Double-blind, Randomized Controlled Study to Assess the Analgesic Effect of 2 g of Magnesium Dipyrone (Metamizol) and Changes in Plasma Beta-endorphin Immunoreactivity Values in Patients Undergoing Elective Inguinal Herniorrhaphy Under Epidural Anesthesia.

Study Overview
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Brief Summary
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A double-blind, randomized controlled study is designed to assess the analgesic effect of a single intravenous dose of 2 g of magnesium dipyrone (metamizol) and whether the administration of the active drug will be associated with changes in plasma beta-endorphin immunoreactivity values in patients undergoing elective inguinal herniorrhaphy (Bassini operation) under epidural anesthesia. Participants, care givers, and those assessing the outcomes will be blinded to group assignment. Participants will be randomized to receive dipyrone or a placebo. The active drug or placebo will be administered as an intravenous infusion over 10 min. Pain will be evaluated by the patient according to a 100-mm visual analogue scale. Assessments will be carried out the day before surgery, immediately after operation, at the time of drug administration, and 60 and 180 min after treatment. At the same time as pain will be evaluated, blood samples will be drawn for plasma beta-endorphin immunoreactivity measurement (immunoradiometric assay).

Official Title
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Double-blind, Randomized Controlled Study to Assess the Analgesic Effect of a Single Intravenous Dose of 2 g of Magnesium Dipyrone (Metamizol) and Changes in Plasma Beta-endorphin Immunoreactivity (Beta-EPIr) Values in Patients Undergoing Elective Inguinal Herniorrhaphy (Bassini Operation) Under Epidural Anesthesia.

Conditions
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Pain, Beta-endorphin, Dipyrone, Hernia Surgery

Intervention / Treatment
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* Drug: Dipyrone administration
* Behavioral: Pain assessment
* Biological: beta-endorphin immunoreactivity
* Other: Placebo administration


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-70 years, elective surgery, routine laboratory tests (blood cell count, biochemical profile, urinalysis), chest radiography, twelve-lead electrocardiography, body mass index (BMI), blood pressure, pulse rate normal or abnormal values without clinical relevance and a mental status sufficient to be able to complete efficacy tests. Exclusion Criteria: Patients who had taken other analgesics or anti-inflammatory drugs 24 h before surgery, as those with known hypersensitivity to the drug or with any other disorder contradicting the administration of dipyrone. Patients with hypersensitivity to non-steroidal anti-inflammatory agents.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Dipyrone group<br>Dipyrone 2 g (Nolotil®, Europharma, Madrid, Spain); one ampoule in 50 mL of 0.9% saline solution as an intravenous infusion over 10 min. | Drug: Dipyrone administration<br>* Dipyrone 2 g (Nolotil®, Europharma, Madrid, Spain); one ampoule in 50 mL of 0.9% saline solution as an intravenous infusion over 10 min.<br>Behavioral: Pain assessment<br>* Pain will be evaluated by the patient according to a 100-mm visual analogue scale (VAS) (from point 0 no pain to point 10 unbearable pain).<br>Biological: beta-endorphin immunoreactivity<br>* Plasma beta-EPIr levels will be measured by an immunoradiometric assay (Allegro Beta-endorphin, Nichols Institute Diagnostics, SAN JUAN DE CAPISTRANO, CA) (normal values 29-40 pg/mL). It will be obtained by venous blood samples (5 mL) at the same time points at pain will be measured.<br>|
| Placebo Comparator: Placebo group<br>The placebo will be matched to the study drug for, color, and size. Placebo will be administered in a single dose in 50 mL of 0.9% saline solution as an intravenous infusion over 10 min. | Behavioral: Pain assessment<br>* Pain will be evaluated by the patient according to a 100-mm visual analogue scale (VAS) (from point 0 no pain to point 10 unbearable pain).<br>Biological: beta-endorphin immunoreactivity<br>* Plasma beta-EPIr levels will be measured by an immunoradiometric assay (Allegro Beta-endorphin, Nichols Institute Diagnostics, SAN JUAN DE CAPISTRANO, CA) (normal values 29-40 pg/mL). It will be obtained by venous blood samples (5 mL) at the same time points at pain will be measured.<br>Other: Placebo administration<br>* Placebo in 50 mL of 0.9% saline solution as an intravenous infusion over 10 min.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Analgesic efficacy-Pain relief | Visual Analogue Scale score | 30 seconds | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Beta-endorphins levels. | Beta-endorphin immunoreactivity levels | 1 minute |