Although used in Europe, Canada and Mexico,[1] spiramycin is still considered an experimental drug in the United States, but can sometimes be obtained by special permission from the FDA for toxoplasmosis in the first trimester of pregnancy.
[2] Spiramycin has been used in Europe since the year 2000 under the trade name "Rovamycine", produced by Rhone-Poulenc Rorer, Sanofi and Famar Lyon, France and Eczacıbaşı İlaç, Turkey.
Resistance to spiramycin can develop by several mechanisms and its prevalence is to a considerable extent proportional to the frequency of prescription in a given area.
This difference between the effectiveness in vitro and in vivo is explained above all by the great affinity of spiramycin to tissues where it achieves concentrations many times higher than serum levels.
An important part is played also by the slow release of the antibiotic from the tissue compartment, the marked action on microbes in sub-inhibition concentrations and the relatively long persisting post-antibiotic effect.