Reconstituted thiopentone retains its alkalinity without bacterial contamination for up to four weeks

Abstract

The manufacturers of thiopentone recommend that after reconstitution, it should be kept only for 24 hr to reduce the risk of contamination. However, there are no studies to support this practice and compliance with this recommendation has economic implications. The reasons for discarding a reconstituted bottle of thiopentone are related to concerns about chemical and physical (pH) stability, contamination with infectious agents, and contamination with cellular material. We studied the incidence of bacterial contamination and pH stability of thiopentone in clinical use, as well as the pH stability of thiopentone not in clinical use, and surveyed the eight hospitals affiliated with the University of British Columbia to determine their protocols for thiopental preparation and storage. Cost comparisons were made between our current practice of discarding thiopentone when depleted and the practice of routinely discarding it 24 hr after reconstitution. Samples of thiopentone in clinical use were cultured daily and the pH was measured. The bottles had been in clinical use from 1 to 25 days (mean 4.23 +/- 4.32 SD). Of 106 samples there were no positive bacteriological cultures and there were only minor changes in pH. The telephone survey of the eight hospitals revealed that only one had a policy to discard thiopentone after 24 hr. Cost comparisons indicate that discarding thiopentone 24 hr after reconstitution would result in increased cost. In conclusion, reconstituted thiopentone retains its alkalinity for up to four weeks, and has an acceptably low risk of bacterial contamination for periods beyond 24 hr, therefore thiopentone need not be discarded after 24 hr.

Evaluation of the Antibacterial Activities of the Agents Used for Sedation in Intensive Care Unit In Vitro Method

“…In previous studies, antimicrobial effects of various sedative agents have been studied, but the mechanism underlying their antibacterial activity has not been fully understood. Several studies found that the antimicrobial effects of some of the sedative agents may depend on their molecular weight, pH, and thermodynamic activity (12)(13)(14). A number of researchers revealed the interaction between the cytoplasmic membrane and macromolecule, through which the agents can alter membrane functions by decreasing the number of viable cells and causing the lysis of protoplasts, thus changing the permeability (12).…”

A comparison of microbial growth in alfaxalone, propofol and thiopental

“…Three positive cultures obtained from different thiopental vials in our study at 24 hours, seven days and 14 days were considered to be the result of survival of organisms washed up on the side or lid of the vial after agitation, or were due to laboratory contamination. Thiopental is frequently used for longer after reconstitution than recommended by the manufactures in many human hospitals (Wong and others 1992).…”

“…The pH of propofol and alfaxalone provides a suitable environment for bacterial replication, whereas the strongly alkaline pH of thiopental creates a bactericidal environment for most pathogenic microorganisms. Although reconstituted barbiturates are unstable in solution, Wong and others (1992) showed that even uncapped bottles of 2·5 per cent thiopental maintained their pH for at least four weeks at room temperature. In our study, the three anaesthetic agents were kept at room temperature, although the manufactures of thiopental recommend storage at 2 to 8°C after reconstitution.…”

Do Intensive Care Drug Infusions Support Microbial Growth?

“…• midazolam HCl (Roche)-as supplied 10 mg/ml; 1 mg/ml in normal saline; 1 mg/ml in 5% dextrose • morphine sulphate (David Bull Laboratories)-as supplied 10 mg/ml; 1 mg/ml in normal saline; 1 mg/ml in 5% dextrose • fentanyl citrate (Astra)-as supplied 50 µg/ml; 10 µg/ml in normal saline; 10 µg/ml in 5% dextrose • pethidine HCl (Sigma)-as supplied 50 mg/ml; 10 mg/ml in normal saline; 10 mg/ml in 5% dextrose • bupivacaine HCl (Astra)-as supplied 0.5%; as supplied 0.25%; 0.1% in normal saline. After review of the literature [7][8][9] , the following protocol was followed.…”