Indications

Azo (azithromycin) is a macrolide antibiotic indicated for infections caused by susceptible organisms, including:

• Lower Respiratory Tract Infections: Bronchitis and pneumonia.
• Upper Respiratory Tract Infections: Sinusitis, pharyngitis, and tonsillitis.
• Otitis media.
• Skin and soft tissue infections.
• Sexually Transmitted Diseases (STDs): Non-gonococcal urethritis and cervicitis caused by Chlamydia trachomatis in both men and women.

Pharmacology

Azithromycin is an acid-stable antibiotic that is well-absorbed orally, with absorption being greater on an empty stomach. It works by binding to the 50S ribosomal subunit of bacteria, interfering with protein synthesis. This action is bacteriostatic. Due to its high concentration in phagocytes, it is actively transported to the site of infection, where its tissue concentration can be over 50 times higher than in the blood. It has a long terminal elimination half-life of 68 hours, allowing for a shorter course of treatment. The major route of elimination is biliary excretion, with about 6% of the dose appearing in the urine.

Dosage

• Oral (Adults):
  • For most infections: 500 mg once daily for 3 days OR an initial dose of 500 mg on Day 1, followed by 250 mg once daily on Days 2-5.
  • For STDs (Chlamydia trachomatis): A single dose of 1 gram OR 500 mg on Day 1, followed by 250 mg once daily for 2 days.
• Oral (Children):
  • For most infections: 10 mg/kg of body weight once daily for 3 days.
  • For typhoid fever: 500 mg once daily for 7-10 days.
• Intravenous (IV) Infusion (Adults):
  • Community-Acquired Pneumonia: 500 mg as a single daily dose for at least two days, followed by 500 mg orally once daily to complete a 7-10 day course.
  • Pelvic Inflammatory Disease: 500 mg as a single daily dose for one or two days, followed by 250 mg orally once daily to complete a 7-day course. If anaerobic microorganisms are suspected, an additional agent with anaerobic activity should be used.
• Children under 16: The safety and effectiveness of azithromycin injection have not been established.

Administration

Oral azithromycin should be taken at least 1 hour before or 2 hours after a meal. For the suspension, shake the bottle, add boiled and cooled water up to the marked line, and shake until the powder is fully mixed.

Interaction

• Antacids: Take azithromycin at least 1 hour before or 2 hours after an antacid.
• Cyclosporin, Digoxin, and Theophylline: Macrolides can interfere with the metabolism of these drugs. Caution should be used, and plasma levels should be monitored if co-administered.
• Ergot derivatives: Co-administration is contraindicated due to the theoretical possibility of ergotism.
• Warfarin: Azithromycin can be co-administered with warfarin, but prothrombin time should continue to be monitored.

Contraindications

Azo is contraindicated in patients with:

• Hypersensitivity to azithromycin or any macrolide antibiotic.
• Hepatic disease.
• Co-administration with ergot derivatives.

Side Effects

Azithromycin is generally well tolerated. The most common side effects are gastrointestinal, including nausea, abdominal pain, vomiting, diarrhea, and loose stools. Allergic reactions, such as rash or photosensitivity, have occurred, with rare reports of serious hypersensitivity reactions. Reversible elevations in liver enzymes and rare cases of cholestatic jaundice have been observed. Transient reductions in neutrophil counts and reversible hearing impairment have also been reported, particularly with higher, prolonged doses.

Pregnancy & Lactation

Azithromycin is a Pregnancy Category B drug. Animal studies have shown no evidence of harm to the fetus. However, there are no adequate studies in pregnant women. It should be used during pregnancy only if necessary. It is not known whether azithromycin is secreted in breast milk, so caution should be exercised when administering it to nursing women.

Precautions & Warnings

Rare but serious allergic reactions, including angioedema and anaphylaxis, have been reported. Some of these reactions have recurred and required a long period of observation and treatment.

• Renal Impairment: No dose adjustment is needed for mild renal impairment, but caution should be used in patients with more severe renal impairment due to lack of data.
• Hepatic Impairment: As the liver is the main route of excretion, azithromycin should not be used in patients with hepatic disease.

Overdose Effects

There is limited data on overdose with Azo. Typical symptoms with macrolide antibiotics include hearing loss, severe nausea, vomiting, and diarrhea. Gastric lavage and general supportive measures are indicated.

Therapeutic Class

Azo is a macrolide antibiotic.

Storage Conditions

Keep in a dry place away from light and heat. Keep out of the reach of children.