Frusemide or Furosemide, a diuretic, is rapid acting and should be cleared within 15-24 hrs under normal physiologic conditions. However, please refer to the following resources for more precise information

Academic: Medications then enter name of drug

Pharmaceutical mfg: Furosemide 20mg/2ml Injectable Ampoule, Injectable solutions

Federal Drug Admin: http://www.fda.gov/drugs/drugsafety/.../ucm111085.htm then search drug by name.

Independent web resources:
1) Complete Furosemide information from Drugs.com
2) Lasix (Furosemide) Drug Information: User Reviews, Side Effects, Drug Interactions and Dosage at RxList

Should you need further clarification (medical terminology, etc) in relation to the above resources please let us know.

You are always wise to check on your prescribed medications and I congratulate you for doing so.