A nurse is preparing to administer two different IV medications through the same IV line. Which step must be performed between medications?

IV DRUG COMPATIBILITY and proper flushing between medications is a patient safety requirement, not an optional step. WHY FLUSHING MATTERS: Many IV drugs are INCOMPATIBLE with each other — when they mix in the IV tubing, they can: precipitate (form a solid that can cause emboli); inactivate each other (reducing drug effectiveness); form toxic compounds; change pH in ways that cause pain at the IV site or vein damage. FLUSH PROCEDURE: Before the second drug: flush with the facility-approved flush solution (typically normal saline 5-10 mL for peripheral IV, 10-20 mL for central lines); the flush volume clears the tubing of the first drug before the second is introduced; after the second drug: another flush to ensure the full dose enters the bloodstream and the line is clear. COMPATIBLE FLUSH SOLUTIONS: Normal saline (NS/0.9% NaCl) is compatible with most IV drugs and is the standard flush; Dextrose 5% water (D5W) is compatible with some but not all; heparinized saline was previously used for some lines — now less common. SPECIFIC HIGH-RISK INCOMPATIBILITIES: Phenytoin (Dilantin) + ANY dextrose-containing solution → precipitates immediately; Ceftriaxone (Rocephin) + calcium-containing solutions (including Lactated Ringer's) → can cause fatal precipitate (especially in neonates — black box warning); Furosemide and many aminoglycosides; Ampicillin + gentamicin. RESOURCE: Clinical pharmacists and IV compatibility resources (Lexi-IV, King Guide) should be consulted for any uncertain combinations.