Plasma Morphine Research Articles

High-performance liquid chromatographic determination of morphine, morphine-3-glucuronide, morphine-6-glucuronide and codeine in biological samples using multi-wavelength forward optical detection

An isocratic high-performance liquid chromatographic method has been developed for the determination of morphine, morphine-3-glucuronide, morphine-6-glucuronide and codeine in plasma, urine and cerebrospinal fluid. The use of an efficient solid-phase extraction procedure together with a forward optical scanning detector allows a detection limit of 500 pg/ml. The method was evaluated by examination of biological samples taken from newborn infants following the intravenous administration of morphine sulfate.

Antidepressants in Cancer Pain

Studies conducted in recent years have helped define the role of antidepressant drugs in the management of cancer pain. The antinociceptive action of these agents seems to be independent of beneficial effect on depression or mood. Among antidepressant drugs, those of the tricyclic class are preferred when an analgesic effect is sought. Their primary application is for pain due to nerve injury, so-called "neuropathic pain". Although the co-administration of tricyclic antidepressants may increase plasma morphine concentrations, any potentiation of morphine analgesia is thought not to be due to an increased bioavailability of the opiate, but to an intrinsic analgesic effect of antidepressants. On this basis, the use of antidepressants in combination with opioids for the treatment of cancer pain is suitable when a component of deafferentation is present or when there is concomitant depressive illness.

Plasma morphine and morphine-6-glucuronide during chronic morphine therapy for cancer pain: plasma profiles, steady-state concentrations and the consequences of renal failure

Morphine-6-glucuronide (M-6-G) is an active metabolite of morphine that may contribute to drug effects. To understand better the relationship between morphine and M-6-G in cancer patients receiving chronic therapy, we employed high performance liquid chromatography with electrochemical detection to measure: 1. (1) morphine and M-6-G plasma concentrations following discontinuation of dosing in 2 patients, one receiving oral therapy and the other an intravenous infusion 2. (2) morphine and M-6-G concentrations in random blood samples taken at apparent steady state from 8 patients, 7 with normal renal function and 1 with mild renal insufficiency, who were receiving continuous morphine infusions 3. (3) morphine and M-6-G concentrations in random blood samples taken over a period of weeks from 4 patients, 2 with stable and 2 with declining renal function. Results demonstrated a slightly slower decline in plasma M-6-G than morphine concentrations following drug discontinuation, as would be expected for metabolite and parent relationship; roughly similar M-6-G: morphine ratios (mean molar ratio = 1.22) across a broad range of morphine doses in patients with normal renal function; and an increase in this ratio over time in patients with progressive renal dysfunction. These data illustrate the kinetics of M-6-G in cancer patients receiving chronic morphine therapy and confirm the importance of renal function in determining the concentration of the metabolite.

Chronic morphine therapy for cancer pain

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.

Oral diamorphine: lack of effect on dyspnoea and exercise tolerance in the "pink puffer" syndrome

The aim of this study was to assess the effects of diamorphine on breathlessness and exercise tolerance in patients with severe chronic airflow obstruction and normal arterial carbon dioxide tension (PCO2) levels ("pink puffer" syndrome). In this double-blind, cross-over, randomized study we examined both acute and chronic effects of single and multiple doses of oral diamorphine in 14 "pink puffer" patients. Their mean resting forced expiratory volume in one second (FEV1) was 36% predicted normal, mean arterial oxygen tension (PaO2) was 9.2 kPa and mean PaCO2 was 5.2 kPa. Ten patients took either diamorphine 2.5 or 5 mg or placebo elixir 6 hourly for 2 weeks, recording on a diary card dyspnoea, sleepiness and well-being on a visual analogue scale (VAS). The final treatment was given 30 min before measuring spirometry, arterial blood gases, plasma morphine levels, 6 min walking distances, time walked on treadmill and self-assessment of dyspnoea on a VAS scale after exercise. On two further days, eight patients took two doses, 4 h apart, of either diamorphine 7.5 mg or placebo elixir. Spirometry, 6 min walking distance with a VAS score for dyspnoea were measured before and at 1 h after each dose. Morphine levels and blood gases were also measured. Whether given in single or repeated doses, oral diamorphine had no significant effect on exercise tolerance and breathlessness when compared with placebo. Diamorphine 2.5-7.5 mg produced neither sleepiness nor a deterioration in blood gases. However, plasma levels associated with analgesic efficacy were not achieved with these doses. Thus, as given in this study, oral diamorphine is unlikely to have therapeutic potential in the treatment of dyspnoea in the "pink puffer" syndrome.

Impact of environmental and genetic factors on codeine analgesia

The polymorphic cytochrome P-450 DB1 (P-450 IID6) is responsible for the O-demethylation of codeine to morphine by human liver microsomes. The influence of P-450 DB1 variable activity on the bioactivation of codeine in vivo to morphine and on its analgesic effect was investigated in phenotyped healthy volunteers--7 extensive [EM] and 1 poor [PM] metabolizer of debrisoquine. After pretreatment with oral placebo or quinidine sulphate 50 mg, codeine phosphate 100 mg or placebo were administered orally according to a double-blind randomized crossover design. In EM subjects the plasma morphine Cmax was 17.9 nmol/l, whereas virtually no morphine was detectable after quinidine pretreatment (1.5 nmol/l), and in the PM subject (0.60 nmol/l). In EM codeine significantly increased subjective (VAS) and objective (R-III reflex) pain thresholds in response to selective transcutaneous nerve stimulation, whereas no significant analgesia was detected after placebo, or after codeine with quinidine pretreatment, or in the PM. In PM of genetic origin, or due to environmental alteration of the phenotypic expression (i.e. drug interaction), codeine is not activated into morphine and is an inefficient analgesic.

Morphine kinetics after diamorphine infusion in premature neonates.

1. The pharmacokinetics of morphine were studied in 26 newborn premature neonates (26-38 weeks gestational age) who were given a loading dose of 50 micrograms kg-1 of diamorphine followed by an intravenous infusion of 15 micrograms kg-1 h-1 of diamorphine. Plasma concentrations of morphine were measured during the infusion at steady-state and for 24 h after the cessation of the diamorphine infusion. 2. The mean steady-state plasma morphine concentration (+/- s.d.) for a diamorphine infusion rate of 15 micrograms kg-1 h-1 was 62.5 +/- 22.8 ng ml-1. 3. Morphine clearance was 3.6 +/- 0.9 ml min-1 kg-1, the elimination half-life was 8.9 +/- 3.3 h and the volume of distribution was 2.7 +/- 1.01 kg-1. 4. Morphine elimination kinetics were described by a mono-exponential function. 5. There was a direct relationship between the gestational age of the patients and the clearance (r2 = 0.31, P = 0.003) and half-life (r2 = 0.35, P = 0.01) of morphine, but no relationship was found between gestational age and volume of distribution. 6. The results suggest that the currently used dosing regimen of diamorphine achieves a safe and effective morphine concentration in the premature newborn but that the loading dose could be modified to achieve a more rapid onset of analgesia.

Pain characterization in cancer patients and the analgetic response to epidural morphine

In 48 patients with pain related to malignancy, a pain characterization was performed during oral opioid therapy. After an optimal epidural morphine regimen had been established, the alteration in pain relief was evaluated by means of a visual analogue scale. The CSF and plasma morphine concentrations at minimum steady state were then analysed in 28 patients and related to the degree of pain relief. The efficacy of the spinal treatment ranked in the following order: somatic > visceral > radiating = 0, but the difference was only significant between the somatic and radiating pain groups. There was a tendency for continuous pain to be better relieved than intermittent pain. No correlations were found between the CSF or plasma morphine concentrations and the degree of pain relief, suggesting that not all pain impulses are modulated in a dose-dependent manner by morphine at the spinal level. Pain characterization may be instrumental in providing an optimal spinal opioid analgesia in malignancy. Moreover, there is a need for better defined diagnostic criteria for clinical pain characterization.

Heroin intoxication: the relation between plasma morphine concentration and clinical state at admission

Heroin intoxication: the relation between plasma morphine concentration and clinical state at admission

PLASMA CONCENTRATIONS OF MORPHINE IN CHILDREN WITH CHRONIC PAIN—COMPARISON OF CONTROLLED RELEASE AND REGULAR MORPHINE SULPHATE TABLETS

Comparative plasma concentrations of morphine in two children with chronic pain who received controlled-release and regular morphine sulphate tablets are described. The controlled-release tablets were given every 12 h and regular tablets every 4 h. At steady-state, the maximum morphine plasma concentration (Cmax) was 24.1 ng/ml at 45 mg and 18.7 ng/ml at 30 mg of controlled-release morphine sulphate tablets. The Cmax was 17.6 ng/ml at 15 mg and 31.4 ng/ml at 20 mg dose of the regular tablets. The maximum concentration occurred at 2.0 and 2.5 h after controlled-release and 0.25 and 1.5 h after regular tablets. The minimum morphine plasma concentrations and the area under the plasma concentration-time curve normalized for dose were comparable for the controlled-release and regular tablets. These data indicate that controlled-release morphine sulphate may be well absorbed in relation to the regular tablets. If these results are confirmed in a large group of patients, the controlled-release morphine sulphate tablets may offer a convenient (less frequent) dosing compared with regular tablets in children suffering from chronic pain due to malignancy.

Determination of morphine and 6-acetylmorphine in plasma by high-performance liquid chromatography with fluorescence detection

A method is described for the simultaneous determination of morphine and 6-acetylmorphine in small volumes of human plasma by normal-phase high-performance liquid chromatography using solid-phase extraction, dansyl derivatisation and fluorescence detection. The lower limits of quantitation in a 0.1-ml plasma sample are 10 ng/ml for morphine and 25 ng/ml for 6-acetylmorphine. The method has been applied to determine concentrations of morphine and 6-acetylmorphine in plasma samples from premature babies administered an intravenous infusion of diamorphine.

High-performance liquid chromatographic determination of morphine and its 3- and 6-glucuronide metabolites: improvements to the method and application to stability studies

Improvements to previously reported methods for the determination of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in human plasma are described. The improved methods involve the use of a solid-phase extraction cartridge and a chromatographic system which uses paired-ion reversed-phase high-performance liquid chromatography with a radially compressed column. Only one cartridge is used to prepare each sample for chromatography and each cartridge may be used for at least fourteen 1-ml plasma samples. The recovery is greater than 85%. The improvements to the method of sample pretreatment and in the chromatographic conditions have allowed determination of morphine, M3G and M6G in human plasma down to 13.3 nmol/l (coefficient of variation = 9.3%), 108 nmol/l (6.6%) and 41 nmol/l (6.7%), respectively, using ultraviolet detection alone. It was shown that all three compounds were stable in plasma for up to 101 weeks when stored at −20°C.

Morphine pharmacokinetics and pain assessment after intracerebroventricular administration in patients with terminal cancer

Morphine pharmacokinetics and pain relief were evaluated after intracerebroventricular administration of morphine (0.4 +/- 0.11 mg) in seven patients with cancer suffering from intractable pain. Ventricular cerebrospinal fluid (CSF), lumbar CSF, and plasma morphine concentrations were analyzed by a specific morphine radioimmunoassay. A two-compartment model was sufficient to describe the kinetics of morphine in ventricular CSF. Morphine diffuses to the lumbar level, and the mean maximum concentration was 192 +/- 105 ng/ml at 4.5 +/- 1.3 hours. Ventricular and lumbar CSF morphine kinetics showed a similar decline during the elimination phase, with terminal half-lives of 3.8 +/- 0.6 hours and 4.2 +/- 1.6 hours, respectively. Pain relief was evaluated by a visual analog scale: the test showed a rapid onset of analgesia (less than 10 minutes). Analgesic effectiveness reached a maximum between 6 and 10 hours. The relationship between pharmacologic effect and morphine concentrations in ventricular CSF resulted in an anticlockwise hysteresis curve. The presence of morphine in lumbar CSF suggested an additive spinal action of morphine, which probably plays a role in the duration of analgesia.

Patient-controlled analgesic administration. A comparison of steady-state morphine infusions with bolus doses

The authors have shown previously that bone marrow transplant (BMT) patients who self-administered bolus doses of morphine gained equal oral mucositis pain relief while using less drug compared with similar patients receiving morphine by staff-controlled continuous infusion. In a follow-up study they compared the efficacy and side effects of morphine in two groups of marrow transplant patients who controlled their own analgesic administration either by conventional bolus-dose, patient-controlled analgesia (PCA) or by adjusting the rate of continuous morphine infusion to increase or decrease their plasma morphine concentration. Patients controlling their morphine infusion rates (pharmacokinetically based patient-controlled analgesia [PKPCA] group) obtained more relief from oral mucositis pain than did patients using conventional PCA. Patients in the PKPCA group used more morphine than PCA patients and achieved superior pain relief without significant increases in side effects (e.g., nausea, mood changes, sedation). The authors conclude that PKPCA improves the management of prolonged, severe pain in marrow transplant patients and that this approach to patient-controlled analgesia may be useful in other types of persistent pain.

Subcutaneous morphine

AnaesthesiaVolume 46, Issue 1 p. 75-75 Free Access Subcutaneous morphine T.J. Semple, T.J. Semple Royal Adelaide Hospital, Adelaide, South Australia 5000Search for more papers by this authorP.E. Macintyre, P.E. Macintyre Royal Adelaide Hospital, Adelaide, South Australia 5000Search for more papers by this author T.J. Semple, T.J. Semple Royal Adelaide Hospital, Adelaide, South Australia 5000Search for more papers by this authorP.E. Macintyre, P.E. Macintyre Royal Adelaide Hospital, Adelaide, South Australia 5000Search for more papers by this author First published: January 1991 https://doi.org/10.1111/j.1365-2044.1991.tb09334.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Reference 1 Semple TJ, Southall EG, Macintyre PE, Mather LE, Runciman WB. Pharmacokinetics of subcutaneous morphine in the elderly postoperative patient. Pain (Suppl.) 5: 5240. 2 Kirkpatrick T, Henderson PD, Nimmo WS. Plasma morphine concentrations after intramuscular injection into the deltoid or gluteal muscles. Anaesthesia 1988; 43: 293– 5. 3 Rigg JRA, Braune RA, Davis C, Khadelwal JK, Goldsmith CH. Variation in the disposition of morphine after IM administration in surgical patients. British Journal of Anaesthesia 1978; 50: 1125– 30. Citing Literature Volume46, Issue1January 1991Pages 75-75 ReferencesRelatedInformation

アルギン酸含有モルヒネ持続性坐剤によるとう痛管理の臨床的評価

The rapid initial absorption and the subsequent prolonged absorption of morphine were obtained simultaneously by using sustained-release suppository (MA), which can be prepared simply by mixing sodium alginate with morphine hydrochloride in VOSCO® H-15 base, in rabbits. The clinical effects of MA were evaluated in patients with severe pain such as the terminal cancer patients. Of 35 patients receiving MA, 21 and 13 could achieve acceptable analgesia on a twice and a once daily dose schedule, respectively. Conventional morphine suppository without alginic acid, however, relieved pain only for 8 hours on the same single-dose. The efficacy of MA is also supported by the sustained plasma morphine level in six female operating patients receiving MA. The MA dosing interval lengthened to every 12 to 24 hours resulted in a decrease in the total daily morphine requirement below 40 mg, The clinically desirable sedation was obtained during night and day in all patients, and the side effects such as vomitting and constipation observed in 29 percent of the patients were mild and controlled by simptomatic treatment. The advantage of less frequent dosing by MA may lead to improvement of the quality of life of terminal patients with pain.

Chronic ethanol consumption causes increased glucuronidation of morphine in rabbits

1. Male rabbits were given an i.p. injection of 15 mg/kg morphine and plasma concentrations of morphine and morphine-3-glucuronide (M3G) were simultaneously quantified by h.p.l.c. After 14 days of 10% ethanol in the rabbits' drinking water, a second injection of morphine was administered and plasma concentrations were determined again. 2. Morphine plasma clearance increased significantly by 42% after ethanol treatment. The area under the plasma concentration time curve (AUC) for morphine decreased by 23% while the AUC for the glucuronide increased by 22%. 3. The ratio of the AUCs (glucruonide/morphine) increased by 72%. These results demonstrate that chronic ethanol treatment of rabbits results in increased clearance of morphine after an i.p. dose. The increase in clearance is most likely due to induction of UDP-glucuronosyltransferase isozymes by ethanol.

Further development of a morphine hydrogel suppository.

1. A sustained release monolithic morphine hydrogel suppository (MHS) was developed and administered to five volunteers. 2. The MHS delivered a mean of 55 mg morphine over 12 h. The mean plasma morphine concentration was 15 ng ml-1 from 2 to 12 h after administration. 3. Plasma morphine concentrations were comparable with those reported for the same dose given orally over the same time period. 4. The morphine hydrogel suppository appears to be an effective means of delivering morphine and may be of value in the management of chronic pain.

Codeine increases pain thresholds to copper vapor laser stimuli in extensive but not poor metabolizers of sparteine

The analgesic efficacy and kinetics of a single oral dose of 75 mg codeine was investigated in 12 extensive metabolizers and 12 poor metabolizers of sparteine in a double-blind, placebo-controlled crossover study. The cosegregation of the O-demethylation of codeine to morphine with the sparteine oxidation polymorphism was confirmed. Hence morphine could not be detected in the plasma of any of the poor metabolizers, whereas detectable morphine plasma levels were found in 10 of 12 extensive metabolizers. Pain thresholds to laser stimuli were determined before drug intake and 90, 150, and 210 minutes after drug intake. Codeine significantly increased the pricking pain thresholds in the extensive metabolizers (p less than 0.05), whereas there were no significant changes in the poor metabolizers. No change in pain thresholds occurred with placebo in any of the two phenotypes. In the extensive metabolizers there was a significant positive correlation between the increase in pain threshold and plasma concentration of codeine. The study supports the hypothesis that morphine formation is essential for achievement of analgesia during codeine treatment.

Studies on the effects of antidepressant drugs on the antinociceptive action of morphine and on plasma morphine in rat and man

In the rat we studied the effect of 3 tricyclic antidepressants: chlorimipramine, amitriptyline and nortriptyline, and the atypical antidepressant trazodone on pain thresholds when administered alone or together with morphine. Moreover, we evaluated the effect of the antidepressants on free morphine plasma concentrations both in the rat and in man. We observed that chlorimipramine and amitriptyline, two tricyclic antidepressants active on the serotoninergic system, induce analgesia and potentiate morphine analgesia in a dose-related fashion. The noradrenergic tricyclic nortriptyline and trazodone did not elicit analgesia and inconsistently affected morphine analgesia. In the rat, all drugs tested increased plasma concentrations of morphine with the exception of amitriptyline. In man, only chlorimipramine and amitriptyline increased the plasma concentration of the free opiate.