Pharmacists Can Help with Opioid Constipation
About half of physicians who prescribe opioids for long-term use do not take steps to ensure their patients are getting adequate prophylaxis for a common, debilitating side effect of the pain medication—opioid-induced constipation (OIC), a new study suggests.
Fortunately, pharmacists in at least one health-system are stepping up to the challenge by enacting a prophylactic bowel regimen in the palliative care unit.
Such efforts are sorely needed, given the prevalence of OIC: “Constipation is a top side effect” of opioid use, said study author Sharon Hwang, MD, MPH, medical director of CE Outcomes, a health care research firm in Birmingham, Ala.
“Among surveyed clinicians, there was a lot of varied understanding of OIC,” she said, specifically citing differences in knowledge of the condition between nurse practitioners, primary care physicians and pain specialists.
With support from Takeda Pharmaceuticals, which is developing a drug, Amitiza, for the market, Dr. Hwang posed a series of questions to clinicians to ascertain their perceptions of OIC. Based on responses of more than 300 health care professionals, Dr. Hwang and her colleagues observed “many gaps in the care of patients with chronic pain and OIC.”
For example, they found that only half of primary care physicians and pain specialists regularly prescribe a prophylaxis regimen for opioid users. Alternatively, about three-fourths of nurse practitioners prescribe prophylactic medication to long-term opioid users more than 40% of the time.
Dr. Hwang noted that some survey respondents had not considered OIC as a side effect of treatment with opioids. She believes that nurse practitioners, by virtue of the increased time they spend with patients, are the most likely to recognize OIC and prescribe prophylactics accordingly.
“You have to ask the right question,” to determine if patients are suffering from OIC, Dr. Hwang said—and not all clinicians take that step.
“The first step is making everyone aware this is a big issue,” said Gyanprakash Ketwaroo, MD, a gastroenterologist at Beth Israel Deaconess Medical Center, in Boston. “There are multiple approaches, but no real comparison studies yet.”
Pharmacists Spearhead Prophylaxis Efforts
One approach to managing OIC is under way at Abington Memorial Hospital, near Philadelphia, where Maria Foy, PharmD, a clinical specialist in pain management, has enacted a prophylactic bowel regimen in the palliative care unit.
Over two year long trials, from November 2011 to February 2012 and April 2012 to March 2013, clinicians carried out the regimen, aimed at reducing the effects of OIC. In the first year of the trial, 29 palliative care patients were eligible for the initiative; of these, 25 (86%) had bowel movements within 72 hours after treatment. The second trial demonstrated similar results, with 24 of 31 patients achieving laxation within 72 hours.
Once a regimen is recommended, clinicians at Abington Memorial Hospital rely on several techniques for treating OIC. A typical regimen begins with the use of a stimulant and stool softener combination. Depending on the patient, Dr. Foy said, she might titrate up to nine tablets of senna per day—three tablets, three times daily.
“Most people wouldn’t think of going that high,” Dr. Foy said, but she maintains that it is a safe and effective way to manage constipation.
If laxatives are insufficient, next steps include tap water enemas and suppositories. After 72 to 96 hours of constipation and failure of rectal treatments, clinicians may administer methylnaltrexone (Relistor, Salix).
For example, when she encounters a patient who hasn’t had a bowel movement in about 10 days, Dr. Foy said, “I will use Relistor right off the bat.” Although effective, methylnaltrexone is a restricted-use drug at Abington Memorial Hospital because of its cost. The average price for a single-use vial of methylnaltrexone is $48, and a seven-dose kit is $336 (Am Fam Physician2010;82:678-681).
The high cost of laxatives isn’t the only way that OIC can put a squeeze on budgets. Based on a retrospective review of Medicare and commercial claims data from more than 16,000 chronic opioid users, researchers at Pharmerit International in Bethesda, Md., and Takeda found that patients who developed OIC had higher than average health care costs compared with patients without constipation. The average annual cost of health care (including inpatient and outpatient care) for a nonelderly patient with OIC was more than $23,000, significantly higher than the $13,000 average annual cost for a patient without OIC (P<0.001). The same study revealed that clinicians prescribed laxatives to significantly more patients with OIC compared with non-OIC patients (8.8% vs. 0.8%, respectively; P<0.001). The Pharmerit and Takeda researchers also found that the incidence of OIC among chronic opioid users without cancer ranges from 2.9% among nonelderly patients to 6.6% among elderly patients, and up to 15% in long-term care patients without cancer. Eye-Opening Findings Dr. Ketwaroo described the prevalence of OIC as “somewhat eye-opening.” Clinicians should try to do more, he said, to increase awareness about OIC. As a gastroenterology fellow, he receives a “fair amount” of tertiary care referrals for OIC, but practitioners in community care may not be as cognizant of the side effect, he said. “Everything has its own side effects,” Dr. Ketwaroo said. “Can we minimize the number of opioids we are prescribing? I think that’s a fair question to ask.” Half of the clinicians who spoke with Dr. Hwang voiced concern that constipation or sedation, as side effects of treatment with opioids, would result in poor adherence or discontinuation of the drugs for long-term pain management. “If we can control constipation in clinical opioid use,” Dr. Hwang said, “we can optimize patient adherence.” The results of Dr. Hwang’s surveys were presented at the 2013 PAINWeek meeting (abstract 54), as were the results of Dr Foy’s OIC interventions (abstract 133).