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Published on: December 25, 2015
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Initiation of an Emulsion Microinfusion: Flow Direction Influences Delivery Onset Rate.
Amy C Tsao1, Michael J Parker2, Mark A Lovich3
1Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
Summary
Delivery of emulsion drugs via microinfusion depends on flow direction. Upward flow can cause a rapid drug delivery, while downward or horizontal flow results in significant delays, impacting patient safety.
Area of Science:
- Anesthesiology
- Pharmacology
- Biomedical Engineering
Background:
- Critically ill patients often receive medications via continuous intravenous infusion.
- Microinfusion delivers concentrated drugs using low-volume carriers, conserving fluid.
- Delivery onset lag times are known for water-soluble drugs but not emulsions.
Purpose of the Study:
- To investigate if an emulsion's physical characteristics affect its microinfusion delivery onset.
- To compare the delivery kinetics of a water-soluble drug surrogate versus an emulsion surrogate in vitro.
Main Methods:
- An in vitro microinfusion model was adapted to test delivery onset.
- Methylene blue (water-soluble surrogate) and a 10% lipid emulsion were used.
- Delivery was tested with vertical upward, vertical downward, and horizontal carrier flow.
Main Results:
- Emulsion delivery into upward vertical flow showed rapid initial delivery, exceeding model predictions.
- Emulsion delivery into horizontal and downward vertical flows exhibited long lag times to steady state.
- Water-soluble drug surrogate delivery was not affected by carrier flow orientation.
Conclusions:
- Carrier flow orientation significantly impacts emulsion microinfusion delivery onset.
- Upward flow may lead to a relative bolus of emulsion drugs, while downward/horizontal flow causes delays.
- These differences in delivery kinetics have potential clinical implications for efficacy and safety of potent emulsion drugs.
