men	1 g PO x1	Urethritis, non-gonococcal initial infection

Pediatric Dosing

Bacterial sinusitis

• Children ≥6 months: Oral: 10mg/kg PO once daily for 3 days (maximum: 500mg daily)

Pharyngitis (as an alternative agent in penicillin allergic patients)

• Children ≥2 years and Adolescents: Oral: 12mg/kg/dose once daily for 5 days (maximum: 500mg daily)

Indications by Disease

Disease	Dose	Context
Acute diarrhea	10mg/kg/day once daily x 3 days	Pediatric travelers diarrhea
Acute diarrhea	10mg/kg PO day 1 (max 500mg), then 5mg/kg/day x 4 days	Pediatric Shigella
Acute diarrhea	10mg/kg PO day 1, then 5mg/kg/day x 4 days	Pediatric Salmonella
Acute diarrhea	10mg/kg PO daily x 3 days (max 500mg)	Pediatric Campylobacter
Acute diarrhea	10mg/kg/day once daily x 3 days	Pediatric travelers diarrhea
Diarrhea aguda	10mg/kg/day once daily x 3 days	Pediatric travelers diarrhea
Acute otitis media	10mg/kg/day x 1 day and 5mg/kg/day x 4 remaining days	Penicillin Allergy
Bacterial conjunctivitis	1% ophthalmic solution 1 drop BID x 2 days then daily x 5 days	Pediatric
Endocarditis	15mg/kg PO (max 500mg)	Pediatric Dental Prophylaxis, PCN Allergy
Gonorrheal conjunctivitis	20mg/kg PO once daily x 3 days	Chlamydial Conjunctivitis, Newborn
Neonatal conjunctivitis	20mg/kg PO once daily x 3 days	Chlamydial conjunctivitis
Pertussis	10mg/kg (max 500mg/day) daily x 5 days	>1 month old
Pertussis	10mg/kg (max 500mg/day) daily x 5 days	<1 month old
Pharyngitis	Children ≥2 years and Adolescents: Oral: 12mg/kg/dose once daily for 5 days (maximum: 500mg daily)	Pharyngitis (as an alternative agent in penicillin allergic patients)
Pneumonia (peds)	2.5mg/kg q12hrs	1-3 month afebrile pneumonitis
Sinusitis	Children ≥6 months: Oral: 10mg/kg PO once daily for 3 days (maximum: 500mg daily)	Bacterial sinusitis
Streptococcal pharyngitis	12mg/kg PO day 1 (max 500mg), then 6mg/kg daily x 4 days (max 250mg)	Pediatric PCN Allergy (severe)
Traveler's diarrhea	10mg/kg/day once daily x 3 days	Pediatric travelers diarrhea
Typhoid fever	10-20mg/kg PO daily x 5-7 days (max 1g)	Pediatric, Oral

Special Populations

• Pregnancy Rating: B
• Lactation risk: Excreted in low amounts of breast milk and may lead to rash, somnolence, and diarrhea in nursing infants
• Renal Dosing: Caution in patients with GFR <10 mL/minute, though primarily elimated through hepatic metabolism
• Hepatic Dosing: Caution is indicated for potential hepatotoxicity though it is rare, and there are no specific dosage adjustments indicated for patients with liver failure

Contraindications

• Hypersensitivity to azithromycin or other macrolides or any component of the formulation
• History of cholestatic jaundice/hepatic dysfunction with prior Azithromycin use

Adverse Reactions

Serious

• Prolonged QT
• Torsades
• hepatic necrosis
• Eaton-Lambert
• Myasthenia gravis
• Corneal erosion

Common

• Vomiting
• Diarrhea
• Abdominal pain
• Headache
• Vision changes

Pharmacology

• Half-life: 68 hrs
• Metabolism: Hepatic
• Excretion: Biliary
• Mechanism of Action:Binds 50S ribosomal subunit interfering with microbial protein synthesis

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	I
	Strep. Pneumoniae	I
	Viridans strep	X1
	Strep. anginosus gp	X1
	Enterococcus faecalis	R
	Enterococcus faecium	R
	MSSA	S
	MRSA	R
	CA-MRSA	I
	Staph. Epidermidis	R
	C. jeikeium	R
	L. monocytogenes	S
Gram Negatives	N. gonorrhoeae	I
	N. meningitidis	X2
	Moraxella catarrhalis	S
	H. influenzae	S
	E. coli	R
	Klebsiella sp	R
	E. coli/Klebsiella ESBL+	R
	E coli/Klebsiella KPC+	R
	Enterobacter sp, AmpC neg	R
	Enterobacter sp, AmpC pos	R
	Serratia sp	X1
	Serratia marcescens	R
	Salmonella sp	I
	Shigella sp	I
	Proteus mirabilis	X1
	Proteus vulgaris	R
	Providencia sp.	X1
	Morganella sp.	X1
	Citrobacter freundii	X1
	Citrobacter diversus	X1
	Citrobacter sp.	X1
	Aeromonas sp	X1
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	R
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	R
	Yersinia enterocolitica	R
	Francisella tularensis	X1
	Brucella sp.	R
	Legionella sp.	S
	Pasteurella multocida	X1
	Haemophilus ducreyi	S
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	S
	Mycoplasm pneumoniae	S
	Rickettsia sp	X1
	Mycobacterium avium	S
Anaerobes	Actinomyces	S
	Bacteroides fragilis	R
	Prevotella melaninogenica	S
	Clostridium difficile	X1
	Clostridium (not difficile)	S
	Fusobacterium necrophorum	R
	Peptostreptococcus sp.	S

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia

See Also

• Antibiotics (Main)

References

• Epocrates
• Micromedex