Propofol formulated with long-/medium-chain triglycerides reduces the pain of injection by target controlled infusion

Pain Intensity at Injection Site during Esophagogastroduodenoscopy Using Long- and Medium-Chain versus Long-Chain Triglyceride Propofol: A Randomized Controlled Double-Blind Study

Background/Aims

The intensities of injection pain resulting from the use of long- and medium-chain triglyceride (LCT/MCT) propofol and conventional LCT propofol during esophagogastroduodenoscopy (EGD) have yet to be compared. We aimed to determine the pain intensity caused by different formulations of propofol and to evaluate the formulation that would be preferred by patients as a sedative agent during their next procedure.

Methods

This study was a single-center, randomized, controlled, and double-blind trial. Pain intensity was estimated 30 seconds after propofol injection by an examiner who was blinded to the group assignment using a numeric (0-10) pain rating scale (NPRS). After 1 week, the patients were asked whether they could recall the pain and were willing to receive the same agent for their next EGD.

Results

One hundred twenty-nine patients were randomly assigned to LCT/MCT or LCT group. Although there was no significant difference in pain incidence between the LCT/MCT and LCT groups (52.9% vs 65.6%, p=0.156), the pain intensity was significantly lower in the LCT/MCT group (NPRS median [interquartile range]; 1 (0-2) vs 2 (0-5), p=0.005). After 1 week, fewer patients in the LCT/MCT group recalled the pain (19.1% vs 63.9%, p<0.001) and more patients in the LCT/MCT group were more willing to use the same agent for their next procedure (86.8% vs 72.1%, p=0.048) than in the LCT group.

Conclusions

LCT/MCT propofol significantly reduced injection pain intensity compared to LCT propofol during EGD and preferred by patients as a sedative agent during their next EGD.

Median Effective Dose of Lidocaine for the Prevention of Pain Caused by the Injection of Propofol Formulated with Medium- and Long-Chain Triglycerides Based on Lean Body Weight

OBJECTIVE

To determine the median effective dose (ED50) of prophylactic intravenous lidocaine for the prevention of propofol medium-chain triglyceride/long-chain triglyceride (MCT/LCT) emulsion injection pain.

DESIGN

Prospective trial, Dixon up-and-down sequential method.

SETTING

Operating room of a single hospital.

PATIENTS

Thirty patients aged 18-65 years with American Society of Anesthesiologists (ASA) status I or II who were scheduled for elective surgery under general anesthesia (GA) were included.

INTERVENTIONS

The initial dose of prophylactic lidocaine before propofol MCT/LCT emulsion injection was set at 0.5 mg/kg lean body weight (LBW). The lidocaine dose was adjusted according to the degree of patients' injection pain using the Dixon up-and-down sequential method.

MEASUREMENTS

The ED50 and 95% confidence intervals (CIs) of lidocaine were calculated using the Dixon-Massey formula. Vital signs and adverse effects were recorded. In the postanesthesia care unit (PACU), patients were asked if they recalled feeling any injection pain with visual analog scale (VAS) evaluation.

RESULTS

The ED50 of lidocaine for the prevention of propofol MCT/LCT emulsion injection pain was 0.306 mg/kg LBW (95% CI, 0.262-0.357 mg/kg LBW). No adverse reactions to lidocaine occurred. In the PACU, 90.9% of patients who experienced injection pain recalled this pain (VAS score, 2.8±1.8).

CONCLUSIONS

Prophylactic intravenous lidocaine (0.306 mg/kg LBW) effectively prevented propofol MCT/LCT emulsion injection pain in 50% of patients scheduled for elective surgery under GA with no adverse reaction occurring.

The Effect of Propofol Infusion Before Administration of Its Bolus Dose on Propofol Injection Pain and Serum Complement C3 Levels; A Randomized Clinical Trial

Background

Pain on injection with propofol is still a major problem associated with anesthesia. Several factors involved in this event have been studied with respect to their pain attenuating effects.

Objectives

The purpose of this study was to evaluate the effect of propofol infusion before administration of its bolus dose of propofol on the resulted pain at its induction dose and on serum complement C3 levels.

Methods

This clinical trial was performed on patients undergoing surgery under general anesthesia divided into three groups, including A (without intervention), B (propofol infusion at a dose of 50 µg/kg/min before anesthesia induction), and C (propofol infusion at a dose of 100 µg/kg/min 100 before anesthesia induction). During anesthesia induction by propofol, the presence, absence or severity of pain was determined using the Numerical Rating Pain Scale. Serum complement C3 levels were measured and their relationships with pain scores were compared between three groups. The data were analyzed using SPSS V. 22 software.

Results

There were significant differences in the mean pain scores between three groups (P < 0.05). However, no significant difference in the mean pain scores was observed between the groups B and C (P > 0.05). The mean and standard deviation of the differences in complement C3 values in the three groups before and after injection were 72.15 ± 14.9, 27.65 ± 9.82, and 18.95 ± 4.68, respectively, which demonstrated a significant difference between three groups (P < 0.05). However, the difference in complement C3 values between the groups B and C was not significant (P > 0.05).

Conclusions

According to the obtained results, the low doses of infused propofol, 2 minutes before administration of its bolus dose, seems to have a considerable attenuating effect on its pain score.

Efficacy of lidocaine on preventing incidence and severity of pain associated with propofol using in pediatric patients: A PRISMA-compliant meta-analysis of randomized controlled trials

BACKGROUND

Propofol injection pain was considered as one conundrum during clinical anesthesia. The systematic review about the effect of lidocaine in reducing injection pain among children has not been established. The aim of the study was to systematically evaluate the efficacy and safety of such intervention.

METHODS

The literature search was performed from the inception to the May 31, 2016 in PubMed, Ovid EMBASE, and Cochrane database. All randomized controlled trials that using lidocaine for propofol injection pain in children were enrolled. The primary outcome included the incidence of injection pain and the incidence of propofol injection pain in different degrees. The data were combined to calculate the relative ratio and relevant 95% confidence interval. A meta-analysis was performed following the guidelines of the Cochrane Reviewer's Handbook and the PRISMA statement.

RESULTS

Data from the included 11 studies indicated that the incidence of injection pain was lower in lidocaine group than the incidence in saline control group and in propofol lipuro (medium- and long-chain triglycerides) group (pain occurrence: 22.1% in lidocaine vs 66.8% in saline, RR with 95% 0.34 [0.26, 0.43], I = 38%; 30.5% in lidocaine vs 46.9% in propofol lipuro, RR with 95% 0.68 [0.46, 1.00], I = 9%). There was no difference between lidocaine and ketamine/alfentanil both in reducing pain occurrence and in reducing pain severity (pain occurrence: 29.7% in lidocaine vs 25.8% in ketamine, RR with 95% 1.47 [0.16, 13.43], I = 94%; 31.0% in lidocaine vs 30.7% in alfentanil, RR with 95% 1.01 [0.69, 1.46], I = 11%). And the reported side effects revealed that the safety of lidocaine in pediatric patients was acceptable.

CONCLUSION

Compared with ketamine and alfentanil, lidocaine would be served as one more effective treatment in consideration of its well-matched efficacy, acceptable accessibility, and reasonable safety. However, more high-quality evidences in pediatric patients are necessary.

[Fospropofol: A new prodrug of propofol]

The development of new propofol formulations has advanced rapidly in the last ten years with the achievement of the marketing a new prodrug of propofol: fospropofol, pharmacologically different from the original compound. It is a water soluble compound that requires metabolism of the prodrug to propofol, which leads to a time delay between its administration and the appearance of its pharmacological effect. Its pharmacokinetic and pharmacodynamic characteristics are different to the original formula. Due to its formulation it does not cause pain on intravenous injection, does not lead to hyperlipidaemia or excess bacterial growth. Although it is currently unavailable in Spain, it has been approved by the FDA (American Food and Drug Administration) for sedation in controlled care in diagnostic and therapeutic procedures in adults. It must only be administered by personnel qualified to administer anaesthesia, and the patients must be monitored throughout the whole procedure.

Pain on injection from propofol may be avoided by changing its formulation

BACKGROUND

After using propofol for a decade, pain on injection had been considered routine by patients and medical personnel. When given propofol from a different manufacturer, patients did not complain. Two preparations of propofol were compared.

METHODS

A comparative, double-blind, randomized study was conducted in 22 adult patients undergoing pain relief procedures; they received sedation by an intravenous injection of 1.7 mg/kg of propofol and then were treated with paravertebral injections. Pain on injection was assessed by verbal complaint, movement of the extremity, of the whole body and recollection of pain at induction, when discharged. Propofol from Baxter Laboratories, mixed with either 5 ml of 2% lidocaine or 5 ml of NaCl 0.9%, was compared with propofol Laboratorios Gray, which was similarly mixed. Injections were randomly administered four times, blindly, to each of 22 patients. Statistical analysis was conducted using the analysis of variance method.

RESULTS

A total of 352 propofol injections were given. Each of the four propofol solutions was administered 88 times; of patients receiving Baxter propofol+saline, 74 (84%) had pain; when mixed with 2% lidocaine 45 (50.2%) complained. After propofol Gray with NaCl 0.9% was given, two patients (2.2%) experienced pain. Propofol Gray with 2% lidocaine produced no pain. None of the latter group remembered having pain, whereas, those given propofol Baxter 54 (61.3%) and 26 (29.5%) remembered experiencing pain at injection. Pain on injection was prevented and statistically reduced (<0.01) with the propofol from Laboratorios Gray.

CONCLUSIONS

By changing the formulation (size of molecules and their dispersion) of propofol, pain on injection was avoided.

Pain on injection with microemulsion propofol

AIMS

To evaluate the incidence and severity of injection pain caused by microemulsion propofol and lipid emulsion propofol in relation to plasma bradykinin generation and aqueous free propofol concentrations.

METHODS

Injection pain was evaluated in 147 patients. Aqueous free propofol concentrations in each formulation, and in formulation mixtures containing agents that reduce propofol-induced pain, were measured by high-performance liquid chromatography. Plasma bradykinin concentrations in both formulations and in their components mixed with blood sampled from six volunteers were measured by radioimmunoassays. Injection pain caused by 8% polyethylene glycol 660 hydroxystearate (PEG660 HS) was evaluated in another 10 volunteers.

RESULTS

The incidence of injection pain [visual analogue scale (VAS) >30 mm] caused by microemulsion and lipid emulsion propofol was 69.7 and 42.3% (P < 0.001), respectively. The median VAS scores for microemulsion and lipid emulsion propofol were 59 and 24 mm, respectively (95% confidence interval for the difference 12.5, 40.0). The aqueous free propofol concentration of microemulsion propofol was seven times higher than that of lipid emulsion propofol. Agents that reduce injection pain did not affect aqueous free propofol concentrations. Microemulsion propofol and 8% PEG660 HS enhanced plasma bradykinin generation, whereas lipid emulsion propofol and lipid solvent did not. PEG660 HS did not cause injection pain.

CONCLUSIONS

Higher aqueous free propofol concentrations of microemulsion propofol produce more frequent and severe pain. The plasma kallikrein-kinin system may not be involved, and the agents that reduce injection pain may not act by decreasing aqueous free propofol concentrations.

Emulsion of flurbiprofen axetil reduces propofol injection pain due to a decrease in free propofol concentration

PURPOSE

Flurbiprofen axetil emulsion (FA), a prodrug of nonsteroidal anti-inflammatory drugs (NSAIDs) that is widely used for perioperative pain relief in Japan, has been effective for reducing propofol injection pain, but the mechanism is unclear. The purpose of this study was to test the hypothesis that the reduction of propofol injection pain by FA may be attributed to a decrease in free propofol concentration.

METHODS

Diprivan (propofol emulsion; Dipri; AstraZeneca, Cheshire, UK) and Propofol-Lipuro (Lipuro; B. Braun, Melsungen, Germany) were used. A randomized double-blind study was performed to compare pain on injection with six kinds of propofol solution: plain Dipri, a 3 : 1 (v/v) mixture of Dipri and saline (Dipri-S), a 3 : 1 mixture of Dipri and FA (Dipri-FA), plain Lipuro, a 3 : 1 mixture of Lipuro and saline (Lipuro-S), and a 3 : 1 mixture of Lipuro and FA (Lipuro-FA). Three hundred patients (American Society of Anesthesiologists [ASA] physical status [PS] I-II) scheduled for elective surgery received one of these six propofol emulsions (n = 50, each group). Injection pain was evaluated every 10 s after the start of a 1-min infusion of up to 2 mg x kg(-1) propofol. We also measured the in vitro free propofol concentrations of the propofol preparations that we tested (n = 5, each).

RESULTS

The mixture of FA with propofol decreased the incidence of injection pain, compared with plain propofol, for Lipuro (P < 0.01) but not for Dipri. The free propofol concentration in each emulsion in vitro was also decreased by mixing the propofol with saline or FA. The incidence of pain was reduced in a free-propofol concentration-dependent manner (R(2) = 0.926).

CONCLUSION

The findings suggest that the reduction of propofol injection pain by FA may be explained, at least in part, by a reduction in the free propofol concentration.

Development of a new generation of propofol

PURPOSE OF REVIEW

The current advance in development of a new generation of propofol and its clinical implications are reviewed.

RECENT FINDINGS

All currently available formulations of propofol have side effects related to propofol itself, as well as to the emulsion delivery systems. A search for better and safer propofol continues. Improvement of the emulsion delivery systems is one of approaches, which can be achieved by identifying better inactive components, enhancing stability, and applying new technologies such as nanotechnology. Modification of chemical structure is another approach, particularly with the development of propofol prodrugs.

SUMMARY

There is a continuous need to develop a better and safer propofol. The development of a new propofol should be focused on minimizing the unwanted side effects, while preserving the beneficial profiles. Hopefully, just such a new propofol will be available in the near future for clinical use.

Low-dose propofol reduces the incidence of moderate to severe local pain induced by the main dose

BACKGROUND

Local pain on injection of propofol remains a considerable problem in clinical anaesthesiology. As slow infusion of a low dose of propofol induces little or no pain at the site of injection, and as propofol-induced pain fades during prolonged exposure, this randomized, double-blind, clinical cross-over study was designed to test whether pain on injection of propofol is attenuated by initial slow injection of a low dose of propofol by the same intravenous line.

METHODS

Seventy-seven adult surgical patients were cannulated in a dorsal vein on each hand. In each cannula, a 0.5-ml priming dose of either propofol 10 mg/ml dissolved in an emulsion of medium- and long-chain triglycerides or aqueous sodium chloride 9.0 mg/ml was injected over 30 s, and followed 120 s later by a main dose of 2.0 ml of the same propofol formula over 6 s. After each injection, the patients were asked by a blind investigator to score the maximal pain intensity on a visual analogue scale (VAS).

RESULTS

Although the decrease in maximal pain intensity did not reach statistical significance (P= 0.070), significantly fewer patients reported moderate or severe pain intensity (corresponding to 3.0 VAS units or more) after the main dose of propofol was preceded by a priming dose of propofol than by sodium chloride (P= 0.041).

CONCLUSIONS

The incidence of moderate to severe local pain induced by intravenous propofol can be decreased by a readily applicable technique in which a low dose of propofol emulsion is slowly administered by the same intravenous route 2 min in advance.