• R A Prince, D S Lucas, and J L Fox.
• Department of Clinical Sciences and Administration, College of Pharmacy, University of Houston, Texas Medical Center, USA.
• Ann Pharmacother. 1998 Sep 1;32(9):875-7.

ObjectiveTo determine the degree to which a dual-lumen peripheral catheter prevented precipitation of solutions known to be incompatible due to pH during simultaneous infusion in an in vitro model.MethodsAn in vitro model was devised to simulate peripheral venous blood flow from an antecubital source to systemic circulation. Ondansetron was simultaneously infused with fluorouracil, aminophylline, sodium bicarbonate, and ampicillin sodium in concentrations reflective of clinical conditions into the Twin Cath 20/22 (the dual-lumen catheter used in this experiment). Study solutions were primed with the prepared drug solution and administered for 15 minutes. Phase I used Normosol-R as the diluent to gather preliminary data; phase II used human plasma. All samples were obtained immediately before the start of the infusion and at 5, 10, and 15 minutes during the infusion, and 5 minutes after the infusion. Samples were visually inspected at each time point for precipitation and analyzed in duplicate by the appropriate stability-indicating HPLC method (except for sodium bicarbonate). Compatibility was defined as no visual evidence of precipitation and no more than 15% mean change in final versus initial concentration.ResultsPhase I experiments showed immediate precipitation in Normosol-R within the venous flow. However, in phase II, because of the buffering capacity that plasma proteins add to plasma, no precipitation occurred. All the drug combinations used in this study have been reported to be incompatible at the concentrations tested; however, we detected no incompatibilities.ConclusionsThe results of this study indicate that using a dual-lumen peripheral catheter, such as the Twin Cath, may allow solutions incompatible due to pH to be administered simultaneously.

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