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At least 649 records · Page 36Linked to original sources
PubMed2003

Remifentanil versus fentanyl for analgesia based sedation to provide patient comfort in the intensive care unit: a randomized, double-blind controlled trial [ISRCTN43755713].

INTRODUCTION: This double-blind, randomized, multicentre study was conducted to compare the efficacy and safety of remifentanil and fentanyl for intensive care unit (ICU) sedation and analgesia. METHODS: Intubated cardiac, general postsurgical or medical patients (aged >/= 18 years), who were mechanically ventilated for 12-72 hours, received remifentanil (9 microgram/kg per hour; n = 77) or fentanyl (1.5 microgram/kg per hour; n = 75). Initial opioid titration was supplemented with propofol (0.5 mg/kg per hour), if required, to achieve optimal sedation (i.e. a Sedation-Agitation Scale score of 4). RESULTS: The mean percentages of time in optimal sedation were 88.3% for remifentanil and 89.3% for fentanyl (not significant). Patients with a Sedation-Agitation Scale score of 4 exhibited significantly less between-patient variability in optimal sedation on remifentanil (variance ratio of fentanyl to remifentanil 1.84; P = 0.009). Of patients who received fentanyl 40% required propofol, as compared with 35% of those who received remifentanil (median total doses 683 mg and 378 mg, respectively; P = 0.065). Recovery was rapid (median time to extubation: 1.1 hours for remifentanil and 1.3 hours for fentanyl; not significant). Remifentanil patients who experienced pain did so for significantly longer during extubation (6.5% of the time versus 1.4%; P = 0.013), postextubation (10.2% versus 3.6%; P = 0.001) and post-treatment (13.5% versus 5.1%; P = 0.001), but they exhibited similar haemodynamic stability with no significant differences in adverse event incidence. CONCLUSION: Analgesia based sedation with remifentanil titrated to response provided effective sedation and rapid extubation without the need for propofol in most patients. Fentanyl was similar, probably because the dosing algorithm demanded frequent monitoring and adjustment, thereby preventing over-sedation. Rapid offset of analgesia with remifentanil resulted in a greater incidence of pain, highlighting the need for proactive pain management when transitioning to longer acting analgesics, which is difficult within a double-blind study but would be quite possible under normal circumstances.

Adolescent↗
PubMed2000

Constipation and the use of laxatives: a comparison between transdermal fentanyl and oral morphine.

Constipation and the use of laxatives were investigated in patients with chronic cancer pain treated with oral morphine and transdermal fentanyl in an open sequential trial. Forty-six patients were treated with slow-release morphine 30-1000 mg/day for 6 days and 39 of these patients were switched to transdermal fentanyl 0.6-9.6 mg/day with a conversion ratio of 100:1. Median fentanyl doses increased from 1.2 to 3.0 mg/day throughout the 30-day transdermal treatment period. Twenty-three patients completed the study. Two patients died from the basic disease while treated with transdermal fentanyl, 12 patients were excluded for various reasons, and not enough data for evaluation were available for two patients. Mean pain intensity decreased slightly after conversion although the number of patients with breakthrough pain or requiring immediate-release morphine as a rescue medication was higher with transdermal fentanyl. The number of patients with bowel movements did not change after the opioid switch but the number of patients taking laxatives was reduced significantly from 78-87% of the patients per treatment day (morphine) to 22-48% (fentanyl). Lactulose was used mainly and was reduced most drastically, but other laxatives were also used less frequently. In this study transdermal fentanyl was associated with a significantly lower use of laxatives compared to oral morphine. The difference in the degree of constipation between the two analgesic regimens should be confirmed in a randomized double-blind study that takes into account both constipation and use of laxatives.

Administration, Cutaneous↗
PubMed2001

Transdermal fentanyl for the management of cancer pain: a survey of 1005 patients.

Transdermal fentanyl was released in Germany in 1995. From October 1996 to February 1998 transdermal treatment was documented for 1005 patients (506 men and 499 women with a mean age of 60 years, range 20-92 years) with chronic pain in an open survey including 290 physicians from hospitals and general practitioners throughout Germany. Most patients suffered from cancer pain and only 11 patients had chronic pain from non-malignant disease. Physicians were asked to complete a questionnaire for patients treated with transdermal fentanyl on initiation of therapy (day 0), and days 3, 6, 18, 30 thereafter, followed by monthly follow-up intervals. Patients were asked to complete a pain diary. Transdermal therapy was documented from day 0 for 824 patients, while 181 patients had been treated with transdermal fentanyl before admission in the survey. Most of the other 824 patients had been treated with other step 3 opioids (55% of the patients) or step 2 opioids (23%) before conversion to transdermal fentanyl, whereas 8% had been treated only with non-opioids and 14% had received analgesics only as required or not at all before initiation of transdermal therapy. The most important reasons for switching to transdermal opioid therapy were insufficient pain relief with the previous medication followed by a variety of gastrointestinal symptoms impeding oral analgesic therapy. Initial fentanyl doses ranged from 0.6 to 9.6 mg/day (25 to 400 microg/h) with a median of 1.2 mg/day (50 microg/h). Median doses slowly increased throughout the observation period to 2.4 mg/day (100 microg/h) after 4 months of treatment. Most patients continued transdermal therapy until the time of death (47% of patients). Other reasons for discontinuation were inadequate pain relief (10%), pain relief with other analgesic regimens (10%), other symptoms than pain (5%), rejection of transdermal therapy by the patient (6%) or miscellaneous (16%). Adverse events were documented as the reason for discontinuation of transdermal therapy in 49 patients (5%). Dyspnoea was documented for seven patients as the reason for discontinuation. One of these patients, as well as another patient with an episode of apnoea, had to be treated with artificial respiration for several hours, but both patients recovered without sequelae. Transdermal therapy with fentanyl was safe and efficient in this national survey. Transdermal fentanyl can be recommended for treatment of moderate to severe cancer pain and probably may even be used as a first-line drug on step 3 of the World Health Organization recommendations in selected patient groups.

Administration, Cutaneous↗
PubMed1998

Quality of life and cancer pain: satisfaction and side effects with transdermal fentanyl versus oral morphine.

PURPOSE: To compare pain-related treatment satisfaction, patient-perceived side effects, functioning, and well-being in patients with advanced cancer who were receiving either transdermal fentanyl (Duragesic, Janssen Pharmaceuticals, Titusville, NJ) or sustained-release oral forms of morphine (MS Contin, Perdue Frederick Co, Norwalk, CT, or Oramorph SR, Roxanne Laboratories, Columbus, OH). PATIENTS AND METHODS: A total of 504 assessable cancer patients participated in this cross-sectional, quality-of-life study. Relevant elements of four validated scales were used--the Functional Assessment of Cancer Therapy-General (FACT-G) scale, the Brief Pain Inventory (BPI), the Medical Outcomes Study (MOS) questionnaire, and the Memorial Symptom Assessment Scale (MSAS)--as well as original scales that were developed and validated for this study. RESULTS: The majority of patients in both treatment groups had late-stage (IV/D) cancer. Patients who received transdermal fentanyl were more satisfied overall with their pain medication than those who received sustained-release oral forms of morphine (P = .035). Fentanyl patients also experienced a significantly lower frequency (P < .002) and impact (P < .001) of pain medication side effects. These results occurred despite the fact that cancer patients who received fentanyl were significantly older (P < .001) and had significantly lower functioning and well-being scores (P = .001). Measures of pain intensity, sleep adequacy, and symptoms demonstrated no significant differences between treatment groups. CONCLUSION: These data suggest that patients are more satisfied with transdermal fentanyl compared with sustained-release oral forms of morphine. A lower frequency and reduced impact of side effects with transdermal fentanyl may be one reason cancer patients who receive fentanyl are more satisfied with their pain management.

Administration, Cutaneous↗
PubMed1990

Epidural and intravenous fentanyl infusions are clinically equivalent after knee surgery.

The management of postoperative pain with continuous epidural fentanyl infusion was compared with continuous intravenous fentanyl infusion. In a randomized, doubleblind protocol we prospectively studied 20 patients undergoing repair of the anterior cruciate ligament of the knee. The quality of analgesia and the incidence of side effects were documented. Compared with patients receiving continuous intravenous fentanyl infusion, at 18 h postoperatively patients given continuous epidural fentanyl infusion reported similar pain scores both at rest (22 +/- 25 vs 27 +/- 21, P = 0.52) and with ambulation (59 +/- 18 vs 56 +/- 22, P = 0.82). Plasma fentanyl levels were 1.8 +/- 0.4 and 1.7 +/- 0.4 ng/mL (P = 0.91) for the intravenous and epidural groups, respectively. There were no significant differences in the incidence of nausea, pruritus, or urinary retention. There was no respiratory depression in either group. We conclude that when compared with continuous intravenous fentanyl infusion, continuous epidural fentanyl infusion offers no clinical advantages for the management of postoperative pain after knee surgery.

Adolescent↗
PubMed1992

Segmental analgesic effect and reduction of halothane MAC from epidural fentanyl in humans.

To clarify the site of action of epidural fentanyl, we compared the effects of epidural and intravenous fentanyl on the change in pressure pain threshold (PPT) and the minimum alveolar concentration (MAC) of halothane. Seventy patients who underwent gastrectomy in the PPT study group and 84 female patients who underwent hysterectomy in the MAC study group were assigned randomly to seven groups in each study. The seven groups each received a bolus injection of 1, 2, or 4 micrograms/kg of fentanyl, either intravenously or epidurally, and of saline solution epidurally. Compared with intravenous fentanyl, epidural fentanyl significantly increased (P less than 0.01) PPT around surgical incisions by approximately 50%, 100%, and 150% of preadministration levels 1 h after administration of 1, 2, and 4 micrograms/kg, respectively, and significantly reduced (P less than 0.05) halothane MAC at the same doses. These data suggest that the more potent analgesic and anesthetic effects of epidural fentanyl, compared with intravenous fentanyl, are due mainly to the segmental analgesia produced by its spinal analgesic action.

Adult↗
PubMed1993

Use of ketorolac and fentanyl during outpatient gynecologic surgery.

In healthy outpatients undergoing minor gynecologic surgery, the analgesic efficacy of ketorolac was compared to fentanyl and to a combination of the two analgesics. One hundred and nine patients were randomly selected to receive fentanyl 50-100 micrograms, ketorolac 30-60 mg, or a combination of fentanyl 50-100 micrograms and ketorolac 30-60 mg, intravenously (IV). Anesthesia was induced with midazolam 2 mg IV and propofol 1 mg/kg, IV, and maintained with propofol, 50-160 micrograms.kg-1.min-1, IV, and nitrous oxide 67% in oxygen via a face mask. Intraoperative anesthetic conditions, recovery times, and postoperative pain and side effects were evaluated. In the ketorolac group, 75% of patients required supplemental fentanyl intraoperatively (mean dose +/- SD, 47 +/- 54 micrograms), compared to only 19% (13 +/- 30 micrograms) and 18% (6 +/- 15 micrograms) of patients in the fentanyl and combination groups, respectively. In the ketorolac group, 74% of patients moved in response to surgical stimulation compared to only 16% and 19% of patients in the fentanyl and combination groups, respectively. Although there were no significant differences in intraoperative mean arterial pressure, heart rate, and oxygen saturation of hemoglobin values among the three treatment groups, the ketorolac group manifested significantly more rapid respiratory rates throughout the procedure compared with the fentanyl and combination groups. Recovery times, postoperative side effects, and pain scores, as well as postoperative analgesic and antiemetic requirements, were similar in all three treatment groups. However, the ketorolac group reported significantly higher pain scores in the early postoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Prolonged intrathecal fentanyl analgesia via 32-gauge catheters after thoracotomy.

We hypothesized that intrathecal fentanyl infusion would provide excellent analgesia, require lower doses than necessary for the epidural or intravenous route of administration, and reduce the incidence and/or severity of side effects. Accordingly, we studied 12 patients during 48 h after thoracotomy (three pneumonectomies, six lobectomies, and three multiple resections of metastases or pleural surgery). The mean dose of fentanyl infused intrathecally was 0.81 +/- 0.26 microgram.kg-1 x h-1, and plasma fentanyl concentrations ranged between 0.49 +/- 0.19 and 0.72 +/- 0.34 ng/ml. Four patients needed a supplementary bolus of intrathecal fentanyl. Pain scores decreased below 30/100 within 1 h when measured at rest but required 24 h to decrease to the same level during coughing. Pulmonary function tests returned to approximately 50% of preoperative values within 1 h of fentanyl infusion. Mean respiratory rates averaged 19 +/- 4, and no episode of apnea was detected. Pruritus, nausea, and headache occurred, respectively, in four, one, and zero patients. Excessive pressure in the infusion system occurred frequently, limiting fentanyl infusion in two patients. All catheters were removed intact; however, one broke outside of the patient's back. This study demonstrates that intrathecal fentanyl infusion can safely provide rapid and intense analgesia but that current 32-gauge intrathecal catheters are not well suited for prolonged postoperative use.

Adult↗
PubMed1994

The use of fentanyl added to morphine-lidocaine-epinephrine spinal solution in patients undergoing cesarean section.

Because of its slow onset of action, intrathecal morphine may not be the optimal drug for intraoperative analgesia during short cases, such as cesarean sections. It is not known whether adding fentanyl to a morphine-lidocaine spinal solution would provide any benefits to patients undergoing cesarean sections. Sixty-two women scheduled for elective cesarean section received intrathecal 5% lidocaine with dextrose (50-70 mg), epinephrine 200 micrograms, preservative-free morphine 0.2 mg, and either 10 micrograms of fentanyl (study group) or preservative-free normal saline (placebo group) in a 0.2-mL volume. Patients were asked to rate their severity of pain on a visual analog scale (VAS) intraoperatively as the uterus was exteriorized and again when the dermatomal level had receded to L1. Intravenous fentanyl was administered if the patient experienced intraoperative discomfort. The VAS scores were 0.8 +/- 1.5 and 2.3 +/- 1.6 (mean +/- SD) in the placebo group at the time of uterine extrusion and in the post-anesthesia care unit (PACU). The corresponding scores in the fentanyl group were 0.4 +/- 1.1 and 2.7 +/- 2.2. There was a significant difference between the two groups in the VAS scores intraoperatively (P < 0.014) but not in the PACU (P not significant). There was also a significant difference (P < 0.015) in the need for supplementation with intravenous (i.v.) fentanyl. Six patients in the placebo group received i.v. fentanyl as compared with none of the patients in the fentanyl group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1994

An isobolographic study of epidural clonidine and fentanyl after cesarean section.

Although the epidural administration of clonidine and fentanyl provides pain relief after surgery, the interaction between the two drugs has not been examined formally. This study used an isobolographic method to determine whether epidurally administered fentanyl and clonidine interact in an additive or synergistic manner. Ninety women with moderate to severe pain after elective cesarean section under epidural anesthesia were studied. Using a randomized, double-blind protocol, we assigned each patient to receive a single epidural injection of one of three doses of fentanyl, clonidine, or a fixed ratio combination. Pain relief, blood pressure (BP), heart rate (HR), and sedation were measured 15 min after injection. Each drug alone and in combination produced analgesia, as measured by pain relief scores, and reduced need for intravenous morphine. Although the effective dose producing analgesia in 50% of patients (ED50) for the mixture was only 52% of that predicted by an additive interaction, this did not differ significantly from additivity, likely due to large variability. Clonidine, alone or in combination with fentanyl, produced a minor reduction in BP, but did not affect HR or cause more sedation than fentanyl. Unlike studies in rodents, this clinical study did not demonstrate synergy between fentanyl and clonidine. This could reflect a true species difference or differences in methodologies used. Nonetheless, a reduced dose of fentanyl and clonidine can be combined for excellent analgesia.

Adult↗
PubMed2003

Intravenous alprostadil, an analog of prostaglandin E1, prevents thiamylal-fentanyl-induced bronchoconstriction in humans.

UNLABELLED: Prostaglandin (PG) E(1) relaxes airway smooth muscle in animals. However, no clinical data have been published on the bronchorelaxant effects of IV alprostadil, an analog of PGE(1). We have described experimental thiamylal-fentanyl-induced bronchoconstriction in humans; we now report the effect of IV alprostadil on thiamylal-fentanyl-induced bronchoconstriction. Thirty-two patients were allocated randomly to a control group (n = 16) and alprostadil group (n = 16). Anesthesia was induced with thiamylal 5 mg/kg and vecuronium 0.3 mg/kg and maintained with a continuous infusion of thiamylal 15 mg. kg(-1). h(-1). The lungs of the patients were ventilated with 50% nitrous oxide in oxygen. Twenty minutes after the induction of anesthesia, patients in the control group were given a continuous infusion of normal saline 20 mL/h, and those in the alprostadil group received a continuous infusion of alprostadil 0.2 micro g. kg(-1). min(-1) (20 mL/h), both for 60 min. Both groups were then given fentanyl 5 micro g/kg. Systolic and diastolic arterial blood pressure, heart rate, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured at the baseline, just before the fentanyl injection (T30), at three consecutive 6-min intervals after fentanyl injection (T36, T42, and T48), and 30 min after fentanyl injection (T60). Baseline Rawm, Rawe, and Cdyn values were comparable between groups. In the control group, both Rawm and Rawe were significantly increased at T36-60, and Cdyn was significantly decreased at T36-60 compared with the baseline. Patients given alprostadil showed no change in Rawm, Rawe, or Cdyn at T36-60. Thus, IV alprostadil seems to have a bronchodilator effect in humans. IMPLICATIONS: IV alprostadil, an analog of prostaglandin E(1), prevents thiamylal-fentanyl-induced bronchoconstriction in humans. This finding suggests that IV alprostadil has a bronchodilator effect.

Adult↗
PubMed2004

Intrathecal midazolam II: combination with intrathecal fentanyl for labor pain.

UNLABELLED: Recent investigations have sought to improve intrathecal analgesia by combining opioids with other classes of analgesics. In this study we assessed the ability of intrathecal midazolam to increase the potency and duration of the analgesic effects of intrathecal fentanyl without causing adverse effects. Thirty parturients with cervical dilations 2-6 cm were randomized to receive either intrathecal midazolam 2 mg, fentanyl 10 micro g, or both combined to initiate analgesia. Pain scores were recorded before and at 5-min intervals for 30 min after the injection and then every 30 minutes until the patient requested further analgesia. The presence and severity of nausea, emesis, pruritus, headache, and sedation, in addition to arterial blood pressure, heart rate, respiratory rate, sensory changes to ice, motor impairment, cardiotocograph, and Apgar score were also recorded. The parturients were assessed after 2 days and 1 mo for neurologic impairment. Preinjection pain scores were unaltered by intrathecal midazolam alone and moderately decreased by fentanyl. Intrathecal midazolam increased the analgesic effect of fentanyl. No treatment altered cardiorespiratory variables or caused motor impairment. The addition of intrathecal midazolam to fentanyl did not increase the occurrence of any maternal adverse event or abnormalities on the cardiotocograph. We conclude that intrathecal midazolam enhanced the analgesic effect of fentanyl without increasing maternal or fetal adverse effects. IMPLICATIONS: Treatment of labor pain with epidural injections of local anesthetic is complicated by decreases in arterial blood pressure and leg weakness. This study showed that a mixture of two drugs, fentanyl and midazolam, could provide powerful pain relief when the drugs were given together spinally without such side effects.

Adult↗
PubMed2005

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.

Adolescent↗
PubMed2005

Preoperative "fentanyl challenge" as a tool to estimate postoperative opioid dosing in chronic opioid-consuming patients.

UNLABELLED: When opioids are used for postoperative pain control, it is useful to define the dose-response relationship for analgesia and respiratory depression. We studied 20 chronically opioid-consuming patients having elective multilevel spine fusion. Preoperatively, each patient received a fentanyl infusion of 2 microg x kg(-1) x min(-1) until the respiratory rate was <5 breaths/min. Pharmacokinetic simulations were used to estimate the effect site concentration at the time of respiratory depression and to predict the patient-controlled analgesia settings that would provide an effect-site fentanyl concentration that was 30% of the concentration associated with respiratory depression. Postoperatively, patient-controlled analgesia settings were adjusted to achieve 2-3 demand doses per hour. At steady-state patient-controlled analgesia settings, arterial blood gases and plasma fentanyl levels were measured. Sixteen patients required no adjustment or one patient-controlled analgesia adjustment. The median arterial Pco(2) level was 41 mm Hg and the interquartile range was 39-46 mm Hg. Plasma fentanyl levels demonstrated a significant correlation to the estimated effect-site concentration associated with respiratory depression determined during the preoperative fentanyl challenge. A preoperative fentanyl challenge used with pharmacokinetic simulations may be a useful tool to individualize the administration of analgesics to chronically opioid-consuming patients. IMPLICATIONS: In chronically opioid-consuming patients, doses causing respiratory depression and analgesia may differ from those in opioid-naive individuals. A preoperative infusion of fentanyl, used in conjunction with pharmacokinetic simulation, may be a valuable tool for identifying clinical end-points, such as respiratory depression and analgesia, and individualizing postoperative treatment of pain in patients who chronically consume opioids.

Analgesics, Opioid↗
PubMed2005

Prolonged injection time and light smoking decrease the incidence of fentanyl-induced cough.

We designed this study to evaluate the effect of injection time and smoking on fentanyl-induced cough. Four-hundred-fifty ASA class I-II patients, aged 18-80 yr and weighing 40-90 kg, scheduled for elective surgery were included. All patients received fentanyl (100 microg for patients weighing 40-69 kg and 150 microg for patients weighing 70-90 kg for clinical convenience) via the proximal port of a peripheral IV line on the forearm. Patients were randomly assigned to 3 groups of 150 patients each. Patients in Group I received fentanyl injection over 2 s, whereas for patients in Groups II and III the fentanyl was injected at a constant rate over 15 s and 30 s, respectively. We recorded the number of coughs of each patient during and 30 s after fentanyl injection. The incidence of cough was 18% in group I, 8% in Group II, and 1.3% in Group III, significantly less (P < 0.05) with a longer injection time. Current smokers had a less frequent incidence of cough than nonsmokers; however, this effect was only significant in light smokers (<10 cigarettes per day or <10 smoking years or <10 pack-years). In conclusion, a longer injection time reduces the incidence of fentanyl-induced cough, and light smoking may be a protective factor against fentanyl-induced cough.

Adolescent↗
PubMed1976

Fentanyl and tooth pulp evoked responses in the spinal trigeminal nucleus caudalis region.

Electrical activities evoked by tooth pulp stimulation were recorded in the subnucleus caudalis region of the spinal trigeminal nucleus, and the action of fentanyl, a short-acting narcotic, on these activities was investigated in the alpha-cholinergic anesthetized cat. Fentanyl (20 to 40 mug/kg i.v.) depressed the first peak and potentiated the second one of negative potentials evoked by pulp stimulation in the border area betaeen the nucleus proprius (Pr) and the lateral reticular formation (LRF). Neurons, whose responses to pulp stimulation were depressed by fentanyl, were also predominantly localized in this region. Pulp-induced monophasic negative potential and spike discharges in the more ventro-medial portion of the LRF were not affected by fentanyl. The effect of fentanyl on cells in the marginal zone varied from unit to unit. The selective action of fentanyl on neurons in the border area between the Pr and the LRF may partially explain the analgesic action of fentanyl.

Animals↗
PubMed2001

Involvement of potassium channels in spinal antinociceptions induced by fentanyl, clonidine and bethanechol in rats.

In the central nervous systems, intracellular and extracellular movement of potassium ions plays an important role in regulating neuronal excitability and the release of neurotransmitters. The purpose of our study was to determine whether nicorandil (adenosine triphosphate-sensitive K+ channel opener) exerts antinociceptive effects by itself or in combination with fentanyl, clonidine and bethanechol and whether glibenclamide (adenosine triphosphate-sensitive K+ channel blocker) and charybdotoxin (Ca2+-activated K+ channel blocker) may antagonize the antinociceptive action of fentanyl, clonidine and bethanechol. Antinociceptive effects were assessed using the tail-flick test in rats. Nicorandil (100 microg) and antinociceptively ineffective doses of fentanyl (1 microg), clonidine (2.5 microg) or bethanechol (10,ug) were coadministered intrathecally (i.t.). Glibenclamide (100 microg) or charybdotoxin (2.5 ng) were administered i.t. at 5 min before each effective dose of fentanyl (2.5 microg), clonidine (10 microg) or bethanechol (40 microg). The present findings demonstrated that i.t. administration of nicorandil alone exerted no influence on the tail-flick latency. However, concomitant administrations of antinociceptively inactive doses of fentanyl, clonidine or bethanechol with nicorandil elicited significant suppression of the thermonociceptive response. Also, each antinociception induced by fentanyl, clonidine or bethanechol was partially antagonized by both glibenclamide and charybdotoxin. These findings showed that activation of the K+ channel might enhance the antinociceptive effects of fentanyl, clonidine and bethanechol.

Adenosine Triphosphatases↗
PubMed2000

Transdermal fentanyl compared with parenteral buprenorphine in post-surgical pain in swine: a case study.

The use of pigs as research animals in survival surgery has increased greatly in the last 15 years. Personnel conducting pig research have been hampered by a lack of proven long-acting analgesics for treatment of surgical pain of longer duration, and by a lack of reliable non-subjective parameters for the assessment of pain relief. The efficacy of the mixed opioid agonist-antagonist buprenorphine hydrochloride 0.10 mg/kg pr (n = 2) in the treatment of post-thoracotomy pain was compared with that of a transdermal therapeutic system (TTS) delivering 25 microg/h (n = 3) or 50 microg/h (n = 2) of the mu opioid agonist fentanyl hydrochloride. Food consumption, pain score, activity level and rate of movement were assessed under four conditions: normal pre-operative control (24h), pre-operative with analgesic alone (24h) and post-operative days 1, 2, 3 (72h). Serum concentration-time curves for fentanyl in clinical cases revealed that female Yorkshire cross pigs weighing 26.2+ 2.1 kg achieved serum values in the recognized human therapeutic range when treated with TTS fentanyl at 50 microg/h and experienced adequate pain control. Pigs treated with 25 microg/h TTS fentanyl had serum levels below the human analgesic range, experienced less adequate analgesia, and required supplemental analgesia in some cases. Based on existing pharmacokinetic data for fentanyl in pigs, the rate of uptake of TTS fentanyl when attached on inter-scapular skin was lower than predicted. Clinical pain scores and time intervals between each major postural change were not affected by analgesics in the absence of pain, but increased in all groups after surgery regardless of treatment. Food consumption was unaffected by analgesic treatment alone but decreased in all groups after surgery regardless of treatment. Analgesic effects on postoperative activity level were variable. TTS fentanyl at appropriate doses is a cost effective means of delivering basal analgesia following major surgery in pigs.

Administration, Cutaneous↗