How long does iv zosyn take to get out of your system after stopping?

Answer 1

The halflife is between 0.7 and 1.2 hours. However, perfusion into various tissues allows for a peak plasma distribution if given IV every 6-8 hours. I'm guessing you're clear after 48 hours. Additional information:

As a general rule, steady-state plasma (or tissue) levels are reached after 5 half-lives and, conversely, non-pharmacologic concentrations are reached in the same amount of time.

IV medications complicate things somewhat, since peak and steady-state levels are reached immediately as the medication is delivered directly to the blood stream. Given the half life of Zosyn is 0.7-1.2 hours, and peak plasma concentration is reached immediately after the infusion, it should take 3.5-6 hours for the drug to be completely (or at least to the point of almost not being able to detect it) out of your system. If you look at the tables on the link below, this appears to bear out.

Tissue concentrations may vary, however - tissue concentrations are roughly 50-100 percent of plasma concentration and I cannot find any data to suggest it is more apt to stay in the tissues vs re-distributing to the bloodstream as plasma levels fall, so I have to assume that tissue concentrations follow plasma concentration, which gives us the same time-table. For completely being out of your system (not just pharmacologically out of your system), it probably is completely cleared by 24 hours after a single dose. Multiple doses may complicate the picture, however, and require more time for clearance. Renal function will also play a factor, as this drug is cleared by the kidney.