The Pharmacologic Management of Cancer Pain

Impact of Black Race on Peripheral Neuropathy in Patients With Newly Diagnosed Multiple Myeloma Receiving Bortezomib Induction

PURPOSE

The incidence of multiple myeloma (MM) is two to three times higher in Black patients compared with other races, making it the most common hematologic malignancy in this patient population. Current treatment guidelines recommend the combination of a proteasome inhibitor, an immunomodulatory agent, and a corticosteroid as preferred induction therapy. Bortezomib use comes with the risk of peripheral neuropathy (PN) and potential need for dose reduction, therapy interruption, and additional supportive medications. Known risk factors for bortezomib-induced peripheral neuropathy (BIPN) include diabetes mellitus, previous thalidomide, advanced age, and obesity. We aimed to determine the potential association between Black race and incidence of BIPN.

PATIENTS AND METHODS

We identified a cohort of 748 patients with newly diagnosed MM who received induction with bortezomib, lenalidomide, and dexamethasone from 2007 to 2016. One hundred forty Black patients were matched with 140 non-Black patients on age, sex, BMI, and route of bortezomib administration. Incidence of BIPN was a binary event defined as new use of a neuropathy medication, bortezomib dose reduction, dose omission, or discontinuation because of PN.

RESULTS

The incidence of BIPN was higher in Black patients (46%) compared with non-Black patients (34%; P = .05) in both univariate (odds ratio [OR], 1.61; 95% CI, 1.00 to 2.61; P = .052) and multivariable analyses (OR, 1.64; 95% CI, 1.01 to 2.67; P = .047). No significant differences in BIPN were seen when stratified by route of administration.

CONCLUSION

These data indicate that Black race is an independent risk factor for the development of BIPN. Additional prevention strategies, close monitoring, and appropriate supportive care measures are warranted for these patients.

Opioid Use at End-Of-Life Among Nova Scotia Patients With Cancer

Purpose: To determine the factors associated with opioid analgesic prescriptions as measured by community pharmacy dispensations to all Nova Scotia (NS) patients with cancer at end-of-life from 2005 to 2009.

Methods: The NS Cancer Registry and the NS Prescription Monitoring Program (NSPMP) were used to link Nova Scotians who had a cancer diagnosis and received a prescription for opioids in their last year of life (n = 6,186) from 2005 to 2009. The association of factors with opioid dispensations at end-of-life were determined (e.g., patient demographics, type of prescriber, type of cancer, and opioid type, formulation, and dose).

Results: Almost 54% (n = 6,186) of the end-of-life study population with cancer (n = 11,498) was linked to the NSPMP and therefore dispensed opioids. Most prescriptions were written by general practitioners (89%) and were for strong opioids (81%). Immediate-release formulations were more common than modified-release formulations. Although the annual average parenteral morphine equivalents (MEQ) did not change during the study period, the number of opioid prescriptions per patient per year increased from 5.9 in 2006 to 7.0 in 2009 (p < 0.0001). Patients age 80 and over received the fewest prescriptions (mean 3.9/year) and the lowest opioid doses (17.0 MEQ) while patients aged 40–49 received the most prescriptions (mean 14.5/year) and the highest doses of opioid (80.2 MEQ).

Conclusion: Our study examined opioid analgesic use at end-of-life in patients with cancer for a large real-world population and determined factors, trends and patterns associated with type and dose of opioid dispensed. We provide information regarding how general practitioners prescribe opioid therapy to patients at end-of-life. Our data suggest that at the time of this study, there may have been under-prescribing of opioids to patients with cancer at end-of-life. This information can be used to increase awareness among general practitioners, and to inform recommendations from professional regulatory bodies, to aid in managing pain for cancer patients at end-of-life. Future work could address how opioid prescribing has changed over time, and whether efforts to reduce opioid prescribing in response to the opioid crisis have affected patients with cancer at end-of-life in Nova Scotia.

Changes in Percutaneous Absorption of Fentanyl Patches in Rats Treated with a Sebum-Like Secretion

The percutaneous absorption of a fentanyl (FEN)-patch is affected by various external factors including the volume of sebum secretion, which causes changes in the skin surface environment. In this study, we prepared a lard-based sebum-like secretion (SLS), and applied it to investigate the effect of different skin surface conditions on the drug penetration of a FEN-patch. In vitro work to test drug release using the Franz diffusion cell indicated that drug release was significantly suppressed by treatment with 5% SLS, which is equivalent to the amount of daily human sebum secretion. Conversely, in ex vivo experiments using rat skin, the amount of FEN that accumulated in the skin tissue of the 5% SLS-treated rats was higher in comparison with the non-SLS treated group. Furthermore, in vivo experiments indicated that the plasma FEN concentration in rats treated with the FEN-patch was significantly increased by treatment with 5% SLS. These results suggest that the sebum affected the release, accumulation, and absorption of FEN from the FEN-patch, and the FEN concentration in the blood was reflected by the balance of the suppression of drug release and the enhancement of drug accumulation in the skin with SLS.

Latin-American guidelines for cancer pain management

Cancer is a major public health issue. Poor pain management has devastating consequences that seriously affect quality of life, diminish functionality and place a huge emotional burden on patients and their relatives. A group of Latin American opinion leaders were invited to participate in a meeting to discuss areas associated with cancer pain. The expert panel reviewed the latest literature to draft region-specific guidelines for effective pain management. The guidelines make recommendations on tailoring treatment to the specific type of pain and provide local physicians with the state-of-the art findings in the field. Management should be with pharmacological approaches (nonopioid, adjuvant and opioid analgesics, as well as oncologic therapies and interventional procedures) and nonpharmacological approaches.

Impact of Race/Ethnicity on Pain Management Outcomes in a Community-Based Teaching Hospital Following Inpatient Palliative Care Consultation

Objective

To examine race/ethnicity differences in pain management outcomes following inpatient palliative care consultation.

Methods

We conducted a retrospective study based on data from a community-based teaching hospital in Fresno, CA, USA, from April 2014 to July 2015. One hundred sixty-one patients with life-limiting diagnoses and palliative care pain-related consultations were included. The patients were categorized into four racial groups: Caucasians, African-Americans, Hispanics, and Asians/Others. Demographics and baseline pain scores using the Visual Analogue Scale (VAS) were obtained. The outcome measures included the length of stay, time to consult, and pain scores at admission, 24 hours before the consultation, 24–48 hours after consultation, and at discharge.

Results

The initial median pain scores were not significantly different between the groups, however, the Asians had slightly higher pain scores compared to the other groups. African-Americans, Caucasians, and Hispanics had significant differences in pain outcomes after consultation compared to 24 hours prior to consultation (p = 0.01, p < 0.01 and p = 0.02, respectively). Caucasians and Hispanics had significant differences in pain outcomes after palliative consultation compared to initial admission assessment (p < 0.01). The differences between discharge and admission pain scores were significant only for Asians, Caucasians, and Hispanics (p = 0.04, p < 0.01, p < 0.01, respectively) but not African-Americans. There were no significant pain score differences across the racial groups following consultations.

Conclusion

There were no significant differences in pain reduction amongst the racial groups, suggesting that pain can adequately be managed in individual racial groups after inpatient palliative care consultations.

Oral tapentadol for cancer pain

BACKGROUND

A large proportion of people with advanced cancer will experience moderate to severe pain. Tapentadol is a novel, centrally acting analgesic medicine acting at the μ-opioid receptor and inhibiting noradrenaline reuptake. The efficacy of tapentadol is stated to be comparable to morphine and oxycodone.

OBJECTIVES

To assess the analgesic efficacy of tapentadol for the relief of cancer pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE from January 2005 to July 2015, together with reference lists of retrieved papers and review articles, and two clinical trial registries. Searches started from 2005 because this covered the period during which clinical trials were conducted. We contacted the manufacturer of tapentadol in the UK to find additional trials not identified by electronic searches. We did not restrict searches by language.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of tapentadol compared with placebo or active controls in adults with moderate to severe cancer pain. Pain had to be measured using a validated assessment tool, and studies had to include at least 10 participants per treatment arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data using a standard form and assessed risk of bias. We extracted available data on study design, participant details, interventions, and outcomes, including analgesic outcome measures, withdrawals, and adverse events.

MAIN RESULTS

We included four studies with 1029 participants. All the studies used a parallel-group design, and included an initial titration phase to determine the maximum effective and tolerated dose, followed by a maintenance phase. Tapentadol medication was taken twice daily and doses ranged from 50 to 500 mg per day. Rescue medication (morphine or oxycodone immediate-release) was available to participants in all studies.Overall, 440 participants were randomised in classically designed RCTs, and 589 participants were enrolled in enriched-enrolment, randomised-withdrawal (EERW) trials. A total of 476 participants were randomised to titration with tapentadol and 338 participants took tapentadol throughout the maintenance phase of their trial.All studies used numerical rating scores, Patient Global Impression of Change scores, and use of rescue medication as measures of efficacy, and all reported on adverse events and withdrawals.All studies enrolled fewer than 200 participants per treatment arm and were therefore at risk of overestimating efficacy. One study was terminated early due to problems with supply of rescue medication, with fewer than 20 participants enrolled per treatment arm in the maintenance phase of the trial. We judged another study at high risk of bias due to an open-label design.There were insufficient data for pooling and statistical analysis. Response rates for pain intensity were comparable across treatment groups in each study. In one EERW study, response rates were high across both treatment and placebo arms during the maintenance phase (62% tapentadol, 69% morphine, 50% placebo). For pain relief, tapentadol is no more and no less effective than oxycodone or morphine (low quality evidence).Treatment emergent adverse event rates were high, approximately 50% to 90%. The most common adverse events were gastrointestinal (nausea, vomiting, constipation) (low quality evidence). There was no advantage of tapentadol over morphine or oxycodone in terms of serious adverse events. The number of people experiencing effects on consciousness, appetite, or thirst was low.

AUTHORS' CONCLUSIONS

Information from RCTs on the effectiveness and tolerability of tapentadol was limited. The available studies were of moderate or small size and used different designs, which prevented pooling of data. Pain relief and adverse events were comparable between the tapentadol and morphine and oxycodone groups.

Meta-analysis of oral Chinese herbal medicine as an adjuvant treatment in relieving pain secondary to bone metastases

OBJECTIVE

To assess the effectiveness of oral Chinese herbal medicine (CHM) in relieving pain secondary to bone metastases in patients.

METHODS

The searched electronic literature databases included both English and Chinese articles published in the MEDLINE, EMBASE, Wanfang database and China National Knowledge Infrastructure (up to December 2012). The studies included randomized controlled trials (RCTs) comparing CHM plus conventional treatment with conventional treatment alone for patients with pain secondary to bone metastases. The outcomes were the odds ratio (OR) with 95% confidence intervals (CI) for the pain-relief rate and adverse events.

RESULTS

A total of 16 RCTs involving 1,008 patients were identified and analyzed. All of the included RCTs were associated with a moderate to high risk of bias. In the metaanalysis, CHM plus conventional treatment increased the pain-relief rate compared with the conventional treatment alone (OR, 2.59; 95% CI 1.95 to 3.45). In subgroup analysis, the pooled OR of the pain-relief rate of CHM plus conventional treatment compared with conventional treatment was 3.11 (95% CI 2.01 to 4.79) for CHM plus bisphosphonates, 2.24 (95% CI 1.33 to 3.78) for CHM plus analgesics, 2.28 (95% CI 1.09 to 4.79) for CHM plus radiotherapy, and 2.22 (95% CI 0.95 to 5.15) for CHM plus analgesics and bisphosphonates. The adverse events included nausea, vomiting, dizziness, fever, and constipation. No serious adverse events were reported in any of the included studies.

CONCLUSIONS

CHM interventions appear to have beneficial effects on pain secondary to bone metastases in patients. However, published efficacy trials are small in size to draw any firm conclusions.

Transdermal fentanyl for cancer pain

BACKGROUND

Opioid drugs have been used for many years to relieve pain. Transdermal fentanyl offers one option for delivering and maintaining pain relief in patients with moderate or severe cancer pain.

OBJECTIVES

To determine the analgesic efficacy of transdermal fentanyl for relief of cancer pain, and to assess the adverse events associated with the use of transdermal fentanyl for relief of cancer pain.

SEARCH METHODS

The following databases were searched: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 4 of 12); MEDLINE (1966 to May 2013); EMBASE (1974 to May 2013; CANCERLIT (PubMED) (November 2012); and ClinicalTrials.gov (May 2013).

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two review authors. We extracted any available data on the number or proportion of patients with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales), together with information about adverse events and withdrawals.

MAIN RESULTS

We identified nine studies meeting the inclusion criteria, including a Turkish study that is awaiting formal translation. There were 1244 participants randomised in classically designed RCTs, of whom 1197 had evaluable data, and 138 patients enrolled in an enriched enrolment, randomised withdrawal (EERW) trial. Overall, 600 participants were treated with transdermal fentanyl patches, 382 with various formulations of morphine, 36 with methadone, and 221 with paracetamol plus codeine. There were major sources of potential bias, including lack of blinding, small size, high levels of attrition, and inconsistent reporting.We could not compare data in a meaningful analysis regarding adverse events such as nausea, abdominal pain, gastrointestinal bleeding, and confusion. These events may have been attributable to the underlying disease process.There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNT) for the analgesic effect. In seven studies with 461 participants reporting pain intensity results after about two weeks, the mean or median pain scores were on the borderline of mild and moderate pain. Most participants would have had no worse than mild pain on treatment. Another reported that 77% of participants using transdermal fentanyl had an undefined successful outcome. Fewer participants experienced constipation with transdermal fentanyl (28%) than with oral morphine (46%), giving a risk ratio of 0.61 (95% CI 0.47 to 0.78); the NNT to prevent constipation was 5.5 (95% CI 3.8 to 10).

AUTHORS' CONCLUSIONS

The randomised trial literature for effectiveness of transdermal fentanyl is limited, but it is an important medicine. Most studies recruited fewer than 100 participants and did not provide data appropriate for meta-analysis. Only a few reported how many patients had good pain relief but, where data were reported, a majority had no worse than mild pain within a reasonably short time period. The evidence pointed to a useful and significant reduction in complaints about constipation for transdermal fentanyl compared with oral morphine.

Pathobiology and management of prostate cancer-induced bone pain: recent insights and future treatments

Prostate cancer (PCa) has a high propensity for metastasis to bone. Despite the availability of multiple treatment options for relief of PCa-induced bone pain (PCIBP), satisfactory relief of intractable pain in patients with advanced bony metastases is challenging for the clinicians because currently available analgesic drugs are often limited by poor efficacy and/or dose-limiting side effects. Rodent models developed in the past decade show that the pathobiology of PCIBP comprises elements of inflammatory, neuropathic and ischemic pain arising from ectopic sprouting and sensitization of sensory nerve fibres within PCa-invaded bones. In addition, at the cellular level, PCIBP is underpinned by dynamic cross talk between metastatic PCa cells, cellular components of the bone matrix, factors associated with the bone microenvironment as well as peripheral components of the somatosensory system. These insights are aligned with the clinical management of PCIBP involving use of a multimodal treatment approach comprising analgesic agents (opioids, NSAIDs), radiotherapy, radioisotopes, cancer chemotherapy agents and bisphosphonates. However, a major drawback of most rodent models of PCIBP is their short-term applicability due to ethical concerns. Thus, it has been difficult to gain insight into the mal(adaptive) neuroplastic changes occurring at multiple levels of the somatosensory system that likely contribute to intractable pain at the advanced stages of metastatic disease. Specifically, the functional responsiveness of noxious circuitry as well as the neurochemical signature of a broad array of pro-hyperalgesic mediators in the dorsal root ganglia and spinal cord of rodent models of PCIBP is relatively poorly characterized. Hence, recent work from our laboratory to develop a protocol for an optimized rat model of PCIBP will enable these knowledge gaps to be addressed as well as identification of novel targets for drug discovery programs aimed at producing new analgesics for the improved relief of intractable PCIBP.

Topical treatment with Tong-Luo-San-Jie gel alleviates bone cancer pain in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The herbal analgesic gel Tong-Luo-San-Jie (TLSJ) and its modifications are used in traditional Chinese medicine to manage cancer pain. However, its mechanisms are still unknown.

AIM OF THE STUDY

To investigate the effects and mechanisms of TLSJ gel on bone cancer pain in a rat model.

MATERIALS AND METHODS

A bone cancer pain rat model was established by inoculating Walker 256 rat carcinoma cells directly into the right tibial medullary cavity of Sprague-Dawley rats (150-170 g); Phosphate buffered saline (PBS) tibial inoculation was used as control. Cancer-bearing rats were treated twice a day with external TLSJ gel (0.5 g/cm(2)/day) or inert gel control for 21 day (n=10/group). Behavioral tests such as mechanical threshold and paw withdrawal latency (PWL) were carried out. Osteoclastic activities were determined and carboxyterminal pyridinoline cross-linked type I collagen telopeptides (ICTP) and bone-specific alkaline phosphatase (BAP) concentrations were detected with ELISA after treatment. Adverse effects were monitored, and biochemical and histological tests were performed in naïve rats treated with local TLSJ gel for six weeks.

RESULTS

TLSJ treatment significantly restored bone cancer-induced decrease of PWL and mechanical threshold compared to inert gel. It also decreased the level of blood serum ICTP and BAP and inhibited osteoclast activities. No adverse effects or abnormal biochemical and histological changes were detected after TLSJ treatment.

CONCLUSION

The present study shows that TLSJ significantly inhibits bone cancer-induced thermal and mechanical sensitization. It suggests that the gel may be useful in managing cancer pain and that it may act by inhibiting osteoclastic activity.

Management of Severe Neuropathic Cancer Pain

Neuropathic cancer pain is common, very disabling and difficult to treat. It can be related to tumor invasion of neural structures and neuronal damage by surgery, chemotherapy and radiation therapy. Adjuvant analgesics are often used with opioids to control neuropathic pain in cancer patients. Methadone, a synthetic opioid with multiple mechanisms of action, is gaining increasing importance as an effective agent in the treatment of cancer related neuropathic pain. This case illustrates the challenges of managing severe pain in a patient with head and neck cancer while undergoing anti-tumor treatment. A review of the adjuvant analgesics and opioids, particularly methadone, in the management of neuropathic pain is also included.

Acupuncture for the treatment of cancer pain: a systematic review of randomised clinical trials

PURPOSE

Controlling cancer-related pain is an important component in the palliative care of cancer patients. The objective of this review was to assess the effectiveness of acupuncture for treating cancer pain.

METHODS

Fourteen databases were searched from their inception through April 2011. Randomised clinical trials (RCTs) were included if acupuncture was used as the sole treatment or as a part of a combination therapy for cancer pain. Studies were included if they were controlled with a placebo or controlled against a drug-therapy or no-treatment group. The Cochrane criteria were used to assess the risk of bias.

RESULTS

A total of 15 RCTs met our inclusion criteria. All of the included RCTs were associated with a high risk of bias. The majority of acupuncture treatments or combination therapies with analgesics exhibited favourable effects compared with conventional treatments in individual studies. However, a meta-analysis suggested that acupuncture did not generate a better effect than drug therapy (n = 886; risk ratio (RR), 1.12; 95% CI 0.98 to 1.28; P = 0.09). The comparison between acupuncture plus drug therapy and drug therapy alone demonstrated a significant difference in favour of the combination therapy (n = 437; RR, 1.36; 95% CI 1.13 to 1.64; P = 0.003). The results of this systematic review provide no strong evidence for the effectiveness of acupuncture in the management of cancer pain.

CONCLUSION

The total number of RCTs included in the analysis and their methodological quality were too low to draw firm conclusions. Future rigorous RCTs will be necessary to assess the clinical efficacy of acupuncture in this area.

Inconsistencies in opioid equianalgesic ratios: clinical and research implications

Cancer pain is common, occurring in up to 60% of patients and opioid conversion may be required for effective pain management. Conversion from one opioid to another can be problematic due to differences in equianalgesic ratios found in established resources. This study explores the implications of using various published equianalgesic ratios when converting to a common opioid unit. This secondary analysis includes 105 advanced cancer patients who reported use of transdermal fentanyl, long-acting oxycodone, or oral methadone. Common clinically used equianalgesic ratios were identified and utilized to calculate a parenteral morphine equivalent for each of the selected agents. When the equianalgesic ratios were applied to each drug, there were substantial differences in the calculated morphine equivalent for transdermal fentanyl (2-fold difference) and methadone (100-fold difference). The calculated difference for oxycodone was lower, with a 1.5-fold difference. This study demonstrates large variability in opioid conversions based on the use of common equianalgesic ratios for transdermal fentanyl, long-acting oxycodone, and methadone. These findings have important clinical and research implications. First, this study substantiates the use of these ratios as only guidelines for treatment. Second, it supports the need for well-designed, rigorous studies to evaluate opioid conversions. Third, this study demonstrates the need for a standard reporting system of opioid equianalgesic ratios employed in clinical trials.

Methadone for Cancer Pain

Pain is one of the most common and incapacitating symptoms experienced by patients with advanced cancer. Methadone is a potent opioid with strong affinity for the µ opioid receptor. In addition to being a potent µ opioid receptor ligand, methadone blocks the N-methyl-D-aspartic acid receptor and modulates neurotransmitters involved in descending pain modulation. These 3 properties enhance analgesic activity. Methadone's lack of active metabolites makes it an attractive option when opioid responsiveness declines and renal insufficiency complicates opioid therapy. A lipophilic opioid, methadone can be given by multiple routes. Clinical trial data show equivalence with morphine as an analgesic in moderate to severe cancer pain. Further investigations are needed to define the role of methadone in the management of breakthrough pain and neuropathic pain and to determine whether it is truly superior to morphine, the gold standard of cancer analgesia.

Bortezomib in the management of multiple myeloma

Multiple myeloma (MM) is a B-cell malignancy characterized by clonal expansion of plasma cells within the bone marrow, the presence of a serum and/or urine monoclonal protein, lytic bone lesions, and anemia. On a cellular level, the disease is characterized by complex interactions between tumor cells and the surrounding bone marrow microenvironment. Understanding of the relationship between malignant plasma cells and the microenvironment has sparked ongoing efforts to develop targeted therapeutic agents for treatment of this disease. The successful development of the first-in-class small-molecule proteasome inhibitor bortezomib occurred as a result of these efforts. This review focuses on the rationale for bortezomib therapy in the treatment of patients with newly diagnosed and relapsed MM, important treatment-related side effects, and future directions for use of bortezomib and other, emerging proteasome inhibitors.

Tramadol and flurbiprofen depress the cytotoxicity of cisplatin via their effects on gap junctions

PURPOSE

Cancer patients are often concurrently treated with analgesics and antineoplastic drugs, yet the influence of analgesic agents on therapeutic activity of antineoplastic drugs is largely unexplored. This study investigates the effects of three commonly used analgesics, which produce analgesia by different mechanisms, on cytotoxicity induced by cisplatin, a widely used antitumor agent, and the relation between those effects and modulation of gap junction function by the analgesics.

EXPERIMENTAL DESIGN

The role of gap junctions in the modulation of cisplatin toxicity is explored by manipulation of connexin expression, and gap junction presence and function, using clinically relevant concentrations of the analgesics and cisplatin.

RESULTS

Short-term exposure of transformed cells to cisplatin reduced the clonogenic survival in low-density cultures (without gap junction formation) and in high density (with gap junction formation), but the toxic effect was greater at high density. In the absence of connexin expression or with block of connexin channels, cell density had no effect on cisplatin toxicity. Tramadol and flurbiprofen, but not morphine, significantly reduced cisplatin cytotoxicity, but this effect required functional gap junctions between the cells. Tramadol and flurbiprofen inhibited dye-coupling through gap junctions, but morphine did not.

CONCLUSIONS

The results suggest that the density dependence of cisplatin toxicity is mediated by gap junctions. They further indicate that tramadol and flurbiprofen depress cisplatin cytotoxicity through inhibition of gap junction activity, and more generally, that agents that depress junctional communication can counteract the effects of antitumor agents.

Clinical challenges associated with bortezomib therapy in multiple myeloma and Waldenströms Macroglobulinemia

Rapid development of the small molecule proteasome inhibitor bortezomib has yielded important clinical benefit for patients with multiple myeloma. Early phase clinical trials suggest the agent has similar efficacy in Waldenströms Macroglobulinemia. Optimization of bortezomib-based therapy, though, requires an understanding of the various challenges associated with use of the drug. This review highlights the rationale for bortezomib therapy in patients with multiple myeloma and Waldenströms Macroglobulinemia, mechanisms of bortezomib resistance, important therapy-related side effects, and new directions for the use of proteasome inhibitors in these disorders.

Prevalence of opioid dispensings and concurrent gastrointestinal medications in Quebec

BACKGROUND

Opioids are frequently prescribed for moderate to severe pain. A side effect of opioid usage is the inhibition of gastrointestinal (GI) motility, known as opioid-induced bowel dysfunction (OBD). OBD is typically treated prophylactically with laxatives and/or acid suppressants.

AIM

The present study describes the prevalence of outpatient opioid dispensing, opioid patient demographics, and concomitant dispensing of opioids and GI medications in the Quebec Public Prescription Drug Insurance Plan in 2005.

METHODS

Using a retrospective cohort design, opioid dispensings were identified using claims and reimbursement data. Laxative and acid suppressant dispensings were also identified. Concurrent use was defined as having at least one 'GI medication-exposed day' overlapping an 'opioid-exposed day'.

RESULTS

More than 11% of the drug plan population was dispensed an opioid in 2005, and dispensings increased with age. Approximately two-thirds of patients who received an opioid were given codeine. Approximately one-third of opioid patients were concomitantly dispensed a GI medication, yet only 2% were dispensed a laxative.

CONCLUSIONS

Although the GI side effects of opioids are well known, these side effects appear to increase with age and duration of opioid use. Opioid-related side effects, particularly OBD, should be effectively managed so as not to lead to the cessation of opioid therapy.

Bortezomib-induced peripheral neuropathy in multiple myeloma: a comprehensive review of the literature

Bortezomib has demonstrated significant activity in clinical trials, mainly against recurrent or newly diagnosed multiple myeloma (MM). Peripheral neuropathy is a significant toxicity of bortezomib, requiring dose modification and potential changes in the treatment plan when it occurs. The mechanism underlying bortezomib-induced peripheral neuropathy (BIPN) is unknown. Metabolic changes resulting from the accumulation of bortezomib in the dorsal root ganglia cells, mitochondrial-mediated disregulation of Ca(++) homeostasis, and disregulation of neurotrophins may contribute to the pathogenesis of BIPN. It is increasingly recognized that BIPN may be a proteasome inhibitor class effect, producing primarily a small fiber and painful, axonal, sensory distal neuropathy. Incidence of BIPN is mainly related to various risk factors, including cumulative dose and evidence of preexisting neuropathy. Assessment of BIPN is based primarily on neurologic clinical examination and neurophysiologic methods. To date, apart from the use of dose reduction and schedule change algorithm, there is no effective treatment with neuroprotective agents for BIPN. Analgesics, tricyclic antidepressants, anticonvulsants, and vitamin supplements have been used as symptomatic treatment against bortezomib-associated neuropathic pain with some success. This review looks critically at the pathogenesis, incidence, risk factors, diagnosis, characteristics, and management of BIPN, and highlights areas for future research.