<p>Plasma concentrations ranging from 1 to 400 mcg/mL are about 91-99% bound in healthy individuals. The unbound fraction is about 2.3-4.1% at therapeutic concentrations.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Lasix Oral (furosemide) Product Monograph" href="#reference-L9659">12</a></sup> Furosemide mainly binds to serum albumin.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Furosemide - FDA Label" href="#reference-L7958">9</a></sup></p>