Spiramycin concentrations in the human respiratory tract: a review.

Spiramycin has exceptionally good distribution properties, especially in respiratory tract tissues and fluids. Three hours after a single oral dose of 3 g spiramycin, the serum concentration ranged from 1.6 to 2.8 mg/l and the reported half-life was approximately 8 h. Studies of lung tissue concentrations showed that high pulmonary levels were achieved after a loading dose of 3 g; the levels were higher after multiple doses and reached approximately 30 to 45 mg/kg in lung tissue and 6.5 to 36 mg/kg in bronchial mucosa; in bronchial secretions and in sputum the concentrations of spiramycin ranged from 1.5 to 7.3 mg/l (after 1 g, multiple doses). In upper respiratory tract tissues and fluids, high levels of spiramycin were reached as well: 8 to 13 mg/kg in sinus mucosa; 15 to 29.5 mg/kg in tonsils or adenoids.