What is the recommended dosage and treatment duration for Clarithromycin in bacterial infections?

Clarithromycin Dosing and Treatment Duration for Bacterial Infections

For most common bacterial respiratory infections in adults, clarithromycin should be dosed at 500 mg orally twice daily for 7-14 days depending on the specific infection, or as extended-release formulation at 1000 mg once daily with food. 1

Standard Dosing Regimens by Infection Type

Respiratory Tract Infections (Adults)

Acute bacterial exacerbation of chronic bronchitis:

• Extended-release: 1000 mg once daily for 7 days 1
• Immediate-release: 500 mg twice daily for 7-14 days 2

Community-acquired pneumonia:

• Extended-release: 1000 mg once daily for 7 days 1
• Immediate-release: 500 mg twice daily for 7-10 days 3, 2
• This provides coverage for atypical pathogens including Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella species 3, 1

Acute maxillary sinusitis:

• Extended-release: 1000 mg once daily for 14 days 1
• Note the longer duration compared to other respiratory infections 1

Atypical Pathogen Coverage

For Chlamydophila pneumoniae:

• 500 mg orally twice daily for 10 days 3
• Alternative to azithromycin when first-line therapy is not suitable 3

For Legionella species:

• 500 mg orally twice daily for 7-10 days 3
• Can be used as alternative to fluoroquinolones 3

Mycobacterial Infections

Mycobacterium avium complex (MAC) treatment:

• 500 mg twice daily in combination with ethambutol 15 mg/kg daily 3, 2
• Continue for life as chronic maintenance therapy after initial treatment 3
• Critical warning: Doses of 1000 mg twice daily are associated with higher mortality and should never be used 3

MAC prophylaxis (secondary prevention):

• 7.5 mg/kg twice daily (maximum 500 mg per dose) plus ethambutol 3, 2

Other Specific Infections

Lyme disease (when patient is intolerant to first-line agents):

• 500 mg twice daily for 14-21 days 3, 2
• Reserved for patients who cannot tolerate amoxicillin, doxycycline, or cefuroxime 3

Pertussis (whooping cough):

• Adults: 1000 mg per day in two divided doses (500 mg twice daily) for 7 days 2

Helicobacter pylori eradication:

• 500 mg twice daily for 14 days as part of triple therapy with PPI and amoxicillin or metronidazole 2

Pediatric Dosing

Standard pediatric dose (children >1 month):

• 15 mg/kg/day divided into 2 doses (maximum 1000 mg/day) 3, 2
• For pertussis: same dosing for 7 days 2

For NTM infections in children 1 month-11 years:

• 7.5 mg/kg twice daily (maximum 500 mg per dose) 2

Toxoplasmosis prophylaxis in HIV-infected children:

• 7.5 mg/kg twice daily (maximum 500 mg per dose) 3

Critical Dosage Adjustments

Renal Impairment

Severe renal impairment (CrCl <30 mL/min):

• Reduce dose by 50% 1

Moderate renal impairment (CrCl 30-60 mL/min) with concomitant atazanavir or ritonavir:

• Reduce dose by 50% 1

Severe renal impairment (CrCl <30 mL/min) with concomitant atazanavir or ritonavir:

• Reduce dose by 75% 1

Drug Interaction Adjustments

When co-administered with atazanavir:

• Decrease clarithromycin dose by 50% 1

Administration Requirements

Extended-release formulation:

• Must be taken with food 1
• Swallow whole; do not chew, break, or crush tablets 1
• This is critical for maintaining proper drug release and absorption 1

Immediate-release formulation:

• Can be taken with or without food 4
• Absorption is unaffected by food 5, 4

Important Clinical Considerations

Contraindications and Warnings

Absolute contraindications:

• Hypersensitivity to macrolides 1
• Concomitant use with cisapride or pimozide (risk of fatal cardiac arrhythmias) 1
• History of cholestatic jaundice or hepatic dysfunction with prior clarithromycin use 1
• Concomitant use with lomitapide, lovastatin, or simvastatin 1
• Colchicine in patients with renal or hepatic impairment 1

QT prolongation risk:

• Avoid in patients with known QT prolongation, ventricular arrhythmias, hypokalemia, hypomagnesemia, or significant bradycardia 1
• Do not use with Class IA or III antiarrhythmics 1

Drug Interactions

Clarithromycin is a potent CYP3A4 inhibitor, leading to numerous clinically significant drug interactions 1, 4. Monitor closely when used with:

• Carbamazepine, cyclosporin, digoxin, theophylline, warfarin 4
• Calcium channel blockers and other CYP3A4 substrates 1

Enzyme inducers reduce clarithromycin effectiveness:

• Rifampin and rifabutin significantly decrease clarithromycin concentrations 4

Monitoring Recommendations

For prolonged therapy (>2 weeks):

• ECG monitoring at baseline and after 2 weeks in patients at risk for QT prolongation 2
• Audiometry at baseline and if hearing loss symptoms develop 2
• Routine CBC, renal and liver function tests 2

Comparative Efficacy

Clarithromycin demonstrates equivalent clinical efficacy to:

• Beta-lactam agents and cephalosporins for respiratory infections 5, 6, 7
• Azithromycin for most indications 3, 5
• Superior tolerability compared to erythromycin with 5-fold lower withdrawal rates due to adverse events 7

The extended-release formulation provides equivalent efficacy to immediate-release with improved gastrointestinal tolerability and once-daily convenience 8.