Pharmacokinetics and efficacy of rectal versus oral sustained-release morphine in cancer patients

Revision of Pharmacological Treatment Recommendations for Cancer Pain: Clinical Guidelines from the Japanese Society of Palliative Medicine

Background: Pain is one of the most common symptoms in cancer patients. The Japanese Society for Palliative Medicine (JSPM) first published its clinical guidelines for the management of cancer pain in 2010. Since then, more research on cancer pain management has been reported, and new drugs have become available in Japan. Thus, the JSPM has now revised the clinical guidelines using a validated methodology. Methods: This guideline was developed through a systematic review, discussion, and the Delphi method, following a formal guideline development process. Results: Thirty-five recommendations were created: 19 for the pharmacological management of cancer pain, 6 for the management of opioid-induced adverse effects, and 10 for pharmacological treatment procedures. Due to the lack of evidence that directly addressed our clinical questions, most of the recommendations had to be based on consensus among committee members and other guidelines. Discussion: It is critical to continue to build high-quality evidence in cancer pain management, and revise these guidelines accordingly.

Oral morphine for cancer pain

BACKGROUND

This is the third updated version of a Cochrane review first published in Issue 4, 2003 of The Cochrane Library and first updated in 2007. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain, and to assess the incidence and severity of adverse events.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 9); MEDLINE (1966 to October 2015); and EMBASE (1974 to October 2015). We also searched ClinicalTrials.gov (1 October 2015).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) using placebo or active comparators reporting on the analgesic effect of oral morphine in adults and children with cancer pain. We excluded trials with fewer than 10 participants.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which were checked by another review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNTs) for the analgesic effect. We extracted any available data on the number or proportion of participants with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales).

MAIN RESULTS

We identified seven new studies in this update. We excluded six, and one study is ongoing so also not included in this update. This review contains a total of 62 included studies, with 4241 participants. Thirty-six studies used a cross-over design ranging from one to 15 days, with the greatest number (11) for seven days for each arm of the trial. Overall we judged the included studies to be at high risk of bias because the methods of randomisation and allocation concealment were poorly reported. The primary outcomes for this review were participant-reported pain and pain relief.Fifteen studies compared oral morphine modified release (Mm/r) preparations with morphine immediate release (MIR). Fourteen studies compared Mm/r in different strengths; six of these included 24-hour modified release products. Fifteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Three studies compared MIR with MIR by a different route of administration. Two studies compared Mm/r with Mm/r at different times and two compared MIR with MIR given at a different time. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine.In the previous update, a standard of 'no worse than mild pain' was set, equivalent to a score of 30/100 mm or less on a visual analogue pain intensity scale (VAS), or the equivalent in other pain scales. Eighteen studies achieved this level of pain relief on average, and no study reported that good levels of pain relief were not attained. Where results were reported for individual participants in 17 studies, 'no worse than mild pain' was achieved by 96% of participants (362/377), and an outcome equivalent to treatment success in 63% (400/638).Morphine is an effective analgesic for cancer pain. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12- or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration was undertaken with both instant release and modified release products. A small number of participants did not achieve adequate analgesia with morphine. Adverse events were common, predictable, and approximately 6% of participants discontinued treatment with morphine because of intolerable adverse events.The quality of the evidence is generally poor. Studies are old, often small, and were largely carried out for registration purposes and therefore were only designed to show equivalence between different formulations.

AUTHORS' CONCLUSIONS

The conclusions have not changed for this update. The effectiveness of oral morphine has stood the test of time, but the randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Only a few reported how many people had good pain relief, but where it was reported, over 90% had no worse than mild pain within a reasonably short time period. The review demonstrates the wide dose range of morphine used in studies, and that a small percentage of participants are unable to tolerate oral morphine. The review also shows the wide range of study designs, and inconsistency in cross-over designs. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in cross-over design studies. It was not clear if these trials were sufficiently powered to detect any clinical differences between formulations or comparator drugs. New studies added to the review for the previous update reinforced the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence that oral morphine has much the same efficacy as other available opioids.

Alternative routes to oral opioid administration in palliative care: a review and clinical summary

OBJECTIVE

A major goal of palliative care is to provide comfort, and pain is one of the most common causes of treatable suffering in patients with advanced disease. Opioids are indispensable for pain management in palliative care and can usually be provided by the oral route, which is safe, effective, and of lowest cost in most cases. As patients near the end of life, however, the need for alternate routes of medication increases with up to 70% of patients requiring a nonoral route for opioid administration. In order to optimize patient care, it is imperative that clinicians understand existing available options of opioid administration and their respective advantages and disadvantages.

METHODS

We performed a literature review to describe the most commonly used and available routes that can substitute for oral opioid therapy and to provide a summary of factors affecting choice of opioid for use in palliative care in terms of benefits, indications, cautions, and general considerations.

RESULTS

Clinical circumstances will largely dictate appropriateness of the route selected. When the oral route is unavailable, subcutaneous, intravenous, and enteral routes are preferred in the palliative care population. The evidence supporting sublingual, buccal, rectal, and transdermal gel routes is mixed.

CONCLUSIONS

This review is not designed to be a critical appraisal of the quality of current evidence; rather, it is a summation of that evidence and of current clinical practices regarding alternate routes of opioid administration. In doing so, the overarching goal of this review is to support more informed clinical decision making.

Impact of morphine, fentanyl, oxycodone or codeine on patient consciousness, appetite and thirst when used to treat cancer pain

BACKGROUND

There is increasing focus on providing high quality care for people at the end of life, irrespective of disease or cause, and in all settings. In the last ten years the use of care pathways to aid those treating patients at the end of life has become common worldwide. The use of the Liverpool Care Pathway in the UK has been criticised. In England the LCP was the subject of an independent review, commissioned by a Health Minister. The Neuberger Review acknowledged that the LCP was based on the sound ethical principles that provide the basis of good quality care for patients and families when implemented properly. It also found that the LCP often was not implemented properly, and had instead become a barrier to good care; it made over 40 recommendations, including education and training, research and development, access to specialist palliative care services, and the need to ensure care and compassion for all dying patients. In July 2013, the Department of Health released a statement that stated the use of the LCP should be "phased out over the next 6-12 months and replaced with an individual approach to end of life care for each patient".The impact of opioids was a particular concern because of their potential influence on consciousness, appetite and thirst in people near the end of life. There was concern that impaired patient consciousness may lead to an earlier death, and that effects of opioids on appetite and thirst may result in unnecessary suffering. This rapid review, commissioned by the National Institute for Health Research, used standard Cochrane methodology to examine adverse effects of morphine, fentanyl, oxycodone, and codeine in cancer pain studies as a close approximation to possible effects in the dying patient.

OBJECTIVES

To determine the impact of opioid treatment on patient consciousness, appetite and thirst in randomised controlled trials of morphine, fentanyl, oxycodone or codeine for treating cancer pain.

SEARCH METHODS

We assessed adverse event data reported in studies included in current Cochrane reviews of opioids for cancer pain: specifically morphine, fentanyl, oxycodone, and codeine.

SELECTION CRITERIA

We included randomised studies using multiple doses of four opioid drugs (morphine, fentanyl, oxycodone, and codeine) in cancer pain. These were taken from four existing or ongoing Cochrane reviews. Participants were adults aged 18 and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted adverse event data, and examined issues of study quality. The primary outcomes sought were numbers of participants experiencing adverse events of reduced consciousness, appetite, and thirst. Secondary outcomes were possible surrogate measures of the primary outcomes: delirium, dizziness, hallucinations, mood change and somnolence relating to patient consciousness, and nausea, vomiting, constipation, diarrhoea, dyspepsia, dysphagia, anorexia, asthenia, dehydration, or dry mouth relating to appetite or thirst.Comparative measures of harm were known to be unlikely, and we therefore calculated the proportion of participants experiencing each of the adverse events of interest with each opioid, and for all four opioid drugs combined.

MAIN RESULTS

We included 77 studies with 5619 randomised participants. There was potential bias in most studies, with small size being the most common; individual treatment groups had fewer than 50 participants in 60 studies. Participants were relatively young, with mean age in the studies typically between 50 and 70 years. Multiple major problems with adverse event reporting were found, including failing to report adverse events in all participants who received medication, all adverse events experienced, how adverse events were collected, and not defining adverse event terminology or whether a reporting system was used.Direct measures of patient consciousness, patient appetite, or thirst were not apparent. For opioids used to treat cancer pain adverse event incidence rates were 25% for constipation, 23% for somnolence, 21% for nausea, 17% for dry mouth, and 13% for vomiting, anorexia, and dizziness. Asthenia, diarrhoea, insomnia, mood change, hallucinations and dehydration occurred at incidence rates of 5% and below.

AUTHORS' CONCLUSIONS

We found no direct evidence that opioids affected patient consciousness, appetite or thirst when used to treat cancer pain. However, somnolence, dry mouth, and anorexia were common adverse events in people with cancer pain treated with morphine, fentanyl, oxycodone, or codeine.We are aware that there is an important literature concerning the problems that exist with adverse event measurement, reporting, and attribution. Together with the known complications concerning concomitant medication, data collection and reporting, and nomenclature, this means that these adverse events cannot always be attributed unequivocally to the use of opioids, and so they provide only a broad picture of adverse events with opioids in cancer pain. The research agenda includes developing definitions for adverse events that have a spectrum of severity or importance, and the development of appropriate measurement tools for recording such events to aid clinical practice and clinical research.

Oral morphine for cancer pain

BACKGROUND

This is the second updated version of a Cochrane review first published in Issue 4, 2003 of The Cochrane Library and first updated in 2007. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain, and assess the incidence and severity of adverse effects.

SEARCH METHODS

We searched the following databases: Cochrane Pain, Palliative and Supportive Care Group Trials Register (June 2013); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 5, May); MEDLINE (1966 to June 2013); and EMBASE (1974 to June 2013).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) using placebo or active comparators reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Trials with fewer than ten participants were excluded.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which were checked by another review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNTs) for the analgesic effect. We extracted any available data on the number or proportion of participants with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales).

MAIN RESULTS

Ten new studies (638 participants) were identified for this update, bringing the total of included studies to 62, with 4241 participants. Thirty-six studies used a cross-over design ranging from one to 15 days, with the greatest number (11) for seven days for each arm of the trial.Fifteen studies compared oral morphine modified release (Mm/r) preparations with morphine immediate release (MIR). Fourteen studies compared Mm/r in different strengths; six of these included 24-hour modified release products. Fifteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Three studies compared MIR with MIR by a different route of administration. Two studies compared Mm/r with Mm/r at different times and two compared MIR with MIR given at a different time. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine.In this update a standard of 'no worse than mild pain' was set equivalent to a score of 30/100 mm or less on a visual analogue pain intensity scale (VAS), or the equivalent in other pain scales. Eighteen studies achieved this level of pain relief on average, and no study reported that good levels of pain relief were not attained. Where results were reported for individual participants in 17 studies, 'no worse than mild pain' was achieved by 96% of participants (362/377), and an outcome equivalent to treatment success in 63% (400/638).Morphine is an effective analgesic for cancer pain. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12- or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration was undertaken with both instant release and modified release products. A small number of participants did not achieve adequate analgesia with morphine. Adverse effects were common and approximately 6% of participants discontinued treatment because of intolerable adverse effects.

AUTHORS' CONCLUSIONS

The effectiveness of oral morphine has stood the test of time, but the randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Only a few reported how many people had good pain relief, but where it was reported, over 90% had no worse than mild pain within a reasonably short time period. The review demonstrates the wide dose range of morphine used in studies, and that a small percentage of participants are unable to tolerate oral morphine. The review also shows the wide range of study designs, and inconsistency in cross-over designs. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in cross-over design studies. It was not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs. New studies added to the review reinforce the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence that oral morphine has much the same efficacy as other available opioids.

A Comparative Study of 2 Sustained-Release Morphine Preparations for Pain in Advanced Cancer

Purpose: Several sustained-release morphine (SRM) formulations are available internationally. This study compared 2 such products available in the United States, SR1 and SR2.

Patients and Methods: In an open-label study, patients with advanced cancer pain were randomized to receive SR1 or SR2 every 12 hours around-the-clock (ATC) for 5 days, with immediate release (IR) liquid morphine for rescue dosing (RD). Efficacy, safety, and patient acceptability were determined.

Results: A total of 32 patients were evaluable for efficacy and toxicity. Pain scores, RD dosage, RD frequency over 5 days, RD within 3 hours before and after the scheduled SRM, and 8 of the 11 evaluated side effects were higher in the SR1 group. At presumed morphine steady state (day 3), pain scores (P = .05), RD dosage (P = .07), RD frequency (P = .07), and number of RD ±3 hours from scheduled SRM dose (P = .05) were consistently greater in the SR1 group (despite a higher median morphine dose in that group). There was a clinically important and directionally consistent trend that favored SR2, although not all were statistically significant. Patient preference favored SR2 (P < .05). Neither group had difficulty swallowing SR1 or SR2.

Conclusions: This is the first study that directly compared two 12-hour SRM formulations. The data suggested, by multiple clinically important measures, that SR2 may provide superior analgesic efficacy and less toxicity compared to SR1. It also supports the concept that it cannot be assumed that different SR formulations of a given opioid are clinically equivalent. A larger study is needed to confirm our findings.

Opioids and the management of chronic severe pain in the elderly: consensus statement of an International Expert Panel with focus on the six clinically most often used World Health Organization Step III opioids (buprenorphine, fentanyl, hydromorphone, methadone, morphine, oxycodone)

SUMMARY OF CONSENSUS: 1. The use of opioids in cancer pain: The criteria for selecting analgesics for pain treatment in the elderly include, but are not limited to, overall efficacy, overall side-effect profile, onset of action, drug interactions, abuse potential, and practical issues, such as cost and availability of the drug, as well as the severity and type of pain (nociceptive, acute/chronic, etc.). At any given time, the order of choice in the decision-making process can change. This consensus is based on evidence-based literature (extended data are not included and chronic, extended-release opioids are not covered). There are various driving factors relating to prescribing medication, including availability of the compound and cost, which may, at times, be the main driving factor. The transdermal formulation of buprenorphine is available in most European countries, particularly those with high opioid usage, with the exception of France; however, the availability of the sublingual formulation of buprenorphine in Europe is limited, as it is marketed in only a few countries, including Germany and Belgium. The opioid patch is experimental at present in U.S.A. and the sublingual formulation has dispensing restrictions, therefore, its use is limited. It is evident that the population pyramid is upturned. Globally, there is going to be an older population that needs to be cared for in the future. This older population has expectations in life, in that a retiree is no longer an individual who decreases their lifestyle activities. The "baby-boomers" in their 60s and 70s are "baby zoomers"; they want to have a functional active lifestyle. They are willing to make trade-offs regarding treatment choices and understand that they may experience pain, providing that can have increased quality of life and functionality. Therefore, comorbidities--including cancer and noncancer pain, osteoarthritis, rheumatoid arthritis, and postherpetic neuralgia--and patient functional status need to be taken carefully into account when addressing pain in the elderly. World Health Organization step III opioids are the mainstay of pain treatment for cancer patients and morphine has been the most commonly used for decades. In general, high level evidence data (Ib or IIb) exist, although many studies have included only few patients. Based on these studies, all opioids are considered effective in cancer pain management (although parts of cancer pain are not or only partially opioid sensitive), but no well-designed specific studies in the elderly cancer patient are available. Of the 2 opioids that are available in transdermal formulation--fentanyl and buprenorphine--fentanyl is the most investigated, but based on the published data both seem to be effective, with low toxicity and good tolerability profiles, especially at low doses. 2. The use of opioids in noncancer-related pain: Evidence is growing that opioids are efficacious in noncancer pain (treatment data mostly level Ib or IIb), but need individual dose titration and consideration of the respective tolerability profiles. Again no specific studies in the elderly have been performed, but it can be concluded that opioids have shown efficacy in noncancer pain, which is often due to diseases typical for an elderly population. When it is not clear which drugs and which regimes are superior in terms of maintaining analgesic efficacy, the appropriate drug should be chosen based on safety and tolerability considerations. Evidence-based medicine, which has been incorporated into best clinical practice guidelines, should serve as a foundation for the decision-making processes in patient care; however, in practice, the art of medicine is realized when we individualize care to the patient. This strikes a balance between the evidence-based medicine and anecdotal experience. Factual recommendations and expert opinion both have a value when applying guidelines in clinical practice. 3. The use of opioids in neuropathic pain: The role of opioids in neuropathic pain has been under debate in the past but is nowadays more and more accepted; however, higher opioid doses are often needed for neuropathic pain than for nociceptive pain. Most of the treatment data are level II or III, and suggest that incorporation of opioids earlier on might be beneficial. Buprenorphine shows a distinct benefit in improving neuropathic pain symptoms, which is considered a result of its specific pharmacological profile. 4. The use of opioids in elderly patients with impaired hepatic and renal function: Functional impairment of excretory organs is common in the elderly, especially with respect to renal function. For all opioids except buprenorphine, half-life of the active drug and metabolites is increased in the elderly and in patients with renal dysfunction. It is, therefore, recommended that--except for buprenorphine--doses be reduced, a longer time interval be used between doses, and creatinine clearance be monitored. Thus, buprenorphine appears to be the top-line choice for opioid treatment in the elderly. 5. Opioids and respiratory depression: Respiratory depression is a significant threat for opioid-treated patients with underlying pulmonary condition or receiving concomitant central nervous system (CNS) drugs associated with hypoventilation. Not all opioids show equal effects on respiratory depression: buprenorphine is the only opioid demonstrating a ceiling for respiratory depression when used without other CNS depressants. The different features of opioids regarding respiratory effects should be considered when treating patients at risk for respiratory problems, therefore careful dosing must be maintained. 6. Opioids and immunosuppression: Age is related to a gradual decline in the immune system: immunosenescence, which is associated with increased morbidity and mortality from infectious diseases, autoimmune diseases, and cancer, and decreased efficacy of immunotherapy, such as vaccination. The clinical relevance of the immunosuppressant effects of opioids in the elderly is not fully understood, and pain itself may also cause immunosuppression. Providing adequate analgesia can be achieved without significant adverse events, opioids with minimal immunosuppressive characteristics should be used in the elderly. The immunosuppressive effects of most opioids are poorly described and this is one of the problems in assessing true effect of the opioid spectrum, but there is some indication that higher doses of opioids correlate with increased immunosuppressant effects. Taking into consideration all the very limited available evidence from preclinical and clinical work, buprenorphine can be recommended, while morphine and fentanyl cannot. 7. Safety and tolerability profile of opioids: The adverse event profile varies greatly between opioids. As the consequences of adverse events in the elderly can be serious, agents should be used that have a good tolerability profile (especially regarding CNS and gastrointestinal effects) and that are as safe as possible in overdose especially regarding effects on respiration. Slow dose titration helps to reduce the incidence of typical initial adverse events such as nausea and vomiting. Sustained release preparations, including transdermal formulations, increase patient compliance.

Oral morphine for cancer pain

BACKGROUND

This is an updated version of a previous Cochrane review first published in Issue 4, 2003 of The Cochrane Library. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain and to assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The following databases were searched: Cochrane Pain, Palliative and Supportive Care Group Trials Register (December 2006); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4); MEDLINE (1966 to December 2006); and EMBASE (1974 to December 2006).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Any comparator trials were considered. Trials with fewer than ten participants were excluded.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which was checked by the other review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers-needed-to-treat (NNT) for the analgesic effect.

MAIN RESULTS

In this update, nine new studies with 688 participants were added. Fifty-four studies (3749 participants) met the inclusion criteria. Fifteen studies compared oral modified release morphine (Mm/r) preparations with immediate release morphine (MIR). Twelve studies compared Mm/r in different strengths, five of these included 24-hour modified release products. Thirteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Two studies compared MIR with MIR by a different route of administration. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine. Morphine was shown to be an effective analgesic. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12 or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration were undertaken with both instant release and modified release products. Adverse effects were common but only 4% of patients discontinued treatment because of intolerable adverse effects.

AUTHORS' CONCLUSIONS

The randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in crossover design studies. It was not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs. Studies added to the review reinforce the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence for effectiveness of oral morphine which compares well to other available opioids. There is limited evidence to suggest that transmucosal fentanyl provides more rapid pain relief for breakthrough pain compared to morphine.

Oral morphine for cancer pain

BACKGROUND

Morphine has been used to relieve pain for many years. Oral morphine in either immediate release or sustained release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain. To assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The following databases were searched: The Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 4, 2002; the trials register of the Cochrane Pain, Palliative and Supportive Care group (February 2002); MEDLINE 1966 to December 2002; EMBASE 1988 to December 2002; and the Oxford Pain Relief database 1950 to 1994.

SELECTION CRITERIA

Published randomised controlled trials (full reports) reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Any comparator trials were considered. Trials with fewer than 10 subjects were excluded.

DATA COLLECTION AND ANALYSIS

One reviewer extracted data, and the findings were checked by two other reviewers. There were insufficient comparable data for meta-analysis to be undertaken, or to produce numbers-needed-to-treat (NNT) for the analgesic effect.

MAIN RESULTS

Forty five studies (3061 subjects) met the inclusion criteria. Fourteen studies compared oral sustained release morphine (MSR) preparations with immediate release morphine (MIR). Eight studies compared MSR and MSR in different strengths. Nine studies compared MSR with other opioids. Five studies compared MIR with other opioids. Two studies compared oral MSR with rectal MSR. One study was found comparing each of the following: MSR tablet with MSR suspension; MSR with MSR at different dose frequencies; MSR with non-opioids; MIR with non-opioids; oral morphine with epidural morphine; and MIR with MIR by a different route of administration. Morphine was shown to be an effective analgesic. Pain relief did not differ between MSR and MIR. Sustained release versions of morphine were effective for 12 or 24 hour dosing depending on the formulation. Adverse effects were common but only 4% of patients discontinued treatment because of intolerable adverse effects.

REVIEWER'S CONCLUSIONS

The randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants, and did not provide appropriate data for meta-analysis. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing subjects over in crossover design studies. It is not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs.

Managing pain and psychological issues in palliative care

The management of psychological issues and pain in dying patients have steadily improved. With currently available drugs and techniques, it should be possible for nearly all women with terminal gynaecological cancer to be pain-free. The World Health Organization (WHO) Analgesic Ladder can be effectively utilized for pharmacological treatment of cancer pain. Most side-effects of opioid therapy can be well controlled. Patients whose pain cannot be adequately relieved by systemic opioid therapy may benefit from invasive anaesthetic or neurosurgical techniques. Terminal sedation should be used only after all other therapy has failed. This chapter describes the assessment and management of opioid analgesics and the treatment of their side-effects. Adjuvant analgesic drugs and therapies are also presented.

Bedside perspectives on the use of opioids: transferring results of clinical research into practice

1. Transference of research findings to clinical practice has been a challenge for those managing chronic pain. Generally, pain is not well controlled in hospitals and steps need to be taken to make pain control more effective. 2. Clinical trials of opioids have shown that pain can be controlled in the great majority of patients. Apart from the use of the World Health Organization Analgesic Ladder, a 'pain diagnosis' should be made and a comprehensive view of pain needs to be considered by the clinician. This would include pain and other physical symptoms, psychological issues and social and spiritual stresses. 3. Respiratory depression and tolerance for opioids are often seen as negative aspects of opioids and, therefore, may lead to inadequate control of pain. The evidence cited suggests that, in the long-term treatment of cancer pain, respiratory depression almost never occurs. The only situation that warrants caution is when an anaesthetic block or similar procedure relieves pain treated by opioids, when that patient has been receiving large doses of opioids. Long-term studies with opioids show that tolerance may occur, but is not a clinical problem and should not impair their use in adequate doses to relieve the patient's pain. 4. The active morphine metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) do need to be considered when administering morphine. There seems to be considerable interindividual variation in the production and elimination of metabolites. In cases of renal failure or in the elderly, the ratios of M3G and M6G to morphine accumulate exponentially, making opioid toxicity more likely. Even different routes of administration seem to be associated with different ratios of metabolites. A knowledge of these sources of pharmacokinetic variability may lead to more effective use of the opioids in clinical practice.

The influence of the route of administration: a comparative study at steady state of oral sustained release morphine and morphine sulfate suppositories

Steady state pharmacokinetics of morphine (M), morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) were investigated in 6 patients with intractable cancer pain administered orally with MST (Mundipharma, Limburg, Germany) and, subsequently, rectally with MSR to make a judgment whether orally administered morphine can be replaced by rectally administered morphine. The parent drug and glucuronide metabolites were measured simultaneously using high-performance liquid chromatography (HPLC) and native fluorescence detection. The mean morphine area under the curve (AUC) value (0-8 h) was smaller (434.3 +/- 170.2 nmolL(-1)h) in the oral administration than in the rectal administration (574.8 +/- 285.0 nmolL(-1)h) (p < 0.05). The rectal administration resulted in less production of M3G and M6G. There were no significant differences in the mean steady state concentrations (C(ss)) of morphine, M3G, and M6G between the oral and rectal administrations (p > 0.05). The median AUC ratio--M3G/M and M6G/M, 12.58 and 1.85--following MSR rectal administration was smaller than following MST oral administration in 6 patients (19.97 and 2.59; p < 0.05), whereas the median AUC ratio M3G/M6G in the rectal dosing was 6.24 (range 5.2-7.6) was almost the same as the median ratio M3G/M6G in the oral dosing was 6.49 (range 5.8-8.5; p > 0.1). Four of the 6 patients had a greater Cmax of M3G and M6G after oral administration than after rectal administration. The same 4 had lower fluctuation rates for morphine, M3G (p < 0.05), and M6G (p < 0.05) after rectal administration. Therefore, during chronic morphine treatment, it still seems difficult to decide whether oral administration can be replaced by rectal administration.

Long-term effects of continuous intrathecal opioid treatment in chronic pain of nonmalignant etiology

In the present retrospective investigation, the long-term effects of continuous intrathecal opioid therapy via implantable infusion pump systems were examined in 120 patients with chronic, nonmalignant pain syndromes. The follow-up period was 6 months to 5.7 years (mean 3.4 years +/- 1.3 standard error of the mean). Deafferentation pain and neuropathic pain showed the best long-term results, with 68% and 62% pain reduction (visual analog scale), respectively. The mean morphine dosage initially administered was 2.7 mg/day (range 0.3-12 mg/day); after an average of 3.4 years, it was 4.7 mg/day (range 0.3-12 mg/day). In a long-term observation of 28 patients who received intrathecal morphine for longer than 4 years. 18 patients (64.3%) had a constant dosage history and 10 patients (35.7%) showed an increase in morphine dosage to more than 6 mg/day 1 year after dosage determination. In seven cases, a tolerance developed: in four patients the tolerance was controlled by means of "drug holidays"; but in three patients it was necessary to remove the pump systems. Explantation of the pump system occurred in 22 additional cases for other reasons. Throughout the follow-up period, 74.2% of the patients profited from the intrathecal opiate therapy: the average pain reduction after 6 months was 67.4% and, as of the last follow-up examination, it was 58.1%. Ninety-two percent of the patients were satisfied with the therapy and 81% reported an improvement in their quality of life. The authors' 6-year experience with administration of intrathecal opioid medications for nonmalignant pain should encourage the use of this method in carefully selected patients.

Practical use of rectal medications in palliative care

The rectal route of drug administration is an efficient and economical method for pharmacologic intervention in the terminally ill patient for whom the oral route is precluded. This review first describes the physiology and general considerations surrounding rectal drug administration, then evaluates the literature pertaining to analgesic and adjuvant medications and dosage forms that are and are not approved for rectal administration by the U.S. Food and Drug Administration. A paucity of studies deal with rectal administration in terminally ill patients, and data have been gathered from pharmacokinetic studies or studies in which the drugs were used for other indications. Where plausible, practical clinical recommendations for the rectal use of opioids, nonopioid analgesics, anxiolytics, and other adjuvants are formulated.

Rectal controlled-release morphine: plasma levels of morphine and its metabolites following the rectal administration of MST Continus 100 mg

Eight patients undergoing major maxillary surgery were given sustained-release morphine (100 mg MST Continus) rectally, immediately after induction of general anaesthesia. Blood samples for assay were taken just prior to morphine administration, together with a further 11 samples over the following 24 h. Assay of the plasma for morphine, morphine-3-glucuronide and morphine-6-glucuronide was carried out using a validated high-performance liquid chromatography technique. Morphine Tmax ranged from 3 h to 12 h (median 6 h), Cmax 8.0-40.0 ng/ml and AUC0-24 90.1-429.7 ng/h/ml in subjects offering blood samples over the 24-h period. Likewise, morphine-3-glucuronide Tmax ranged from 3 h to 24 h (median 9 h), Cmax 153-370 ng/ml and AUC0-24 2776-4390 ng/h/ml. Morphine-6-glucuronide Tmax ranged from 8 h to 12 h (median 10 h), Cmax 24-59 ng/ml and AUC0-24 137-803 ng/h/ml. Morphine and morphine metabolite AUC0-24 ratios were calculated, but they did not correlate with analgesic needs. The AUC0-24 ratios were similar to those following oral and rectal dosing in other studies involving cancer patients. The wide variation of individual morphine and metabolite plasma levels, and their AUC ratios indicates considerable interpatient variability in the absorption and metabolism of rectal sustained-release morphine. This large interpatient variation may indicate that it is not suitable for acute pain, because analgesic requirements change much more rapidly than in the chronic pain situation where individual patient titration can take place.