What is the appropriate dose of Zithromax (azithromycin) for a patient with mycoplasma pneumonia?

Azithromycin Dosing for Mycoplasma Pneumonia

Critical Information Missing

The patient's weight is listed as "[AGE] pounds" which appears to be a placeholder error - I need the actual weight in pounds or kilograms to calculate the precise dose. However, I will provide the complete dosing algorithm below so you can calculate it once the weight is known.

Pediatric Dosing Algorithm

For pediatric patients with Mycoplasma pneumonia, administer azithromycin 10 mg/kg (maximum 500 mg) as a single dose on day 1, followed by 5 mg/kg (maximum 250 mg) once daily on days 2-5, for a total 5-day course. 1, 2

Step-by-Step Calculation:

• Day 1: 10 mg/kg × patient's weight in kg = dose (maximum 500 mg)
• Days 2-5: 5 mg/kg × patient's weight in kg = dose (maximum 250 mg daily)
• Total course: 30 mg/kg over 5 days 2

Practical Dosing Examples from FDA Label:

For reference, here are weight-based doses 2:

• 5 kg (11 lbs): Day 1: 2.5 mL of 100 mg/5 mL suspension; Days 2-5: 1.25 mL daily
• 10 kg (22 lbs): Day 1: 5 mL (1 tsp); Days 2-5: 2.5 mL (½ tsp) daily
• 20 kg (44 lbs): Day 1: 5 mL of 200 mg/5 mL suspension; Days 2-5: 2.5 mL daily
• 30 kg (66 lbs): Day 1: 7.5 mL (1½ tsp); Days 2-5: 3.75 mL (¾ tsp) daily
• 40 kg (88 lbs): Day 1: 10 mL (2 tsp); Days 2-5: 5 mL (1 tsp) daily
• ≥50 kg (≥110 lbs): Day 1: 500 mg; Days 2-5: 250 mg daily

Adult Dosing

For adults with Mycoplasma pneumonia, the standard regimen is 500 mg as a single dose on day 1, followed by 250 mg once daily on days 2-5. 3, 2

Alternative Adult Regimens:

The Taiwan pneumonia guidelines list azithromycin as an alternative (not first-line) for Mycoplasma pneumoniae, with the regimen: 500 mg PO on day 1, then 250 mg PO daily for 4 days 3

Note that doxycycline is actually the preferred first-line agent for Mycoplasma pneumoniae in adults (100 mg IV/PO twice daily for 7-14 days), with azithromycin listed as an alternative 3

Administration Considerations

• Can be taken with or without food 2
• Avoid concurrent aluminum- or magnesium-containing antacids as they reduce absorption; separate administration times if antacids are necessary 1
• Monitor for QT prolongation if used with other QT-prolonging medications 1

Clinical Monitoring

• Review patient after 48 hours of treatment; if not improving or deteriorating, re-evaluation is necessary 4
• Maintain oxygen saturation above 92% if respiratory compromise is present 4
• Most patients become afebrile within 48 hours of starting treatment 5, 6

Special Populations

Severe Disease Requiring Hospitalization:

For severe Mycoplasma pneumonia requiring IV therapy, consider adding azithromycin to beta-lactam coverage for hospitalized patients 3

Renal Impairment:

No dosage adjustment needed for GFR 10-80 mL/min; use caution with GFR <10 mL/min 2

Hepatic Impairment:

No specific dose adjustment recommendations available; use with caution 2

Common Pitfalls to Avoid

• Do not use doxycycline in children under 7 years due to dental staining concerns 4
• Do not exceed maximum doses even in heavier patients (500 mg day 1,250 mg days 2-5) 2
• If patient vomits within 30 minutes of the 30 mg/kg single-dose regimen (used for otitis media), re-dosing has been studied but safety not fully established 2
• Azithromycin's long half-life (68 hours) creates prolonged subinhibitory concentrations that may select for resistant organisms 3