Single-dose dipyrone for acute postoperative pain

CB1 receptor-dependent desensitisation of TRPV1 channels contributes to the analgesic effect of dipyrone in sensitised primary sensory neurons

BACKGROUND AND PURPOSE

While dipyrone is a widely used analgesic, its mechanism of action is not completely understood. Recently, we have reported that the dipyrone metabolite 4-aminoantipyrine (4-AA) reduces PGE2 -induced pain-related behaviour through cannabinoid CB1 receptors. Here, we ascertained, in naive and PGE2 -induced "inflamed" conditions, both in vivo and in vitro, the molecular mechanisms involved in the 4-AA-induced analgesic effects.

EXPERIMENTAL APPROACH

The effect of local administration of 4-AA (160 μg per paw) on capsaicin (0.12 μg per paw) injection-induced pain-related behaviour and 4-AA's effect on 500-nM capsaicin-induced changes in intracellular calcium concentration ([Ca2+ ]i ) in cultured primary sensory neurons were assessed in vivo and in vitro, respectively.

KEY RESULTS

4-AA reduced capsaicin-induced nociceptive behaviour in naive and inflamed conditions through CB1 receptors. 4-AA (100 μM) reduced capsaicin-induced increase in [Ca2+ ]i in a CB1 receptor-dependent manner, when PGE2 was not present. Following PGE2 application, 4-AA (1-50 μM) increased the [Ca2+ ]i . Although 4-AA activated both TRPV1 and TRPA1 channels, increased [Ca2+ ]i was mediated through TRPV1 channels. Activation of TRPV1 channels resulted in their desensitisation. Blocking CB1 receptors reduced both the excitatory and desensitising effects of 4-AA.

CONCLUSION AND IMPLICATIONS

CB1 receptor-mediated inhibition of TRPV1 channels and TRPV1-mediated Ca2+ -influx- and CB1 receptor-dependent desensitisation of TRPV1 channels contribute to the anti-nociceptive effect of 4-AA in naive and inflamed conditions respectively. Agonists active at both CB1 receptors and TRPV1 channels might be useful as analgesics, particularly in inflammatory conditions.

The using of a piglets as a model for evaluating the dipyrone hematological effects

BACKGROUND

Dipyrone (MET, metamizole) is a non-steroidal anti-inflammatory drug commonly used both in human and in veterinary medicine. After oral administration, is broken down rapidly to metabolites which largely retain the activity of the parent drug. Its metabolites have analgesic, antipyretic and anti-inflammatory effects.

RESULTS

The subjects were eight healthy male Large White post-suckling piglets, weighing between 5.0 to 7.4 kg, of ages 35 ± 10 days. The animals were administered MET (100 mg/kg) by an intramuscular (I.M.) injection. The study calculated the value of several hemorheological parameters. Significant impact of MET treatment (p < 0.05) was proven in case: activated partial thromboplastin time; ratio of activated partial thromboplastin time; hemoglobin; hematocrit; mean corpuscular hemoglobin; mean corpuscular volume; red blood cells volume; white blood cells volume; prothrombin time index.

CONCLUSIONS

In summation, our observations suggest that a piglet model is useful for studying the impact of MET on hemorheological parameters.

WITHDRAWN: Dipyrone for acute primary headaches

The original authors of this review are unable to update it. The Cochrane Pain, Palliative and Supportive Care Review Group (PaPaS) is seeking new authors to update and split the review into two separate reviews on migraine and tension‐type headache. If you are interested, please contact the Managing Editor of PaPaS (contact details provided under 'Contact Person').

At July 2014, this review has been withdrawn. This review is out of date although it is correct as of the date of publication. The latest version is available in the ‘Other versions’ tab on The Cochrane Library, and may still be useful to readers.

The editorial group responsible for this previously published document have withdrawn it from publication.

WITHDRAWN: Single dose dipyrone for acute postoperative pain

BACKGROUND

Dipyrone (metamizole) is a non‐steroidal anti‐inflammatory drug used in some countries to treat pain (postoperative, colic, cancer, and migraine); it is banned in others because of an association with life‐threatening blood agranulocytosis. This review updates a 2001 Cochrane review, and no relevant new studies were identified, but additional outcomes were sought.

OBJECTIVES

To assess the efficacy and adverse events of single dose dipyrone in acute postoperative pain.

SEARCH METHODS

The earlier review searched CENTRAL, MEDLINE, EMBASE, LILACS and the Oxford Pain Relief Database to December 1999. For the update we searched CENTRAL, MEDLINE,EMBASE and LILACS to February 2010.

SELECTION CRITERIA

Single dose, randomised, double‐blind, placebo or active controlled trials of dipyrone for relief of established moderate to severe postoperative pain in adults. We included oral, rectal, intramuscular or intravenous administration of study drugs.

DATA COLLECTION AND ANALYSIS

Studies were assessed for methodological quality and data extracted by two review authors independently. Summed total pain relief over six hours (TOTPAR) was used to calculate the number of participants achieving at least 50% pain relief. Derived results were used to calculate, with 95% confidence intervals, relative benefit compared to placebo, and the number needed to treat (NNT) for one participant to experience at least 50% pain relief over six hours. Use and time to use of rescue medication were additional measures of efficacy. Information on adverse events and withdrawals was collected.

MAIN RESULTS

Fifteen studies tested mainly 500 mg oral dipyrone (173 participants), 2.5 g intravenous dipyrone (101), 2.5 g intramuscular dipyrone (99); fewer than 60 participants received any other dose. All studies used active controls (ibuprofen, paracetamol, aspirin, flurbiprofen, ketoprofen, dexketoprofen, ketorolac, pethidine, tramadol, suprofen); eight used placebo controls. Over 70% of participants experienced at least 50% pain relief over 4 to 6 hours with oral dipyrone 500 mg compared to 30% with placebo in five studies (288 participants; NNT 2.4 (1.9 to 3.2)). Fewer participants needed rescue medication with dipyrone (7%) than with placebo (34%; four studies, 248 participants). There was no difference in participants experiencing at least 50% pain relief with 2.5 g intravenous dipyrone and 100 mg intravenous tramadol (70% vs 65%; two studies, 200 participants). No serious adverse events were reported.

AUTHORS' CONCLUSIONS

Based on very limited information, single dose dipyrone 500 mg provides good pain relief to 70% of patients. For every five individuals given dipyrone 500 mg, two would experience this level of pain relief who would not have done with placebo, and fewer would need rescue medication, over 4 to 6 hours.

Novel bioactive metabolites of dipyrone (metamizol)

Dipyrone is a common antipyretic drug and the most popular non-opioid analgesic in many countries. In spite of its long and widespread use, molecular details of its fate in the body are not fully known. We administered dipyrone orally to mice. Two unknown metabolites were found, viz. the arachidonoyl amides of the known major dipyrone metabolites, 4-methylaminoantipyrine (2) and 4-aminoantipyrine (3). They were identified by ESI-LC-MS/MS after extraction from the CNS, and comparison with reference substances prepared synthetically. The arachidonoyl amides were positively tested for cannabis receptor binding (CB(1) and CB(2)) and cyclooxygenase inhibition (COX-1 and COX-2 in tissues and as isolated enzymes), suggesting that the endogenous cannabinoid system may play a role in the effects of dipyrone against pain.

Single dose dipyrone for acute postoperative pain

BACKGROUND

Dipyrone (metamizole) is a non-steroidal anti-inflammatory drug used in some countries to treat pain (postoperative, colic, cancer, and migraine); it is banned in others because of an association with life-threatening blood agranulocytosis. This review updates a 2001 Cochrane review, and no relevant new studies were identified, but additional outcomes were sought.

OBJECTIVES

To assess the efficacy and adverse events of single dose dipyrone in acute postoperative pain.

SEARCH STRATEGY

The earlier review searched CENTRAL, MEDLINE, EMBASE, LILACS and the Oxford Pain Relief Database to December 1999. For the update we searched CENTRAL, MEDLINE,EMBASE and LILACS to February 2010.

SELECTION CRITERIA

Single dose, randomised, double-blind, placebo or active controlled trials of dipyrone for relief of established moderate to severe postoperative pain in adults. We included oral, rectal, intramuscular or intravenous administration of study drugs.

DATA COLLECTION AND ANALYSIS

Studies were assessed for methodological quality and data extracted by two review authors independently. Summed total pain relief over six hours (TOTPAR) was used to calculate the number of participants achieving at least 50% pain relief. Derived results were used to calculate, with 95% confidence intervals, relative benefit compared to placebo, and the number needed to treat (NNT) for one participant to experience at least 50% pain relief over six hours. Use and time to use of rescue medication were additional measures of efficacy. Information on adverse events and withdrawals was collected.

MAIN RESULTS

Fifteen studies tested mainly 500 mg oral dipyrone (173 participants), 2.5 g intravenous dipyrone (101), 2.5 g intramuscular dipyrone (99); fewer than 60 participants received any other dose. All studies used active controls (ibuprofen, paracetamol, aspirin, flurbiprofen, ketoprofen, dexketoprofen, ketorolac, pethidine, tramadol, suprofen); eight used placebo controls.Over 70% of participants experienced at least 50% pain relief over 4 to 6 hours with oral dipyrone 500 mg compared to 30% with placebo in five studies (288 participants; NNT 2.4 (1.9 to 3.2)). Fewer participants needed rescue medication with dipyrone (7%) than with placebo (34%; four studies, 248 participants). There was no difference in participants experiencing at least 50% pain relief with 2.5 g intravenous dipyrone and 100 mg intravenous tramadol (70% vs 65%; two studies, 200 participants). No serious adverse events were reported.

AUTHORS' CONCLUSIONS

Based on very limited information, single dose dipyrone 500 mg provides good pain relief to 70% of patients. For every five individuals given dipyrone 500 mg, two would experience this level of pain relief who would not have done with placebo, and fewer would need rescue medication, over 4 to 6 hours.

Parecoxib versus dipyrone (metamizole) for postoperative pain relief after hysterectomy : a prospective, single-centre, randomized, double-blind trial

BACKGROUND AND OBJECTIVE

Selective cyclo-oxygenase-2 (COX-2) inhibitors provide postoperative pain relief similar to conventional NSAIDs. However, many of these non-opioid analgesics are available only for oral administration, and are therefore ineffective in patients experiencing postoperative nausea or vomiting. The aim of this study was to compare the analgesic efficacy of the COX-2 inhibitor parecoxib with that of dipyrone (metamizole) administered intravenously for 48 hours after vaginal hysterectomy.

METHODS

Fifty women undergoing vaginal hysterectomy under general anaesthesia were randomly assigned to two groups: the parecoxib group, who received intravenous parecoxib 40 mg intraoperatively and every 12 hours after surgery over a period of 48 hours, and the dipyrone group, who received intravenous dipyrone 2.5 g injected intraoperatively, followed by dipyrone 1 g every 6 hours after surgery over a period of 48 hours. Because of the double-blinded study protocol, patients in the parecoxib groups were required to receive placebo infusions 6, 18, 30 and 42 hours after the operation. Visual analogue scale (VAS [scale 0-10]) scores were recorded 0.5, 1, 2, 3, 4, 6, 9, 12, 15, 18, 24, 36 and 48 hours after surgery. To assess the cumulative opioid administration, all patients were fitted with an intravenous patient-controlled analgesia (PCA) device containing the opioid piritramide. An alpha value of 0.05 was considered statistically significant.

RESULTS

VAS scores did not differ between groups with one exception: VAS scores were lower in the parecoxib group 12 hours after surgery than in the dipyrone group (1 and 2, respectively; p < 0.05). No significant differences in cumulative piritramide administration were measured between groups 1 hour or 24 hours after surgery (parecoxib 14.7 [+/- SD 4.4] and 30.6 [+/- 12.8] mg, respectively; dipyrone 11.8 [+/- 4.9] and 36.5 [+/- 10.7] mg, respectively).

CONCLUSIONS

Parecoxib 40 mg twice daily provides postoperative pain relief equivalent to that of dipyrone 4 g daily during the first 48 hours in patients after hysterectomy.