ACOS 500 mg

Description

Indications
Acos is prescribed for infections caused by susceptible organisms. It is used to treat lower respiratory tract infections such as bronchitis and pneumonia, as well as upper respiratory tract infections including sinusitis and pharyngitis/tonsillitis. Additionally, it is effective in otitis media and infections of the skin and soft tissues. In the treatment of sexually transmitted diseases, Acos is used for non-gonococcal urethritis and cervicitis caused by Chlamydia trachomatis.

Pharmacology
Azithromycin is acid-stable, allowing for oral administration without the need for protection from gastric acids. It is well absorbed, with better absorption occurring on an empty stomach. The peak concentration in adults is reached within 2.1 to 3.2 hours. Azithromycin accumulates in phagocytes and is actively transported to infection sites, where it is released during active phagocytosis. Tissue concentrations can exceed plasma levels by more than 50 times due to ion trapping and high lipid solubility.

With a prolonged half-life, a single large dose of azithromycin can maintain effective bacteriostatic levels in infected tissues for several days. Following a 500 mg dose, the drug exhibits a polyphasic decline in plasma concentration, with an apparent plasma clearance of 630 mL/min and a terminal elimination half-life of 68 hours. Biliary excretion is the primary elimination route, with approximately 6% of the administered dose excreted unchanged in urine over a week.

Microbiology
Azithromycin works by binding to the 50S ribosomal subunit of susceptible microorganisms, inhibiting protein synthesis without affecting nucleic acid synthesis. It is active against various pathogens, including:

• Aerobic and facultative gram-positive bacteria: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes.
• Aerobic and facultative gram-negative bacteria: Haemophilus ducreyi, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae.
• Other microorganisms: Chlamydia pneumoniae, Chlamydia trachomatis, Mycoplasma pneumoniae.
• Additional strains: Streptococci (Groups C, F, G), Viridans group streptococci, Bordetella pertussis, Legionella pneumophila.
• Anaerobic bacteria: Peptostreptococcus species, Prevotella bivia.

Dosage and Administration

• Adults: 500 mg once daily for 3 days or 500 mg on the first day followed by 250 mg daily for 4 more days. For sexually transmitted infections caused by Chlamydia trachomatis, a single 1 g dose or 500 mg on day 1 followed by 250 mg daily for 2 more days is recommended.
• Children: Dosage varies based on body weight:
  • 10 mg/kg 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 (IV Use Only):
  • Community-acquired pneumonia: 500 mg IV once daily for at least two days, followed by 500 mg orally for 7-10 days.
  • Pelvic inflammatory disease: 500 mg IV once daily for 1-2 days, followed by 250 mg orally for 7 days.

Azithromycin injection is not recommended for children under 16 years.

Reconstitution of Suspension

1. Shake the bottle well to loosen the powder.
2. Add boiled and cooled water up to the indicated mark.
3. Shake until the powder is fully dissolved.
   Azithromycin should be taken at least 1 hour before or 2 hours after meals.

Drug Interactions

• Antacids: Take azithromycin at least 1 hour before or 2 hours after antacids.
• Carbamazepine, methylprednisolone, theophylline: No significant interaction observed.
• Cyclosporin: Monitor cyclosporin levels if co-administered.
• Digoxin: May increase digoxin levels, requiring monitoring.
• Ergot derivatives: Avoid co-administration due to risk of ergotism.
• Warfarin: Routine monitoring of prothrombin time is recommended when used together.
• Terfenadine: No significant effect on cardiac repolarization (QTc interval) observed.

Contraindications
Azithromycin is contraindicated in individuals allergic to azithromycin or other macrolide antibiotics. It should not be used with ergot derivatives or in patients with liver disease.

Side Effects
Common side effects include nausea, abdominal pain, vomiting, diarrhea, flatulence, and loose stools. Some patients may experience allergic reactions such as rash or photosensitivity. Rare cases of cholestatic jaundice and reversible hearing impairment have been reported.

Use During Pregnancy and Lactation
Azithromycin is classified as Pregnancy Category B, meaning animal studies show no risk, but adequate human studies are lacking. It should be used in pregnancy only when no safer alternatives are available. The excretion of azithromycin in breast milk is unknown, so caution is advised in breastfeeding mothers.

Precautions and Warnings
Serious allergic reactions, including anaphylaxis and angioedema, have been reported. These may require prolonged medical observation.

• Renal impairment: No dose adjustment needed for mild impairment (creatinine clearance >40 mL/min), but caution is advised in severe cases.
• Hepatic impairment: Avoid use in patients with liver disease.
• Driving and machinery operation: No evidence suggests impairment.

Overdose Management
Overdose symptoms include nausea, vomiting, diarrhea, and hearing loss. Treatment involves gastric lavage and supportive care.

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

Common Questions

• What is Acos 500 mg Tablet used for?
  It is used to treat respiratory, skin, soft tissue, and sexually transmitted infections.
• Is Acos 500 mg an antibiotic?
  Yes, it is a macrolide antibiotic.
• Can Acos 500 mg cause diarrhea?
  Yes, it can cause diarrhea by disrupting gut bacteria. Consult a doctor if symptoms persist.
• Is it safe to take Acos 500 mg?
  Yes, if used as prescribed by a doctor.
• What if my symptoms don’t improve?
  Consult your doctor if symptoms persist after three days of treatment.

Quick Tips

• Complete the full course of treatment to prevent resistance.
• Take 1 hour before or 2 hours after food.
• Avoid antacids within 2 hours of taking Acos.
• Inform your doctor if diarrhea persists or worsens.
• Seek medical help if you experience allergic reactions.