ABSTRACT
The zero-order input in this chapter refers to the administration of solution with known concentration of a compound into the systemic circulation via intravenous administration over a period of time. Thus, the input is not instantaneous, as was discussed in Chapter 10, and the constant rate of input is considered zero-order kinetics. The specialized infusions through routes of administration such as epidural or intrathecal are not a part of this discussion. Intravenous infusion is used commonly to treat illnesses that require long-term exposure and duration of action, or when the administration of bolus dose can be hazardous to the human subject or experimental animals. Often the long-term exposure to organic solvents that can absorb through inhalation and enter the systemic circulation without impediment can also be considered zero-order input. An intravenous infusion requires that the compound remains stable and soluble in the solution, and tolerable by the subject. The vehicles are usually solutions containing water of highest purity and sterility with dextrose, saline or other specialized additives and/or medications.
