Modelling aerosol processes related to the atmospheric dispersion of sarin.

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

Microbiological stability of a fentanyl, bupivacaine and clonidine mixture in a 0.9% sodium chloride infusion stored in syringes and reservoirs.

Combinations of extradural opioids and local anesthetic solutions are used in clinical practice, although little information exists on their microbiological or chemical stability. Currently there are no commercially available, prepacked, ready-to-use epidural mixtures of these medications and all mixtures must be prepared by the pharmacist. Epidural analgesic mixtures have been prepared on an as-needed basis. The aim of this study was to investigate the microbiological stability of a fentanyl, bupivacaine and clonidine mixture in a 0.9% sodium chloride infusion (without preservatives), prepared by the pharmacist in order to provide a basis for recommendations on the exchange of containgers (polypropylene syringes and polyvinylchloride [PVC] reservoirs). This mixture maintained microbiological stability for at least 28 days when prepared under aseptic conditions using a laminar air flow station, with a grade A environment and a B background, and using sterile clothes and equipment. During aseptic preparation in a grade A environment, less than 1 colony forming unit (CFU)/m3 and less than 3500 particles greater than 0.5 micrometers with no particle being greater than 5 micrometers, and in a grade B environment less than 10 CFU/m3 and less than 350,000 particles greater than 0.5 micrometers and less than 2,000 particles greater than 5 micrometers are allowed. Putatuive in situ antimicrobial activity of the drug mixture did not interfere with sterility testing. A pH difference was observed over time between the polypropylene syringes and the PVC reservoirs.

Stability of buprenorphine, haloperidol and glycopyrrolate mixture in a 0.9% sodium chloride solution.

Combinations of opioids and adjuvant drug solutions are often used in clinical practice while little information is available on their microbiological or chemical stability. Currently there are no commercially available, prepacked, ready-to-use epidural or subcutaneous mixtures. Thus, epidural and subcutaneous analgesic mixtures must be prepared in the pharmacy on an as-needed basis. Such mixtures are typically used for the treatment of severe pain in cancer patients. The aim of this study was to investigate the microbiological and chemical stability of a buprenorphine, haloperidol and glycopyrrolate mixture in a 0.9% sodium chloride solution. A high performance liquid chromatographic (HPLC) method and pH-meter were used to conduct the analyses. Antimicrobial activity of each component was studied by an agar dilution method. According to the results from the chemical and microbiological stability studies, this mixture can be stored in polypropylene (PP) syringes and polyvinyl chloride (PVC) medication cassettes for at least 30 days at either 21 degrees C or 4 degrees C, and for 16 days in PP syringes at 36 degrees C, and for 9 days in PVC medication cassettes at 36 degrees C.

Stability of Sufentanil in a Syringe Pump under Simulated Epidural Infusion.

Sufentanil is a potent micro-opioid and centrally acting analgesic. In the management of acute postoperative pain, sufentanil is often administered epidurally using a standard syringe pump. For epidural administration, sufentanil is diluted to a concentration of 1 to 2 micrograms/mL with 0.9% sodium chloride injection. The stability of sufentanil in a syringe pump under simulated epidural infusion was studied using a stability-indicating high-performance liquid chromatography method. The concentration of sufentanil was determined in polypropylene syringes connected with a polyethlyene or polyvinyl chloride (PVC) tubing, filter and epidural catheter. Sufentanil concentrations remained constant in polypropylene syringes connected to epidural catheters and in the whole epidural infusion system using polyethylene tubing. Sufentanil concentrations decreased 7% to 15% in syringes connected to PVC tubing, polyethylene tubing and the whole epidural infusion system using PVC tubing. Adsorption of 17% of the sufentanil onto an epidural filter occurred during the first hour of the infusion; thereafter, sufentanil concentration remained stable at levels that were 5% to 15% below the theoretical concentration. In conclusion, adsorption of sufentanil should be considered when a new filter and tubing of different materials are used.