1. Introduction
Clarithromycin is a macrolide antibiotic used to treat various bacterial infections. It works by inhibiting bacterial protein synthesis through binding to the 50S ribosomal subunit, thereby stopping bacterial growth. It is effective against a wide range of gram-positive and gram-negative bacteria and is particularly useful for respiratory tract infections, skin infections, and Helicobacter pylori eradication.
2. Indications
- Approved Indications:
- Respiratory tract infections (e.g., pneumonia, bronchitis, sinusitis, pharyngitis).
- Skin and soft tissue infections.
- Helicobacter pylori eradication in peptic ulcer disease (as part of triple or quadruple therapy).
- Mycobacterium avium complex (MAC) infections in HIV patients.
- Acute otitis media (children).
- Off-Label Uses:
- Prevention of pertussis (whooping cough) in contacts of infected individuals.
3. Dosage
- Adults:
- General infections: 250–500 mg every 12 hours for 7–14 days.
- Severe infections: 500 mg every 12 hours.
- Helicobacter pylori eradication: 500 mg twice daily, in combination with other antibiotics and a proton pump inhibitor, for 7–14 days.
- Children:
- 7.5 mg/kg twice daily (maximum 500 mg per dose), for 7–14 days.
- For Mycobacterium avium complex (MAC):
- Adults: 500 mg twice daily (used in combination therapy).
- Children: Dose based on body weight, up to 15 mg/kg/day divided twice daily.
- Maximum Dose:
- Adults: 1000 mg/day.
- Children: Not to exceed 1000 mg/day.
4. Administration
- Can be taken with or without food.
- Extended-release tablets should be taken with food and swallowed whole; do not crush or chew.
- Oral suspension should be shaken well before use.
5. Forms Available
- Tablets: 250 mg, 500 mg.
- Extended-release tablets: 500 mg.
- Oral suspension: 125 mg/5 mL, 250 mg/5 mL.
6. Side Effects
6.1. Common Side Effects
- Nausea.
- Diarrhoea.
- Abdominal pain.
- Altered taste (metallic or bitter taste).
6.2. Less Common Side Effects
- Headache.
- Rash.
- Dizziness.
6.3. Rare but Serious Side Effects
- Hepatotoxicity (jaundice, elevated liver enzymes).
- QT prolongation, leading to arrhythmias.
- Clostridioides difficile-associated diarrhoea.
- Severe allergic reactions (e.g., anaphylaxis).
7. Warnings
- Avoid in patients with a history of QT prolongation or ventricular arrhythmias.
- Use cautiously in patients with severe hepatic impairment or renal impairment.
- Do not use in patients with a known hypersensitivity to macrolides.
8. Precautions
- Monitor for signs of hepatotoxicity, especially in prolonged use.
- Use cautiously in patients taking drugs that prolong the QT interval or those at risk of arrhythmias.
- Avoid unnecessary use to reduce the risk of antibiotic resistance.
9. Interactions
- Drug-Drug Interactions:
- Statins (e.g., simvastatin, atorvastatin): Increased risk of myopathy and rhabdomyolysis.
- Warfarin: Enhanced anticoagulant effect, increasing bleeding risk.
- Benzodiazepines (e.g., midazolam): Increased sedative effects.
- CYP3A4 substrates (e.g., carbamazepine, theophylline): Increased plasma levels of these drugs.
- Drug-Food Interactions:
- No significant interactions, but taking extended-release tablets with food improves absorption.
10. Monitoring Parameters
- Monitor for improvement in infection symptoms (e.g., reduced fever, pain, or inflammation).
- Liver function tests in prolonged or high-dose therapy.
- ECG monitoring in patients with a history of arrhythmias or prolonged QT interval.
11. Use in Children
- Approved for children in appropriate weight-based doses.
- Monitor closely for gastrointestinal side effects.
12. Use in Pregnancy
- Category C: Use only if potential benefits outweigh risks.
- Limited data; avoid unless necessary, especially during the first trimester.
13. Use in Elderly
- Use with caution due to an increased risk of QT prolongation and drug interactions.
14. Use in Kidney Disease
- Dose adjustment required in severe renal impairment (CrCl <30 mL/min): Reduce dose by 50%.
15. Use in Liver Disease
- Avoid in patients with severe liver impairment.
- Use with caution in mild to moderate hepatic dysfunction.
16. Patient Counselling Points
- Complete the full course of treatment, even if symptoms improve early.
- Report any unusual symptoms such as jaundice, severe diarrhoea, or heart palpitations immediately.
- Avoid grapefruit juice as it may increase the risk of side effects by altering drug metabolism.
- Extended-release tablets should be taken with food.
- Shake the oral suspension well before use and measure doses with a calibrated spoon or syringe.
17. Table of Brand Names, Manufacturers, and Prices
Brand Name | Manufacturer | Price (USD) |
---|---|---|
Biaxin | Abbott Laboratories | $40–60 (14 tablets, 500 mg) |
Klaricid | Aspen Pharmacare | $30–50 (14 tablets, 500 mg) |
Generic Options | Various | $10–20 (14 tablets, 500 mg) |
18. FAQs (15 Questions)
- What is clarithromycin used for?
It is used to treat bacterial infections, including respiratory infections, skin infections, and Helicobacter pylori eradication. - How does clarithromycin work?
It inhibits bacterial protein synthesis, stopping bacterial growth. - Can clarithromycin treat viral infections?
No, clarithromycin is ineffective against viral infections such as the flu or common cold. - What are the common side effects of clarithromycin?
Nausea, diarrhoea, abdominal pain, and altered taste. - Can clarithromycin be taken during pregnancy?
It should only be used if the benefits outweigh the risks, particularly during the first trimester. - Is clarithromycin safe for children?
Yes, it is approved for children when dosed appropriately. - How should clarithromycin be taken?
Tablets can be taken with or without food, but extended-release tablets should be taken with food. - Does clarithromycin interact with other medications?
Yes, it interacts with statins, warfarin, benzodiazepines, and other drugs metabolised by CYP3A4. - How long does clarithromycin take to work?
Symptom improvement is typically seen within 2–3 days, but the full course should be completed. - What should I do if I miss a dose?
Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double the dose. - Can clarithromycin cause heart problems?
Yes, it may cause QT prolongation, increasing the risk of arrhythmias in susceptible individuals. - Can clarithromycin be used for Helicobacter pylori eradication?
Yes, it is part of standard triple or quadruple therapy for H. pylori infections. - Does clarithromycin cause liver problems?
Rarely, it may cause hepatotoxicity. Report symptoms like jaundice or abdominal pain immediately. - Can clarithromycin be taken with alcohol?
It is advisable to avoid alcohol to minimise side effects like nausea or dizziness. - How should clarithromycin be stored?
Store tablets at room temperature and oral suspension in the refrigerator, discarding unused suspension after 14 days.