Recovery of Tissue Bound Polymyxin B and Colistimethate 1

Abstract

Summary

A method for recovery of tissue bound polymyxin B and colistimethate has been developed. It is based on the finding that these drugs bind strongly to acid phospholipids present in cell membranes. The method employs extraction of lipid fractions by chloroform-methanol followed by release from the binding sites by dilute H₂SO₄. Polymyxin B and colistimethate differ markedly in binding properties probably related to coverage of free amino groups in the latter compound by methane-sulfonation. This method should prove useful in understanding the pharmacologic behavior of these antibiotics when employed in animal models.

This approach may also prove useful in studies of the behavior in the body of other highly positively charged compounds.