Efficacy and safety of dipyrone versus tramadol in the management of pain after hysterectomy: a randomized, double-blind, multicenter study

Metamizole-associated adverse events: a systematic review and meta-analysis

Background

Metamizole is used to treat pain in many parts of the world. Information on the safety profile of metamizole is scarce; no conclusive summary of the literature exists.

Objective

To determine whether metamizole is clinically safe compared to placebo and other analgesics.

Methods

We searched CENTRAL, MEDLINE, EMBASE, CINAHL, and several clinical trial registries. We screened the reference lists of included trials and previous systematic reviews. We included randomized controlled trials that compared the effects of metamizole, administered to adults in any form and for any indication, to other analgesics or to placebo. Two authors extracted data regarding trial design and size, indications for pain medication, patient characteristics, treatment regimens, and methodological characteristics. Adverse events (AEs), serious adverse events (SAEs), and dropouts were assessed. We conducted separate meta-analyses for each metamizole comparator, using standard inverse-variance random effects meta-analysis to pool the estimates across trials, reported as risk ratios (RRs). We calculated the DerSimonian and Laird variance estimate T² to measure heterogeneity between trials. The pre-specified primary end point was any AE during the trial period.

Results

Of the 696 potentially eligible trials, 79 trials including almost 4000 patients with short-term metamizole use of less than two weeks met our inclusion criteria. Fewer AEs were reported for metamizole compared to opioids, RR = 0.79 (confidence interval 0.79 to 0.96). We found no differences between metamizole and placebo, paracetamol and NSAIDs. Only a few SAEs were reported, with no difference between metamizole and other analgesics. No agranulocytosis or deaths were reported. Our results were limited by the mediocre overall quality of the reports.

Conclusion

For short-term use in the hospital setting, metamizole seems to be a safe choice when compared to other widely used analgesics. High-quality, adequately sized trials assessing the intermediate- and long-term safety of metamizole are needed.

Estimation of the minimum effective dose of tramadol for postoperative analgesia in infants using the continual reassessment method

Tramadol is a potent analgesic. However, the analgesia efficacy of tramadol, particularly its minimum effective dose (MED), is not clear. The aim of this study is to find MED of tramadol for postoperative analgesia in infants. The continual reassessment method (CRM) was performed to find MED. Infants undergoing surgeries were included in the 3 phases of this series. In each phase, 24 participants were allocated a different tramadol dose. Pain intensity was measured by face, legs, activity, cry, consolability (FLACC) measurement at 3-hour intervals. Tramadol was considered ineffective if the FLACC score was higher than 4 in 10 at anytime. In phase 1, seven dose levels were used within the range 0.1-0.4 mg·kg(-1)·h(-1). Phase 1 was insufficient to identify the MED, and we increased the dose to 0.4-0.8 mg·kg(-1)·h(-1) in phase 2. Phase 2 was insufficient to identify the MED. In phase 3, local anesthetic wound infiltration was introduced, and the tramadol dose levels tested were the same as in phase 1. The successful analgesia probability of tramadol 0.4 mg·kg(-1)·h(-1) was 82.1% (95% CI, 0.742-0.925) in phase 1. In phase 2, it was 84.7% (95% CI, 0.789-0.991) with the dose 0.8 mg·kg(-1)·h(-1). Phase 1 and phase 2 were insufficient to identify the MED. In phase 3, the successful analgesia probability for dose 0.35 mg·kg(-1)·h(-1) was 96.7% (95% CI, 0.853-0.997).We have demonstrated that tramadol provides insufficient analgesia for surgeries considered to cause moderate-to-severe postoperative pain in infants if used as the sole analgesic, and that local anesthetic wound infiltration enhances the efficacy of tramadol.

Influence of COX-inhibiting analgesics on the platelet function of patients with subarachnoid hemorrhage

BACKGROUND

Platelet function of patients with subarachnoid hemorrhage (SAH) may play an important part in both rebleeding and delayed cerebral ischemia, but little is known about aggregation pathways during the acute phase of stroke. Analgesics are used regularly in the first days after bleeding, and some can potentially inhibit the cyclooxygenase (COX) enzyme. We examined the platelet function of patients with SAH in order to describe their basal situation and determine whether the administration of intravenous nonsteroidal antiinflammatory drugs (NSAIDs) affected platelet aggregation.

METHODS

Arachidonic acid (AA)-induced aggregation and the platelet function analyzer (PFA)-100 test with collagen/epinephrine cartridges were used to study a group of SAH patients that was treated with dexketoprofen and dipyrone and to compare them to patients that had received no analgesia.

RESULTS

Ninety-six consecutive SAH patients prospectively enrolled in platelet studies. Twenty-seven patients were taking NSAIDs (10 on dexketoprofen and 17 on dipyrone), and there were 15 cases in the control group. AA-induced aggregation was 10% ± 3.2% for NSAIDs (mean ± standard error), specifically 17.2% ± 7% for dexketoprofen and 5.7% ± 1% for dipyrone. Aggregation in the control group was 72.4% ± 6% (P = .001). Both analgesics slowed the platelet plug formation during the PFA-100 test, with closure times of 237.2 ± 25 seconds for dexketoprofen and 198.4 ± 22 seconds for dipyrone and 138.1 ± 21 seconds in controls (P = .02).

CONCLUSIONS

The administration of COX-inhibiting analgesics leads to an hypoaggregability state in the first days of SAH. Further insight into their impact on complications such as rebleeding and delayed cerebral ischemia is needed in order to optimize the headache treatment of SAH.

Effects of flurbiprofen on CRP, TNF-α, IL-6, and postoperative pain of thoracotomy

OBJECTIVE

The aims of this study were to evaluate serum levels of acute phase reactants, such as CRP and cytokines (TNF-α and IL-6) in patients who have undergone thoracotomy and to investigate the effects of flurbiprofen on postoperative inflammatory response.

METHODS

Forty patients undergoing posterolateral thoracotomy were randomly divided into 2 groups of 20 each. Control group received tramadol (4 x 100 mg) intravenously for four days, and flurbiprofen group received both tramadol (4 x 100 mg) and flurbiprofen (2 x 100 mg). Blood samples were collected before surgery and at the 3th and 168th hours after surgical procedure to measure serum CRP, IL-6, and TNF-α. Pain visual analog scales were recorded daily during the first four postoperative days. Spirometric measurement of forced expiratory volume in the first second (FEV 1) was done before and four days after the operation.

RESULTS

The serum CRP, IL-6, and TNF-α levels in both groups increased significantly at 3th hour after thoracotomy. Serum TNF-α levels did not differ significantly between the groups at postoperative 4th day. However, IL-6 and CRP were significantly lower in flurbiprofen group than in control group at the same day (p < 0.05). Visual analog scale was significantly lower in flurbiprofen group at 6th, 12th, 48th, 72th, and 96th hours postoperatively (p < 0.05). The patients receiving flurbiprofen had higher FEV 1 values when compared with control group at postoperative 4th day.

CONCLUSIONS

Patients undergoing thoracotomy showed reduced postoperative pain, mean additional analgesic consumption, and serum IL-6 and CRP levels, when flurbiprofen was added to systemic analgesic therapy. Analgesia with anti-inflammatory drug may contribute to the attenuation of the postoperative inflammatory response and prevent postoperative pain in patients undergoing thoracotomy.

Efficacy of lornoxicam for acute postoperative pain relief after septoplasty: a comparison with diclofenac, ketoprofen, and dipyrone

STUDY OBJECTIVES

To compare the efficacy of injectable lornoxicam with diclofenac, ketoprofen, and dipyrone for acute postoperative pain.

DESIGN

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

SETTING

University hospital.

PATIENTS

200 ASA physical status I patients who were scheduled for elective septoplasty with general anesthesia.

INTERVENTIONS

Patients were divided into 5 groups according to the intramuscularly administered analgesic drug: lornoxicam 8 mg (twice daily), diclofenac 75 mg (twice daily), ketoprofen 100 mg (twice daily), dipyrone 1 g (three times daily), and placebo (twice daily).

MEASUREMENTS

Pain intensity was evaluated with a 0 to 100 mm Visual Analog Scale (VAS) at the 2nd, 4th, 6th, 8th, 12th, 16th, 20th, and 24th hour postoperatively. Intramuscular pethidine 1 mg/kg was administered to patients requiring additional analgesia, and treatment-related adverse effects were noted.

MAIN RESULTS

Pethidine requirement was found to be significantly higher in the placebo group (1.8 mg/kg per 24 hours; 95% confidence interval, 1.5-2.2) than in the other groups (P = 0.001). No significant difference in opioid requirement was found among the treated groups (P > 0.05). Postoperative VAS scores were significantly lower at specific hours in the treatment groups when compared with placebo group (P < 0.05). No statistically significant difference in adverse effects was found among the groups studied (P > 0.05).

CONCLUSIONS

Efficacy of lornoxicam in the management of acute postoperative pain was not superior to that of other nonopioid analgesics used in this study.

Clinical pharmacology of tramadol

Tramadol, a centrally acting analgesic structurally related to codeine and morphine, consists of two enantiomers, both of which contribute to analgesic activity via different mechanisms. (+)-Tramadol and the metabolite (+)-O-desmethyl-tramadol (M1) are agonists of the mu opioid receptor. (+)-Tramadol inhibits serotonin reuptake and (-)-tramadol inhibits norepinephrine reuptake, enhancing inhibitory effects on pain transmission in the spinal cord. The complementary and synergistic actions of the two enantiomers improve the analgesic efficacy and tolerability profile of the racemate. Tramadol is available as drops, capsules and sustained-release formulations for oral use, suppositories for rectal use and solution for intramuscular, intravenous and subcutaneous injection. After oral administration, tramadol is rapidly and almost completely absorbed. Sustained-release tablets release the active ingredient over a period of 12 hours, reach peak concentrations after 4.9 hours and have a bioavailability of 87-95% compared with capsules. Tramadol is rapidly distributed in the body; plasma protein binding is about 20%. Tramadol is mainly metabolised by O- and N-demethylation and by conjugation reactions forming glucuronides and sulfates. Tramadol and its metabolites are mainly excreted via the kidneys. The mean elimination half-life is about 6 hours. The O-demethylation of tramadol to M1, the main analgesic effective metabolite, is catalysed by cytochrome P450 (CYP) 2D6, whereas N-demethylation to M2 is catalysed by CYP2B6 and CYP3A4. The wide variability in the pharmacokinetic properties of tramadol can partly be ascribed to CYP polymorphism. O- and N-demethylation of tramadol as well as renal elimination are stereoselective. Pharmacokinetic-pharmacodynamic characterisation of tramadol is difficult because of differences between tramadol concentrations in plasma and at the site of action, and because of pharmacodynamic interactions between the two enantiomers of tramadol and its active metabolites. The analgesic potency of tramadol is about 10% of that of morphine following parenteral administration. Tramadol provides postoperative pain relief comparable with that of pethidine, and the analgesic efficacy of tramadol can further be improved by combination with a non-opioid analgesic. Tramadol may prove particularly useful in patients with a risk of poor cardiopulmonary function, after surgery of the thorax or upper abdomen and when non-opioid analgesics are contraindicated. Tramadol is an effective and well tolerated agent to reduce pain resulting from trauma, renal or biliary colic and labour, and also for the management of chronic pain of malignant or nonmalignant origin, particularly neuropathic pain. Tramadol appears to produce less constipation and dependence than equianalgesic doses of strong opioids.