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PubMed1999

Reproducible fentanyl doses delivered intermittently at different time intervals from an electrotransport system.

The electrotransport transdermal fentanyl system (ET [fentanyl]), uses a small electrical current to enhance delivery of fentanyl to systemic circulation. Intermittent doses can be administered by periodic application of the current. The purpose of this study was to compare the effects of the frequency of intermittent drug delivery by ET (fentanyl) and compare the drug delivery to systemic circulation by ET (fentanyl) with intravenous administration. The topical safety was also determined for the ET (fentanyl) system. Nine adult male volunteers completed this three-treatment, randomized, 24-h, crossover study. ET (fentanyl) treatments with 200 microA direct current applied for 30 min at frequent (hourly) or infrequent (4-hourly) intervals over a 24-h period were compared. Also, the drug delivery to systemic circulation from ET (fentanyl) was compared with intravenous fentanyl 75 microg infused over 30 min every 4 h over a 24-hour period. The mean serum fentanyl concentration achieved with the hourly ET (fentanyl) regimen was higher than that for the 4-hourly ET (fentanyl) regimen as expected from the higher frequency of drug doses. The amount of fentanyl delivered estimated per dose from the ET (fentanyl) system using the iv fentanyl treatment as the reference was similar for the two ET regimens throughout the dosing period. This indicates consistent drug delivery regardless of the frequency of ET dosing. The majority of subjects reported either no, or barely perceptible, erythema 24 h after removal of the system.

Administration, Cutaneous↗

PubMed2003

Plasma fentanyl concentrations in awake cats and cats undergoing anesthesia and ovariohysterectomy using transdermal administration.

OBJECTIVE: To measure the plasma fentanyl concentrations achieved over time with transdermal fentanyl patches in awake cats and cats undergoing anesthesia and ovariohysterectomy. STUDY DESIGN: Randomized prospective experimental study. ANIMALS: Twenty-four purpose-bred cats. METHODS: Cats were randomly assigned to three groups for Part I of a larger concurrent study. Group P received only a 25 micro g hour-1 transdermal fentanyl patch. Group P/A received the patch and anesthesia. Group A received only anesthesia. After a minimum 1-week washout period, the cats were randomly reassigned to two groups for Part II of the larger study. Group P/A/O received the patch, anesthesia and ovariohysterectomy. Group A/O received anesthesia and ovariohysterectomy. Patches were left in place for 72 hours and plasma samples were obtained for fentanyl analysis while the patches were in place, and for 8 hours after patch removal for cats in Group P, P/A, and P/A/O. RESULTS: The 25 micro g hour-1 transdermal fentanyl patches were well tolerated by the cats in this study (mean body weight of 3.0 kg) and no overt adverse effects were noted. Mean plasma fentanyl concentrations over time, mean plasma fentanyl concentrations at specific times (8, 25, 49, and 73 hours after patch placement), time to first detectable plasma fentanyl concentration, time to reach maximum plasma fentanyl concentration, maximum plasma fentanyl concentration, mean plasma fentanyl concentration from 8 to 73 hours, elimination half-life, and total area under concentration (AUC) were not statistically different among the groups. CONCLUSIONS: Halothane anesthesia and anesthesia/ovariohysterectomy did not significantly alter the plasma fentanyl concentrations achieved or pharmacokinetic parameters measured, when compared with awake cats. There was a high degree of individual variability observed both within and between groups of cats in parameters measured. CLINICAL SIGNIFICANCE: The high degree of variability observed suggests that careful observation of cats with fentanyl patches in place is required to assess efficacy and any potential adverse effects. Anesthesia and anesthesia/ovariohysterectomy do not appear to alter plasma fentanyl concentrations achieved by placement of a 25 micro g hour-1 transdermal fentanyl patch when compared to cats not undergoing these procedures.

Administration, Cutaneous↗

PubMed2003

Effect-site concentration of propofol for recovery of consciousness is virtually independent of fentanyl effect-site concentration.

UNLABELLED: Fentanyl reduces the amount of propofol necessary to prevent responses to surgical stimuli. However, opioids have relatively little effect on consciousness. We, therefore, tested the hypothesis that fentanyl minimally alters the effect-site concentration of propofol associated with awakening. Fifty women having gynecologic laparotomy with propofol anesthesia were randomly allocated into the following target effect-site fentanyl concentrations: 0.8, 1.0, 1.4, 2.0, and 3.0 ng/mL. Fentanyl was continued at the designated rate through the initial postoperative phase. The propofol effect-site concentration associated with eye opening in response to verbal command was regarded as the awakening concentration. The estimated propofol effect-site concentrations at awakening did not differ significantly among the groups and were 1.9 +/- 0.5 micro g/mL with a fentanyl effect-site concentration of 0.8 ng/mL; 1.6 +/- 0.4 micro g/mL with 1.0 ng/mL of fentanyl; 1.6 +/- 0.2 micro g/mL with 1.4 ng/mL of fentanyl; 1.7 +/- 0.4 micro g/mL with 2.0 ng/mL of fentanyl; and 1.6 +/- 0.34 micro g/mL with 3.0 ng/mL of fentanyl (mean +/- SD). Seventy percent of the subjects in the 0.8 ng/mL fentanyl group spontaneously complained of pain, whereas none of the patients in the 2 or 3 ng/mL groups did. Five (56%) of 9 women in the 3 ng/mL group had a postoperative respiratory rate <6 breaths/min. Heart rate in one of these women decreased to <40 bpm. These data suggest that the optimal fentanyl effect-site concentration in patients recovering from gynecologic laparoscopy is between 1.4 and 2.0 ng/mL. IMPLICATIONS: The effect-site concentration for propofol at awakening was virtually independent of the fentanyl effect-site concentration over the range of 0.8 to 3.0 ng/mL; however, 0.8 ng/mL of fentanyl was associated with inadequate postoperative analgesia, and 3.0 ng/mL of fentanyl was associated with respiratory toxicity. The optimal postoperative fentanyl effect-site concentration during recovery from propofol general anesthesia for laparotomy thus appears to be near 2 ng/mL.

Adult↗

PubMed1994

The interaction of fentanyl on the Cp50 of propofol for loss of consciousness and skin incision.

BACKGROUND: We have previously demonstrated that the minimum alveolar concentration of isoflurane at 1 atm that is required to prevent movement in 50% of patients or animals exposed to a maximal noxious stimulus is markedly reduced by increasing fentanyl concentrations. Total intravenous anesthesia with propofol is increasing in popularity, yet the propofol concentrations required for total intravenous anesthesia or the interaction between propofol and fentanyl have not yet been defined. METHODS: Propofol and fentanyl were administered via computer-assisted continuous infusion to provide pseudo-steady-state concentrations and allow equilibration between plasma-blood concentration and their biophase concentration. For the induction of anesthesia patients were randomly allocated to receive propofol only or propofol plus fentanyl 0.2, 0.8, 1.5, 3.0, and 4.5 ng/ml. In each group patients were randomized to target propofol concentrations of 1.5-10 micrograms/ml. At 7 and 10 min arterial blood samples were taken for subsequent measurement of propofol and fentanyl concentrations. At 10 min loss of consciousness was assessed by the patients' ability to respond to a simple verbal command. Thereafter a new target concentration of propofol was entered to ensure loss of consciousness, and succinylcholine was administered to facilitate tracheal intubation. Patients were rerandomized to a new target concentration of propofol (1-19 micrograms/ml) until skin incision. Before skin incision and 1 min after skin incision, arterial blood samples were again obtained for subsequent measurement of fentanyl and propofol concentrations. At skin incision and for 1 min the patient was observed for purposeful movement. Only samples in which the pre- and poststimulus drug concentrations were within 35% of each other were included. The propofol blood concentration at which 50% or 95% of patients did not respond to verbal command (Cp50s and Cp95s, respectively) and to skin incision (Cp50i and Cp95i, respectively), were calculated by logistic regression. RESULTS: There were 56 evaluable patients for calculating the propofol Cp50s and 53 patients for calculating the propofol Cp50i. For propofol alone the Cp50s was 3.3 micrograms/ml and the Cp95s 5.4 microgram/ml. Increasing fentanyl concentrations reduced the Cp50s (P = 0.03), and increasing age decreased the Cp50s (P = 0.04). For propofol alone the Cp50i was 15.2 (95% confidence interval 7.6-22.8) micrograms/ml and the Cp95i 27.4 micrograms/ml. Increasing fentanyl concentrations markedly reduced the Cp50i (P < 0.01), with a 50% reduction in Cp50i produced by 0.63 ng/ml fentanyl. The propofol Cp50i was decreased by 63% with 1 ng/ml fentanyl and 89% by 3 ng/ml fentanyl. At higher fentanyl concentrations the decrease in Cp50i was proportionally less, demonstrating a ceiling effect. CONCLUSIONS: We defined the propofol concentration required for loss of consciousness and showed that it is reduced by increasing fentanyl concentration and by increasing age. The propofol concentration (alone) adequate for skin incision is high but is markedly reduced by fentanyl. A ceiling effect in the Cp50i for propofol is seen with fentanyl concentrations greater than 3 ng/ml.

Adult↗

PubMed2026

Partially countering the physiological effects of fentanyl with naloxone or d-cysteine ethyl ester in adult goats.

Fentanyl is the leading contributor to opioid-involved overdose (OD) mortality in the United States. Despite the demonstrated efficacy, safety, and wide availability of naloxone (NAL), opioid-involved OD fatalities remain high. This suggests our understanding of the negative integrated physiological effects of fentanyl remains incomplete, and highlights the need to develop additional novel countermeasures. Here we tested whether the physiological and behavioral effects of intravenous fentanyl in adult female goats (n = 12) could be mitigated with NAL or the potential countermeasure d-cysteine ethyl ester (d-CYSee). As hypothesized, intravenous injections of high doses (HD) fentanyl caused immediate ventilatory suppression via reduced breathing frequency leading to hypoventilation and hypoxemia (≥10 min). HD fentanyl elicited immediate and sustained (≥90 min) increases in diaphragm, intercostal, abdominal, and laryngeal constrictor muscle activity along with an increased alveolar to arterial oxygen (A-a O2) gradient and hypertension. Intravenous NAL administered immediately following HD fentanyl mitigated most of these effects except the increased activation of respiratory pump and airway muscles. In contrast, d-CYSee administration immediately following HD fentanyl countered the initial hypoventilation but did not mitigate the increases in muscle activation and persistent hypoxemia. Neither treatment prevented acute withdrawal-like behaviors emerging >90 min after fentanyl administration. The data suggest that there are physiological effects of HD fentanyl that are NAL-insensitive, and d-CYSee can transiently normalize blood gases and counter opioid-induced respiratory depression (OIRD) in adult goats.NEW & NOTEWORTHY Here we determined whether any of the deleterious physiological effects of high-dose fentanyl could be countered by naloxone and/or d-cysteine ethyl ester (d-CYSee) in adult goats. Fentanyl induced hypoventilation and sustained increases in respiratory and airway muscle activity and hypoxemia. Naloxone reversed all fentanyl effects except tonic muscle activation, and d-CYSee reversed fentanyl-induced hypoventilation. These data suggest some effects of fentanyl are naloxone-insensitive and that d-CYSee may be a valuable countermeasure for OIRD.

Animals↗

PubMed1998

Fentanyl delivery from an electrotransport system: delivery is a function of total current, not duration of current.

This open-label, parallel study of 28 men was conducted to evaluate the pharmacokinetics and safety of fentanyl delivered by the E-TRANS (fentanyl) electrotransport transdermal system (ALZA Corporation, Palo Alto, CA). The E-TRANS (fentanyl) system provided electrically assisted, transdermal, continuous delivery of fentanyl. Treatments consisted of no current (group A); a constant current of 100 microA for 26 hours plus 4 additional doses at varying currents for varying times during hour 25 (groups B, C, D); a constant current of 100 microA for 26 hours plus 4 additional doses at 1,200 microA over 2.5 minutes during hour 1 (group E); or 500 microA for 0.5 hours and 100 microA for 3.5 hours (group F). No fentanyl was detected in serum when no current had been applied. Mean serum fentanyl concentrations were similar regardless of current duration during hour 25 (treatments B, C, D). Increases in mean serum fentanyl concentrations were significantly lower during additional dosing for treatment E compared with treatments B, C, and D. Serum fentanyl concentrations sufficient for analgesia (1-3 ng/mL) were attained in treatments using the E-TRANS (fentanyl) system with basal current of 100 microA for 26 hours. There were no safety issues after treatment with E-TRANS (fentanyl) system with concurrent opioid antagonist (naltrexone) administration. The only adverse event requiring treatment was a headache (n = 1). The majority of subjects had no or barely perceptible erythema at the application site 24 hours after system removal. Application of E-TRANS (fentanyl) resulted in therapeutically significant serum fentanyl concentrations over a range of applied currents. Overall serum fentanyl concentrations were higher when the skin had been primed by constant-current fentanyl delivery.

Administration, Cutaneous↗

PubMed1998

Consideration of the optimal epidural fentanyl doses in abdominal surgery.

STUDY OBJECTIVE: To determine an optimal dose of epidural fentanyl in open abdominal surgery by examining the effects of different doses of epidural fentanyl in combination with or without low concentration of lidocaine on hemodynamic and endocrine responses to surgical stress. DESIGN: Prospective, randomized study. SETTING: University hospital. PATIENTS: 40 ASA physical status I and II patients scheduled for elective abdominal surgery including gastrectomy (n = 20), colectomy (n = 10), liver tumor resection (n = 2), pancreatectomy (n = 3), pancreaticoduodenectomy (n = 1), low anterior resection (n = 3), and cholecystectomy (n = 1). INTERVENTIONS: Patients were randomly allocated to one of two groups: epidural fentanyl with 0.5% lidocaine (Group L + F; n = 25) or epidural fentanyl alone (Group F; n = 15). Both two groups were divided into subgroups; in Group L + F, epidural fentanyl was administered as doses of 0, 0.3, 1, 3, and 5 micrograms/kg in 5 patients each. In Group F, epidural fentanyl was administered as doses of 1, 3, and 5 micrograms/kg in 5 patients each. Hemodynamic data and plasma catecholamine concentrations were compared between before the epidural injection and immediately after peritoneal incision. MEASUREMENTS AND MAIN RESULTS: There was no difference in mean arterial pressure (MAP) and heart rate (HR) between Group L + F and Group F at the time before epidural administration of fentanyl, 20 minutes after epidural fentanyl, and immediately after peritoneal incision. However, there were significant decreases in MAP immediately after skin incision in epidural fentanyl 0 and 3 micrograms/kg in Group L + F patients and also in epidural fentanyl 1 and 3 micrograms/kg in Group F patients. HR significantly decreased in epidural fentanyl 5 micrograms/kg of Group L + F at peritoneal incision (p < 0.05). Plasma epinephrine decreased significantly in fentanyl 3 and 5 micrograms/kg in Group L + F immediately after peritoneal incision (p < 0.05), whereas the increase in norepinephrine was significant in Group F (p < 0.01). Plasma dopamine significantly increased only in fentanyl 1 microgram/kg in Group F (p < 0.05). CONCLUSION: Epidural fentanyl 3 micrograms/kg with 0.5% lidocaine may be most adequate for laparotomy because these doses caused neither bradycardia nor increments of norepinephrine perioperatively.

Abdomen↗

PubMed2003

The pharmacokinetics of transdermal fentanyl delivered with and without controlled heat.

Preliminary reports have demonstrated that the application of local heat to the transdermal fentanyl patch significantly increased systemic delivery of fentanyl. The objective of this study was to further evaluate the pharmacokinetic effect of local heat administration on fentanyl drug delivery through the transdermal fentanyl patch delivery system in volunteers. In addition, the study was intended to document the effect of heat on steady-state transdermal fentanyl delivery. This was an open, 3-period, crossover study that evaluated the pharmacokinetics and safety of 25 microg/h transdermal fentanyl administered with and without local heat. During Sessions A and B, subjects received transdermal fentanyl for a 30-hour period. During Session A, heat was applied for 1 hour at the 24-hour time point during the 30-hour period. During Session B, heat was applied for the first 4 hours and then again for 1 hour at the 24-hour time point during the 30-hour period. The order of Sessions A and B was randomized, and a minimum of 2 weeks separated the sessions. Five of the 10 subjects returned to participate in Session C. During Session C, subjects received transdermal fentanyl 25 microg/h for 18 hours. Heat was applied during the first 4 hours of administration and then again for 15-minute periods at the 12- and 16-hour time points. Arterial blood samples for determination of serum fentanyl concentration were collected. Maximum concentration (C(max)), time to maximum concentration (t(max)), and area under the curve (AUC) were determined for each treatment period. Sedation, vital signs, oxygen saturation, and adverse events were recorded. During a period of 36 hours, there were no significant differences in C(max), AUC, or T(max) between transdermal fentanyl delivery with no heat and heat. However, significant differences were seen during the first 4 hours, with C(max) and AUC values almost 3 times higher for the heated administrations than for the administrations without heat. With heat, the mean C(max) was 0.63 ng/mL compared with a C(max) of 0.24 ng/mL without heat (P =.007). With early heat, the mean AUC was 1.22 ng/mL. h compared with 0.42 ng/mL. h without heat (P =.003). There was no statistically significant difference between the median times to achieve peak values (T(max)) during the first 4 hours. The addition of heat at 24 hours resulted in rapid increases in serum fentanyl concentrations for both groups and higher serum fentanyl concentrations for the administration that did not receive heat previously. Applying heat for 15 minutes at the 12-hour and 16-hour time points produced a rapid but short duration increase in serum fentanyl concentrations. The results suggest controlled heat might be used to significantly shorten the time needed to reach clinically important fentanyl concentrations. Controlled heat might be useful to produce rapid increases in serum concentrations for the rapid treatment of breakthrough pain.

Administration, Cutaneous↗

PubMed2002

Intrathecal versus intravenous fentanyl for supplementation of subarachnoid block during cesarean delivery.

UNLABELLED: Forty-eight healthy parturients scheduled for elective cesarean delivery were randomly allocated to receive intrathecally either 12 mg of hyperbaric bupivacaine plus 12.5 microg of fentanyl (n = 23) or bupivacaine alone (n = 25). In the latter group, IV 12.5 microg of fentanyl was administered immediately after spinal anesthesia. We compared the amount of IV fentanyl required for supplementation of the spinal anesthesia during surgery, the intraoperative visual analog scale, the time to the first request for postoperative analgesia, and the incidence of adverse effects. Additional IV fentanyl supplementation amounting to a mean of 32 +/- 35 microg was required in the IV Fentanyl group, whereas no supple- mentation was required in the Intrathecal Fentanyl group (P = 0.009). The time to the first request for postoperative analgesia was significantly longer in the Intrathecal Fentanyl group than in the IV Fentanyl group (159 +/- 39 min versus 119 +/- 44 min; P = 0.003). The incidence of systolic blood pressure <90 mm Hg and the ephedrine requirements were significantly higher in the IV Fentanyl group as compared with the Intrathecal Fentanyl group (P = 0.01). Also, intraoperative nausea and vomiting occurred less frequently in the Intrathecal Fentanyl group compared with the IV Fentanyl group (8 of 23 vs 17 of 25; P = 0.02). IMPLICATIONS: Supplementation of spinal bupivacaine anesthesia for cesarean delivery with intrathecal fentanyl provides a better quality of anesthesia and is associated with a decreased incidence of side effects as compared with supplementation with the same dose of IV fentanyl.

Adjuvants, Anesthesia↗

PubMed1992

A randomized, double-blind comparison of lumbar epidural and intravenous fentanyl infusions for postthoracotomy pain relief. Analgesic, pharmacokinetic, and respiratory effects.

Although epidural opioids frequently are used to provide postoperative analgesia, several articles have suggested that the analgesia after epidural fentanyl is similar to that after an equal dose of fentanyl given intravenously. To address this issue further, 29 postthoracotomy patients were studied in a randomized, double-blinded trial comparing a lumbar epidural fentanyl infusion with an intravenous fentanyl infusion for analgesia, plasma fentanyl pharmacokinetics, and respiratory effects for 20 h postoperatively. In all patients in both groups, good analgesia was achieved (pain score less than 3, maximum 10) over a similar time course, although the patients receiving epidural infusion required a significantly larger fentanyl infusion dose than did the patients receiving intravenous infusion (group receiving epidural fentanyl infusion: 1.95 +/- 0.45 micrograms.kg-1.h-1; group receiving intravenous fentanyl infusion: 1.56 +/- 0.36 micrograms.kg-1.h-1; P = 0.0002). The time course for the plasma fentanyl concentrations was similar in the two groups, and plasma fentanyl concentrations were not significantly different at any sampling period (T7-T20; group receiving epidural fentanyl infusion: 1.8 +/- 0.5 ng/ml; group receiving intravenous fentanyl infusion: 1.6 +/- 0.6 ng/ml; P = 0.06). Similarly, calculated clearance values for the two groups were not significantly different (group receiving epidural fentanyl infusion: 0.95 +/- 0.26 l.kg-1.h-1; group receiving intravenous fentanyl infusion: 0.87 +/- 0.25 l.kg-1.h-1; P = 0.3). Both groups demonstrated a similar degree of mild to moderate respiratory depression postoperatively, which was assessed with continuous respiratory inductance plethysmography and sequential arterial blood gas analysis. Side effects (nausea, vomiting, pruritus) were mild and did not differ between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Interaction of fentanyl and nitrous oxide on peripheral and cerebral hemodynamics in newborn lambs.

BACKGROUND: The ability of opioids to produce complete general anesthesia is controversial. Nitrous oxide (N2O) is often added to fentanyl-based anesthetics to produce unconsciousness and amnesia. The addition of N2O may adversely affects fentanyl's hemodynamic stability and safety. The purpose of this study was to determine the physiologic consequences of combining N2O with fentanyl in newborn animals. METHODS: The effects of 50% nitrous oxide in oxygen (O2), and 50% N2O in O2 combined with 3,000 micrograms/kg fentanyl, on cerebral and peripheral hemodynamics were studied in seven unanesthetized newborn lambs, in whom catheters were previously inserted. After a control period, lambs were placed in a hood in which inspired gas concentrations were controlled and which minimized external stimuli. After 30 min of breathing room air, the lambs breathed 50% N2O in O2 for an additional 30 min. The lambs were then given 3,000 micrograms/kg fentanyl by intravenous bolus and by infusion (1,000 micrograms.kg-1 x h-1) for 60 min while continuing to breathe 50% N2O in O2. RESULTS: All animals responded to pain (tail clamp) and alerted to sound when breathing room air or when N2O was used alone. Adding fentanyl to the N2O abolished all responses to pain, but not to sound. Additionally, fentanyl produced immediate apnea necessitating tracheal intubation and mechanical ventilation. Mean arterial pressure and heart rate increased 27% and 23%, respectively, after fentanyl administration, intubation, and ventilation. It did not change over the course of the fentanyl infusion. Cerebral blood flow, O2 consumption, and O2 delivery did not change when N2O was administered alone or in combination with fentanyl. Splanchnic blood flow was unaffected by treatment over time. Renal blood flow decreased by 21% after fentanyl administration, but was unaffected by N2O alone. Right and left ventricular blood flow increased (47% and 26%, respectively) after fentanyl administration, intubation, and ventilation, but not when N2O was administered alone. CONCLUSIONS: Fentanyl (3,000 micrograms/kg) when combined with 50% N2O in O2 produced a plane of general anesthesia in newborn lambs in which the behavioral responses to painful stimuli were abolished. The response to sound was never eliminated, nor was cerebral oxygen consumption decreased. The combination of 50% N2O in O2, 3,000 micrograms/kg fentanyl, tracheal intubation, and mechanical ventilation did not depress heart rate, blood pressure, or blood flow to any of the major organs, except the kidneys.

Anesthesia, General↗

PubMed2004

Quinidine as a probe for the role of p-glycoprotein in the intestinal absorption and clinical effects of fentanyl.

The mechanism of individual variability in the fentanyl dose-effect relationship is unknown. The efflux pump P-glycoprotein (P-gp) regulates brain access and intestinal absorption of numerous drugs. Evidence exists that fentanyl is a P-gp substrate in vitro, and P-gp affects fentanyl analgesia in animals. However, the role of P-gp in human fentanyl disposition and clinical effects is unknown. This investigation tested the hypothesis that plasma concentrations and clinical effects of oral and intravenous fentanyl are greater after inhibition of intestinal and brain P-gp, using the P-gp inhibitor quinidine as an in vivo probe. Two randomized, double-blind, placebo-controlled, balanced, two-period crossover studies were conducted in normal healthy volunteers (6 males and 6 females) after obtaining informed consent. Pupil diameters and/or plasma concentrations of fentanyl and norfentanyl were evaluated after oral or intravenous fentanyl (2.5 microg/kg), dosed 1 hour after oral quinidine (600 mg) or placebo. Quinidine did not alter the magnitude or time to maximum miosis, time-specific pupil diameter, or subjective self-assessments after intravenous fentanyl but did increase the area under the curve (AUC) of miosis versus time (13.6 +/- 5.3 vs. 8.7 +/- 5.0 mm*h, p< 0.05) and decreased the effect of elimination (k(el) 0.35 +/- 0.16 vs. 0.52 +/- 0.24 h(-1), p < 0.05). Quinidine increased oral fentanyl plasma C(max) (0.55 +/- 0.19 vs. 0.21 +/- 0.1 ng/mL) and AUC (1.9 +/- 0.5 vs. 0.7 +/- 0.3 ng*h*mL(-1)) (both p < 0.05) but had no effect on apparent elimination. Plasma norfentanyl/fentanyl AUC ratios were not diminished by quinidine. Quinidine significantly increased maximum miosis after oral fentanyl (3.4 +/- 1.3 vs. 2.3 +/- 1.3 mm, p< 0.05), commensurate with increases in plasma concentrations, but concentration-effect relationships and the rate constant for the transfer between plasma and effect compartment (k(e0)) (1.9 +/- 1.0 vs. 3.6 +/- 2.6 h(-1)) were not significantly different. Quinidine increased oral fentanyl plasma concentrations, suggesting that intestinal P-gp or some other quinidine-sensitive transporter affects the absorption, bioavailability, and hence clinical effects of oral fentanyl. Quinidine had less effect on fentanyl pharmacodynamics, suggesting that if quinidine is an effective inhibitor of brain P-gp, then P-gp appears to have less effect on brain access of fentanyl.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Spinal 2-chloroprocaine: the effect of added fentanyl.

UNLABELLED: Chloroprocaine is being investigated as a possible replacement for spinal lidocaine. Adding fentanyl to lidocaine increases the quality of spinal anesthesia without prolongation of block. We report the characteristics of 2-chloroprocaine (2-CP) spinal anesthesia with or without fentanyl in 8 volunteers receiving 40 mg 2-CP with saline or 20 micro g fentanyl in a double-blinded, randomized, crossover manner. Spinal anesthesia was successful for all subjects with complete block regression, ambulation, and void by 110 min. Itching occurred in all subjects receiving fentanyl, though medication was not required. No subject reported signs of transient neurological symptoms. Peak block with fentanyl averaged T5 (T3-7) and without fentanyl T9 (L1-T4) (P = 0.005). Regression to L1 was 78 +/- 7 min with fentanyl and 53 +/- 19 min without fentanyl (P = 0.02). Tourniquet was tolerated for 51 +/- 8 min with fentanyl and for 34 +/- 14 min without fentanyl (P = 0.02). Complete regression of block occurred at 104 +/- 7 min with fentanyl and by 95 +/- 9 min without fentanyl (P = 0.02). We conclude that 2-CP spinal anesthesia provides rapid onset and adequate potency, giving it a positive profile for ambulatory surgery. The addition of fentanyl lengthens regression to L1 and tourniquet tolerance while minimally lengthening block duration. IMPLICATIONS: Spinal 2-chloroprocaine (40 mg) provides rapid onset and reliable blockade without signs of transient neurological symptoms, giving it a positive profile for ambulatory surgical settings. The addition of fentanyl appears to lengthen the regression to L1 dermatome and tourniquet time while minimally lengthening duration of block.

Adjuvants, Anesthesia↗

PubMedDate not supplied

Patient-reported utilization patterns of fentanyl transdermal system and oxycodone hydrochloride controlled-release among patients with chronic nonmalignant pain.

BACKGROUND: Although use of long-acting opioid analgesics has increased for chronic nonmalignant pain management, little is known about patient-reported utilization patterns. OBJECTIVE: To assess patient-reported utilization patterns of fentanyl transdermal system and oxycodone hydrochloride (HCl) controlled-release among patients with chronic nonmalignant pain and to compare these patterns to standard dose administration guidelines recommended in the manufacturers. prescribing information (PI). METHODS: Cross-sectional, observational, multicenter study of English-speaking patients who were seeking chronic nonmalignant pain management from 6 outpatient pain clinics. The inclusion criteria for the study were (1) diagnosis of chronic nonmalignant pain, (2) prescription for and current use of either transdermal fentanyl or oxycodone HCl controlled-release, and (3) duration of use for either transdermal fentanyl or oxycodone HCl controlled-release of at least 6 weeks. Patients completed either an oxycodone HCl controlled-release or transdermal fentanyl utilization questionnaire. A conversion table was used to standardize opioid analgesic doses from transdermal fentanyl or oxycodone HCl controlled-release to daily oral morphine equivalents. The principal outcome measures were the average interval between oxycodone HCl controlled-release administrations, the number of days the current transdermal fentanyl patch would be worn, and the percentage of oxycodone HCl controlled-release and transdermal fentanyl patients whose administration frequency exceeded the standard recommendation in the manufacturer.s PI (every 12 hours for oxycodone HCl controlled-release or every 72 hours for transdermal fentanyl). Other outcome measures included the number of oxycodone HCl controlled-release tablets per administration, the daily dose of long-acting opioid, the duration of adequate pain relief, and the difference in daily oral morphine equivalents between transdermal fentanyl and oxycodone HCl controlled-release patients, after adjusting in a multivariate regression model for demographic and clinical characteristics. RESULTS: A total of 690 patients were enrolled in this study; 437 (63.4%) received oxycodone HCl controlled-release and 253 (36.6%) received transdermal fentanyl. Oxycodone HCl controlled-release patients reported taking a median of 1 tablet 3 times per day or a median of 3 tablets per day. A mean of 1.6 tablets per administration and 4.6 tablets per day were taken. The average interval between administrations of oxycodone HCl controlled-release was 7.8 hours, and the median daily dose was 80.0 mg (mean 155.6 mg). Among oxycodone HCl controlled-release patients, 17.5% had an average interval between administrations of 12 or more hours, whereas 1.9% reported the duration of pain relief as 12 or more hours. Transdermal fentanyl patients reported wearing the patch, on average, for 2.5 days (median 2.5),and 41.2% reported wearing the patch for at least 3 days, whereas 14.1% reported the duration of pain relief as at least 3 days. The median daily dosage strength of transdermal fentanyl was 75.0 mcg/hour. In the multivariate regression analysis, oxycodone HCl controlled-release patients had, on average, roughly 22 mg additional oral morphine equivalents per day relative to transdermal fentanyl patients (not statistically significant); the probability that oxycodone HCl controlled-release patients had higher oral morphine equivalents was 82.6%, which suggests a trend toward higher oral morphine equivalents per day in the oxycodone HCl controlled-release group. CONCLUSION: Transdermal fentanyl and oxycodone HCl controlled-release both appear to be used by patients in a manner that is inconsistent with the standard recommendation in the manufacturers' PI;however, the difference between patient-reported utilization and the PI recommendation is more pronounced with oxycodone HCl controlled-release.

Administration, Cutaneous↗

PubMed2005

The effect of dosing frequency on the pharmacokinetics of a fentanyl HCl patient-controlled transdermal system (PCTS).

INTRODUCTION: The fentanyl HCl patient-controlled transdermal system (PCTS) is a noninvasive, needle-free, credit card-sized drug delivery system designed for the on-demand management of acute pain in a medically supervised setting. The objective of these studies was to determine the effect of dosing frequency on the pharmacokinetics of fentanyl delivered by the PCTS. METHODS: All three studies were single-centre, open-label, randomised, crossover studies. The fentanyl HCl PCTS was applied to the upper outer arm of all participants. In the first study, participants (n = 30) received three fentanyl HCl PCTS 25 microg treatments: two sequential doses hourly for 23.33 hours, six sequential doses every 3 hours for 22 hours, and 72 doses continuously over 12 hours. Participants (n = 31) in the second study received three fentanyl HCl PCTS 40 microg treatments: two sequential doses hourly over 23.33 hours, six sequential doses every 3 hours over approximately 10 hours, and 80 doses continuously over 13.33 hours. In the third study, participants (n = 28) received four fentanyl HCl PCTS 40 microg treatments: 6, 18, 36 and 80 doses over 1, 3, 6 and 13.33 hours, respectively. Naltrexone was used to block the opioid effects of fentanyl. Pharmacokinetic parameters, including maximum serum fentanyl concentration (Cmax), time to Cmax (tmax), area under the serum concentration-time curve (AUC) and terminal half-life (t(1/2)) were determined. RESULTS: In the first study, the dose-normalised AUC (AUCn) values for the 2- and 6-dose sequence treatments were not significantly different (p = 0.937), suggesting that the frequency of dosing has little effect on the amount of fentanyl absorbed; however, the AUCn for the 72-dose treatment was significantly lower than that of the other treatments (p = 0.001), which were of longer duration. The results of the second study paralleled those from the first, suggesting that the bioavailability of fentanyl delivered by the PCTS increases as a function of time and is likely to be independent of dosing frequency. Results from the third study suggested that approximately 40% of the nominal 40 microg fentanyl dose is absorbed during the first hour of treatment, with the full nominal dose absorbed after approximately 10 hours. The fentanyl HCl PCTS was well tolerated. CONCLUSION: The amount of fentanyl absorbed from the PCTS increases as a function of time and is independent of both dosing frequency and total number of doses delivered. The fentanyl HCl PCTS is generally safe and well tolerated.

Administration, Cutaneous↗

PubMed2001

Transdermal fentanyl: an updated review of its pharmacological properties and therapeutic efficacy in chronic cancer pain control.

UNLABELLED: Fentanyl is a synthetic opioid agonist which interacts primarily with the mu-opioid receptor. The low molecular weight, high potency and lipid solubility of fentanyl make it suitable for delivery by the transdermal therapeutic system. These patches are designed to deliver fentanyl at a constant rate (25, 50, 75 and 100 microg/h), and require replacement every 3 days. Data from randomised, nonblind trials suggest that transdermal fentanyl is as effective as sustained-release oral morphine in the treatment of chronic cancer pain, as reported by patients using visual and numerical analogue scales as well as verbal description scales. No obvious differences in health-related quality of life were found in patients with chronic cancer pain when comparing transdermal fentanyl with sustained-release oral morphine. Nevertheless, significantly more patients expressed a preference for transdermal fentanyl than for sustained-release oral morphine after a randomised, nonblind, crossover trial. Because of the formation of a fentanyl depot in the skin tissue, serum fentanyl concentrations increase gradually following initial application, generally levelling off between 12 and 24 hours. Thereafter, they remain relatively constant, with some fluctuation, for the remainder of the 72-hour application period. Once achieved, steady-state plasma fentanyl concentrations can be maintained for as long as the patches are renewed. The most frequently observed adverse events during transdermal fentanyl administration (as with other opioid agonists) included vomiting, nausea and constipation. Data from a nonblind, randomised trials suggest that constipation occurs less frequently in patients receiving transdermal fentanyl than in those given sustained-release oral morphine. The most serious adverse event reported in US premarketing trials was hypoventilation, which occurred with an incidence of approximately 2%. Adverse reactions related to skin and appendages (i.e. rash and application site reactions - erythema, papules, itching and oedema) were reported in 153 patients with cancer at a frequency between 1 and 3%. CONCLUSION: Transdermal fentanyl is a useful opioid-agonist for the treatment of moderate to severe chronic cancer pain. The advantages of transdermal fentanyl include ease of administration and the 3-day application interval. These factors coupled with a lower incidence of constipation are likely to contribute to the reported patient preference of transdermal fentanyl over sustained-release oral morphine.

Absorption↗

PubMed2003

Pharmacokinetics of fentanyl following intravenous and transdermal administration in horses.

REASONS FOR PERFORMING STUDY: Although fentanyl has been reported to cause CNS excitation in horses, a transdermal therapeutic system (TTS) containing this mu agonist has recently been used empirically in equine medicine to treat moderate to severe pain. A better understanding of the disposition of fentanyl following transdermal administration would facilitate the clinical use of TTS fentanyl to obtain analgesia in horses. OBJECTIVES: To determine the pharmacokinetics of fentanyl following i.v. and TTS patch administration in healthy, mature horses and to evaluate the tolerance of horses to TTS fentanyl administration. METHODS: The pharmacokinetics of fentanyl in serum were assessed following a single i.v. dose, a single TTS dose, and multiple TTS doses in 6 healthy horses. Physical examinations, haematology and serum biochemistry analyses during transdermal fentanyl application were then performed to determine tolerance of continuous fentanyl administration. RESULTS: Fentanyl was very rapidly and completely absorbed following a single TTS dose. Mean serum fentanyl concentrations consistent with analgesia in other species were reached by 1 h and maintained until 32 h after patch application. Similar steady state serum concentrations were obtained when multiple doses of TTS fentanyl were administered every 48 or 72 h over 8 or 9 days, with less fluctuation in serum concentrations during the 48 h dosing interval. Three horses exhibited brief (< 12 h) episodes of increased body temperature; however, transdermal fentanyl administrations were not associated with other significant changes in haematology and biochemistry panels or physical examination findings. CONCLUSIONS AND POTENTIAL RELEVANCE: Although the pharmacodynamics of fentanyl have not been investigated fully in horses, transdermally-administered fentanyl exhibited a favourable pharmacokinetic profile without clinically relevant side effects and may be a useful analgesic in equine patients.

Administration, Cutaneous↗

PubMed2005

Fentanyl and its analogues in clinical and forensic toxicology.

Fentanyl and its analogues are commonly named synthetic opiates. Some compounds from fentanyl group (e.g. fentanyl, alfentanil, sufentanil, remifentanil) are used as anaesthetic and analgesic of high potency and short duration of action. Effects of acting fentanyls are indistinguishable from those produced by nasal inhalation of street heroin. In view of this, fentanyls are very "attractive" for the narcotic market. In least years an increase in number of reports about illegal production and non-medical use of fentanyl and its analogues have appeared. Numerous fentanyl analogues are sold under one name synthetic heroine or China white. Fentanyl and its analogues also can be used as gas warfare agents. One of fentanyl-related compound was used during action of easing hostages from Dubrovka theatre. Because of respiratory depression, which was caused by used compound, died over 100 hostages. Because of high potency fentanyl-related compounds are used in very low doses. So fentanyls appear in biological material in very low concentrations, not higher than several nanograms per millilitre or per gram. The drugs in these concentrations cannot be detected by means of routinely used screening procedures. Therefore direct methods for determination of this group of compounds are needed. Screening method for determination of fentanyl and its analogues was elaborated and validated. Liquid chromatography-mass spectrometry (LC/MS) technique was applied. The method is characterised by the limit of quantification (LOQ) and the limit of detection (LOD) ranged from 0.6 to 2 ng/ml and from 0.2 to 0.6 ng/ml, respectively for four above-mentioned compounds. The method was used for determination of fentanyl in three forensic cases. The blood, bile and blood from lung samples were taken during autopsy of persons who died shortly after surgical procedure in which fentanyl was used as an adjunct to general anaesthesia.

Analgesics, Opioid↗