Biodistribution of radio-labeled rifampicin in animals.
Throughout the duration of the trial, the rats were in good health.
Animals ”exhibited normal feed consumption” and was well-tolerated.
There was no influence on body weight during the trial period, and the
body weight was unrelated to dose amounts.
Figure 5 represents the distribution of labeled rifampicin in percentage
administered dose per gram of organ (%AD/g). Approximately 2.7%,
1.24%, 0.58%, 0.5%, and 0.99% drug was found in lungs, liver,
thyroid, kidneys, and stomach, respectively, at 30 minutes after oral
administration of 4mg/kg rifampicin containing 100-200 µCi of activity.
The highest percentage of radio-activity was found in the stomach
because of the oral administration of labeled rifampicin, which acts as
the source organ. At 4 and 8 h, the percentage of activity in the lungs
starts to decrease. Subsequently, the radio-activity in the kidneys and
liver starts to increase. The peak percentage of activity in the lungs
was found at 30 min and decreased over 8 hours post oral administration
of labeled rifampicin (Fig.5). Thus, attachment of99mTc to the rifampicin molecule does not affect the
PK of rifampicin.