Azithromycin concentrations in sinus fluid and mucosa after oral administration

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Abstract
The concentrations of azithromycin in sinus fluid and mucosal tissue were determined in a total of 23 patients with acute or chronic sinusitis. Five patients with acute sinusitis and four with chronic sinusitis were administered a five-day course of oral azithromycin (500 mg on day 1, 250 mg on days 2–5, all as single doses), and the remaining 14 patients, all with chronic sinusitis, received single oral doses of azithromycin (500 mg). With the five-day regimen, the mean levels of azithromycin in sinus fluid were markedly higher in patients with acute sinusitis (1.34 µg/ml) than in patients with chronic sinusitis (0.25 µg/ml) 24 h after the first dose. The levels of azithromycin in the sinus fluid increased from the first to the last dose in both patient groups; the mean levels of azithromycin 24 h after the last dose were 2.33 µg/ml in acute sinusitis patients and 0.38 µg/ml in chronic sinusitis patients. In chronic sufferers, the mean levels of azithromycin in the sinus fluid following a single oral dose were 0.25, 0.41, 0.57 and 0.22 µg/ml at 24, 48, 72 and 96 h, respectively, after administration. In these patients the mean sinus drug concentrations were much greater in the mucosal tissue (1.23 µg/g) than in the sinus fluid (0.41 µg/ml) 48 h after administration of the single dose. There were no treatment-related changes in laboratory function tests, and side effects were described as mild to moderate (five patients complained of nausea, abdominal pain or headache). It is concluded that azithromycin penetrates into sinus fluid and tissue, particularly in patients with acute sinusitis, and persists at significant levels for up to four days after administration.