The SLCO1A2 -189_-188InsA polymorphism reduces clearance of rocuronium in patients submitted to elective surgeries

PURPOSE

Rocuronium (ROC) is a neuromuscular blocker mainly eliminated by biliary excretion dependent on organic anion transporting polypeptide 1A2 (OATP1A2) hepatocellular uptake. However, the influence of SLCO1A2 (gene encoding OATP1A2) genetic polymorphism on ROC pharmacokinetics was never described before. The objective of this work was to evaluate the influence of genetic polymorphisms of SLCO1A2 on the pharmacokinetics of rocuronium (ROC).

METHODS

Patients undergoing elective surgeries under general anesthesia using rocuronium as a neuromuscular blocker were genotyped for SLCO1A2 polymorphisms in the coding region (41A>G, 382A>T, 404A>T, 502C>T, 516A>C, 559G>A, 830C>A, and 833delA) and in the promoter region (-1105G>A, -1032G>A, -715T>C, -361G>A, and -189_-188insA). Rocuronium pharmacokinetic parameters were estimated by non-compartmental analysis.

RESULTS

None of the patients had heterozygous or homozygous variant of 404A>T, 382A>T, 502C>T, 833delA, 830C>A, 41A>G, and -715T>C. A linkage disequilibrium was found between -1105G>A and -1032G>A genotypes. Patients genotyped as -A or AA (n = 17) for SLCO1A2 -189_-188InsA showed reduced total clearance of ROC compared to patients genotyped as -/- (n = 13) (151.6 vs 207.1 mL/min, p ≤ 0.05). The pharmacokinetics parameters of ROC were not significantly different between other SLCO1A2 genotypes.

CONCLUSION

SLCO1A2 -189_-188InsA polymorphism is related to the reduced clearance of rocuronium in patients submitted to elective surgeries under general anesthesia.

TRIAL REGISTRATION

NCT 02399397 ( ClinicalTrials.gov ).

Comparison of sustained-release morphine with sustained-release oxycodone in advanced cancer patients

The antinociceptive effect of morphine and oxycodone is mediated preferentially at μ and κ receptors, respectively. The aim of this study was to evaluate the analgesic profile of the combination of morphine and oxycodone in cancer pain, compared to the standard administration of morphine alone. Controlled-release formulations of oxycodone (CRO) and morphine (CRM) were compared in 26 patients. The study started with an open-label, randomised titration phase to achieve stable pain control for 7 days, followed by a double-blind, randomised crossover phase in two periods, 14 days each. At any point, patients were allowed to use oral immediate-release morphine (IRM) as needed, in order to keep visual analogue scale ⩽4. Pain, satisfaction, adverse effects and number of daily rescue morphine tablets were assessed. A total of 22 patients were evaluated. The weekly upload consumption ratio in morphine/oxycodone was 1 : 1.8 (1.80, 1.83, 1.76, 1.84). The weekly IRM consumption was higher in patients having CRM compared to patients having CRO (ratio morphine/oxycodone: 1.6, 1.6, 1.6, 1.7) (P<0.05). Patients receiving oxycodone complained of less nausea and vomiting. The rescue morphine analgesic consumption was 38% higher in patients receiving only morphine, compared to patients receiving both morphine and oxycodone. The results suggest that the combination of morphine/oxycodone (opioids with differential preferential sites of action) can be a useful alternative to morphine alone, resulting in a better analgesia profile and less emesis.

The effect of transdermal nitroglycerin on spinal S(+)-ketamine antinociception following orthopedic surgery

STUDY OBJECTIVES

To determine whether combination of transdermal nitroglycerine (a nitric oxide generator) would enhance analgesia from epidural S(+)-ketamine (a N-methyl-D-aspartate antagonist) in patients undergoing orthopedic surgery with combined spinal anesthesia.

DESIGN

Randomized, double-blind study.

SETTING

Orthopedic surgery unit of a teaching hospital.

PATIENTS

60 ASA physical status I and II patients scheduled for minor orthopedic knee surgery.

INTERVENTIONS

Patients were randomized to one of five groups (n = 12) to receive combined epidural/intrathecal anesthesia. A 10-mL epidural injection was first administered to all patients (study drug or normal saline). Intrathecal anesthesia consisted of 15 mg bupivacaine. Twenty to 30 minutes after the spinal puncture, a transdermal patch of either nitroglycerin 5 mg or placebo was applied. The control group (CG) received epidural saline and transdermal placebo. The nitroglycerin group (NG) received epidural saline and transdermal nitroglycerine patch. The 0.1 mg/kg S(+)-ketamine epidural group (1 KG) received 0.1 mg/kg epidural S(+)-ketamine and transdermal placebo. The 0.2 mg/kg S(+)-ketamine epidural group (2 KG) received 0.2 mg/kg epidural S(+)-ketamine and transdermal placebo. Finally, the nitroglycerin/0.1 mg/kg S(+)-ketamine epidural group (1 NKG) received 0.1 mg/kg epidural S(+)-ketamine and transdermal nitroglycerin. Pain and adverse effects were evaluated using a 10-cm visual analog scale (VAS).

MEASUREMENTS AND MAIN RESULTS

The groups were demographically the same. Sensory anesthetic level and VAS score for pain at the time of first rescue medication were similar among groups. The time to first rescue analgesic (min) was less in both the CG and the NG groups compared with the other groups (p < 0.05). Epidural S(+)-ketamine resulted in analgesia to both groups (1 KG < 2 KG; p < 0.05). The 1 NKG and the 2 KG displayed similar analgesia (p > 0.05). The CG required more rescue analgesics in 24 hours compared with the patients who received epidural S(+)-ketamine (p < 0.02).

CONCLUSIONS

Epidural S(+)-ketamine resulted in antinociception, which was enhanced by transdermal nitroglycerin.

Transdermal ketamine as an adjuvant for postoperative analgesia after abdominal gynecological surgery using lidocaine epidural blockade

We examined the postoperative analgesia of a controlled delivery ketamine transdermal patch after minor abdominal gynecological surgery using lidocaine epidural blockade. Fifty-two patients were randomized to one of two groups. Epidural anesthesia was performed with 25 mL 2% plain lidocaine. At the end of the surgical procedure, a controlled delivery transdermal patch containing either ketamine (25 mg/24 h) (Ketamine group) or placebo (Placebo group) was applied. Pain and adverse effects were assessed hourly postoperatively for 24 h. IM dipyrone was available at patient request. The two groups were demographically similar. The time to first rescue analgesic was longer in the Ketamine group (230+/-112 min) compared with the Placebo group (94+/-54 min); (P<0.00001). There were more dipyrone dose injections in 24 h in the Placebo group compared with the Ketamine group (P<0.0001). The incidence of adverse effects was similar between groups. We conclude that the transdermal-controlled delivery of ketamine prolonged the duration of analgesia after minor gynecological procedures.

IMPLICATIONS

Transdermal delivery of ketamine was an useful adjuvant to postoperative analgesia after epidural lidocaine blockade in the population studied.

Transdermal nitroglycerine enhances spinal neostigmine postoperative analgesia following gynecological surgery

BACKGROUND

Intrathecal neostigmine causes analgesia by inhibiting the breakdown of acetylcholine. Experimental data suggest that the production of endogenous nitric oxide is necessary for tonic cholinergic inhibition of spinal pain transmission. The purpose of this study was to determine whether association of transdermal nitroglycerine would enhance analgesia from a low dose of intrathecal neostigmine in patients undergoing gynecologic surgery during spinal anesthesia.

METHODS

Forty-eight patients were randomized to one of four groups. Patients were premedicated with use of 0.05-0.1 mg/kg intravenous midazolam and received 15 mg bupivacaine plus 1 ml test drug intrathecally (saline or neostigmine, 5 microgram). Twenty to 30 min after the spinal puncture, a transdermal patch of either 5 mg nitroglycerin or placebo was applied. The control (Con) group received spinal saline and transdermal placebo. The neostigmine group received spinal neostigmine and transdermal placebo. The nitroglycerin group received spinal saline and a transdermal nitroglycerine patch. Finally, the neostigmine-nitroglycerin group received spinal neostigmine and transdermal nitroglycerine. Pain and adverse effects were evaluated using a 10-cm visual analog scale.

RESULTS

Patients in the groups were similar regarding age, weight, height, and American Society of Anesthesiologists status. Sensory level to pin prick at 10 min, surgical duration, anesthetic duration, and visual analog scale score for pain at the time of administration of first rescue medication were statistically the same for all groups. The time to administration of first rescue analgesic (min) was longer in the neostigmine-nitroglycerin group (550 min; range, 458-1,440 min; median, 25-75th percentile) compared with the other groups (P < 0.001). The neostigmine-nitroglycerin group required fewer rescue analgesics in 24 h than did the control group (P < 0.0005), whereas the neostigmine group required less analgesics compared with the control group (P < 0.02). The incidence of perioperative adverse effects (nausea, vomiting, headache, back pain) was similar among groups (P > 0.05).

CONCLUSION

Although neither intrathecal 5 microgram neostigmine alone nor transdermal nitroglycerine alone (5 mg/day) delayed the time to administration of first rescue analgesics, the combination of both provided an average of 14 h of effective postoperative analgesia after vaginoplasty, suggesting that transdermal nitroglycerin and the central cholinergic agent neostigmine may enhance each other's antinociceptive effects at the dose studied.

Postoperative analgesia by intraarticular and epidural neostigmine following knee surgery

STUDY OBJECTIVES

To define the analgesic efficacy, and to identify a possible site of action, of epidural and intraarticular neostigmine.

DESIGN

Randomized, double-blind study.

SETTING

Postoperative analgesia, teaching hospital.

PATIENTS

58 ASA physical status I and II patients undergoing knee surgery.

INTERVENTIONS

All patients were premedicated with 0.05 to 0.1 mg/kg intravenous midazolam and received combined epidural/intrathecal technique. Intrathecal anesthesia consisted of 20 mg bupivacaine. A 10 mL epidural and intraarticular injection was administered to all patients; this consisted of either the study drug or normal saline. Postoperatively, pain was assessed using the 10 cm Visual Analog Scale (VAS), and intramuscular (IM) 75 mg diclofenac was available at patient request. The control group (CG) received both epidural and intraarticular saline. The 1 microg/kg epidural group (1 microg/kg EG) received epidural neostigmine and intraarticular saline. The 1 microg/kg intraarticular group (1 microg/kg AG) received epidural saline and intraarticular neostigmine. Finally, the 500 microg intraarticular group (500 microg AG) received epidural saline and intraarticular neostigmine.

MEASUREMENTS AND MAIN RESULTS

56 patients were evaluated. Groups were demographically the same and did not differ in intraoperative characteristics. The VAS score at first rescue analgesic and the incidence of adverse effects were similar among groups (p< 0.05). The time (min) to first rescue analgesic was shorter for both the CG (228+/-54) and 1 microg/kg AG (251+/-87) groups compared to the 1 microg/kg EG (333+/-78) and 500 microg AG (335+/- 111) groups (p<0.05). The analgesic consumption (number of IM diclofenac injections (mean [25(th)-75(th) percentile]) in 24 hours was higher in the CG group than both the 1 microg/kg EG and 500 microg AG groups (p<0.05). The overall 24-hour pain VAS score (cm) was higher in the CG group than in the 1 microg/kg EG (p<0.05) group.

CONCLUSION

Although peripheral neostigmine 1 microg/kg did not result in postoperative analgesia, the same dose applied epidurally resulted in over 5 hours of analgesia, similar to a fivefold dose applied peripherally. The results suggest that epidural neostigmine has a greater analgesic efficacy than peripherally applied neostigmine.

Low-dose intrathecal clonidine combined with sufentanil as analgesic drugs in abdominal gynecological surgery

STUDY OBJECTIVES

To determine whether a low dose of spinal clonidine either alone or combined with sufentanil would provide effective analgesia following abdominal surgery, as a supplement to bupivacaine spinal anesthesia.

DESIGN

Randomized double-blind study.

SETTING

Gynecological surgery, teaching hospital.

PATIENTS

73 ASA physical status I and II patients undergoing gynecological abdominal surgery with spinal anesthesia.

INTERVENTIONS

Patients were randomly assigned to one of four groups and prospectively studied to examine anesthesia, analgesia, and adverse effects. The control group received saline as the test drug; the sufentanil group received 10 microg of sufentanil; the clonidine group received 30 microg of clonidine; and the sufentanil/clonidine group received 5 microg of sufentanil plus 15 microg of clonidine. All groups received intrathecal 15 mg of bupivacaine (3 mL) plus the intrathecal test drug (2 mL). The concept of visual analog scale (VAS) was introduced. All patients were premedicated with intravenous midazolam. Rescue analgesics were available.

MEASUREMENTS AND MAIN RESULTS

The groups were demographically the same. Sensory block to pinprick at 10 min was higher for clonidine and sufentanil/clonidine groups compared to the control group (p < 0.02). Anesthetic time (Bromage score 2) was also longer for clonidine and sufentanil/clonidine groups compared to the control and sufentanil groups (p < 0.05). Time to first rescue analgesics was shorter in the control group compared to the other groups (p < 0.02). The number of IM diclofenac dose injections in 24 hours was higher in the control group compared to all other groups (p < 0.05). The incidence of adverse effects and ephedrine consumption were similar among groups.

CONCLUSIONS

Intrathecal 15- and 30-microg clonidine doses expanded the anesthesia sensory block and duration of motor block, and provided analgesia.

Low doses of epidural ketamine or neostigmine, but not midazolam, improve morphine analgesia in epidural terminal cancer pain therapy

STUDY OBJECTIVE

To examine analgesia and adverse effects of combination epidural pain therapy consisting of administration of morphine with either low dose of ketamine, neostigmine, or midazolam in terminal cancer pain patients.

DESIGN

Randomized double-blind study.

SETTING

Teaching hospital.

PATIENTS

48 terminal cancer patients suffering from chronic pain.

INTERVENTIONS

Patients were randomized to one of four groups (n = 12). The concept of visual analog scale (VAS), which consisted of a 10-cm line with 0 equaling "no pain at all" and 10 equaling "the worst possible pain" was introduced. All patients were taking oral amitriptyline 50 mg at bedtime. Pain was initially treated with epidural morphine 2 mg twice daily (12-hr intervals) to maintain the VAS below 4/10. Afterwards, VAS scores > or = 4/10 at any time were treated by adding the epidural study drug (2 ml), which was administered each morning, just after the 2-mg epidural morphine administration. The control group (CG) received 2 mg of epidural morphine (2 ml). The ketamine group (KG) received 0.2 mg/kg epidural ketamine (2 ml). The neostigmine group (NG) received 100 micrograms epidural neostigmine (2 ml). The midazolam group (MG) received 500 micrograms epidural midazolam (2 ml). Patients received the study drugs on a daily basis.

MEASUREMENTS AND MAIN RESULTS

Duration of effective analgesia was measured as time from the study drug administration to the first patient's VAS score > or = 4/10 recorded in days. The groups were demographically the same. The VAS pain scores prior to the treatment were also similar among groups. Only the patients in the KG demonstrated lower VAS scores compared to the MG (p = 0.018). Time since the epidural study drug administration until patient complaint of pain VAS > or = 4/10 was higher for both the KG and NG compared to the CG (KG > CG, p = 0.049; NG > CG; p = 0.0163). Only the KG used less epidural morphine compared to the CG during the period of study (25 days) (p = 0.003).

CONCLUSION

The association of either low-dose epidural ketamine or neostigmine (but not midazolam) to epidural morphine increased the duration of analgesia in the population studied (gt;20 days) compared to the CG and MG (8 to 10 days) when administered in the early stages of terminal cancer pain therapy, without increasing the incidence of adverse effects.

Study of three different doses of epidural neostigmine coadministered with lidocaine for postoperative analgesia

BACKGROUND

Intrathecal neostigmine produces analgesia in volunteers and patients. However, the use of epidural neostigmine has not been investigated. The purpose of the current study was to define the analgesic effectiveness of epidural neostigmine coadministered with lidocaine and side effects in patients after minor orthopedic procedures.

METHODS

After Institutional Review Board approval and informed consent, 48 patients (n = 12) undergoing knee surgery were randomly allocated to one of four groups and studied in a prospective way. After 0.05-0.1 mg/kg intravenous midazolam premedication, patients were randomized to receive 20 mg intrathecal bupivacaine plus epidural lidocaine (85 mg) with saline (control group); 1 microg/kg epidural neostigmine (1 microg group); 2 microg/kg epidural neostigmine (2 microg group); or 4 microg/kg epidural neostigmine (4 microg group). The concept of the visual analog scale, which consisted of a 10-cm line with 0 equaling "no pain at all" and 10 equaling "the worst possible pain" was introduced. Postoperatively, pain was assessed using the visual analog scale, and intramuscular 75 mg diclofenac was available at patient request.

RESULTS

Groups were demographically the same and did not differ in intraoperative characteristics (blood pressure, heart rate, ephedrine consumption, oxyhemoglobin saturation, sensory loss before start of surgery, or duration of sensory motor block). The visual analog scale score at first rescue analgesic and the incidence of adverse effects were similar among groups (P > 0.05). The time (min +/- SD) to first rescue analgesic was as follows: control group: 205+/-48; 1-microg group: 529+/-314; 2-microg group: 504+/-284; 4-microg group: 547+/-263 (P < 0.05). The analgesic consumption (number of intramuscular diclofenac injections [mean, 25th-75th percentile]) in 24 h was as follows: control group: 3 [3 or 4]; 1-microg group: 1 [1 or 2]; 2-microg group: 2 [1 or 2]; 4-microg group: 2 [1-3] (P < 0.05). The 24-h-pain visual analog scale score (cm +/- SD) that represents the overall impression for the last 24 h was as follows: control group: 5+/-1.6; 1-microg group: 1.6+/-1.8; 2-microg group: 1.4+/-1.6; 4-microg group: 2.2+/-1.9 (P < 0.005). The incidence of adverse effects was similar among groups (P > 0.05).

CONCLUSION

Epidural neostigmine (1, 2, or 4 microg/kg) in lidocaine produced a dose-independent analgesic effect (approximately 8 h) compared to the control group (approximately 3.5 h), and a reduction in postoperative rescue analgesic consumption without increasing the incidence of adverse effects.

Oral ketamine and transdermal nitroglycerin as analgesic adjuvants to oral morphine therapy for cancer pain management

BACKGROUND

Guidelines for cancer pain management include nonsteroidal antiinflammatory drugs with opioids administered in a time-contingent manner. This study was designed to evaluate the role of oral ketamine or transdermal nitroglycerin polymer, a nitric oxide donor, as coadjuvants to oral morphine in cancer pain therapy.

METHODS

After institutional approval and informed patient consent were obtained, 60 patients with cancer pain were randomized to one of four groups (n = 15) and studied prospectively to evaluate analgesia and any adverse effects. A visual analog scale that consisted of a 10-cm line with 0 representing "no pain at all" and 10 representing "the worst possible pain" was introduced. All patients were regularly taking oral amitriptyline 50 mg at bedtime. The morphine regimen was adjusted individually to a maximal oral dose of 80-90 mg/day to keep the visual analog scale score less than 4. When patients reported pain (visual analog scale of 4 or more), despite taking 80-90 mg oral morphine daily, the test drug was added as follows: the control group (CG) received an additional 20 mg oral morphine (10 mg at 12-h intervals); the nitroglycerin group (NG) received a 5-mg nitroglycerin patch daily; the ketamine group (KG) received 0.5 mg/kg oral ketamine at 12-h intervals; and the dipyrone group (DG) received 500 mg oral dipyrone at 6-h intervals. Patients were free to manipulate their daily morphine consumption when the test drug was introduced to keep their visual analog scale score less than 4.

RESULTS

The groups were similar with respect to demographic data and visual analog scale pain scores before treatment. The visual analog scale scores after the test drug was introduced were similar among the groups. The daily consumption of oral morphine was as follows: on day 15: CG = DG = NG (P > 0.05), CG > KG (P = 0.036); on day 20: CG > NG = KG (P < 0.02) (CG > KG, P < 0.005; CG > NG, P < 0.02), DG > KG (P < 0.05); on day 30: CG = DG > KG = NG (P < 0.05). Patients in the CG and DG groups reported somnolence, but patients in the NG and KG groups did not.

CONCLUSIONS

Low-dose ketamine and transdermal nitroglycerin were effective coadjuvant analgesics. In conjunction with their opioid tolerance-sparing function, joint delivery of ketamine or nitric oxide donors with opiates may be of significant benefit in cancer pain management.

Transdermal nitroglycerine enhances spinal sufentanil postoperative analgesia following orthopedic surgery

BACKGROUND

Sufentanil is a potent but short-acting spinal analgesic used to manage perioperative pain. This study evaluated the influence of transdermal nitroglycerine on the analgesic action of spinal sufentanil in patients undergoing orthopedic surgery.

METHODS

Fifty-six patients were randomized to one of four groups. Patients were premedicated with 0.05-0.1 mg/kg intravenous midazolam and received 15 mg bupivacaine plus 2 ml of the test drug intrathecally (saline or 10 microg sufentanil). Twenty to 30 min after the spinal puncture, a transdermal patch of either 5 mg nitroglycerin or placebo was applied. The control group received spinal saline and transdermal placebo. The sufentanil group received spinal sufentanil and transdermal placebo. The nitroglycerin group received spinal saline and transdermal nitroglycerine patch. Finally, the sufentanil-nitroglycerin group received spinal sufentanil and transdermal nitroglycerine. Pain and adverse effects were evaluated using a 10-cm visual analog scale.

RESULTS

The time to first rescue analgesic medication was longer for the sufentanil-nitroglycerin group (785+/-483 min) compared with the other groups (P<0.005). The time to first rescue analgesics was also longer for the sufentanil group compared with the control group (P<0.05). The sufentanil-nitroglycerin group group required less rescue analgesics in 24 h compared with the other groups (P<0.02) and had lesser 24-h pain visual analog scale scores compared with the control group (P<0.005), although these scores were similar to the sufentanil and nitroglycerin groups (P>0.05). The incidence of perioperative adverse effects was similar among groups (P>0.05).

CONCLUSIONS

Transdermal nitroglycerine alone (5 mg/day), a nitric oxide generator, did not result in postoperative analgesia itself, but it prolonged the analgesic effect of spinal sufentanil (10 microg) and provided 13 h of effective postoperative analgesia after knee surgery.

A multi-center study of intrathecal neostigmine for analgesia following vaginal hysterectomy

BACKGROUND

Intrathecal neostigmine injection produces analgesia in volunteers and reduces hypotension from intrathecal bupivacaine in animals. Initial clinical trials with neostigmine studied doses of more than 100 microg, but animal studies suggest that smaller doses may be effective. In addition, all controlled clinical trials of neostigmine have come from one Brazilian university. This multicenter, placebo-controlled trial investigated the effects of 25-75 microg intrathecal neostigmine on analgesia and blood pressure in women undergoing vaginal hysterectomy.

METHODS

After institutional review board approval was obtained at the three university centers, and after patients gave informed consent, 92 women scheduled for vaginal hysterectomy were randomized to receive an intrathecal injection of 2 ml bupivacaine, 0.75%, in dextrose plus either 1 ml saline or 25, 50, or 75 microg neostigmine. Blood pressure, heart rate, pain and nausea (both assessed by visual analog scale), and intravenous morphine use were recorded during surgery and at specified intervals afterward.

RESULTS

Morphine use was reduced similarly by all doses of neostigmine. Only the 75-microg dose of neostigmine increased the nausea score in the recovery room. The incidence of treatment for nausea was greater in patients receiving neostigmine (61%) than in those receiving saline placebo (29%) and was unaffected by neostigmine dose. Neostigmine did not reduce the incidence of hypotension from bupivacaine.

CONCLUSION

These data in patients after vaginal hysterectomy suggest that analgesia from intrathecal neostigmine may occur at doses less than 50 microg. In these doses, neostigmine does not reduce spinal bupivacaine-induced hypotension but may increase the need for treatment of nausea.

Combined intrathecal fentanyl and neostigmine: therapy for postoperative abdominal hysterectomy pain relief

STUDY OBJECTIVE

To evaluate the analgesic action of spinal neostigmine as part of a multimodal analgesic therapy approach including spinal neostigmine and spinal fentanyl for postoperative pain relief

DESIGN

Randomized, prospective study.

SETTING

Teaching hospital.

PATIENTS

50 ASA physical status I and II patients undergoing abdominal hysterectomy.

INTERVENTIONS

Patients were assigned to one of five groups (n = 10) to receive 15 mg bupivacaine plus 1 ml of the test drug intrathecally. The control group (CG) received saline as the test drug, the fentanyl group (FG) received 25 microg fentanyl; the neostigmine group (NG) received 25 microg neostigmine; the fentanyl-neostigmine 10 microg group (FNG10) was given 10 microg fentanyl plus 10 microg neostigmine; and the fentanyl-neostigmine 25 microg group (FNG25) received 25 microg fentanyl plus 25 microg neostigmine. Pain and nausea were evaluated using a 10-cm visual analog scale (VAS).

MAIN RESULTS

The analgesic consumption, in 24 hours was greatest in CG, next highest in NG, FG, and FNG10 where consumption was the same in the three groups; and least in FNG25 (p < 0.05). The time to first rescue analgesic medication was greatest for FNG25 compared with the other groups (>5 hours compared with 2 to 3 hours; p < 0.05). VAS showed no statistically significant differences for pain impression, intraoperative and postoperative nausea, or occurrence of vomiting (p > 0.05).

CONCLUSION

The combination of 25 microg neostigmine with 25 microg fentanyl given intrathecally with 15 mg of hyperbaric bupivacaine delayed postoperative pain and lowered the number of rescue analgesics. Because the better quality of analgesia was obtained with an increased (although not statistically significant difference) incidence of untoward side effects, larger samples should be studied before its routine use is recommended.

Postoperative analgesia and antiemetic efficacy after intrathecal neostigmine in patients undergoing abdominal hysterectomy during spinal anesthesia

BACKGROUND AND OBJECTIVES

Postoperative analgesia and antiemetic efficacy after intrathecal neostigmine were investigated in a randomized, double-blind, placebo-controlled trial of 100 patients undergoing abdominal hysterectomy.

METHODS

The patients were assigned to one of five groups (n = 20), and received intravenous prior to the spinal block the antiemetic test drug (except propofol) and 0.05 mg/kg midazolam. The control group (group C), the neostigmine group (group N), and the propofol group (group P) received saline as the test drug. The droperidol group (group D) received 0.5 mg intravenous droperidol, and the metoclopramide group (group M) 10 mg intravenous metoclopramide. Group P was single-blinded and had an intravenous continuous propofol infusion (2-4 mg/kg/h) turned on 10 minutes after the spinal injection. The intrathecal drugs administered were 20 mg hyperbaric bupivacaine (0.5%) associated with either 100 microg neostigmine or saline (for group C). Nausea, emetic episodes, and the need for rescue medication were recorded for the first 24 hours postoperative and scored by the Visual Analog Scale (VAS).

RESULTS

Time-to-first-rescue medication and rescue medications in 24 hours were similar among the groups (P = .2917 and P = .8780, respectively). Intrathecal 100 microg neostigmine was associated with a high incidence of nausea and vomiting perioperative, leading to a high consumption of antiemetics (P < .002). None of the antiemetic test drugs were effective in preventing nausea and vomiting after 100 microg neostigmine.

CONCLUSIONS

Intrathecal neostigmine (100 microg) was ineffective for postoperative analgesia after abdominal hysterectomy due to side effects of nausea and vomiting.

Intrathecal neostigmine for postoperative analgesia after orthopedic surgery

STUDY OBJECTIVE

To establish a dose-response curve for the analgesic effect of intrathecal neostigmine in patients undergoing below knee surgery with spinal anesthesia. To assess adverse effects, principally nausea and vomiting.

DESIGN

Randomized, double-blind, prospective study.

SETTING

Teaching hospital.

PATIENTS

60 ASA physical status I and II premedicated patients undergoing orthopedic surgery (tibial or ankle reconstruction).

INTERVENTION

Spinal anesthesia was performed at the sitting position, L3-L4 interspace, 4 ml final volume, injected at a rate of 1 ml/10 sec. The control group (CG) received 15 mg hyperbaric bupivacaine 0.5% plus saline. The 25 micrograms neostigmine group (25NG) received 15 mg hyperbaric bupivacaine plus 25 micrograms neostigmine; the 50 micrograms neostigmine group (50NG) received 15 mg hyperbaric bupivacaine plus 50 micrograms neostigmine; and the 100 micrograms neostigmine group (100NG) received 15 mg hyperbaric bupivacaine plus 100 micrograms neostigmine. Patients were placed supine after the spinal punction.

MEASUREMENTS AND MAIN RESULTS

Time to first rescue analgesics, analgesia, and adverse effects at constant intervals were assessed using the 10 cm visual analog scale (VAS). Intrathecal neostigmine produced a dose-independent reduction in the postoperative rescue analgesic consumption (p < 0.0001). The time to first rescue analgesics was similar among groups (p > 0.05), and the overall 24-hour VAS pain scores were lowest for patients who had spinal neostigmine (p < 0.02). The 100NG group had the highest incidence of postoperative nausea and vomiting of all the groups (p < 0.05).

CONCLUSION

Intrathecal neostigmine produced a dose-independent analgesia and a dose-dependent incidence of adverse effects with the doses studied.

Postoperative analgesia and antiemetic efficacy after subarachnoid neostigmine in orthopedic surgery

BACKGROUND AND OBJECTIVES

The efficacy of operatively administered spinal neostigmine to provide analgesia and that of different antiemetics to prevent neostigmine-related nausea and vomiting were evaluated in patients undergoing tibial or ankle reconstruction.

METHODS

One hundred patients were randomized to five groups (n = 20). The intravenous antiemetic test drug (except propofol) was given as premedication in the holding room, after intravenous midazolam, 0.05 mg/kg. The subarachnoid drugs administered were 20 mg bupivacaine (0.5%) in conjunction with 100 micrograms neostigmine, except for the saline group (S group), which received bupivacaine and saline. The S group, the neostigmine group (N group), and the propofol group (P group) received saline as the intravenous test drug. The droperidol group (D group) received intravenous droperidol 0.5 mg, and the metoclopramide group (M group) received intravenous metoclopramide 10 mg. The P group had a continuous intravenous propofol infusion (2-4 mg/kg/hr), started 10 minutes after the spinal injection. Nausea, emetic episodes, and the need for analgesic (disclofenac) or antiemetic medication were recorded for the first 24 hours following surgery and scored by a 10-cm visual analog scale (VAS).

RESULTS

Subarachnoid neostigmine 100 micrograms did not affect subarachnoid bupivacaine analgesia as measured by time to first rescue analgesic in most patients, but it decreased the overall 24-hour visual analog scale (VAS) scores and the need for postoperative analgesics in 24 hours (P < .001). The incidence of intraoperative nausea and vomiting was higher in the N, D, and M groups than in the S group (P < .001). Following surgery, the 3-hour VAS assessment for emesis was higher for the N, P, and M groups than for the S group (P < .05). The overall 24-hour assessment was similar among groups.

CONCLUSIONS

Subarachnoid neostigmine reduced postoperative pain scores and analgesic requirements. Whether it prolonged the duration of action of diclofenac or enhanced the mechanisms involved in spinal analgesia cannot be determined from these data. Although propofol and droperidol appeared to be more effective during and after surgery, respectively, all neostigmine groups were associated with a high consumption of antiemetics.

Propofol decreases ocular pressure in outpatients undergoing trabeculectomy

STUDY OBJECTIVE

To examine the effect of a continuous low-dose intravenous (i.v.) infusion of propofol on ocular pressure in outpatients undergoing trabeculectomy.

DESIGN

Randomized, prospective study.

SETTING

Teaching hospital.

PATIENTS

40 unpremedicated outpatients with history of primary open angle glaucoma undergoing trabeculectomy.

INTERVENTIONS

In the operating room, an infusion of 5% dextrose into a peripheral vein was started. The propofol group (n = 20) received 0.5 mg/kg i.v. propofol bolus followed immediately by a continuous 0.5 mg/kg/hr infusion. The control group (n = 20) received only the dextrose solution. A peribulbar block was performed with bupivacaine with added adrenaline, plus lidocaine. The ocular pressure (tonometer) on the eye undergoing trabeculectomy and the other eye, blood pressure (BP), and heart rate (HR) were measured at the following times: (1) preoperatively; (2) 2 minutes; (3) 5 minutes; (4) 10 minutes; (5) 15 minutes after propofol bolus administration for the propofol group (approximately 4 minutes after the peribulbar blockade on the eye undergoing surgery for the propofol and control groups).

MEASUREMENTS AND MAIN RESULTS

Ocular pressure decreased 2 minutes after propofol infusion (p < 0.0001) and remained significantly lower than in the control group throughout the study period. All patients remained awake and cooperative during all procedures. Mean BP and HR were kept constant throughout the study.

CONCLUSION

Low-dose propofol sedation resulted in a decrease in ocular pressure, was quick in onset, and was unrelated to BP and HR. The decrease in ocular pressure may be due to relaxation of extraocular muscles by propofol.

Tramadol and beta-cyclodextrin piroxicam: effective multimodal balanced analgesia for the intra- and postoperative period

BACKGROUND AND OBJECTIVES

This study was conducted to evaluate the analgesic efficacy of tramadol, an analgesic with both opioid and nonopioid actions (norepinephrine and serotonin pathways), with beta-cyclodextrin piroxicam, a nonsteroidal antiinflammatory drug, in the perioperative setting.

METHODS

The study population consisted of 48 patients scheduled for minor abdominal procedures, who were assigned to one of four groups of 12 patients each. The premedication was either a placebo tablet or a 192.1-mg beta-cyclodextrin piroxicam tablet, administered orally 30-40 minutes before anesthesia induction. After intravenous administration of tramadol 1.5 mg/kg, anesthesia was induced with an intravenous loading dose of propofol. Anesthesia was maintained an intravenous infusion of propofol at 6-12 mg/kg/h plus either saline or tramadol at 1.2 mg/kg/h, atracurium, and a 2:1 nitrous oxide-oxygen mixture. The control group received a placebo tablet and an infusion of saline with propofol for anesthesia maintenance; the tramadol group received a placebo tablet and a continuous tramadol-propofol infusion; the beta-cyclodextrin piroxicam (BCP) group received a BCP tablet and a continuous saline-propofol infusion; and the beta-cyclodextrin piroxicam-tramadol (BCPT) group received beta-cyclodextrin piroxicam and a continuous tramadol-propofol infusion.

RESULTS

The relative propofol consumption by the four groups was control = BCP (P > .05) >tramadol (P < .001) > B-CPT (P < .0002). The time for analgesic rescue decreased in the order BCPT > BCP (P < .0002) = tramadol > control (P < .001). The degree of sedation and the visual analog scores 10-cm scale at the time patients requested rescue analgesics were similar among the groups (P > .05).

CONCLUSIONS

The combination of tramadol and beta-cyclodextrin piroxicam provided better perioperative analgesia than tramadol alone.

Subarachnoid neostigmine does not affect blood pressure or heart rate during bupivacaine spinal anesthesia

BACKGROUND AND OBJECTIVES

Intraspinal administration of neostigmine has been shown to prevent induction of hypotension in rats by bupivacaine spinal block, and thus to provide greater hemodynamic stability. This study was undertaken to determine whether subarachnoid neostigmine would prevent bupivacaine spinal anesthesia from causing hypotension or bradycardia in patients undergoing abdominal hysterectomy.

METHODS

Of 40 patients scheduled for abdominal hysterectomy under spinal anesthesia, 20 were randomly assigned to each of two groups. The control group (CG) received 1.5 mL subarachnoid saline followed by 15 mg (3 mL) of hyperbaric bupivacaine 0.5%. The neostigmine group (NG) received 75 micrograms (1.5 mL) of subarachnoid neostigmine followed by 15 mg (3 mL) of hyperbaric bupivacaine 0.5%. No preload was given. Hypotension was treated with 4-mg intravenous boluses of ephedrine to keep blood pressure above 75% of the baseline value. The skin body temperature was measured with probes at the suprascapular region and at the foot.

RESULTS

Spinal neostigmine (75 micrograms) failed to prevent bupivacaine-induced hypotension. There was no statistical difference in the incidence of brady-cardia between the groups (NG, 2/20; CG 1/20), although the bradycardia appeared to be qualitatively different, being somewhat delayed in the NG. Spinal neostigmine did not alter the onset or duration of sensory block and did not affect skin body temperature in either anesthetized or unanesthetized sites. The incidence of intraoperative nausea was 20% in the NG and 5% in the CG.

CONCLUSION

A 75-micrograms subarachnoid neostigmine dose does not affect blood pressure or heart rate during bupivacaine spinal anesthesia.

Intravenous ketamine or fentanyl prolongs postoperative analgesia after intrathecal neostigmine

The purpose of this study was to determine whether intravenous (i.v.) ketamine would enhance analgesia from intrathecal (IT) neostigmine compared with combining i.v. fentanyl with IT neostigmine. Sixty patients undergoing vaginoplasty under spinal anesthesia were assigned to one of six groups (n = 10). Patients were premedicated with midazolam plus the i.v. test drug. The IT drugs were 20 mg bupivacaine plus saline or 50 micrograms neostigmine. The control group (CG) received saline i.v. and IT. The neostigmine control group (NCG) received saline i.v. and neostigmine IT. The ketamine group (KG) received ketamine 0.2 mg/kg i.v. and saline IT, and the ketamine neostigmine group (KNG), ketamine i.v. and neostigmine IT. The fentanyl group (FG) received fentanyl 1 microgram/kg i.v. and saline IT, and the fentanyl neostigmine group (FNG), fentanyl i.v. and neostigmine IT. The time to first rescue analgesic was longer for the FNG and KNG compared with the CG, with less rescue analgesic consumption (P < 0.02 and P < 0.01, respectively). Only the FNG had significantly intraoperative nausea/vomiting (P < 0.02). In conclusion, the combination of i.v. ketamine and IT neostigmine results in prolonged postoperative analgesia and less intraoperative nausea and vomiting than the combination of i.v. fentanyl and IT neostigmine.

Dose-response study of intrathecal morphine versus intrathecal neostigmine, their combination, or placebo for postoperative analgesia in patients undergoing anterior and posterior vaginoplasty

This study was designed to examine postoperative analgesia with intrathecal neostigmine in a randomized, blinded trial with morphine as the active control in patients undergoing anterior and posterior vaginoplasty. A secondary aim was to provide preliminary data on the interaction between these two drugs. The incidence of adverse effects was also assessed. Forty-eight patients were divided into eight groups (50 micrograms, 100 micrograms, and 200 micrograms morphine [M]; saline; 50 micrograms, 100 micrograms, and 200 micrograms neostigmine [N]; and 50 micrograms morphine + 50 micrograms neostigmine). Anesthesia was provided with a balanced technique. All patients stayed 24 h in the recovery room where adequacy of postoperative analgesia and side effects were assessed. Increasing doses of intrathecal morphine (50 micrograms, 100 micrograms, and 200 micrograms) and intrathecal neostigmine (50 micrograms, 100 micrograms, and 200 micrograms) showed a dose-dependent pattern of analgesia (P < 0.001). The M50 + N50 combination resulted in a better analgesic effect with fewer side effects than M50, N50, and control groups. These preliminary data suggest that spinal neostigmine produces analgesia for vaginoplasty surgery similar in duration to spinal morphine and that the combination of morphine and neostigmine may allow a reduction in the dose of each component for postoperative analgesia.

The effects of intrathecal neostigmine on somatic and visceral pain: improvement by association with a peripheral anticholinergic

This study was designed to qualitatively evaluate the analgesic actions of intrathecal neostigmine alone and with intravenous (IV) N-butyl-scopolamine on somatic and visceral pain. Twenty-seven patients scheduled for both tubal ligation and vaginoplasty were divided into three groups. Patients received a standard anesthetic with thiopental, atracurium, and N2O/O2/enflurane. N-butyl-scopolamine, 20 mg, or saline was administered as a 2-mL IV bolus 20 min before the end of the surgical procedure. The control group (CG) received spinal and IV saline; the neostigmine group (NG), spinal neostigmine and IV saline; and the neostigmine-N-butyl-scopolamine group (NSG), spinal neostigmine and IV N-butyl-scopolamine. Postoperatively, patients assessed their pain on a 10-cm visual analog scale (VAS). The CG had both visceral and somatic pain at the first 30-min assessment, and all patients requested morphine. Patients from the NG had only visceral pain from the first assessment; however, they had lower VAS scores (P = 0.026) and requested less morphine (P = 0.037). Patients from the NSG were pain free during all assessment times (P < 0.0001). Neostigmine was more effective for somatic pain than visceral pain. N-butyl-scopolamine administration acted peripherally as an effective complement for treatment of visceral pain, reflecting an association between central cholinergic effects and peripheral anticholinergic effects in the treatment of visceral postoperative pain.

Biochemical aspects of chronic pain and its relationship to treatment

This review presents an overview of the neurotransmitters and neuromodulators involved in acute and chronic pain. Although there is little evidence that the neuronal pathways differ in the two types of pain, it is clear that different transmitters or receptor types are involved in hyperalgesia and chronic pain. While most attention has been focussed on spinal processes, it is apparent that some types of chronic pain have both a peripheral and a supraspinal component. The presently available drugs are probably adequate for acute pain, but the treatment of chronic pain may need to be tailored to the individual patient.

The activity of opioid analgesics in seizure models utilizing N-methyl-DL-aspartic acid, kainic acid, bicuculline and pentylenetetrazole

Morphine, fentanyl and pethidine exhibited a biphasic dose response relationship with respect to their effects on seizure thresholds to bicuculline, pentylenetetrazole, N-methyl-DL-aspartate (NMDLA) and kainic acid in mice. The usual pattern was for low doses to be anticonvulsant and higher doses to be proconvulsant. However this pattern was reversed for fentanyl and pethidine when NMDLA was used to induce seizures. The low dose effects of all three opioid drugs was sensitive to 1 mg kg-1 naloxone in all seizure models. The responses to high doses of pethidine were unaffected or enhanced by this dose of naloxone. Naloxone reversed the effects of the higher doses of morphine and fentanyl in all models except bicuculline induced seizures.

Modification by drugs used in anaesthesia of CNS stimulation induced in mice by laudanosine and strychnine

We have investigated in mice the effects of several drugs which may be administered as part of an anaesthetic technique on the convulsive threshold to laudanosine and to strychnine, which is reported to have a similar mechanism of action. I.v. administered propofol, thiopentone and midazolam increased the dose of convulsant necessary to produce seizure when administered 2 min before the convulsive stimulus. In contrast, methohexitone and etomidate exhibited a proconvulsant effect, although with the latter this was significant only in laudanosine-treated mice. Pethidine was proconvulsant in both laudanosine- and strychnine-treated mice, but morphine was proconvulsant only in strychnine-treated mice. The effects of morphine, but not pethidine, were antagonized by naloxone 1 mg kg-1. Laudanosine, but not strychnine caused arousal from anaesthesia in subconvulsive doses. This and other evidence suggests that the mechanism of the CNS excitation produced by strychnine and laudanosine are not the same.