Zithrox 500 mg

Description

Indications Zithrox is prescribed for infections caused by susceptible organisms, including lower respiratory tract infections such as bronchitis and pneumonia, as well as upper respiratory tract infections like sinusitis, pharyngitis, and tonsillitis. It is also used to treat otitis media, skin and soft tissue infections, and sexually transmitted diseases such as non-gonococcal urethritis and cervicitis caused by Chlamydia trachomatis.

Pharmacology Azithromycin is acid-stable, allowing it to be taken orally without protection from gastric acids. It is well absorbed, particularly on an empty stomach, with peak plasma concentrations reached within 2.1 to 3.2 hours. Azithromycin accumulates in phagocytes and is actively transported to infection sites, where large concentrations are released during active phagocytosis. Tissue concentrations of azithromycin can be significantly higher than in plasma due to ion trapping and its lipid solubility. The drug has a prolonged terminal half-life of approximately 68 hours, allowing for a shorter treatment duration while maintaining therapeutic levels in infected tissues. The primary route of elimination is biliary excretion, with a small portion excreted unchanged in urine.

Microbiology Azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, without affecting nucleic acid synthesis. It is effective against various microorganisms, including:

• Gram-positive bacteria: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes.
• Gram-negative bacteria: Haemophilus ducreyi, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae.
• Other microorganisms: Chlamydia pneumoniae, Chlamydia trachomatis, Mycoplasma pneumoniae.
• Additional organisms: Bordetella pertussis, Legionella pneumophila, Peptostreptococcus species, Prevotella bivia.

Dosage & Administration

• Adults: 500 mg once daily for 3 days, or 500 mg on day 1 followed by 250 mg daily for 4 more days.
• Sexually Transmitted Infections: 1 g as a single dose, or 500 mg on day 1 followed by 250 mg daily for 2 more days.
• Children:
  • 10 mg/kg once daily for 3 days for children over 6 months.
  • 15-25 kg: 200 mg daily for 3 days.
  • 26-35 kg: 300 mg daily for 3 days.
  • 36-45 kg: 400 mg daily for 3 days.
  • Typhoid fever: 500 mg once daily for 7-10 days.

Intravenous Infusion (Adults Only)

• Community-Acquired Pneumonia: 500 mg IV once daily for at least 2 days, followed by oral azithromycin (500 mg daily) to complete a 7-10 day course.
• Pelvic Inflammatory Disease: 500 mg IV daily for 1-2 days, followed by oral azithromycin (250 mg daily) to complete a 7-day course. If anaerobic bacteria are suspected, an additional antimicrobial agent should be used.

Administration

• For oral suspension:
  1. Shake the bottle to loosen the powder.
  2. Add boiled and cooled water up to the marked level.
  3. Shake well until fully mixed.
• Azithromycin should be taken at least 1 hour before or 2 hours after meals.

Drug Interactions

• Antacids: Should be taken 1 hour before or 2 hours after azithromycin.
• Cyclosporin: Caution is advised; monitor cyclosporin levels if co-administered.
• Digoxin: Potential for increased digoxin levels; monitoring is recommended.
• Ergot Derivatives: Co-administration is not recommended due to risk of ergotism.
• Warfarin: No known interaction, but routine monitoring of prothrombin time is advised.
• Methylprednisolone & Theophylline: No significant interaction reported, but caution is recommended.

Contraindications Azithromycin is contraindicated in patients with known hypersensitivity to azithromycin, other macrolides, or any of its components. It should not be used in patients with hepatic disease or in combination with ergot derivatives.

Side Effects Common side effects include nausea, abdominal pain, vomiting, diarrhea, flatulence, and occasional allergic reactions such as rash or photosensitivity. Rare side effects include liver enzyme elevation, cholestatic jaundice, and transient mild neutropenia. In rare cases, prolonged use at high doses may lead to reversible hearing impairment.

Use in Pregnancy & Lactation

• Pregnancy: Classified as Category B. Animal studies indicate no fetal harm, but human studies are limited. Use only if alternatives are unavailable.
• Lactation: Unknown if excreted in breast milk; use with caution in nursing mothers.

Precautions & Warnings

• Rare but serious allergic reactions, including anaphylaxis and angioedema, have been reported.
• Caution is advised in patients with severe renal impairment (creatinine clearance <40 ml/min).
• Not recommended for use in patients with hepatic impairment.
• No known effects on the ability to drive or operate machinery.

Overdose Effects Overdose symptoms may include hearing loss, severe nausea, vomiting, and diarrhea. Treatment involves gastric lavage and supportive measures.

Storage Conditions Store in a cool, dry place away from light and heat. Keep out of reach of children.

Common Questions

• What is Zithrox 500 mg Tablet used for?
  • It treats respiratory, skin, soft tissue, and sexually transmitted infections.
• Can it cause diarrhea?
  • Yes, as it affects gut bacteria. If severe, consult a doctor.
• Is it safe?
  • Yes, when used as prescribed.
• What should I do if symptoms persist?
  • Consult your doctor if symptoms do not improve within 3 days.

Quick Tips

• Complete the full course, even if you feel better.
• Take it at least 1 hour before or 2 hours after meals.
• Avoid antacids within 2 hours of taking azithromycin.
• If you experience an allergic reaction, stop use and seek medical help immediately.