Pharmacokinetics and pharmacodynamics of metamizol in co-administration with morphine under acute and chronic treatments in arthritic rats.

Objective: To investigate the relationship between metamizol pharmacokinetics and the antinociceptive effect produced after subcutaneous administration of metamizol (177.8 mg/kg) alone or in combination with morphine (3.2 mg/kg), under acute and chronic treatments.

High-performance liquid chromatographic assay for metamizol metabolites in rat plasma: application to pharmacokinetic studies.

In order to evaluate the pharmacokinetics of metamizol in the presence of morphine in arthritic rats, after subcutaneous administration of the drugs, an easy, rapid, sensitive and selective analytical method was proposed and validated. The four main metamizol metabolites (4-methylaminoantipyrine, 4-aminoantipyrine, 4-acetylaminoantipyrine and 4-formylaminoantipyrine) were extracted from plasma samples (50-100μl) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography with diode-array detection. Standard calibration graphs for all metabolites were linear within a range of 1-100μg/ml (r(2)≥0.

Antinociceptive effects of tramadol in co-administration with metamizol after single and repeated administrations in rats.

Combinations of two analgesic drugs of the same or different class are widely used in clinical therapy to enhance its antinociceptive effects and reduce the side effects. In order to evaluate a possible antinociceptive synergistic interaction of metamizol s.c.

Effect of metamizol on morphine pharmacokinetics and pharmacodynamics after acute and subchronic administration in arthritic rats.

The aim of the present study was to investigate whether metamizol alters the pharmacokinetics of morphine and to determine the relationship between morphine plasma levels and antinociceptive effect produced after co-administration of drugs under acute and subchronic treatments using the pain-induced functional impairment model in rat (PIFIR model). Administration of morphine+metamizol under acute treatment produced a significantly higher antinociceptive effect than that obtained with morphine alone (P<0.05).

Anti-nociceptive synergism of morphine and gabapentin in neuropathic pain induced by chronic constriction injury.

In order to detect an anti-nociceptive interaction between morphine and gabapentin, the anti-allodynic and anti-hyperalgesic effects of these drugs, administered either separately or in combination, were determined using the von Frey and acetone tests in a rat model of neuropathic pain (Bennett model). Morphine and gabapentin individually induced moderate attenuation of mechanical hyperalgesia, whereas the morphine and gabapentin combination completely decreased hyperalgesia. Morphine showed its maximal effect at 30 min post-injection in the acetone test; however, this effect gradually returned to the baseline value.

The antinociceptive efficacy of morphine, metamizol, or their combination in an experimental rat model with different levels of inflammatory pain.

The purpose of this work was to evaluate the antinociceptive efficacy of an optimal morphine and metamizol combination on different levels of nociception (levels I, II, and III) using the "Pain-induced functional impairment model in the rat". The effect of acetylsalicylic acid was examined as a reference drug at the same levels of nociception. The antinociceptive effects produced by morphine (3.

[Antinociceptive effects of the combination metamizol + morphine in rats with intense pain (arthritic gout-type pain produced with AU)].

Background: The antinociceptive effects of metamizol and morphine administered either separately or in combination were determined in the "Pain-Induced Functional Impairment Model in the Rat" (PIFIR antinociceptive model).

Methods: Intense nociception (or intense pain) was induced by the intra-articular injection of uric acid (50%) in the right hind limb inducing its dysfunction. Animals then received analgesic agents, and the recovery of functionality over time was assessed as an expression of antinociception.

High-performance liquid chromatographic assay for morphine in small plasma samples: application to pharmacokinetic studies in rats.

In order to perform a reliable pharmacokinetic study of morphine during subchronic treatment in rats, an easy, rapid, sensitive and selective analytical method was proposed and validated. The analyte and internal standard (naloxone) were extracted from plasma samples (100 microL) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography (HPLC) along with electrochemical detection (ED). Standard calibration graphs were linear within a range of 3.

Comparison of dissolution profiles for albendazole tablets using USP apparatus 2 and 4.

The in vitro dissolution of albendazole from three different commercially available products (200 mg tablets) was studied using U.S. Pharmacopeia (USP) Apparatus 2 and USP Apparatus 4 in order to compare the release performance of the drug in two essentially different dissolution systems.