Effect of primary fluids and dilutional volumes on the delivery of cefazolin sodium by a membrane infusion device.

The influence of primary fluids and dilutional volumes on the accuracy of in vitro delivery of cefazolin sodium by gravity flow through a new controlled-release membrane infusion device was studied. For primary fluid studies, cefazolin 1 g (as the sodium salt) in 10 mL of sterile water for injection was injected into the drug chamber, which is separated by a membrane from the fluid chamber; the entire dose passes into the fluid chamber over a set time. The inlet port of the fluid chamber was connected to the 1-L primary fluid bag, and the outlet port was connected to an administration set. The primary fluids included 0.9% sodium chloride injection; 5% dextrose injection; 10% dextrose injection; 5% dextrose and 0.45% sodium chloride injection; 5% dextrose, 0.45% sodium chloride, and potassium chloride 20 meq/L injection; and 2.2% amino acids with electrolytes in 25% dextrose injection. For dilutional volume studies, cefazolin sodium 1 g diluted in 5, 10, and 15 mL of sterile water for injection was infused with 0.9% sodium chloride injection. The flow rate was set at 1 mL/min. Serial samples were collected in triplicate every five minutes over a 90-minute period and analyzed by high-performance liquid chromatography. The time needed to deliver more than 95% of the cefazolin doses ranged from 35 to 50 minutes using various primary fluids and from 35 to 55 minutes using various dilutional volumes. The manufacturer recommends that a cefazolin dose be delivered completely within 30-60 minutes. The solutes in the primary fluids and the volume injected did not appear to affect the delivery of cefazolin by a controlled-release membrane device.