What is azithromycin (Zithromax, Z-Pak)?

Azithromycin is a semi-synthetic macrolide antibiotic chemically related to erythromycin and clarithromycin (Biaxin).

Azithromycin is effective against susceptible bacteria causing:

It also is effective for acute pelvic inflammatory disease and several sexually transmitted infectious diseases (STDs) such as nongonococcal urethritis and cervicitis.

What brand names are available for azithromycin?

Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, Zmax are the brand names available for azithromycin in the US.

Is azithromycin available as a generic drug?

Yes

Do I need a prescription for azithromycin?

Yes

Does azithromycin treat COVID-19 coronavirus disease?

Though azithromycin is an antibiotic and thus ineffective alone against viruses, some clinicians have seen limited success in COVID-19 coronavirus disease patients when adding it to chloroquine (Aralen) and/or hydroxycholoroquine (Plaquenil) in the sickest patients.

As of March 30, 2020, there is little solid evidence for this drug combination's effectiveness in general against COVID-19, however.

The initial COVID-19 data about azithromycin came from just a few patients in an observational "open label" study, which makes it difficult to isolate variables and say whether a particular drug is working.

Chloroquine and hydroxychloroquine are decades-old malaria drugs French doctors tested on coronavirus patients. Six patients in the tiny study of about 20 happened to also be on azithromycin for other conditions while also being administered the malaria drugs. All six patients recovered.

Researchers are still testing the malaria drugs and their combination with azithromycin to fight coronavirus.

As of March 30, 2020 available study results on malaria drugs' effectivness against COVID-19 were mixed, but a French study of 80 patients published that day in the International Journal of Antimicrobial Agents showed encouraging results for both the effectiveness of the malaria drugs and for the addition of azithromycin to the drug cocktail.

The FDA has released both malaria drugs for emergency use in COVID-19, despite the dearth of evidence.

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What are the side effects of azithromycin (Zithromax, Z-Pak)?

The most common side effects of azithromycin are:

Other possible side effects of azithromycin include:

Possible serious side effects of azithromycin include:

Antibiotics can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile, which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting azithromycin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

What is the dosage for azithromycin (Zithromax, Z-Pak)?

  • Azithromycin (except Zmax) can be taken with or without food, but food reduces stomach upset.
  • Zmax should be taken on an empty stomach 1 hour before or 2 hours after a meal since food reduces its absorption.
  • The adult azithromycin dose is 500-2000 mg in multiple or single doses.
  • For most infections, azithromycin is taken once daily for a relatively short course of treatment (usually five days).
  • The first dose is often a "double dose," twice as much as the remainder of the doses given.
  • For acute bacterial sinusitis, azithromycin way be taken once daily for three days.
  • Zmax usually is given as a single 2 gm dose.

Which drugs or supplements interact with azithromycin (Zithromax, Z-Pak)?

  • Azithromycin (except Zmax) should not be taken at the same time as aluminum- or magnesium-based antacids, such as Mylanta or Maalox, because antacids will bind the azithromycin and prevent it from being absorbed from the intestine.

Is azithromycin (Zithromax, Z-Pak) safe to use during pregnancy or while breastfeeding?

  • There are no adequate studies of azithromycin in pregnant women. Azithromycin should only be used during pregnancy if it is clearly necessary.
  • It is not known if azithromycin is secreted in breast milk.

What else should I know about azithromycin (Zithromax, Z-Pak)?

What preparations of azithromycin (Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, Zmax) are available?
  • Tablets: 250, 500, and 600 mg.
  • Suspension: 100 mg/5 ml (teaspoon), 200 mg/5 ml (teaspoon).
  • Powder for suspension (extended release): 2 g.
  • Powder for oral suspension: 1 g.
  • Powder for Injection: 500 mg. Z-PAK (Blister pack containing six 250 mg tablets); TRI-PAK (Blister pack containing three 500 mg tablets).
How should I keep azithromycin (Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, Zmax) stored?
  • Tablets should be stored at room temperature between 15 C to 30 C (59 F to 86 F).
  • Suspension and solution for injection should be kept between 5 C to 30C (41 F to 86 F).
How does azithromycin (Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, Zmax) work?
  • Azithromycin, like all macrolide antibiotics, prevents bacteria from growing by interfering with their ability to make proteins. Because of the differences in the way proteins are made in bacteria and humans, the macrolide antibiotics do not interfere with production of proteins in humans. It is an unusual antibiotic in that it stays in the body for quite a while (has a long half-life), allowing for once-a-day dosing and for shorter treatment courses for most infections.
When was azithromycin (Zithromax, Zithromax Tri-Pak, Zithromax Z-Pak, Zmax) approved by the FDA?
  • The FDA approved azithromycin in November 1991.

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Summary

Azithromycin (Zithromax, Z-Pak, Tri-Pak, Zmax) is an antibiotic prescribed for the treatment of a wide variety of bacterial infections such as otitis media (middle ear infection), laryngitis, bronchitis, pneumonia, and others. Though azithromycin is an antibiotic and thus ineffective against viruses, some clinicians have seen limited success in COVID-19 coronavirus disease patients when added to chloroquine and/or hydroxycholoroquine in the sickest patients. There is little good evidence for this drug combination's effectiveness in general against COVID-19.

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See more info: azithromycin on RxList
Medically Reviewed on 3/30/2020
References
Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine

FDA Prescribing Information

"Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial"
Philippe Gautret, et al
March 2020
International Journal of Antimicrobial Agents

Some data on COVID-19 use from Aileen Chi, Pharm. D., of Dova Pharmaceuticals
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