D J Cerbone | PubMed Health

PubMed1991

Chronic nausea and morphine-6-glucuronide.

Morphine-6-glucuronide is an active metabolite of morphine that has analgesic properties and is measurable in the plasma and cerebrospinal fluid of patients treated with this opioid. Decreased clearance of the compound has been observed in patients with renal insufficiency, and this has been associated with an increase in the ratio of morphine-6-glucuronide to morphine. Clinical effects from accumulation of morphine-6-glucuronide have not been described with the exception of case reports in which patients with renal failure were noted to develop opioid toxicity with high plasma levels of the metabolite and low levels of the parent drug. We describe a patient who experienced chronic nausea and an episode of confusion while treated with a small, stable dose of oral morphine in the setting of mild renal insufficiency. Relatively high levels of morphine-6-glucuronide were measured and all symptoms resolved promptly as the concentration of this metabolite declined. This case provides suggestive evidence that morphine-6-glucuronide can produce clinically significant effects in patients with mild renal insufficiency.

Adenocarcinoma↗

PubMed1991

Chronic morphine therapy for cancer pain: plasma and cerebrospinal fluid morphine and morphine-6-glucuronide concentrations.

Morphine-6-glucuronide (M-6-G) is an active metabolite that may contribute to the clinical effects produced by systemic administration of morphine. To help clarify the extent to which M-6-G may cross the blood-brain barrier and exert effects, we employed high-performance liquid chromatography with electrochemical detection to measure the concentrations of M-6-G and morphine in the plasma and either ventricular (three patients) or lumbar (eight patients) CSF of cancer patients receiving chronic morphine therapy. The mean ratio of morphine in ventricular CSF:morphine in plasma was 0.71; the same ratio for M-6-G was only 0.077. The average molar ratio of M-6-G: morphine in ventricular CSF was 0.207, and the average molar ratio in plasma was 1.89. Although sampling problems render the lumbar CSF results less reliable, they were very similar. Thus, plasma contained approximately twice as much M-6-G as morphine, whereas CSF contained only one-fifth to one-third as much. These data confirm that M-6-G in plasma is distributed into CSF, but to a far lesser extent than morphine. They help explain animal data demonstrating much higher potency of M-6-G on administration into CSF than systemic administration and indicate that the degree to which M-6-G contributes to morphine effects in humans remains an unresolved question.

Adult↗