azithromycin
Table of Contents
azithromycin
see also:
introduction
- azithromycin is a broad spectrum antibiotic which acts by inhibition of protein synthesis in bacteria by binding to the 50S ribosomal subunit and preventing translocation of peptides.
- it is the first of a class of antibiotics designated chemically as azalides, a subclass of macrolide antibiotics
- category B1 in pregnancy
- should only be used in breastfeeding women where adequate alternatives are not available as no data available on excretion into milk.
- safety not verified in children
antibiotic spectrum
- Gram positive aerobic bacteria including St. aureus, Streptococcus pyogenes, Strep. pneumoniae
- cross resistance with erythromycin resistant Gram positive strains
- In Australia, macrolide resistance for Strep. pneumoniae and Staph. aureus has been increasing since the late 1990s. Resistance rates of 15% or more are regularly reported.
- Gram negative aerobic bacteria including H. influenzae, Legionella, B. pertussis, Shigella, V. cholerae
- variable activity against E.coli, Salmonella, Enterobacter, Klebsiella
- Proteus, Serratia, Morganella and Pseudomonas are usually resistant
- Anaerobic bacteria including Bacteroides, Clostridium perfringens, Propionibacterium acnes
- sexually transmitted infections (STDs/STIs) organisms including Chlamydia, syphilis, gonococcus
- other bacteria including Borrelia, Mycoplasma, Ureaplasma, Campylobacter, Listeria and Mycobacterium avium-intracellulare complex.
contraindications
- Known hypersensitivity to azithromycin, erythromycin or any macrolide or ketolide antibiotic
adverse effects
- allergic reactions including anaphylaxis but these are rare
- diarrhoea, nausea, abdominal pain occur uncommonly
- candidiasis
- interstitial nephritis
- prolonged QTc (rare) thus avoid with drugs that also prolong QTc
- hepatitis and cholestatic jaundice which in rare cases may be fatal
- deafness and tinnitus have been reported
drug interactions of note
- may increase toxicity of colchicine via increased concentrations
- may increase risk of rhabdomyolysis in patients on statins
- in patients receiving ergot derivatives, ergotism has been precipitated by coadministration of some macrolide antibiotics
- care with concurrent administration with cyclosporin as cyclosporin serum levels increase
- macrolide antibiotics may alter gut flora and cause increased serum levels of digoxin in patients on digoxin.
- avoid concomitant antacid administration with oral doses as reduces peak concentration of azithromycin
indications
Australian PBS approved indications
- trachoma
- uncomplicated urethritis or cervicitis due to Chlamydia trachomatis
- prevention of Mycobacterium avium complex in patients with HIV / AIDS and low CD4 counts
- respiratory tract infections (Repat schedule only)
other indications
- community acquired pneumonia
- pertussis
- Legionella
- bronchiectasis, COPD - 3 doses per week reduces exacerbation rates but may increase macrolide-resistance especially in children, some may develop irreversible hearing loss
- sexually transmitted infections (STDs/STIs) such as epididymo-orchitis, pelvic inflammatory disease (PID), chancroid, granuloma inguinale
- bacterial enteritis such as Camplylobacter, Salmonella, cholera, traveller's diarrhoea, Salmonella typhi (typhoid enteric fever), paratyphoid enteric fever
- severe Cat scratch disease
- Australian tick typhus or scrub typhus
- as an immunomodulator (although new non-antibiotic agents will avoid antibiotic risks):
- lung transplants resulting in bronchiolitis obliterans syndrome
- cystic fibrosis
- sepsis - to reduce cytokine storm
- severe respiratory viral infections
dosage
- no dose adjustment is needed in patient's with mild or moderate renal impairment (GFR 10-80 mL/min).
- no dose adjustment is recommended for patients with mild to moderate hepatic impairment but care sghould be taken in those with liver impairment.
iv infusion dose
- do not administer as an iv bolus or as an intramuscular injection
- administer iv dose as an intravenous infusion over not less than 60 minutes
- infusion should be either 1 mg/mL over three hours or 2 mg/mL over one hour1)
- usual adult dose 500mg daily for 2 days then change to oral
adult oral dose
-
- 1g oral as single dose or weekly for up to 3 weeks
- pneumonia following initial 2 days of iv Rx:
- 500mg o daily for 7-10days
- prevention of disseminated Mycobacterium avium complex disease:
- 1.2 g once wkly (+/- rifabutin)
- other indications:
- 500 mg on day 1, 250 mg daily on days 2-5; alternative regimen: 500 mg daily for 3 days;
1)
MIMS Zithromax PI 2011
azithromycin.txt · Last modified: 2015/06/06 07:58 by 127.0.0.1