A single dose vial containing 100 mg of fam-trastuzumab derux tecan-ki as a white to yellowish white lyophilized powder for reconstitution and subsequent dilution is available for injection. A complete dose may necessitate the use of more than one vial. Determine the dosage (in milligrammes), total amount of reconstituted Enhertu solution, and number of Enhertu vials needed. Using a sterile syringe, slowly inject 5 mL of Sterile Water for Injection, USP into each 100 mg vial to reconstitute them at a final dosage of 20 mg/mL. Enhertu 100 mg injection is moderately priced, and the required dosage is available from a limited number of specialty wholesalers and pharmacy providers.