Physical Compatibility of Propofol-Sufentanil Mixtures.

BACKGROUND: Combined infusions of propofol and sufentanil preparations are frequently used in clinical practice to induce anesthesia and analgesia. However, the stability of propofol emulsions can be affected by dilution with another preparation, sometimes leading to particle coalescence and enlargement. Such unwanted effects can lead to fat embolism syndrome after intravenous application. This study describes the physical stability of 5 commercially available propofol preparations mixed with sufentanil citrate solutions. METHODS: Two common markers of emulsion stability were used in this study; namely, the zeta potential and size distribution of the emulsion droplets. Both were measured using dynamic light scattering. The data for the pure propofol preparations and their mixtures with sufentanil citrate solution were compared. RESULTS: The absolute value of zeta potential decreased in 4 of the 5 propofol preparations after they had been mixed with sufentanil citrate. This effect indicates a lowering of repulsive interactions between the emulsion droplets. Although this phenomenon tends to cause agglomeration, none of the studied mixtures displayed a substantial increase in droplet size within 24 hours of blending. However, our long-term stability study revealed the instability of some of the propofol-sufentanil samples. Two of the 5 studied mixtures displayed a continual increase in particle size. The same 2 preparations showed the greatest reductions in the absolute value of zeta potential, thereby confirming the correlation of both measurement methods. The increase in particle size was more distinct in the samples stored at higher temperatures and with higher sufentanil concentrations. CONCLUSIONS: To ensure the microbial stability of an emulsion infusion preparation, clinical regulations require that such preparations should be applied to patients within 12 hours of opening. In this respect, we can confirm that during this period, none of the studied propofol-sufentanil mixtures displayed any physical instability that could lead to particle enlargement; thus, fat embolism should not be a risk after their intravenous application. However, our long-term stability study revealed differences between commercially available preparations containing the same active ingredient; some of the mixtures showed an increase in particle size and polydispersity over a longer period. Although our results should not be generalized beyond the particular propofol-sufentanil preparations and concentrations studied here, they do suggest that, as a general principle, a compatibility study should be performed for any preparation before the first intravenous application to exclude the risk of droplet aggregation.

[Optimal way of administration of high dose intravenous furosemide - continuous infusion or bolus?]. / Optimální zpusob podání vysokodávkového i.v. furosemidu - kontinuálne nebo bolusove?

INTRODUCTION: Furosemide is a loop diuretic used in states of volume overload. The need for high doses is due to its reduced efficacy caused by lower concentration of furosemide achieved at the site of action in the renal tubule lumen and adaptation mechanisms. High doses have been associated with the development of ionic dysbalance, direct toxicity and intravascular volume fluctuations. The way of furosemide administration (intermitent versus continuously) to influence efficacy and safety is contradictory evaluated in EBM. AIM: The aim of this study is to analyze the available data for evaluation of the efficacy and safety of intermittent versus continuous dose regimens. METHODS: A systematic search on PubMed from 1990 to 2013 using the keywords - furosemide, loop diuretic, bolus, continuous infusion, efficacy, safety, heart failure, ICU, critical care. CONCLUSION: The pharmacokinetic and pharmacodynamic knowledge of furosemide create a theoretical assumption for the preference of continuous infusions before intermittent boluses. Assessement of available studies, however, yet in clinical practice did not proof the advantage of one over the other route of administration.