Description

Simple

An antibiotic medication used to treat a variety of infections caused by bacteria.

Clinical

A macrolide antibiotic used to treat a variety of bacterial infections.

Overview

Azithromycin is a broad-spectrum macrolide antibiotic with a long half-life and a high degree of tissue penetration [3]. It was initially approved by the FDA in 1991 [4].

It is primarily used for the treatment of respiratory, enteric and genitourinary infections and may be used instead of other macrolides for some sexually transmitted and enteric infections. It is structurally related to erythromycin [2].

Azithromycin [9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin] is a part of the _azalide_ subclass of macrolides, and contains a 15-membered ring, with a methyl-substituted nitrogen instead of a carbonyl group at the 9a position on the aglycone ring, which allows for the prevention of its metabolism. This differentiates azithromycin from other types of macrolides [Read more

Pharmacology

Indication

Azithromycin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria in order to prevent the development antimicrobial resistance and maintain the efficacy of azithromycin [FDA label].

Azithromycin is indicated for the treatmen... Read more

Pharmacodynamic

Macrolides stop bacterial growth by inhibiting protein synthesis and translation, treating bacterial infections [ Read more

Mechanism of action

In order to replicate, bacteria require a specific process of protein synthesis, enabled by ribosomal proteins [ Read more

Absorption

Bioavailability of azithromycin is 37% following oral administration. Absorption is not affected by food. Macrolide absorption in the intestines is believed to be mediated by P-glycoprotein (ABCB1) efflux transporters, which are known to be encoded by the _ABCB1_ gene [ Read more

Protein binding

The serum protein binding of azithromycin varies in humans, decreasing from 51% at 0.02 g/mL to 7% at 2 g/mL [FDA label].

Volume of distribution

After oral administration, azithromycin is widely distributed in tissues with an apparent steady-state volume of distribution of 31.1 L/kg [FDA label]. Significantly greater azithromycin concentrations have been measured in the tissues rather than in plasma or serum [FDA label], [ Read more

Clearance

Mean apparent plasma cl=630 mL/min (following single 500 mg oral and i.v. dose) [FDA label]

Half life

Terminal elimination half-life: 68 hours [FDA label]

Route of elimination

Biliary excretion of azithromycin, primarily as unchanged drug, is a major route of elimination. Over a 1 week period, approximately 6% of the administered dose is found as unchanged drug in urine [FDA label].

Toxicity

**Rat Oral LD50**: >2000 mk/kg [MSDS]

Possible major adverse effects include cardiovascular arrhythmias and hearing loss. Macrolide resistance is also an ongoing issue [ Read more

Adverse Effects

Contraindications

  • Regions: US
  • Patient Conditions:
      • Name: Cholestatic jaundice
      • Drugbank Id: DBCOND0094562
  • Patient Conditions Associated With:
      • Name: Prior azithromycin use
      • Drugbank Id: DBCOND0117160
  • Regions: US
  • Patient Conditions:
      • Name: Hepatic dysfunction
      • Drugbank Id: DBCOND0094733
  • Patient Conditions Associated With:
      • Name: Prior azithromycin use
      • Drugbank Id: DBCOND0117160
  • Regions: US
  • Patient Conditions:
      • Name: Known hypersensitivity to any ketolide
      • Drugbank Id: DBCOND0117159
  • Regions: US
  • Patient Conditions:
      • Name: Known hypersensitivity to any macrolide
      • Drugbank Id: DBCOND0117158
  • Regions: US
  • Patient Conditions:
      • Name: Known hypersensitivity to erythromycin
      • Drugbank Id: DBCOND0117157
  • Regions: US
  • Patient Conditions:
      • Name: Known hypersensitivity to azithromycin
      • Drugbank Id: DBCOND0117156

Food Interactions

  • Do not take Aluminum or magnesium antacids or supplements while on this medication.
  • Take on empty stomach: 1 hour before or 2 hours after meals.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
(R)-warfarin
The risk or severity of adverse effects can be increased when Azithromycin is combined with (R)-warfarin.
(S)-Warfarin
The risk or severity of adverse effects can be increased when Azithromycin is combined with (S)-Warfarin.
4-hydroxycoumarin
The risk or severity of adverse effects can be increased when Azithromycin is combined with 4-hydroxycoumarin.
6-Deoxyerythronolide B
The metabolism of Azithromycin can be decreased when combined with 6-Deoxyerythronolide B.
7-ethyl-10-hydroxycamptothecin
The metabolism of Azithromycin can be decreased when combined with 7-ethyl-10-hydroxycamptothecin.
9-aminocamptothecin
The metabolism of 9-aminocamptothecin can be decreased when combined with Azithromycin.
Abatacept
The metabolism of Azithromycin can be increased when combined with Abatacept.
Abciximab
The risk or severity of adverse effects can be increased when Azithromycin is combined with Abciximab.
Abemaciclib
The serum concentration of Abemaciclib can be increased when it is combined with Azithromycin.
Abexinostat
The risk or severity of QTc prolongation can be increased when Azithromycin is combined with Abexinostat.
Acalabrutinib
The metabolism of Azithromycin can be decreased when combined with Acalabrutinib.
Acebutolol
The serum concentration of Acebutolol can be increased when it is combined with Azithromycin.
Acenocoumarol
The risk or severity of adverse effects can be increased when Azithromycin is combined with Acenocoumarol.
Aceprometazine
The risk or severity of QTc prolongation can be increased when Azithromycin is combined with Aceprometazine.
Acetaminophen
The serum concentration of Acetaminophen can be increased when it is combined with Azithromycin.
Acetazolamide
The metabolism of Azithromycin can be decreased when combined with Acetazolamide.
Acetyldigitoxin
The serum concentration of Acetyldigitoxin can be increased when it is combined with Azithromycin.
Acetyldigoxin
The serum concentration of Acetyldigoxin can be increased when it is combined with Azithromycin.
Acetylsalicylic acid
The risk or severity of adverse effects can be increased when Azithromycin is combined with Acetylsalicylic acid.
Acrivastine
The risk or severity of QTc prolongation can be increased when Acrivastine is combined with Azithromycin.
11 References
  1. 1 . Noedl H, Krudsood S, Chalermratana K, Silachamroon U, Leowattana W, Tangpukdee N, Looareesuwan S, Miller RS, Fukuda M, Jongsakul K, Sriwichai S, Rowan J, Bhattacharyya H, Ohrt C, Knirsch C: Azithromycin combination therapy with artesunate or quinine for the treatment of uncomplicated Plasmodium falciparum malaria in adults: a randomized, phase 2 clinical trial in Thailand. Clin Infect Dis. 2006 Nov 15;43(10):1264-71. Epub 2006 Oct 12.PubMed: 17051490
  2. 2 . Peters DH, Friedel HA, McTavish D: Azithromycin. A review of its antimicrobial activity, pharmacokinetic properties and clinical efficacy. Drugs. 1992 Nov;44(5):750-99. doi: 10.2165/00003495-199244050-00007.PubMed: 1280567
  3. 3 . McMullan BJ, Mostaghim M: Prescribing azithromycin. Aust Prescr. 2015 Jun;38(3):87-9. Epub 2015 Jun 1.PubMed: 26648627
  4. 4 . Fohner AE, Sparreboom A, Altman RB, Klein TE: PharmGKB summary: Macrolide antibiotic pathway, pharmacokinetics/pharmacodynamics. Pharmacogenet Genomics. 2017 Apr;27(4):164-167. doi: 10.1097/FPC.0000000000000270.PubMed: 28146011
  5. 5 . Champney WS, Miller M: Inhibition of 50S ribosomal subunit assembly in Haemophilus influenzae cells by azithromycin and erythromycin. Curr Microbiol. 2002 Jun;44(6):418-24.PubMed: 12000992
  6. 6 . Champney WS, Burdine R: Macrolide antibiotics inhibit 50S ribosomal subunit assembly in Bacillus subtilis and Staphylococcus aureus. Antimicrob Agents Chemother. 1995 Sep;39(9):2141-4.PubMed: 8540733
  7. 7 . Dinos GP: The macrolide antibiotic renaissance. Br J Pharmacol. 2017 Sep;174(18):2967-2983. doi: 10.1111/bph.13936. Epub 2017 Aug 10.PubMed: 28664582
  8. 8 . Singlas E: [Clinical pharmacokinetics of azithromycin]. Pathol Biol (Paris). 1995 Jun;43(6):505-11.PubMed: 8539072
  9. 9 . Zithromax FDA label File
  10. 10 . Azithromycin, Ophthalmic FDA label File
  11. 11 . Sandoz Azithromycin Canadian Monograph File