Background: Acute bacterial sinusitis is one of the most common causes for antibacterial treatment. Oral Penbactam (ampicillin- sulbactum or Sultamicillin) is a broad spectrum antibiotic and it has no significant side effect. To our knowledge, this is the first study in Iran in which, oral Penbactam has been prescribed for patients with acute bacterial sinusitis.

Methods: A randomized clinical trial was performed on 44 outpatients diagnosed with acute bacterial sinusitis in Amir- Aalam Hospital from March 2003-2004 to August 2004. Patients were randomized in 2 group: 23 to oral Penbactam (375 mg twice daily), and 21 to oral Co-amoxicolav (625 mg three times daily). Duration of treatment was 10 days for both groups.

Results: Both groups showed a significant clinical improvement after 10 days of treatment. In the Penbactam group, 19 of 23 (86.36%) and in the Co-amoxicolav group ,18 of 21 (85.71%) showed clinical improvement. In the Penbactam group, one patient (4.3 %) developed diarrhea and the medication was discontinued.

Conclusion: Oral Penbactam is an effective and safe antibiotic in the treatment of acute bacterial sinusitis and could be used as an alternative medication for acute bacterial sinusitis.