Related Experiment Videos
Diamorphine and bupivacaine mixtures: an in vitro study of microbiological safety
T M Cook1, P A James, C F Stannard
1Anaesthesia, Royal United Hospital, Bath, UK.
Abstract:
A small survey confirms that epidural infusions are often prepared by clinicians and solutions may be changed each day because of fears of microbiological contamination. We have assessed the microbiological safety of six mixtures of diamorphine (0.01-1.0%) and bupivacaine (0.1-0.5%) representing the spectrum of clinically useful concentrations for use as extradural infusions. The solutions were studied for antibacterial activity against common contaminants of fluids: Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and a coagulase negative Staphylococcus sp. A saline control was included. Challenge experiments used an inoculum of approximately 5.0 x 10(6) cfu/ml. Mixtures were incubated at 30 degrees C for up to 7 days. Viable counts of all organisms decreased with time for all the formulations tested. Formulations containing 0.5% bupivacaine were rapidly bactericidal, and increasing diamorphine concentrations increased this effect. Formulations with 0.5% bupivacaine had more activity than those with 0.1% bupivacaine. Mixtures of diamorphine and bupivacaine in concentrations used clinically have bactericidal activity against commonly encountered skin organisms. The common practice of changing every day epidural infusions containing these drugs is unnecessary.
Insights
Daily changes of epidural infusions containing diamorphine and bupivacaine are unnecessary. These mixtures demonstrate significant antibacterial activity, reducing contamination risks in clinical settings.
Area of Science:
- Anesthesiology
- Microbiology
- Pharmaceutical Sciences
Background:
- Epidural infusions are often prepared by clinicians.
- Concerns about microbiological contamination lead to daily changes of these solutions.
Purpose of the Study:
- To assess the microbiological safety of epidural infusion mixtures.
- To evaluate the antibacterial activity of diamorphine and bupivacaine formulations.
Main Methods:
- Tested six mixtures of diamorphine (0.01-1.0%) and bupivacaine (0.1-0.5%) against common bacteria (E. coli, P. aeruginosa, E. faecalis, Staph. sp.).
- Conducted challenge experiments with an inoculum of ~5.0 x 10(6) cfu/ml.
- Incubated mixtures at 30°C for up to 7 days, monitoring viable bacterial counts.
Main Results:
- All tested formulations showed decreasing viable bacterial counts over time.
- Formulations with 0.5% bupivacaine exhibited rapid bactericidal effects.
- Higher diamorphine concentrations enhanced the bactericidal activity, especially with 0.5% bupivacaine.
Conclusions:
- Clinically relevant concentrations of diamorphine and bupivacaine mixtures possess significant bactericidal activity.
- The practice of changing epidural infusions daily due to contamination fears is not supported by these findings.
- These findings suggest extended stability and safety for epidural infusions with these drug combinations.