Morphine-3-glucuronide prevents tolerance to morphine-6-glucuronide in mice.
Daily subcutaneous (s.c.) pretreatment with morphine-3-glucuronide (6 mg/kg) was found to reduce morphine-6-glucuronide (4 mg/kg s.c.)-induced antinociception, with no decrease in the effect over 5 days. Morphine-6-glucuronide administration (4 mg/kg s.c.) on Day 6, without morphine-3-glucorinide pretreatment, results in a significant increase in antinociception (from 24% on Day 5 to 70%; p< or =0.05). Morphine-3-glucuronide may prevent tolerance to morphine-6-glucuronide by reducing morphine-6-glucuronide-induced antinociception.
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Departamento de Farmacologia y Terapéutica, Universidad Miguel Hernandez, Alicante, Spain.
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Horga
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JF