Inclusion criteria

Patients meeting all of the following criteria will be considered for enrollment in the study:

• A documented history of asthma for >6 months
• Presenting within 24 hours of initial medical care in an urgent care clinic, emergency room, or in-patient hospital setting. To qualify for enrollment they must present with the following signs and symptoms of an acute deterioration in asthma control: (reduced PEFR, increased wheeze, and dyspnea, with or without cough).
• A PEFR less than 80% of predicted normal

• Females who meet the following conditions:

  • postmenopausal for at least 1 year, or
  • surgically incapable of bearing children, or

  • of childbearing potential, and all of the following conditions are met:

    • had a normal menstrual flow within 1 month before study entry and
    • has a negative pregnancy test (serum b-subunit human chorionic gonadotropin [hCG]) immediately before study entry and
    • must agree to abstinence or use of an accepted method of contraception

Exclusion criteria

Patients presenting with any of the following will not be included in the study:

• Requiring immediate placement in an Intensive Care Unit
• Obvious known allergic precipitant for this episode of acute severe asthma (e.g., acute exposure to animal dander)
• Pneumonia
• Known long QT syndrome or familial history of long QT syndrome (if no previous electrocardiogram [ECG] has invalidated this risk factor), or personal history of coronary disease, ventricular arrhythmia, bradycardia <50 beats/min, or known uncorrected hypokalemia or magnesemia
• Known impaired hepatic or renal function
• Known diagnosis of myasthenia gravis
• Active or quiescent tuberculosis infections of the respiratory tract
• Acute exacerbation of chronic bronchitis, chronic obstructive pulmonary disease, cystic fibrosis, or emphysema
• A history of smoking of 10 pack-years or more
• Women who are breast feeding or are pregnant, as demonstrated by serum or urine pregnancy tests
• Suspected or known hypersensitivity to, or suspected serious adverse reaction to the macrolide class of antibiotics
• A concomitant condition (including clinically relevant cardiovascular, hepatic, neurologic, endocrine, or other major systemic disease) that would make implementation of the protocol or interpretation of the study results difficult
• A recent (within the previous 3 months) history of alcohol or recreational drug misuse.

• Immunocompromised patients, including but not limited to:

  • patients with known human immunodeficiency virus (HIV) infection and have either had or have an AIDS defining condition (e.g., Kaposi's sarcoma, Pneumocystis carinii pneumonia) or a CD4 + T lymphocyte count of <200/mL
  • patients with neutropenia (<1500 neutrophils/mm3)
  • patients with metastatic or hematological malignancy
  • splenectomized patients or patients with known hyposplenia or asplenia
• Planned surgical treatment at any time during the course of the study that would be incompatible with the objectives of this study
• Other disease conditions or infections that could interfere with the evaluation of study treatment efficacy or safety
• Oral steroid-dependent asthma
• Antibiotic use within 30 days prior to enrollment
• Treated within 2 weeks prior to inclusion with CYP3A4 inducers such as rifampicin, phenytoin, carbamazepine, and St. John's Wart
• Currently receiving medication known to prolong QT interval such as cisapride, pimozide, astemizole and terfenadine, or potent CYP3A4 inhibitors such as antiproteases or ketoconazole.
• Patients in whom an antibiotic is clearly indicated.
• Have received treatment with any other investigational drug within 1 month prior to study entry, or have such treatment planned for the study period during treatment and follow-up phase