Azithromycin as Cystic Fibrosis Treatment

• Zithromax
• Distributed by Pfizer

Azithromycin is an oral macrolide antibiotic that is sometimes used along with other medications to treat Pseudomonas aeruginosa in people with cystic fibrosis (CF). The exact way that azithromycin helps people with CF is not yet known. Azithromycin does not kill P. aeruginosa, but can help reduce its growth in the lungs. Azithromycin may also reduce swelling of the airways, which can improve lung function and prevent long hospital stays.

Azithromycin is an antibiotic that is used to treat many types of infections in people with and without cystic fibrosis. People with cystic fibrosis who take azithromycin to treat P. aeruginosa:

• Are at least 6 years old
• Weigh at least 55 pounds
• Have mild to moderate lung disease with an FEV₁ >30%

• People who are allergic to azithromycin or other antibiotics in the same family (macrolides)

Azithromycin is taken orally, either in a tablet or in an a liquid suspension. For short-term treatment of most infections, azithromycin is taken once daily. For long-term treatment of P. aeruginosa in people with cystic fibrosis, azithromycin is usually taken three times per week.

Azithromycin should be stored at room temperature, away from extreme heat or intense light. The oral suspension must be discarded 10 days after it has been mixed, but can be kept in powder form until the expiration date on the bottle and reconstituted with water when a dose is needed.

Some common side effects of azithromycin include:

• Nausea
• Abdominal discomfort
• Mild diarrhea
• Headache
• Unpleasant taste in the mouth
• Dizziness

Serious side effects are rare, but have been reported. Notify your doctor immediately if you have:

• Severe or bloody diarrhea
• Swelling or tingling of the throat, lips, mouth, or face
• Chest pain or tightness
• Red, blistered skin
• Yellow skin or eyes
• Dark urine

Before taking azithromycin, tell your doctor if you:

• Are also taking digoxin, ergotamine, triazolam, warfarin or other blood thinners, tacrolimus, cyclosporine, or antacids
• Are allergic to azithromycin or other macrolide antibitotics such as erythromycin or clarithromycin
• Are pregnant or breastfeeding
• Have kidney or liver disease

A 30-day supply of azithromycin costs between $50 to $400, depending on the dose, brand, and formula. It is covered by most insurance plans. If you do not have insurance, or your insurance does not cover azithromycin, you may be able to qualify for Pfizer’s assistance program for Zithromax.

_Sources:

Pfizer Labs. Zithromax Prescribing Information. August 2007.

Saiman, et al. “Azithromycin in Patients With Cystic Fibrosis Chronically Infected With Pseudomonas aeruginosa”. 2003. JAMA (290)13:1749-1756.