Opioid utilization and health-care costs among patients with diabetic peripheral neuropathic pain treated with duloxetine vs. other therapies

Duloxetine protects against experimental diabetic retinopathy in mice through retinal GFAP downregulation and modulation of neurotrophic factors

Diabetic retinopathy (DR) is recognized as one of the leading causes of blindness worldwide. Searching and validation for a novel therapeutic strategy to prevent its progress are promising. This work aimed to assess the retinal protective effects of duloxetine (DLX) in Alloxan-induced diabetic mice model. Animals were equally and randomly divided to four groups (eight mice per group); group 1: is the control group, 2: diabetic group, 3&4: diabetic and after 9 weeks received DLX for 4 weeks (15 mg/kg and 30 mg/kg), respectively. Quantitative real-time PCR (qPCR) analysis revealed nerve growth factor (NGF), inducible nitric oxide synthase (iNOS) and transforming growth factor beta (TGF-β) genes upregulation in the diabetic group compared to controls. Also, increased retinal malondialdehyde (MDA) and the decline of reduced glutathione (GSH) levels were observed. The morphometric analysis of diabetic retina revealed a significant reduction in total retinal thickness compared to control. Diabetic retinal immunostaining and Western blot analyses displayed glial fibrillary acidic protein (GFAP) and vascular endothelial cell growth factor (VEGF) proteins expression upregulation as well as glucose transporter-1 (GLUT-1) downregulation comparing to controls. However, DLX-treated groups showed downregulated NGF, iNOS, and TGF-β that was more obviously seen in the DLX-30 mg/kg group than DLX-15 mg/kg group. Furthermore, these groups showed amelioration of the oxidative markers; MDA and GSH, retaining the total retinal thickness nearly to control, GFAP and VEGF downregulation, and GLUT-1 upregulation compared to diabetic group. Taken together, it could be summarized that duloxetine can attenuate DR via the anti-inflammatory and the anti-oxidative properties as well as modulating the angiogenic and the neurotrophic factors expressions. This could hopefully pave the road to be included in the novel list of the therapeutic regimen for DR after validation in the clinic.

Decreased Endomorphin-2 and μ-Opioid Receptor in the Spinal Cord Are Associated with Painful Diabetic Neuropathy

Painful diabetic neuropathy (PDN) is one of the most common complications in the early stage of diabetes mellitus (DM). Endomorphin-2 (EM2) selectively activates the μ-opioid receptor (MOR) and subsequently induces antinociceptive effects in the spinal dorsal horn. However, the effects of EM2-MOR in PDN have not yet been clarified in the spinal dorsal horn. Therefore, we aimed to explore the role of EM2-MOR in the pathogenesis of PDN. The main findings were the following: (1) streptozotocin (STZ)-induced diabetic rats exhibited hyperglycemia, body weight loss and mechanical allodynia; (2) in the spinal dorsal horn, the expression levels of EM2 and MOR decreased in diabetic rats; (3) EM2 protein concentrations decreased in the brain, lumbar spinal cord and cerebrospinal fluid (CSF) in diabetic rats but were unchanged in the plasma; (4) the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) was significantly higher in diabetic rats than in control rats; and (5) intrathecal injection of EM2 for 14 days in the early stage of PDN partially alleviated mechanical allodynia and reduced MOR expression in diabetic rats. Our results demonstrate that the EM2-MOR signal may be involved in the early stage of PDN.

The narcotic bowel syndrome: a recent update

OBJECTIVES

The paradoxical development of chronic abdominal pain is an underrecognized side effect of opioid use. Narcotic bowel syndrome (NBS), occurring in a small proportion of chronic opioid users, consists of chronic or intermittent abdominal pain, which often increases in severity despite continued or escalating dosages of opioids prescribed to relieve pain.

METHODS

A PubMed search was conducted using terms such as "narcotic bowel syndrome" and "opioid hyperalgesia" through January 2014.

RESULTS

Abdominal pain is the defining symptom of NBS and is thought to be mediated by central nervous system dysfunction; it should be distinguished from the peripheral side effects of opioids, such as nausea, bloating, intermittent vomiting, abdominal distension, and constipation. This latter cluster of symptoms is called opioid bowel dysfunction, although it may co-occur with NBS. Hypothesized mechanisms of the central effects of opioids on nociception in NBS include spinal cord inflammation and dysfunction in opioid receptor activity and related neuroanatomical substrates. With continued use, ∼6% of patients taking narcotics chronically will develop NBS, with profound consequences in terms of daily function. The primary management paradigm for NBS is a structured opioid withdrawal program accompanied by centrally acting adjunctive therapy comprising antidepressants, benzodiazepines, and clonidine to target pain, anxiety, and depression, and prevent withdrawal effects, in addition to peripherally acting agents such as laxatives (e.g., osmotic laxatives and chloride channel activators) to control transient constipation. Such structured withdrawal programs have been prospectively evaluated in small clinical trials and have met with considerable success in the short term.

CONCLUSIONS

Because rates of NBS are likely to rise, integrated intensive pharmacotherapy and psychosocial interventions are needed to help patients with NBS go off and stay off opioids. These programs will likely also reduce comorbid psychopathology and lead to adequate pain control and improved quality of life.

A review of the clinical utility of duloxetine in the treatment of diabetic peripheral neuropathic pain

Diabetes mellitus is a world-wide epidemic with many long-term complications, with neuropathy being the most common. In particular, diabetic peripheral neuropathic pain (DPNP), can be one of the most distressing complications associated with diabetes, leading to decreases in physical and mental quality of life. Despite the availability of many efficient medications, DPNP remains a challenge to treat, and the optimal sequencing of pharmacotherapy remains unknown. Currently, there are only three medications approved by the US Food and Drug Administration specifically for the management of DPNP. Duloxetine (DUL), a selective serotonin-norepinephrine reuptake inhibitor, is one of these. With the goal of optimizing pharmacotherapy use in DPNP population, a review of current literature was conducted, and the clinical utility of DUL described. Along with early clinical trials, recently published observational studies and pharmacoeconomic models may be useful in guiding decision making by clinicians and managed care organizations. In real-world practice settings, DUL is associated with decreased or similar opioid utilization, increased medication adherence, and similar health care costs compared with current standard of care. DUL has consistently been found to be a cost-effective option over short time-horizons. Currently, the long-term cost-effectiveness of DUL is unknown. Evidence derived from randomized clinical trials, real-world observations, and economic models support the use of DUL as a first-line treatment option from the perspective of the patient, clinician, and managed care payer.

A retrospective, matched cohort study of potential drug-drug interaction prevalence and opioid utilization in a diabetic peripheral neuropathy population initiated on pregabalin or duloxetine

Background

Anticipating and controlling drug-drug interactions (DDIs) in older patients with painful diabetic peripheral neuropaty (pDPN) presents a significant challenge to providers. The purpose of this study was to examine the impact of newly initiated pregabalin or duloxetine treatment on Medicare Advantage Prescription Drug (MAPD) plan pDPN patients’ encounters with potential drug-drug interactions, the healthcare cost and utilization consequences of those interactions, and opioid utilization.

Methods

Study subjects required a pregabalin or duloxetine pharmacy claim between 07/01/2008-06/30/2012 (index event), ≥1 inpatient or ≥2 outpatient medical claims with pDPN diagnosis between 01/01/2008-12/31/2012, and ≥12 months pre- and ≥6 post-index enrollment. Propensity score matching was used to balance the pregabalin and duloxetine cohorts on pre-index demographics and comorbidities. Potential DDIs were defined by Micromedex 2.0 and identified by prescription claims. Six-month post-index healthcare utilization (HCU) and costs were calculated using pharmacy and medical claims.

Results

No significant differences in pre-index demographics or comorbidities were found between pregabalin subjects (n = 446) and duloxetine subjects (n = 446). Potential DDI prevalence was significantly greater (p < 0.0001) among duoxetine subjects (56.7%) than among pregabalin subjects (2.9%). There were no significant differences in HCU or costs between pregablin subjects with and without a potential DDI. By contrast, duloxetine subjects with a potential DDI had higher mean all-cause costs ($13,908 vs. $9,830; p = 0.001), more subjects with ≥1 inpatient visits (35.6% vs 25.4%; p = 0.02), and more subjects with ≥1 emergency room visits (32.8% vs. 20.7%; p = 0.005) in comparison to duloxetine subjects without a potential DDI. There was a trend toward a difference between pregabalin and duloxetine subjects in their respective pre-versus-post differences in milligrams (mg) of morphine equivalents/30 days used (60.2 mg and 176.9 mg, respectively; p = 0.058).

Conclusion

The significantly higher prevalence of potential DDIs and potential cost impact found in pDPN duloxetine users, relative to pregabalin users, underscore the importance of considering DDIs when selecting a treatment.

Impact of potential pregabalin or duloxetine drug-drug interactions on health care costs and utilization among Medicare members with fibromyalgia

PURPOSE

To examine the impact of newly initiated pregabalin or duloxetine treatment on fibromyalgia (FM) patients' encounters with potential drug-drug interactions (DDIs), the health care cost and utilization consequences of those interactions, and the impact of treatment on opioid utilization.

PATIENTS AND METHODS

Subjects included those with an FM diagnosis, a pregabalin or duloxetine prescription claim (index event), ≥1 inpatient or ≥2 outpatient medical claims, and ≥12 months preindex and ≥6 postindex enrollment. Propensity score matching was used to help balance the pregabalin and duloxetine cohorts on baseline demographics and comorbidities. Potential DDIs were defined based on Micromedex 2.0 software and were identified by prescription claims.

RESULTS

No significant differences in baseline characteristics were found between matched pregabalin (n=794) and duloxetine cohorts (n=794). Potential DDI prevalence was significantly greater (P<0.0001) among duloxetine subjects (71.9%) than among pregabalin subjects (4.0%). There were no significant differences in all-cause health care utilization or costs between pregabalin subjects with and without a potential DDI. By contrast, duloxetine subjects with a potential DDI had higher mean all-cause costs ($9,373 versus $7,228; P<0.0001) and higher mean number of outpatient visits/member (16.0 versus 13.0; P=0.0009) in comparison to duloxetine subjects without a potential DDI. There was a trend toward a statistically significant difference between pregabalin and duloxetine subjects in their respective pre- versus post-differences in use of ≥1 long-acting opioids (1.6% and 3.4%, respectively; P=0.077).

CONCLUSION

The significantly higher prevalence of potential DDIs and potential cost impact found in FM duloxetine subjects, relative to pregabalin subjects, underscore the importance of considering DDIs when selecting a treatment.

Narcotic bowel syndrome and opioid-induced constipation

Prescription opioid use for chronic non-cancer pain has reached epidemic levels in the USA. With this increased use is the recognition of serious opioid-related gastrointestinal complications such as narcotic bowel syndrome (NBS) and opioid-induced constipation (OIC). NBS consists of a paradoxical worsening of abdominal pain with escalating doses of opioids and is likely mediated by the central nervous system. Therapy requires an intensive multidisciplinary approach to detoxification. OIC is the most common gastrointestinal side effect of opioids. Several novel therapeutics are available to treat OIC that fails to respond to laxative therapy. This review will summarize recent findings on the pathophysiology and treatment approaches to NBS and OIC with a focus on controversies about diagnosis and intervention.

Opioids before and after initiation of pregabalin in patients with diabetic peripheral neuropathy

OBJECTIVES

To examine opioid prescription claims before and after initiation of pregabalin in patients with a diagnosis of diabetic peripheral neuropathy (DPN).

METHODS

This retrospective analysis used a national commercial database of integrated inpatient, outpatient, and prescription claims to identify adults with a DPN diagnosis code within 360 days prior to the first claim for pregabalin between January 1, 2006 and March 31, 2008. Prescription claims for pregabalin or opioids were analyzed in nine consecutive 60-day periods from 180 days before through 360 days after the first pregabalin claim. It was not possible to establish drug administration dates, compliance rates, indications for opioid use, or reasons for treatment discontinuation.

RESULTS

Of the 8004 adults who met eligibility criteria, 6080 (76%) received an opioid within the 180 days before and/or 360 days after their first prescription for pregabalin, including 3956 (49%) both before and after, 1580 (20%) after only, and 544 (7%) before only. The percentage of patients with pregabalin claims covering ≥20 of 60 days (within 60-day periods) was 99% (day 1-60), 63% (day 61-120), 50% (day 121-180), 45% (day 181-240), 42% (day 241-300), and 39% (day 301-360). The percentage of patients with opioid claims covering ≥20 of 60 days within the 60-day periods remained stable (range, 25-30%). Among patients with opioid claims, 73-76% received only short-acting opioids, 6-7% received only long-acting opioids, and 18-20% received both short- and long-acting opioids. In the first year, 982 (12%) patients had opioid claims covering ≥20 of 60 days in every 60-day period (i.e., persistent use of opioids). Coexisting musculoskeletal (95%) or neuropathic (61%) pain conditions were frequent.

CONCLUSION

A majority of patients with DPN receive an opioid before and/or after their first pregabalin claim. Pregabalin neither interferes with nor replaces opioid use for pain management in patients with DPN. Although nearly 1 in 8 patients received opioids throughout the study period, most claims were for short-acting opioids. The majority of this DPN sample had other pain conditions, including musculoskeletal and neuropathic pain conditions. These results highlight the frequency of opioid use with pregabalin, particularly short-acting opioids.

Dosing pattern comparison between duloxetine and pregabalin among patients with diabetic peripheral neuropathic pain

OBJECTIVE

To compare medication dosing patterns of duloxetine and pregabalin among patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

Applying a retrospective cohort study design on a large U.S. healthcare claims database, we examined the dosing patterns of duloxetine and pregabalin among commercially insured patients with DPNP aged 18 to 64 who initiated (a 90-day medication gap) duloxetine or pregabalin therapy in 2006. Selected patients had continuous enrollment during the 12-month pre- and post-index periods. The index mediation was used to classified individuals into the duloxetine or pregabalin cohorts. Initial daily dose, average daily dose over the first post-index year, and average daily dose of the first several prescriptions were estimated and compared across the cohorts.

RESULTS

The study sample included 828 duloxetine and 1934 pregabalin-treated patients with a mean age of 50 years. Cardiovascular diseases, neuropathic pain other than DPNP, osteoarthritis, and diabetic retinopathy were the most common comorbid conditions. The average initial daily doses were 54.3 and 171.8 mg for duloxetine and pregabalin, respectively. The average daily dose over the first post-index year was 55.2 mg for duloxetine and 173.8 mg for pregabalin. The average daily dose for the first 10 duloxetine prescriptions ranged between 54.3 and 61.9 mg, but increased from 171.8 to 264.3 mg for pregabalin.

CONCLUSIONS

The commercially insured patients with DPNP who initiated duloxetine or pregabalin therapy had different dosing patterns. The average daily dose for duloxetine was relatively stable over time, while pregabalin-treated patients had significant dose increase over the 12-month post-index period.