Agent is provided as 5 vials of Ca-DTPA and 5 of Zn-DTPA. This would the agent needed for 5 chelation sessions, which is appropriate to start for essentially all subjects. Hopefully for most, enough for sufficient treatment as well.
Chelation is a 2 day process. Ca-DTPA the first day and Zn- DTPA the second.
The injections are 2.5 ml of Ca-DTPA early after iv started and 2.5 ml Ca-DTPA towards the end of the iv fluid injection on day 1, and the same repeated with Zn-DTPA on day 2.
It is a slow 1 minute push. I have described the thinking of the iv push, the push emulates how the GBCA was administered in the first place - the concept is it should follow the path of where then the GBCA went in the first place. We know from work with iodine and Gd contrast agent administrations that bolus injections and iv drip injections behave differently with tissue enhancement, so I want the chelate to follow the path of the GBCA, as essentially all GBCA injections are bolus > this is how Gd entered the body and tissues, so I want the chelator to follow the same path. To use an old West analogy: I want the DTPA to follow the tracks of the GBCA agent, like a Gd posse.
This protocol is a modification of what the manufacturer developed for removing radio-active metals (and hence FDA approved strategy). Ca is given first as it removes more metal in general, which includes host metals, but critically including more Gd. Zn administered the next day to remove Gd more specifically (but less of it), remove essentially none of the host metals and cations, and to restore Zn that would have also been removed by Ca-DTPA.