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BACKGROUND: Piritramide is a synthetic opioid analgesic which is commonly used for postoperative analgesia. It is structurally related to meperidine, exhibiting full mu-receptor agonism. Pharmacokinetic data of the drug have not been reported so far. METHODS: Plasma protein binding of piritramide was studied in vitro. The kinetics were examined after a single intravenous bolus (0.2 mg/kg) in 10 male patients aged 22-53 years undergoing elective minor surgery. Plasma and urine concentrations were determined by gas chromatography in samples drawn before and after the bolus. The concentration vs. time data were evaluated by nonlinear regression analysis, and the mean values and SD of the individual pharmacokinetic parameters were calculated. A three-compartment body model was fitted to the data. RESULTS: The volume of distribution at steady state was 4.7 (0.7)l/kg, systemic plasma clearance was 7.8 (1.5) (mean (SD)) ml/kg/min. Renal clearance of unchanged piritramide was negligible (0.13 (0.09) ml/kg/min). The terminal elimination half-life was 8.0 (1.4) h. In vitro, the free fraction in plasma of piritramide did not change over the therapeutic concentration range (5.5 (1.3)% at a pH of 7.35) but decreased considerably with pH within the physiological range. CONCLUSION: Since the elimination half-life of piritramide appears to exceed the duration of clinically effective analgesia observed during the treatment of acute pain, the dose of piritramide should be titrated carefully during long-term treatment to avoid accumulation that may lead to adverse effects.
BACKGROUND: The concentration-effect relationship of piritramide, a synthetic opioid analgesic predominantly used for postoperative analgesia and analgosedation, has not been reported so far. METHODS: Twenty-four patients of both genders aged 58.1 (11.7) yr (mean (SD)) received inhalational anaesthesia for abdominal surgery. Postoperative pain was assessed with a visual analogue scale (VAS). Analgesia was provided with piritramide, infused at a rate of 7 micrograms.kg-1.min-1 until analgesia was considered sufficient (VAS < 25) or up to a maximum dose of 0.2 mg/kg. The plasma concentrations of piritramide were determined by gas chromatography. An inhibitory fractional sigmoid Emax-model was used to describe the relation between effect site concentration and perceived pain. RESULTS: The equilibration half-life between plasma and effect site concentrations (T1/2 (keo)) was 16.8 min (median; range: 4.4-41.6 min). The steady-state plasma concentration required to produce 50% of maximum analgesia (EC50) was 12.1 ng/ml (range: 2.9-29.8 ng/ml) and correlated with initial pain intensity. The slope factor gamma was 1.9 (range: 0.5-6.1) and increased with age. Clinically relevant respiratory depression did not occur. Due to the relatively large equilibration half-life of the effect compartment, the context-sensitive half-time of the effect site concentrations after short-time administration (< 2 h) clearly exceeded those of alfentanil, sufentanil, and fentanyl. CONCLUSIONS: The analgesic effect of piritramide was adequately described by an inhibitory fractional Emax-model. In order to overcome the pronounced hysteresis, piritramide should initially be administered as an intravenous bolus of at least 5 mg.
BACKGROUND: Patient-controlled analgesia (PCA) with intravenous piritramide and subarachnoid bupivacaine was studied during postoperative pain management in comparison with nurse-administered bolus injections. METHODS: Following general anaesthesia (n = 60) patients randomly received either 3.75-7.5 mg i.v. piritramide on demand (group P-Bolus) or via PCA (group P-PCA; initial bolus: 3.75 mg i.v. piritramide, baseline rate: 1 mg/h, demand-dose 1.5 mg, lockout time: 20 min). Following continuous spinal anaesthesia (n = 60; CSA; 28-G spinal catheter) patients randomly received a subarachnoid injection of 1.5 ml bupivacaine 0.25% every 2-4 h (group B-Bolus) or a baseline infusion of 0.5 ml/h bupivacaine 0.125% plus 0.5 ml bupivacaine 0.125% on demand via PCA (group B-PCA; lockout time: 30 min). Pain ratings were assessed hourly by patients using a visual analogue scale (0 = no pain, 100 mm = unbearable pain). STATISTICS: multivariate analysis of variance. RESULTS: While pain scores did not differ between group P-Bolus and P-PCA, group B-PCA showed the lowest pain ratings (18 +/- 22 mm) differing significantly from group B-Bolus (41 +/- 32 mm; P < 0.001). Group P-PCA required more piritramide than group P-Bolus (46 +/- 15 mg vs. 31 +/- 13 mg, P = 0.001). In contrast group B-PCA required less bupivacaine than group B-Bolus (18 +/- 4 vs. 23 +/- 7 mg, P = 0.002). CONCLUSION: PCA with CSA was more effective than nurse-administered bolus-administration of bupivacaine, while the present study failed to show superiority of i.v. PCA over i.v. bolus-administration of piritramide. PCA using the subarachnoid route is a promising concept for treatment of postoperative pain in orthopaedic patients, while the PCA piritramide regime of this study warrants improvement.
Patient controlled analgesia (PCA) has not yet gained universal acceptance for the management of postoperative pain in paediatric surgery. In a prospective study we evaluated feasibility and complications of PCA following 90 cases of laparoscopic or open appendicectomy. PCA proved to be a safe and feasible method with few complications (2% of medical complications, no abort of application, 17 technical checks in a total running time of 4125 h). Acceptance by patients was high and children of all age groups worked the system properly. Assessment of application protocols showed, that the consumption of analgesics was significantly reduced following laparoscopic appendicectomy (P < 0.05). PCA is a safe and feasible method for the management of postoperative pain in children and PCA recording provides an excellent insight into the consumptional behaviour of patients, enabling staff to evaluate postoperative pain for various procedures.
The effect of piretanide on renal electrolyte transport was evaluated by simultaneous micropuncture and clearance studies. In chronically thyroparathyroidectomized (TPTX) dogs, the drug caused an increased percentage excretion (%E) of sodium (from 0.6 +/- 0.1 to 15.2 +/= 1.8%, P less than 0.01) as well as of calcium (from 1.0 +/- 0.2 to 17.8 +/- 1.7%, P less than 0.001) and bicarbonate (from 1.2 +/- 0.4 to 5.9 +/- 0.9, P less than 0.001), but there was no change in %E of phosphate (4.0 +/- 0.9 to 6.6 +/- 1.6, P less than 0.10). In the presence of a constant infusion of parathyroid hormone (PTH) the drug caused a greater degree of natriuresis, calciuria, and bicarbonaturia and a significant increase in %E of PO4 (from 7.4 +/- 1.6 to 20.0 +/- 2.1, P less than 0.05). Proximal fractional reabsorption (PFR) of PO4 was unaffected, but there was a significant decrease in PFR of sodium, calcium, and bicarbonate in the TPTX dogs. The presence of PTH did not alter the effects of piretanide on PFR of phosphate and bicarbonate. There was no change in urinary or tubular fluid pH in either group of dogs. These data indicate that piretanide dissociates proximal PO4 transport from that of sodium and bicarbonate. In the presence of PTH, the drug inhibits PO4 transport beyond the late proximal convoluted tubule. In addition, tubular (and urinary) pH appears to be an important regulator of PO4 transport, especially in the absence of PTH.
OBJECTIVE: Additional anesthesia is required to minimize the tolerable pain level in efficiently performed extracorporeal shockwave lithotripsy (ESWL) with electrohydraulic and electromagnetic sources. In order to assess optimum anesthesia for each patient undergoing a standardized ESWL protocol, pain measurement and scoring were carried out. We attempted to determine the individual type and amount of analgesia prior to treatment. METHODS: Patients (n = 95) with urolithiasis underwent pain measurement and scoring prior to ESWL. 'Threshold of pain' (TP) and 'maximal tolerable pain (MTP) were assessed by inducing ischemia pain with the submaximum effort tourniquet technique. Pain intensity was assessed by a verbal rating scale (VRS). The results of pain measurement and amount of analgosedation were correlated in two phases. Patients were administered an oral premedication of 0.1 mg/kg midazolam. Phase 1: 60 patients were randomized into three groups: (1) piritramide (0.1-0.3 mg/kg) and midazolam (1-3 mg) i.v. (2) Lidocaine/prilocaine cream topically (30 g) to skin and diclofenac supp. 100 mg. (3) No analgesia. Phase 2: Based on the data of phase 1, cut-off points for TP and MTP were set for female and male patients. In accordance with these results, 35 patients comprised group 1 for anesthesia with piritramide/midazolam, group 2 with lidocaine/prilocaine cream and diclofenac supp. and group 3 for no analgesia at all. The electromagnetic shockwave sources Modulith SLX and Lithostar Plus were utilized. RESULTS: Phase 1: All patients randomized for group 1 (intravenous analgosedation) were treated in accordance with the protocol. 65% of group 2 (cream/suppository) tolerated treatment as planned. 35% of patients selected for ESWL without analgesia (group 3) remained within this group. Patients requiring additional analgosedation displayed lower TP and MTP. The cut-off points for females and males were TP >/=25/35 s and MTP >/=45/60 s, respectively. Phase 2: 20/35 patients were preselected for a nonintravenous protocol. Five out of these 20 violated the protocol. The rate of additionally administered analgesia was lower than in phase 1: 35:10% in group 2 (cream/supp.), 65:40% in group 3 (no analgesia). CONCLUSIONS: The TP and MTP levels are lower in patients requiring stronger analgesia. The determined parameters are suitable for patient preselection and individual assessment of anesthesia prior to ESWL. It may be assumed that 50% of patients administered intravenous opioids are overtreated. Routine pain measurement for patient depends on the individual pain tolerance level. A third phase of this study recruiting a large number of patients will contribute to the confirmation of these results.
PURPOSE: To investigate the effects of pre-block analgesia and sedation using piritramide on haemodynamic stability, endocrine stress response and patients' pain perception. METHODS: In a randomized, single-blinded, placebo-controlled study, 60 patients having cataract surgery with peribulbar block were randomly assigned into two groups: group A (n = 30) received 0.05 mg/kg piritramide (Dipidolor) intravenously; group B received normal saline intravenously prior to peribulbar block. Mean arterial pressure, heart rate, respiratory rate and pulse oximetry were recorded perioperatively. Pain from peribulbar block was assessed using a verbal analogue scale. Urinary excretion of vanillylmandelic acid was measured to assess the endocrine stress response. Using a questionnaire, patients assessed their anxiety and back pain before and during surgery. RESULTS: Mean arterial pressure remained near baseline in group A. In group B, a significant increase in mean arterial pressure after peribulbar block was found (p < 0.001). In addition, a significant increase in urinary excretion of vanillylmandelic acid was found in group B (p = 0.013). Pain scores (p < 0.001), anxiety before nerve block (p = 0.02) and during surgery (p < 0.001) and back pain (p = 0.003) were significantly lower in group A. CONCLUSION: The presented study suggests that using piritramide for analgesia and sedation prior to peribulbar block produces haemodynamic stability and reduces pain perception and endocrine stress response.
Since the effects in the intact organism are complicated by central as well as peripheral effects, we compared the direct cardiac effects of three commonly used opioids on isolated heart muscle. Concentration-response curves for electrophysiological and inotropic effects of piritramide, pethidine and morphine (10(-6)-10(-4) mol/l) on spontaneously beating and electrically stimulated rat atria were obtained. Piritramide decreased spontaneous frequency, induced arrhythmia and cardiac arrest. It had no significant effect on effective refractory period and electrical threshold for excitation, but decreased contractile force. Pethidine increased effective refractory period, had no effect on electrical threshold and increased contractile force. Morphine induced no significant electrophysiological effects, but decreased contractile force slightly. These results indicate direct negative chronotropic and arrhythmogenic actions of piritramide, possible class III antiarrhythmic action of pethidine and lack of major direct cardiac effects of morphine.
We reviewed our experience with ESWL therapy in 96 patients who presented with upper, middle and lower ureteral calculi; we had 127 treatments in 96 patients, 73 men (76%) and 22 women (24%). All the treatments were performed without general anesthesia and without premedication. The average number of shock waves was 3.000. Repetition of the ESWL therapy had to be performed in 25%.
UNLABELLED: After achieving a reduction of pain scores for 10 h with a single dose wound infiltration after shoulder surgery, we examined in a prospective, placebo-controlled and double-blinded study the analgesic effects of continuous wound infiltration with different concentrations of ropivacaine. Forty-five patients undergoing shoulder surgery were randomly assigned into three groups to receive single dose wound infiltration with 30 mL saline (group S) or ropivacaine 7.5 mg/mL (groups R2 and R3.75) after skin closure. Postoperatively, patients received a continuous wound infiltration with saline (group S), ropivacaine 2 mg/mL (group R2) or ropivacaine 3.75 mg/mL (group R3.75) for 48 h. Supplemental pain relief was provided by IV patient-controlled analgesia with the opioid piritramide. At 1, 2, 3, 4, 24, and 48 h postoperatively visual analogue scale (VAS) values (0-100 mm), piritramide requirements and side effects were registered. Plasma levels of ropivacaine were measured preoperatively and at 24 h and 48 h after surgery. Until 48 h VAS values were smaller in group R3.75 compared with group S (group R3.75, 8 +/- 9 mm; group S, 31 +/- 14 mm; P < 0.005), whereas 4 h and 48 h postoperatively VAS values were even smaller in group R3.75 compared with group R2 (P < 0.05). Cumulative piritramide consumption was always smaller in groups R2 and R3.75 compared with group S (1-24 h, P < 0.005; 48 h, P < 0.05). Plasma ropivacaine levels remained less than the toxic threshold. We conclude that continuous postoperative wound infiltration with ropivacaine, especially using 3.75 mg/mL, provides smaller VAS values and opioid requirement in comparison with saline after shoulder surgery. IMPLICATIONS: The continuous postoperative wound infiltration after shoulder surgery with different concentrations of ropivacaine, 2 mg/mL and 3.75 mg/mL, results in lower pain scores and opioid requirement compared with infiltration with placebo. Plasma levels of ropivacaine remained less than the toxic threshold.
We investigated whether blocking afferent nociceptive inputs by continuous intra- and postoperative thoracic epidural analgesia (TEA) would decrease plasma concentrations of brain natriuretic peptide (BNP) in patients who were at risk for, or had, coronary artery disease. Twenty-eight patients undergoing major abdominal surgery received either general anesthesia supplemented with a continuous thoracic epidural infusion of 1.25 mg/mL bupivacaine and 1 microg/mL sufentanil (n = 14; TEA) or general anesthesia followed by IV patient-controlled analgesia (n = 14; IV PCA). Visual analog scale pain scores, hemodynamics, plasma catecholamines, cardiac troponin T, atrial natriuretic peptide (ANP), and BNP were serially measured preoperatively, 90 min after skin incision, at arrival in the intensive care unit, and in the morning of the first, second, and third postoperative day. Dynamic visual analog scale scores were significantly less in the TEA group. TEA reduced the postoperative heart rate without affecting other hemodynamic variables. Plasma epinephrine increased perioperatively in both groups but was significantly lower in the TEA group. Baseline ANP and BNP concentrations were similar between groups (TEA 3.4 +/- 1.8 and 27.0 +/- 12.3 pg/mL; IV PCA 3.1 +/- 2.0 and 25.9 +/- 13.0 pg/mL, respectively). ANP and BNP increased perioperatively in both groups, with significantly lower postoperative BNP levels in TEA patients (TEA 92.1 +/- 31.9 pg/mL; IV PCA 161.2 +/- 44.7 pg/mL). No such difference was observed in plasma ANP concentrations. Plasma cardiac troponin T concentrations were within normal limits in both groups at all times. We conclude that continuous perioperative TEA using local anesthetics and opioids attenuated the release of BNP in patients undergoing major abdominal surgery who were at risk for, or had, coronary artery disease.
OBJECTIVE: This study was designed to assess the efficacy of perioperative administration of celecoxib (Celebrex; Pharmacia GmbH, Erlangen, Germany) in reducing pain and opioid requirements after single-level lumbar microdiscectomy. METHODS: We studied 34 patients (mean age, 44.26 yr; standard deviation [SD], 13.09 yr) allocated randomly to receive celecoxib 200 mg twice a day for 72 hours starting on the evening before surgery or placebo capsules in a double-blind study. Fourteen patients received 20 to 80 mg dexamethasone intravenously during surgery (mean, 40 mg; SD, 19.22 mg) because of visible signs of compression of the affected nerve root. After lumbar disc surgery, patients were monitored for visual analog scores for pain at rest and on movement, patient-controlled analgesia (PCA) piritramide requirements, and von Frey thresholds in the wound area. RESULTS: Pain scores decreased and wound von Frey thresholds increased continuously until discharge, with no intergroup differences. Mean 24-hour PCA piritramide requirements were 22.63 mg (SD, 23.72 mg) and 26.14 mg (SD, 22.57 mg) in the celecoxib and placebo groups, respectively (P = not significant). However, patients with intraoperative dexamethasone (n = 14) required only 10.29 mg (SD, 8.55 mg) 24-hour PCA piritramide, in contrast to the 34.25 mg (SD, 24.69 mg) needed in those who did not receive intraoperative dexamethasone (P = 0.001). In addition, 24 hours after the operation, pain scores on movement were significantly lower in the dexamethasone subgroup (P = 0.003). CONCLUSION: Celecoxib has no effect on postoperative pain scores and PCA piritramide requirements. The intraoperative use of 20 to 80 mg dexamethasone is able to significantly decrease postoperative piritramide consumption and pain scores on the first day after surgery.
Postoperative pain is a major cause of ineffective breathing after lung surgery, predisposing patients to hypoxemia. Because potent analgesics like opioids depress ventilation and other analgesic techniques are time-consuming, efficient postoperative pain therapy is difficult. Therefore, a less painful surgical approach could be beneficial. Forty-seven patients with diagnosis of a pulmonary nodule were prospectively studied. Patients were assigned to a video-assisted thoracic surgery (VATS) group (n=22) or a group undergoing axillary thoracotomy (n=25). Visual analogue scale (VAS) scores, plasma glucose levels, plasma epinephrine and plasma norepinephrine levels, as well as arterial oxygen (PaO2) and carbon dioxide (PaCO2) tension were determined the day before surgery, and 3, 15, 24, 48, and 72 h after surgery. Postoperative piritramide (a synthetic morphine compound) demand was recorded. VAS values were significantly lower (p<0.05) during the whole observation period in the VATS group. Significantly higher epinephrine levels were observed 3 and 15 h after surgery (267.4 +/- 28 vs 111.8 +/- 13 ng/L; p<0.01; and 176.6 +/- 46.5 vs 96 +/- 14.5 ng/L; p<0.05) in the thoracotomy group, whereas there was no significant difference in norepinephrine (correction of norephinephrine) levels. Piritramide demand was significantly (p<0.05) reduced in the VATS group throughout the whole observation period. There was no difference in PaCO2 values but PaO2 Values were higher in the VATS group over 72 h, with maximum differences occurring at 15 h after operation: 60.9 +/- 1.9 vs 49.2 +/- 2.4 mm Hg (p<0.01). In conclusion, the videoendoscopic approach is associated with less postoperative pain and better oxygenation than traditional surgical approaches.
In an animal study (7 mongrel dogs) the effects of neuroleptanalgesia (NLA) and combinations of NLA with nitrous oxide (N2O) and isoflurane on the macro- and microcirculation of the liver were investigated. Measurements were made in three steps. After NLA alone the dogs were supplementarily ventilated with nitrous oxide/oxygen at a ratio of 2:1. During the last step, 1 MAC isoflurane was added to the inspired gas. From the portal vein, arterial and mixed-venous systems' hemodynamic parameters, blood gases, and acid-base balance were recorded. As a parameter of oxygenation the tissue PO2 of the liver was measured with a multiwire surface electrode. During NLA stable hemodynamic conditions and a balanced acid-base status were observed. The nitrous oxide combination resulted in an increase of the mean pulmonary artery pressure of 16%. The addition of isoflurane had a negative inotropic effect: The heart index decreased to 74% of the starting value and the total peripheral resistance (TPR) increased by 27%. The summarized PO2 histograms under NLA and NLA/N2O showed arithmetic mean values of 34.1 and 35.2 mm Hg, respectively. The addition of isoflurane resulted in a left shift and a decrease of the mean value to 28.6 mm Hg. This histogram corresponds exactly to the oxygen pressure distribution in the dog liver during piritramide basic anesthesia. It seems that NLA and the combination of NLA/N2O increase the liver perfusion with a higher portal-venous and tissue PO2. This effect can be explained only by a massive change of visceral circulation. It is canceled by the addition of isoflurane.
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