The efficacy of standard laxative use for the prevention and treatment of opioid induced constipation during oxycodone use: a small Dutch observational pilot study

Iatrogenic Side Effects of Pain Therapies

Pain regimens, particularly for chronic cancer and noncancer pain, must balance the important analgesic benefits against potential risks. Many effective and frequently used pain control regimens are associated with iatrogenic adverse events. Interventional procedures can be associated with nerve injuries, vascular injuries, trauma to the spinal cord, and epidural abscesses. Although rare, these adverse events are potentially catastrophic. Pharmacologic remedies for pain must also consider potential side effects that can occur even at therapeutic doses of over-the-counter remedies such as paracetamol (acetaminophen) or nonsteroidal anti-inflammatory drugs. Opioids are effective pain relievers but are associated with many side effects, some of which can be treatment limiting. A prevalent and distressing side effect of opioid therapy is constipation. Opioid-induced constipation is caused by binding to opioid receptors in the gastrointestinal system, making conventional laxatives ineffective. Peripherally acting mu-opioid receptor antagonists are a new drug class that offers the benefits of preserving opioid analgesia without side effects in the gastrointestinal system. An important safety concern, particularly among geriatric patients is the increasingly prevalent condition of polypharmacy. Many senior patients take five or more medications, including some that may be contraindicated in geriatric patients, duplicative of other drugs, have potential pharmacokinetic drug-drug interactions, or may not be the optimal choice for the patient's age and condition. Careful assessment of medications in the elderly, including possibly deprescribing with tapering of certain drugs, may be warranted but should be done systematically and under clinical supervision.

Prevalence and Risk Factors for Opioid-Induced Constipation in an Older National Veteran Cohort

Objectives

This research describes the prevalence and covariates associated with opioid-induced constipation (OIC) in an observational cohort study utilizing a national veteran cohort and integrated data from the Center for Medicare and Medicaid Services (CMS).

Methods

A cohort of 152,904 veterans with encounters between 1 January 2008 and 30 November 2010, an exposure to opioids of 30 days or more, and no exposure in the prior year was developed to establish existing conditions and medications at the start of the opioid exposure and determining outcomes through the end of exposure. OIC was identified through additions/changes in laxative prescriptions, all-cause constipation identification through diagnosis, or constipation related procedures in the presence of opioid exposure. The association of time to constipation with opioid use was analyzed using Cox proportional hazard regression adjusted for patient characteristics, concomitant medications, laboratory tests, and comorbidities.

Results

The prevalence of OIC was 12.6%. Twelve positively associated covariates were identified with the largest associations for prior constipation and prevalent laxative (any laxative that continued into the first day of opioid exposure). Among the 17 negatively associated covariates, the largest associations were for erythromycins, androgens/anabolics, and unknown race.

Conclusions

There were several novel covariates found that are seen in the all-cause chronic constipation literature but have not been reported for opioid-induced constipation. Some are modifiable covariates, particularly medication coadministration, which may assist clinicians and researchers in risk stratification efforts when initiating opioid medications. The integration of CMS data supports the robustness of the analysis and may be of interest in the elderly population warranting future examination.

Constipation in the elderly in a Japanese long-term medical facility: An ultrasonographic investigation

This study aims to assess the fecal retention in elderly patients using colonic ultrasonography (US) in Japanese long-term care facility and determine the correlation between nutrition management methods and the fecal retention by US. This cross-sectional, single-center study was conducted in a long-term care facility in Japan. Patients with chronic constipation fulfilled the Rome III criteria for the diagnosis of functional constipation. US was performed on constipation patients with 4-day fecal retention before starting the standard management of constipation. After patients had defecated, nurses checked the outside of feces using King's Stool Chart and Bristol Stool Chart. All of 32 patients underwent the management of suppository laxative, the daily life independence level in grade C. In all cases, the King's Stool Chart did not detect > 200 g of fecal matter; the Bristol Stool Chart revealed type 5-7 in 56.2% of patients. The total parenteral nutrition and tube feeding did not completely detect type 1-2 in 0%. While the fecal retention groups comprised 15.6%, the non-fecal retention groups comprised 84.4%. The total parenteral nutrition did not completely detect the fecal retention in 0%. In the non-fecal retention groups, the King's Stool Chart indicated < 100 g in 81.8%, and the Bristol Stool Chart indicated type 5-7 in 100%. In conclusion, fecal properties of elderly constipation patients with the long-term parenteral nutrition should be assessed in follow-up examination by US, which is possible for personalized medical care by US, to avoid the administered regular management of constipation.

Prolonged-release oxycodone/naloxone reduces opioid-induced constipation and improves quality of life in laxative-refractory patients: results of an observational study

Background

Opioids are an effective treatment for moderate-to-severe pain. However, they are associated with a number of gastrointestinal side effects, most commonly constipation. Laxatives do not target the underlying mechanism of opioid-induced constipation (OIC), so many patients do not have their symptoms resolved. Fixed-dose prolonged-release (PR) oxycodone/naloxone (OXN) tablets contain the opioid agonist oxycodone and the opioid antagonist naloxone. Nal-oxone blocks the action of oxycodone in the gut without compromising its analgesic effects.

Aim

To evaluate the effectiveness of PR OXN in patients with severe pain who had laxative-refractory OIC with their previous opioid.

Methods

The study was carried out in 13 centers across the UK and Ireland, using a bespoke online tool to capture patients’ data. Patients were reviewed according to normal clinical practice of each center and rated any changes in their constipation and quality of life (QoL) since starting PR OXN. Any change in patients’ laxative use was also recorded.

Results

One hundred and seven patients were entered into the database, and 81 went on to attend at least one review. Of these, 54 (66.7%) reported an improvement in constipation and 50 (61.7%) reported an improvement in QoL since starting PR OXN. Fifty-seven patients (70.4%) said they had reduced laxative intake; 48 (59.3%) only needed laxatives as required.

Conclusion

PR OXN reduced symptoms of constipation, improved QoL and reduced laxative intake in patients with OIC. It has a potential place early in any treatment strategy for severe pain in patients using opioids, particularly in patients who may be predisposed to constipation.

Treatment with Naloxegol Versus Placebo: Pain Assessment in Patients with Noncancer Pain and Opioid-Induced Constipation

OBJECTIVE

To summarize results from pain and opioid use assessments with naloxegol in adults with opioid-induced constipation (OIC) and chronic noncancer pain.

METHODS

Two phase 3 randomized, double-blind, 12-week studies evaluated the efficacy and safety of oral naloxegol (12.5 or 25 mg daily) in adults (18 to < 85 years) with confirmed OIC and chronic noncancer pain: KODIAC-04 (NCT01309841) and KODIAC-05 (NCT01323790). Pain level was assessed daily (11-point numeric rating scale [NRS]; 0 = no pain, 10 = worst imaginable pain). Changes from baseline in mean weekly pain scores and opioid dose (weeks 1 through 12) were analyzed using mixed-model repeated measures.

RESULTS

At baseline, mean daily NRS average pain scores ranged from 4.5 to 4.8 for all groups in KODIAC-04 (N = 652) and were 4.6 for each group in KODIAC-05 (N = 700). Respective mean ± SD changes from baseline average pain for placebo, naloxegol 12.5 mg, and naloxegol 25 mg were -0.2 ± 1.07, -0.3 ± 1.05 (P = 0.773 vs. placebo), and 0.2 ± 0.95 (P = 0.837 vs. placebo; KODIAC-04) and -0.1 ± 0.94, -0.1 ± 0.87 (P = 0.744), and 0.0 ± 1.18 (P = 0.572; KODIAC-05). At baseline, mean daily opioid doses ranged from 135.6 to 143.2 morphine equivalent units (MEUs)/day in KODIAC-04, and from 119.9 to 151.7 MEUs/day in KODIAC-05. Respective mean ± SD changes from baseline dose were -1.8 ± 30.19, -2.3 ± 20.52 (P = 0.724 vs. placebo), and 0.4 ± 13.01 (P = 0.188 vs. placebo; KODIAC-04) and -0.3 ± 17.14, -1.3 ± 17.11 (P = 0.669 vs. placebo), and 0.1 ± 8.54 (P = 0.863 vs. placebo; KODIAC-05). Changes in maintenance opioid dose were few; reasons for such changes were similar across treatment groups.

CONCLUSION

Centrally mediated opioid analgesia was maintained during treatment with naloxegol in patients with noncancer pain and OIC.

Pharmacologic Profile of Naloxegol, a Peripherally Acting µ-Opioid Receptor Antagonist, for the Treatment of Opioid-Induced Constipation

Opioid-induced constipation (OIC) is a common side effect of opioid pharmacotherapy for the management of pain because opioid agonists bind to µ-opioid receptors in the enteric nervous system (ENS). Naloxegol, a polyethylene glycol derivative of naloxol, which is a derivative of naloxone and a peripherally acting µ-opioid receptor antagonist, targets the physiologic mechanisms that cause OIC. Pharmacologic measures of opioid activity and pharmacokinetic measures of central nervous system (CNS) penetration were employed to characterize the mechanism of action of naloxegol. At the human µ-opioid receptor in vitro, naloxegol was a potent inhibitor of binding (K_i = 7.42 nM) and a neutral competitive antagonist (pA₂ - 7.95); agonist effects were <10% up to 30 μM and identical to those of naloxone. The oral doses achieving 50% of the maximal effect in the rat for antagonism of morphine-induced inhibition of gastrointestinal transit and morphine-induced antinociception in the hot plate assay were 23.1 and 55.4 mg/kg for naloxegol and 0.69 and 1.14 mg/kg by for naloxone, respectively. In the human colon adenocarcinoma cell transport assay, naloxegol was a substrate for the P-glycoprotein transporter, with low apparent permeability in the apical to basolateral direction, and penetrated the CNS 15-fold slower than naloxone in a rat brain perfusion model. Naloxegol-derived radioactivity was poorly distributed throughout the rat CNS and was eliminated from most tissues within 24 hours. These findings corroborate phase 3 clinical studies demonstrating that naloxegol relieves OIC-associated symptoms in patients with chronic noncancer pain by antagonizing the µ-opioid receptor in the ENS while preserving CNS-mediated analgesia.

Peripherally acting μ-opioid receptor antagonists as treatment options for constipation in noncancer pain patients on chronic opioid therapy

Opioid-induced constipation (OIC), a prevalent and distressing side effect of opioid therapy, does not reliably respond to treatment with conventional laxatives. OIC can be a treatment-limiting adverse event. Recent advances in medications with peripherally acting μ-opioid receptor antagonists, such as methylnaltrexone, naloxegol, and alvimopan, hold promise for treating OIC and thus extending the benefits of opioid analgesia to more chronic pain patients. Peripherally acting μ-opioid receptor antagonists have been clinically tested to improve bowel symptoms without compromise to pain relief, although there are associated side effects, including abdominal pain. Other treatment options include fixed-dose combination products of oxycodone analgesic together with naloxone.