Prevention of Pain on Injection with Propofol: A Quantitative Systematic Review

General anesthetics activate a nociceptive ion channel to enhance pain and inflammation

General anesthetics (GAs) have transformed surgery through their actions to depress the central nervous system and blunt the perception of surgical insults. Counterintuitively, many of these agents activate peripheral nociceptive neurons. However, the underlying mechanisms and significance of these effects have not been explored. Here, we show that clinical concentrations of noxious i.v. and inhalation GAs excite sensory neurons by selectively activating TRPA1, a key ion channel in the pain pathway. Further, these GAs induce pain-related responses in mice that are abolished in TRPA1-null animals. Significantly, TRPA1-dependent neurogenic inflammation is greater in mice anesthetized with pungent compared with nonpungent anesthetics. Thus, our results show that TRPA1 is essential for sensing noxious GAs. The pronociceptive effects of GAs combined with surgical tissue damage could lead to a paradoxical increase in postoperative pain and inflammation.

[Procedural analgesia : concepts and practice]

The effect of severe pain and its hazardous stress-related cardiocirculatory consequences have been well documented for the perisurgical setting. Independently of surgical intervention however, even short and simple measures (e.g. thorax drain removal, repositioning a limb fracture) and longer diagnostic procedures such as MRI are potentially very painful or stressful to the patient. Though longer diagnostic procedures are frequently supported by systemic medication, short interventions regularly lack this aspect. Specific challenges result from the need to counteract sometimes great changes in pain intensity. Moreover procedural analgesia represents a multidisciplinary measure not restricted to anaesthesiology, as most of these measures are performed without anaesthesia. To avoid endangering the patient, the choice of drugs and patient monitoring have to meet certain professional and technical standards. Competence in respiratory management is of paramount importance. This paper outlines these requirements and serves as an orientation outside the anaesthesiological speciality.

A combination of lidocaine (lignocaine) and remifentanil reduces pain during propofol injection

OBJECTIVE

Pain on injection is a well known adverse effect of propofol. The purpose of this study was to compare the analgesic effect of a lidocaine (lignocaine)/remifentanil combination compared with either lidocaine alone or remifentanil alone during propofol injection for induction of anaesthesia.

METHODS

In a randomised, double-blind, prospective trial, 129 patients were allocated to one of three groups (each n = 43) receiving lidocaine 20mg, remifentanil 0.3 microg/kg or lidocaine 20 mg plus remifentanil 0.3 microg/kg as pretreatment, followed by injection of 5 mL of 1% propofol. Pain severity was evaluated on a four-point scale.

RESULTS

Two patients (4.7%) complained of pain in the lidocaine plus remifentanil group compared with 15 (35.7%) in the lidocaine alone group and 18 (42.9%) in the remifentanil alone group (p < 0.001). There was no significant difference in the incidence of injection pain between the lidocaine alone and remifentanil alone groups (p = 0.21).

CONCLUSION

Pretreatment with a combination of lidocaine and remifentanil is more effective than either pretreatment alone in reducing pain on injection of propofol.

Clinical Practice Advisory: Emergency Department Procedural Sedation With Propofol

We present an evidence-based clinical practice advisory for the administration of propofol for emergency department procedural sedation. We critically discuss indications, contraindications, personnel and monitoring requirements, dosing, coadministered medications, and patient recovery from propofol. Future research questions are considered.

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.

Multimodal Analgesia to Prevent Propofol-Induced Pain: Pretreatment with Remifentanil and Lidocaine Versus Remifentanil or Lidocaine Alone

BACKGROUND

Propofol is well-known for its pain on injection. Premixture with lidocaine or pretreatment with remifentanil reduces injection pain. A multimodal approach might offer additional mitigation of propofol injection pain.

METHODS

In a randomized, prospective, double-blind study of 156 patients, we compared the incidence and severity of propofol pain among three groups. Patients in the lidocaine group (n = 54) received 2% lidocaine premixed with propofol (40 mg lidocaine in 180 mg propofol). Patients in the remifentanil group (n = 50), received pretreatment with remifentanil 2 microg x kg(-1) IV over 30 s. Patients in the combination group (n = 52) received both lidocaine and remifentanil.

RESULTS

A significant decrease in the overall incidence of propofol pain at induction was achieved in the combination group (9.6%) compared with that in the remifentanil group (36%) and the lidocaine group (35%) (P = 0.003). The incidence of severe and moderate pain was also significantly different in the combination group (0%), compared with that in the remifentanil (18%) and lidocaine groups (12.9%) (P < 0.02). Similar, statistically significant differences among the three groups were achieved concerning recalled pain in the postanesthesia care unit.

CONCLUSIONS

The combination of two different analgesic modalities, remifentanil and lidocaine completely abolishes moderate and severe pain associated with propofol injection, and significantly reduces the incidence of mild pain when compared with each drug used alone.

Lidocaine is more efficient than the choice of propofol formulations to reduce incidence of pain on induction

BACKGROUND AND OBJECTIVE

Propofol is associated with pain on injection. It is common practice to premix lidocaine with propofol prior to injection. Lipuro propofol, a propofol emulsified in medium- and long-chain triglycerides, has been shown to reduce the intensity of injection pain compared to Diprivan, although a number of studies report no reduction in overall incidence of pain.

METHODS

We conducted this randomized double-blind trial to determine the extent of further pain reduction by adding lidocaine to Lipuro propofol. A total of 328 ASA I-III patients were randomized to one of four groups to receive Diprivan propofol (Group DP), Lipuro propofol (Group LP), Diprivan with lidocaine (Group DL) and Lipuro propofol with lidocaine (Group LL). The drug mixture was administered at a constant rate of 400 mL h(-1) via a 20-G cannula into a dorsal hand vein. Pain was assessed during induction and upon patient recovery, using a 10-point visual analogue scale.

RESULTS

Both the incidence and severity of pain were found to be significantly lower with addition of lidocaine to Lipuro propofol (P < 0.0002) compared to Lipuro alone, Diprivan with or without the addition of lidocaine.

CONCLUSION

Lidocaine added to Lipuro propofol makes induction of anaesthesia less painful compared to Lipuro propofol alone or Diprivan with lidocaine.

RETRACTED: Prevention of pain due to injection of propofol with IV administration of lidocaine 40 mg + metoclopramide 2.5, 5, or 10 mg or saline: A randomized, double-blind study in Japanese adult surgical patients

BACKGROUND

Pain on injection is a recognized adverse event (AE) with propofol, an agent used to induce general anesthesia in surgical patients. Lidocame (LID) has been found efficacious in reducing pain on injection of propofol; however, this type of pain may not be completely eliminated with LID. Metoclopramide (MET) is a dopamine receptor agonist with antiemetic and prokinetic properties used for the treatment of nausea and facilitation of gastric emptying in patients with gastroparesis. MET also has local anesthetic properties similar to those of LID.

OBJECTIVE

The aim of this study was to examine the effects of LID administered with 3 different doses of MET or saline on pain on injection of propofol in Japanese adults undergoing elective surgery.

METHODS

This randomized, double-blind study was conducted at the Department of Anesthesiology, University of Tsukuba Institute of Clinical Medicine, Tsukuba, Japan. Japanese patients aged 20 to 67 years who were scheduled to undergo elective surgery were eligible for participation. Patients were randomized to receive N administration of LID 40 mg + MET 2.5, 5, or 10 mg or saline. A rubber tourniquet was used to perform 1 minute of venous occlusion before administration of the study and control drugs, and then 25% of the total calculated dose of propofol (2 mg/kg) was injected into the dorsal vein of the hand through a 20-G N cannula at a rate of 1 mL/s. During a 10-second pause before the induction of anesthesia, patients were questioned by a blinded investigator about the pain intensity on injection. Pain intensity was assessed through the use of a 4-point verbal rating scale, with scores ranging from 0 (no pain) to 3 (severe pain). Incidence and intensity of pain (as assessed by mean pain scores) were determined in each of the 4 study groups. Extrapyramidal reactions and injection-site AEs, including pain, edema, wheals, and inflammation occurring up to 24 hours after surgery were recorded by a blinded investigator.

RESULTS

The study enrolled 240 patients (126 men, 114 women; mean [SD] age, 43 [13] years [range, 20-67 years]; mean [SD] height, 160 [8] cm [133-181 cm]; mean [SD] body weight, 57 [10] kg [range, 33-85 kg]). There were 60 patients randomized to each of the 4 study groups, which were comparable in distribution of demographic characteristics. Incidence of propofol-induced pain was significantly lower, but the intensity of pain was not less, in the groups that received LID/MET 40/5 or 40/10 (both, 5%) compared with those who received LID/MET 40/2.5 or LID/saline (18% and 20%, respectively) (all, P < 0.05). There were no reports of injection-site AEs or extrapyramidal reactions after injection of the control or study drugs in any of the study groups.

CONCLUSION

Among these 240 Japanese patients undergoing elective surgery, N administration of LID/MET 40/5 or 40/10 was associated with lower incidence, but not lower mean pain intensity scores, of pain on injection of propofol than LID/MET 40/2.5 or LID/saline before induction of anesthesia.

Influence of aging on lidocaine requirements for pain on injection of propofol

STUDY OBJECTIVE

To evaluate the influence of aging on lidocaine requirements for propofol-induced pain on injection.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

The study was undertaken at a University hospital.

PATIENTS

160 ASA physical status I and II adult patients scheduled for elective surgery with general anesthesia.

INTERVENTIONS

Patients received placebo (saline) or lidocaine intravenously at three different doses (10, 20, or 40 mg), with venous occlusion for two minutes, followed by injection of propofol 0.5 mg/kg into a dorsal hand vein.

MEASUREMENT AND MAIN RESULTS

Pain during injection of propofol was evaluated. For young patients, the frequency of propofol-induced pain was 70% in patients receiving lidocaine 10 mg (P = not significant); 50% in those receiving lidocaine 20 mg (P = not significant); and 30% in those receiving lidocaine 40 mg (P < 0.05), compared with placebo (80%). For elderly patients, 15 patients (75%) complained of pain in the placebo group, compared with 13 (65%) in the lidocaine 10 mg group (P = not significant); 5 (25%) in the lidocaine 20 mg group (P < 0.05); and 4 (20%) in the lidocaine 40 mg group (P < 0.05).

CONCLUSIONS

A lidocaine dose of 40 mg for young patients and 20 mg for old patients, with venous occlusion for two minutes, is sufficient to reduce pain on injection of propofol.

Comparison of diphenhydramine and lidocaine for prevention of pain after injection of propofol

BACKGROUND AND OBJECTIVE

Pain on injection is still a problem with propofol. The purpose of the study was to compare the effectiveness of diphenhydramine and lidocaine on pain caused by propofol at the site of injection.

METHODS

One hundred and eighty ASA I-II adults undergoing elective surgery were randomly assigned into three groups of 60 each. Group I (placebo) received 2 mL normal saline, Group II received 2 mL (40 mg) 2% lidocaine and Group III received 2 mL (20 mg) diphenhydramine intravenously (i.v.) during a 1-min venous occlusion, followed by propofol into a cephalic forearm vein of the antecubital fossa. Pain assessment was made immediately after propofol injection.

RESULTS

In the placebo group 25 (41.7%) patients experienced pain during propofol injection as compared to 2 (3.3%) and 3 (5.0%) in the lidocaine and diphenhydramine groups, respectively. The prevalence of pain and pain score were significantly less in both the lidocaine and diphenhydramine groups than in the placebo group (P = 0.00). No difference was found between the diphenhydramine and lidocaine groups (P = 0.60).

CONCLUSION

Previous injection of diphenhydramine with venous occlusion can be considered as an alternative to lidocaine for reducing the prevalence of pain caused by injection of propofol into peripheral veins.

Reduction of pain on injection of propofol: combination of pretreatment of remifentanil and premixture of lidocaine with propofol

BACKGROUNDS AND OBJECTIVE

There is a high incidence of pain following intravenous injection of propofol, and many studies have been conducted to find a way of reducing this. The administration of lidocaine and, recently, remifentanil has also been used for this purpose, but it is only partially effective. Thus, the purpose of this study was to investigate the analgesic effect of a combination of pretreatment with remifentanil and premixture of lidocaine with propofol and to compare either treatment alone during propofol injection in dorsal hand-veins.

METHODS

In a prospective, randomized, double-blinded trial, we studied 141 adult patients scheduled for elective surgery. The combination of pretreatment of remifentanil (0.35 microg kg(-1) min(-1)) and a premixture of lidocaine with propofol (mixture of propofol 1% and lidocaine 1% in a 10:1 ratio) was compared with either treatment alone in the prevention of pain on propofol injection. Pain was assessed on a four-point scale (0=none, 1=mild, 2=moderate, 3=severe) during propofol injection. Patients in Group B received remifentanil (0.35 microg kg(-1) min(-1)) 30 s before the injection of propofol.

RESULTS

The reduction of pain on propofol injection was similar in both the remifentanil pretreatment and lidocaine premixture groups (62.2% vs. 62.2%). Combination therapy was associated with a higher incidence of patients without pain (91.3%) than either treatment alone (P<0.001). On analysing the injection pain scores, we found a significant reduction of the score in the remifentanil and lidocaine Group C compared with the lidocaine Group A (P<0.001) and the remifentanil Group B (P<0.001).

CONCLUSIONS

The combination of pretreatment of remifentanil and premixture of lidocaine with propofol was more effective in reducing the incidence of pain on injection of propofol than either treatment alone.

Small-Dose Ketamine Reduces the Pain of Propofol Injection

BACKGROUND

I.v. injection of propofol during anesthetic induction induces pain. Ketamine has been shown to reduce injection pain. In this study, we established the optimal dose of ketamine to prevent the pain of injection with propofol.

METHODS

Two hundred forty patients presenting for elective surgery were randomly allocated into eight groups; five groups during the first part of the study and three groups during the second part. In Part 1, patients received saline (Group S), lidocaine (Group L), ketamine 10 microg/kg (Group K10), 50 microg/kg (Group K50), or 100 microg/kg (Group K100), respectively, immediately followed by propofol 2.5 mg/kg. In Part 2, the optimal dose of ketamine (100 microg/kg) was administered 3 min before propofol (Group Pre), mixed with propofol solution (Group KP), or after oral midazolam premedication (Group M). An anesthesiologist blinded to the study group monitored each patient's pain score at 5-s intervals.

RESULTS

In Part 1, the incidence and intensity of pain were the lowest in the K100 and L groups (P < 0.001). In Part 2, the patients in the K100 and M groups had significantly lower pain scores compared with the KP and Pre groups (P < 0.05). During induction, there were no significant intergroup differences in mean arterial blood pressure and heart rate in all groups.

CONCLUSIONS

Administration of ketamine 100 microg/kg immediately before propofol injection provided the optimal dose and timing to reduce propofol-induced pain on injection.

Etomidate- ® Lipuro is associated with considerably less injection pain in children compared with propofol with added lidocaine

BACKGROUND

Propofol is associated with a high incidence of injection pain in children, even if given together with lidocaine. A new lipid formulation of etomidate (Etomidate-Lipuro) has been found in adults to cause very little discomfort during i.v. injection. The aim of the present prospective, double-blind, randomized trial was to compare the incidence of injection pain during i.v. induction of anaesthesia between propofol with added lidocaine (previous standard) and this new etomidate formulation in paediatric patients.

METHODS

A total of 110 paediatric patients, aged 2-16 years, scheduled for outpatient surgery were planned to be included in the study. The primary end point of the study was the incidence of injection pain during induction of anaesthesia as assessed by a four-point scale as described previously. The occurrence of myoclonic muscular activity was registered as a secondary end point (four-point scale). An interim analysis after 80 patients was requested by the Ethics' Committee.

RESULTS

The study was stopped after the inclusion of 80 patients. A significantly lower incidence of injection pain was found in the Etomidate-Lipuro group as compared with the propofol-lidocaine group (5.0% vs 47.5%, P<0.001). The use of etomidate was associated with a significantly higher incidence of myoclonic activity compared with propofol-lidocaine (85.0% vs 15%, P<0.001).

CONCLUSIONS

The use of a new lipid formulation of etomidate is associated with significantly less injection pain than propofol with added lidocaine in children. This finding may warrant a change in clinical practice in order to avoid unnecessary pain in children.

Discomfort on injection: a comparison between two formulations of propofol

BACKGROUND AND OBJECTIVE

A randomized double-blind controlled trial was performed to determine if there was a difference in discomfort on injection between two preparations of propofol. A long-chain triglyceride preparation (LCT-propofol (Fresenius)) was compared against a medium- and long-chain triglyceride preparation (MCT/LCT-propofol (BBraun)).

METHODS

One hundred and twenty ASA I-II patients listed for elective procedures were consented and randomized to receive either induction agent. A standard rate of infusion was used for induction of anaesthesia and subjects were questioned about discomfort until contact was lost. Discomfort was recorded as none, mild, moderate or severe. Incidence of postoperative nausea and vomiting and anti-emetic requirements were recorded in the postanaesthetic care unit.

RESULTS

There was seen to be a 54% reduction in moderate/severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.006). There was a 70% reduction in severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.04). The term discomfort was used during the study because there is a wide array of unpleasant sensations felt by patients during propofol induction which are not always reported as pain. There was no significant difference in the incidence of postoperative nausea and vomiting or anti-emetic use between the two groups.

CONCLUSIONS

There is a significant decrease in the incidence of discomfort with MCT/LCT-propofol compared with LCT-propofol. This difference is more marked in subjects reporting severe discomfort.

Preventing pain during injection of propofol: effects of a new emulsion with lidocaine addition

BACKGROUND AND OBJECTIVE

Previous studies found that lidocaine addition to propofol long-chain triglyceride was associated with a lower incidence of injection pain than medium-chain triglyceride/long-chain triglyceride formulation, but the incidence was still high (31-40%). Our study investigated whether the incidence of injection pain could be further reduced by the addition of lidocaine (10 mg, 20:1) to propofol medium-chain triglyceride/long-chain triglyceride.

METHODS

In a randomized double-blind controlled trial 464 patients scheduled to undergo regional anaesthesia were assigned to receive one of the following four options: propofol medium-chain triglyceride/long-chain triglyceride + lidocaine, propofol long-chain triglyceride + lidocaine, propofol medium-chain triglyceride/long-chain triglyceride or propofol long-chain triglyceride. Propofol was injected to reach grade 3 of the Observer's Assessment of Alertness/Sedation scale.

RESULTS

Incidence of injection pain was 18% in the propofol medium-chain triglyceride/long-chain triglyceride + lidocaine group, 31% in the propofol long-chain triglyceride + lidocaine group, 47% in the propofol medium-chain triglyceride/long-chain triglyceride group and 60% in the long-chain triglyceride group. Propofol medium-chain triglyceride/long-chain triglyceride + lidocaine was associated with a statistically significant reduced incidence of injection pain compared with propofol long-chain triglyceride +lidocaine (P =0.0249, number needed to treat =7.7).

CONCLUSIONS

Premixing propofol medium-chain triglyceride/long-chain triglyceride with lidocaine is one of the most effective measures currently available to reduce the incidence of injection pain in sedated patients during regional anaesthesia.

Procedural sedation and analgesia in children

Procedural sedation and analgesia for children--the use of sedative, analgesic, or dissociative drugs to relieve anxiety and pain associated with diagnostic and therapeutic procedures--is now widely practised by a diverse group of specialists outside the operating theatre. We review the principles underlying safe and effective procedural sedation and analgesia and the spectrum of procedures for which it is currently done. We discuss the decision-making process used to determine appropriate drug selection, dosing, and sedation endpoint. We detail the pharmacopoeia for procedural sedation and analgesia, reviewing the pharmacology and adverse effects of these drugs. International differences in practice are described along with current areas of controversy and future directions.

Age-Related Differences in Metoclopramide Requirement for Pain??on Injection of Propofol

OBJECTIVE

Pain on injection is still a major problem with propofol; metoclopramide effectively decreases this pain. The purpose of this study was to evaluate the influence of aging on metoclopramide requirement for propofol-induced pain.

METHODS

In a randomised, double-blind manner, 120 patients, 60 younger (aged 20-40 years) and 60 older (aged 60-80 years) adults, received placebo (saline) or metoclopramide intravenously at two different doses (2.5mg and 5 mg) [younger group n = 20 each, older group n = 20 each], with venous occlusion for 1 minute, followed by administration of propofol 0.5 mg/kg into a dorsal hand vein. A blinded researcher asked the patient to assess the pain according to a pain score (0 = none, 1 = mild, 2 = moderate, 3 = severe) during injection of propofol.

RESULTS

For younger patients, the incidence of propofol-induced pain was 30% in patients receiving metoclopramide 5mg (both p < 0.05), 70% in those receiving metoclopramide 2.5mg and 80% in those receiving placebo. The median pain score was lower in patients receiving metoclopramide 5mg (0) than in those receiving placebo (1.5) [p < 0.05]. For older patients, 15 patients (75%) complained of pain in the placebo group, compared with six (30%) in the metoclopramide 5mg group (p < 0.01) and seven (35%) in the metoclopramide 2.5mg group (p < 0.05). The median pain score was lower in patients receiving metoclopramide 5mg (0) [p < 0.01] or metoclopramide 2.5mg (0) [p < 0.05] than in those receiving placebo (1).

CONCLUSION

This study showed that older patients require less metoclopramide, with venous occlusion for 1 minute, to reduce pain on injection of propofol than do younger patients.

How to decrease pain at rapid injection of propofol: effectiveness of flurbiprofen

PURPOSE

Many studies have been conducted on how to decrease propofol injection pain, but none has been completely successful. In the present study, the most effective method was investigated by adding lidocaine or a nonsteroidal antiinflammatory drug or by changing the solvent.

METHODS

A total of 250 patients scheduled for general anesthesia were divided into five groups. Anesthesia was induced with intravenous administration of flurbiprofen 50 mg followed immediately by propofol in a long-chain triglyceride (LCT) 2 mg.kg(-1) (flurbiprofen group, n = 50), flurbiprofen 50 mg followed by propofol LCT 2 mg.kg(-1) 1 min later (flurbiprofen 1 group, n = 50), 2% lidocaine 40 mg followed immediately by propofol LCT 2 mg.kg(-1) (lidocaine group, n = 50), propofol LCT 2 mg.kg(-1) alone (LCT group, n = 50), or propofol in a mixture of medium-chain triglyceride (MCT) and LCT 2 mg.kg(-1) (MCT/LCT group, n = 50). Pain at injection was assessed 10 and 20 s after starting the propofol infusion.

RESULTS

The numbers of patients with severe and mild pain were larger in the order: LCT group (10 and 31 patients, respectively) > flurbiprofen 1 group (3 and 19) > or = MCT/LCT group (1 and 14) > or = lidocaine group (2 and 11) > flurbiprofen group (0 and 0).

CONCLUSIONS

Flurbiprofen 50 mg i.v. just before propofol injection completely abolished propofol injection pain. When it was administered 1 min before propofol injection it was less effective.

Pain on injection of lipid-free propofol and propofol emulsion containing medium-chain triglyceride: a comparative study

Pain on injection of propofol continues to be a problem for anesthesiologists. A lipid-free formulation of propofol and a propofol emulsion containing medium-chain triglyceride have become available in the Indian market. We performed this study to assess the pain on injection of propofol emulsion containing medium-chain triglyceride as the lipid carrier and lipid-free propofol formulation. One-hundred-thirty adult patients were randomly assigned to one of two groups: Group I received propofol emulsion containing medium-chain triglyceride and Group II received lipid-free propofol. One fourth of the total calculated induction dose was injected over 5 s in the largest vein on the dorsum of a hand. Pain was assessed using verbal response and behavioral signs. Both formulations caused pain on injection. However, the lipid-free propofol solution produced frequent (89%) and severe pain on injection compared with the emulsion containing medium-chain triglyceride (40%).

IMPLICATIONS

Pain on injection of two formulations of propofol was compared. A lipid-free formulation produced more pain on injection as compared with the emulsion containing medium-chain triglyceride.

AQUAVAN® Injection, a Water-soluble Prodrug of Propofol, as a Bolus Injection: A Phase I Dose-escalation Comparison with DIPRIVAN® (Part 1): Pharmacokinetics: Retracted

BACKGROUND

AQUAVAN Injection (AQ) (GPI 15715; Guilford Pharmaceutical Inc., Baltimore, MD) is a water-soluble prodrug of propofol (PropofolGPI). This study aimed to explore the pharmacokinetics of AQ, PropofolGPI, and formate (a metabolite of AQ) and to compare them with the pharmacokinetics of propofol lipid emulsion (PropofolD).

METHODS

After ethics committee approval, 36 healthy volunteers were randomly allocated into six cohorts (male/female: 3/3) and given a single bolus of AQ (5, 10, 15, 20, 25, or 30 mg/kg). For comparison, an equipotent dose (as measured by the Bispectral Index) of PropofolD was given to the same subjects 1 week later. For both drugs, blood samples were collected (1-480 min) to analyze AQ, PropofolGPI, PropofolD, and formate concentrations. Noncompartmental pharmacokinetic analyses were performed for all analytes. A population compartmental model was developed for AQ and PropofolGPI using NONMEM. The models were evaluated using simulations and bootstraps.

RESULTS

The noncompartmental pharmacokinetic comparison revealed different dispositions of PropofolGPI and PropofolD. The maximum plasma concentration was lower for PropofolGPI than for PropofolD at equipotent doses, and apparent clearance and distribution volume were much higher for PropofolGPI than for PropofolD. Formate concentrations were similar when injecting both drugs and were not higher than baseline. Compartmental modeling revealed that the pharmacokinetic behavior of AQ and its liberated PropofolGPI was best described by a nonlinear, six-compartment model, composed of two three-compartment models connected to each other by hydrolysis of AQ to PropofolGPI.

CONCLUSIONS

PropofolGPI showed different noncompartmental pharmacokinetics from PropofolD, hereby revealing the influence of the formulation. The combined model for AQ and PropofolGPI was best modeled by a nonlinear, six-compartment model.

A lidocaine/metoclopramide combination decreases pain on injection of propofol

PURPOSE

Injection pain is a well-known adverse effect of propofol which distresses patients. Lidocaine pretreatment is the most popular method for reducing this pain but this drug cannot entirely eliminate the problem. The purpose of this study was to examine the analgesic effect of lidocaine/metoclopramide combination, compared with lidocaine alone, during propofol injection.

METHODS

In a randomized, double-blind, placebo-controlled trial, 90 patients, 40 males and 50 females, scheduled for elective plastic surgery received either lidocaine 20 mg plus metoclopramide 10 mg iv, lidocaine 20 mg iv, or placebo (saline); (n = 30 in each), with venous occlusion for one minute, followed by administration of propofol 0.5 mg.kg(-1) into a dorsal hand vein. Pain was assessed on a four-point scale (0 = none, 1 = mild, 2 = moderate, 3 = severe) during propofol injection.

RESULTS

25 patients (83%) complained of pain in the placebo group, compared with 12 (40%) in the lidocaine group (P < 0.05) and three (10%) in the combination group (P < 0.05). Pain score (median) was less in the lidocaine (0) and combination (0) groups than in the placebo group (2); (P < 0.05). The difference in the incidence of pain between the combination and lidocaine groups was significant (P < 0.05).

CONCLUSION

A lidocaine/metoclopramide combination is more effective than lidocaine alone for reducing pain on injection of propofol in a peripheral vein.

Effect of nitrous oxide in reducing pain of propofol injection in adult patients

In a randomized, double-blind, prospective trial we compared the efficacy of pre-treatment with nitrous oxide (with or without premixed lignocaine in propofol) for the prevention of propofol-induced pain. Ninety consecutive patients were recruited in the study and divided into three groups of 30 each, who received either 50% nitrous oxide in oxygen along with lignocaine 40 mg mixed in 1% propofol 20 ml (Group NL), 50% nitrous oxide in oxygen without lignocaine in propofol (Group N), and 50% oxygen in air with lignocaine mixed in propofol 40 mg (Group L). Pain scores were graded on a four point verbal rating scale (0-3). Eighty-nine patients completed the study while one patient developed excitement, agitation and tremor during nitrous oxide in oxygen inhalation. Eleven patients (36.7%) complained of pain in the group L compared to 7 (23.3%), and 1 (3.3%), in groups N and NL respectively [group NL vs group L (P < 0.001) and group NL vs N (P < 0.001)]. There was no statistical difference observed between group N and group L. Inhalation of 50% nitrous oxide reduces pain on propofol injection. The combination of 50% nitrous oxide and lignocaine mixed with propofol was the most effective treatment.

A Comparison of Pain on Intravenous Injection Between Two Preparations of Propofol

Propofol is frequently used for sedation, induction, and maintenance of anesthesia. It is, however, associated with pain on injection. Propofol-Lipuro has an oil phase that allows a larger proportion of propofol to be dissolved in it and, thereby, apparently reduces pain. However, studies investigating this have had methodological limitations. We devised a randomized, double-blind, crossover study comparing pain on injection between two preparations of propofol, Diprivan and Propofol-Lipuro, in subanesthetic doses. Sixty healthy patients received the drugs in random order via the same injection site separated by 10 min and a 0.9% saline flush. Pain was assessed using a verbal rating score (VRS) during and at 1-min time points after injection. Differences in VRS between the two propofol preparations at different time points in each patient were analyzed. In patients who were given Diprivan first followed by Propofol-Lipuro (group D-P), pain was significantly reduced with Propofol-Lipuro compared with Diprivan during initial injection (median difference in VRS = 2 [interquartile range 0-2], P = 0.002) and at 1 min (3 [0-4], P < 0.001). In patients who were given Propofol-Lipuro first followed by Diprivan (group P-D), no significant differences in VRS were shown. Propofol-Lipuro is associated with reduced injection pain compared with Diprivan and also seems to attenuate subsequent injection pain of Diprivan when administered first. The mechanism is unknown, but may be related to a reduction in the concentration of propofol in the aqueous phase.

Changes in concentrations of free propofol by modification of the solution

Because free propofol is thought to be responsible for pain on injection, we investigated the changes in concentrations of free propofol by modifying two kinds of propofol products in a medium- and long-chain triglyceride (MCT/LCT) emulsion and in an LCT emulsion. The techniques used in this study were 1) mixing 2% lidocaine (10:1), 2) mixing 5% dextrose in acetated Ringer's solution to reduce pH (10:1), and 3) changing the temperature to 4 degrees , 20 degrees , and 36 degrees C. The propofol preparations were dialyzed for 24 h, and the receptor medium was analyzed using high-performance liquid chromatography. The concentration of free propofol in propofol MCT/LCT was significantly smaller by 30% than that in propofol LCT. Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products, but the concentrations were reduced by a decrease in pH and by an increase in temperature. Because mixing lidocaine can induce instability in an emulsion of propofol and warming can rapidly induce microbial growth, injection of lidocaine before propofol administration is recommended to reduce the pain on injection. The concentrations of free propofol in propofol MCT/LCT were significantly smaller (by approximately 30%-45%) than those in propofol LCT during any situation in this study.

IMPLICATIONS

Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products but the concentrations were reduced by a decrease in pH and by an increase in temperature. Propofol medium- and long-chain triglycerides had significantly smaller concentrations by approximately 30%-45% than those in propofol long-chain triglycerides during any situation in this study.

Propofol injection pain in children: a prospective randomized double-blind trial of a new propofol formulation versus propofol with added lidocaine

BACKGROUND

The incidence of pain on injection of propofol remains unacceptably high in children, despite various strategies to reduce it. A new drug formulation of propofol has, in adult studies, been reported to cause less injection pain compared with other propofol solutions. The aim of the present prospective randomized double-blind clinical trial was to compare the incidence of pain-free injection following the use of this new formulation with that following the use of propofol with added lidocaine in children undergoing day case surgery.

METHODS

Eighty-three children (age range 2-18 yr) were randomized to receive 3 mg kg(-1) of either Propofol-Lipuro (propofol dissolved in a mixture of medium- and long-chain triglycerides [MCT-LCT]; group pL, n=42) or Diprivan (propofol dissolved in long-chain triglycerides [LCT]) with added lidocaine (0.3 mg kg(-1)) (group pD, n=41). A specially trained nurse anaesthetist assessed the occurrence of injection pain using a four-graded pain scale.

RESULTS

Significantly fewer patients had an entirely pain-free propofol injection in group pL (33.3%) than in group pD (61.0%) (P=0.016).

CONCLUSIONS

A new MCT-LCT propofol formulation as a plain solution was associated with a higher incidence of injection pain than LCT propofol with added lidocaine when used for induction of anaesthesia in children.

The Effects of Intravenous Lidocaine on Pain During Injection of Medium- and Long-Chain Triglyceride Propofol Emulsions

Propofol formulated in medium- and long-chain triglycerides (MCT/LCT) is thought to cause less pain on injection. In this study we sought to determine if adding lidocaine to propofol-MCT/LCT is more effective in decreasing pain compared with propofol-MCT/LCT alone or conventional propofol-lidocaine mixtures. Seventy-five patients were randomized into three groups. Group A received conventional propofol-lidocaine mixtures with 20 mg lidocaine, group B received propofol-MCT/LCT with saline, and group C received propofol-MCT/LCT with 20 mg lidocaine. The incidence of pain was 24% in groups A and B and 4% in group C. The number needed to treat to prevent pain was 5. We conclude that propofol-MCT/LCT-lidocaine mixtures significantly reduce pain.

Preventing the withdrawal response associated with rocuronium injection: a comparison of fentanyl with lidocaine

We compared the efficacy of IV fentanyl with IV lidocaine as pretreatment for the prevention of withdrawal response after rocuronium injection. For this prospective, randomized, placebo-controlled, double-blind study we recruited 90 patients aged between 18 and 65 yr, ASA physical status I or II, who had undergone elective surgery requiring general anesthesia and positive pressure ventilation. Patients were randomly allocated to 1 of 3 groups: group F received 2 mL IV fentanyl 50 microg/mL (100 microg), group L received 2 mL of preservative-free lidocaine 2% (40 mg), and group P (placebo) received 2 mL of normal saline. The incidence of withdrawal response after rocuronium was 57%, 30%, and 7% in the placebo, lidocaine, and fentanyl groups, respectively. We found a significant reduction in incidence of withdrawal response in both the fentanyl and lidocaine groups when compared with the placebo group (P < 0.05), with the fentanyl group being most effective (P < 0.05). In conclusion, both fentanyl and lidocaine are effective clinical treatments to alleviate the withdrawal response associated with rocuronium injection, with fentanyl being more effective.

A combination of lidocaine and nitrous oxide in oxygen is more effective in preventing pain on propofol injection than either treatment alone

BACKGROUND AND OBJECTIVE

Propofol is an intravenous (i.v.) anaesthetic agent that possesses many of the qualities of an ideal anaesthetic agent. The most significant side-effect associated with propofol is pain on injection. Despite optimal therapy, the incidence of pain on propofol injection remains a problem. This prospective, randomized, double blinded study evaluated the effect of three different treatment strategies in decreasing pain on propofol injection.

METHODS

We studied 102 adult, ASA I-II patients, scheduled for elective surgical procedures. Combination of i.v. lidocaine and nitrous oxide (N2O) in oxygen (O2) inhalation pre-treatment was compared with either treatment alone in the prevention of pain on propofol injection. A standard propofol injection technique and scoring system, to measure the pain on injection was used.

RESULTS

Demographic variables were similar between the groups. The incidence of no pain on propofol injection was similar in the lidocaine and N2O groups (63.6% vs. 57.5%) (95% confidence interval (CI): 0.17-0.29, P = 0.61). Combination therapy was associated with a greater incidence of no pain on injection (84% vs. 63.6%) (95% CI: 0.06-0.48, P = 0.04).

CONCLUSION

Combination of i.v. lidocaine and N2O in O2 inhalation pre-treatment is more effective than either treatment alone in decreasing pain on propofol injection.

Bacteriostatic saline containing benzyl alcohol decreases the pain associated with the injection of propofol

Bacteriostatic saline is a physiological saline solution containing the bacteriostatic agent benzyl alcohol as a 0.9% solution. It is used mostly for diluting and dissolving drugs for IV injection and as a flush for intravascular catheters. It also has local anesthetic properties. We studied its efficacy in decreasing the pain associated with IV administration of propofol and compared it with mixing lidocaine with propofol. One-hundred-twenty patients were randomly allocated into three groups. All patients received propofol 50 mg. The benzyl alcohol group received bacteriostatic saline as a preinjection, and the lidocaine group received propofol containing lidocaine. The placebo group did not receive bacteriostatic saline or lidocaine. Fifteen of 39 patients (38%) in the benzyl alcohol group complained of pain on injection compared to 33 of 39 (84%) in the placebo group and 22 of 42 (52%) in the lidocaine group. Differences were significant between the benzyl alcohol and placebo groups (P < 0.01) and the lidocaine and placebo groups (P < 0.01). Preinjection with bacteriostatic saline decreases the incidence of pain associated with IV administration of propofol and is comparable to that of mixing lidocaine with propofol.

Pain on Injection: A Double-Blind Comparison of Propofol with Lidocaine Pretreatment Versus Propofol Formulated with Long- and Medium-Chain Triglycerides

The incidence of pain on injection of propofol has been reported to be 70%. A new propofol formulation with a 10% emulsion of long- and medium-chain triglycerides (LCT/MCT) is associated with less pain on injection. Our goal was to compare the effect of propofol-LCT/MCT on the incidence of pain versus propofol with lidocaine 40 mg IV pretreatment injected as a Bier's block. Two hundred healthy women scheduled for ambulatory gynecological procedures were allocated to 1 of 2 groups in a randomized double-blind fashion. Group LIDO received lidocaine 2% 2 mL injected with a tourniquet 1 min before propofol 1% 2 mg/kg IV; group LCT/MCT received NaCl 0.9% 2 mL with tourniquet 1 min before propofol-LCT/MCT 1% 2 mg/kg IV. Spontaneous verbal expressions of pain, movement of hand, frowning, and moaning during the injection were recorded. The incidence and severity of pain were assessed 30 min and 6 h after surgery. Recall of pain was considered with a visual analog scale (VAS) score >1, and pain was graded as VAS 0-10. More women reported spontaneous verbal expression of pain with propofol-LCT/MCT (47% versus 24%; P = 0.0014; relative risk 1.61 [95% confidence interval, 1.22-2.13]). Among women with a painful injection, there was no difference after surgery regarding the intensity of pain or recall of pain. In contrast to previous reports, we found that propofol-LCT/MCT resulted in a more frequent incidence of pain than propofol 1% with IV lidocaine pretreatment. This may be due to the diversity of pain definitions used in studies or to the lack of premedication in our study.

Comparison of Propofol-Lipuro with propofol mixed with lidocaine 10 mg on propofol injection pain

A common drawback of propofol is pain on injection and lidocaine is commonly mixed with propofol to reduce its incidence and severity. We conducted a randomised, prospective, double-blind study to compare injection pain following the administration of two different formulations of propofol in 200 unpremedicated ASA I-III adult patients scheduled for elective surgery under general anaesthesia. Patients were allocated randomly into two groups to receive either Propofol-Lipuro without added lidocaine or Diprivan mixed with lidocaine 10 mg. Five ml of the study solution was injected at a constant rate over 15 s and patients graded any associated pain or discomfort using a four-point verbal rating scale. The incidence of propofol injection pain was virtually identical in both study groups with 37/98 (38%) patients experiencing pain or discomfort following Propofol-Lipuro compared with 35/98 (36%) after Diprivan (p = 0.88). We observed no significant difference in pain scores between the groups (p = 0.67). Moderate or severe injection pain was experienced by 12/98 (12%) patients given Propofol-Lipuro compared with 8/98 (8%) given Diprivan (p = 0.48).

Vein pretreatment with magnesium sulfate to prevent pain on injection of propofol is not justified

PURPOSE

Propofol produces anesthesia with rapid recovery. However, it causes pain or discomfort on injection. A number of techniques have been tried for minimizing propofol-induced pain with variable results. We have compared the efficacy of magnesium and lidocaine for the prevention of propofol induced pain.

METHODS

Three hundred ASA I and II adults undergoing elective surgery were randomly assigned into three groups of 100 each. Group I received magnesium sulfate 1 g, Group II received lidocaine 2% (40 mg) and Group III received normal saline, all in a volume of 2 mL and accompanied by venous occlusion for one minute. Induction with propofol 2.5 mg.kg(-1) was accomplished following the release of venous occlusion. Pain was assessed on a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain at the time of pretreatment and propofol injection. Results were analyzed by 'Z' test. A P value of < 0.05 was considered as significant.

RESULTS

Pain during i.v. pretreatment with magnesium was 31% as compared to 2% for both the lidocaine and control groups (P < 0.05). Seventy-six percent of patients in the control group had pain during i.v. propofol as compared to 32% and 42% in the magnesium and the lidocaine groups respectively (P < 0.05). Lidocaine and magnesium pretreatment were equally effective in attenuating pain during the propofol injection (P > 0.05).

CONCLUSIONS

Intravenous magnesium and lidocaine pretreatment are equally effective in attenuating propofol-induced pain. However, magnesium pretreatment itself causes pain. Therefore, there is no justification in the use of magnesium pretreatment for attenuating pain associated with i.v. propofol.