I am not aware of any reports of intraperitoneal sodium thiosulfate.Its molecular weight is 248 and so it is a bit more than twice the size of creatinine. So, in a four hour dwell in a person with an average transport type, half the intraperitoneally administered dose is anticipated to be absorbed. But there is another issue that is not tested – does it cause peritoneal inflammation if administered as twice the iv dose – that would be needed if administered intraperitoneally? With that, I would suggest that you limit to using iv dose described for HD