Reviews for Primary Care - Fall 2007 - (Page 20) Chronic Constipation and Functional Bowel Disorders continued both been shown to effectively improve stool frequency and stool consistency in patients with occasional constipation.31 The effectiveness of milk of magnesia and sorbitol in patients with constipation has not been demonstrated convincingly in the literature.31,42 To date there have been 2 randomized controlled trials comparing PEG 3350 to lactulose. In both of these trials, PEG 3350 was associated with greater symptom improvement and better tolerability than lactulose.31 The osmotic laxatives are generally well tolerated but have been associated with some adverse events. The incidence of diarrhea in PEG-treated patients has been shown to range from 2% to 40% in individual trials.31 According to prescribing information, high doses of PEG 3350 may produce diarrhea and excessive stool frequency,43 which can be managed in most cases by titrating the dose downward. Other common adverse events with PEG 3350 include nausea, abdominal bloating, cramping, and flatulence. Electrolyte abnormalities (eg, hypermagnesemia, hyperphosphatemia [magnesium-containing compounds only], hypercalcemia, hyponatremia, hypokalemia) and hypovolemia also have been reported with osmotic laxatives.31 The precise incidence of these adverse events is unclear. DiPalma and colleagues recently conducted a randomized, doubleblind, placebo-controlled, parallel, multicenter study of PEG 3350 in a total of 304 subjects with chronic constipation.44 Chronic constipation was defined as a 3-month history, when not taking laxatives, of satisfactory stool being less frequent than 3 per week, and 1 or more of 3 Rome symptom criteria: straining in more than 25% of defecations, lumpy or hard stools in more than 25% of defecations, or sensation of incomplete 100 Relief of modified Rome criteria for constipation for 50% or more of treatment weeks (%) 90 80 70 60 50 40 30 20 10 0 This small randomized, multicenter, placebo-controlled study found PEG 3350 safe and effective for up to 6 months in treating constipation P P 52 .001 61 .001 22 11 PEG 3350 Placebo Total group (N 304) PEG 3350 Placebo Subgroup of elderly (n 75) Figure 7. Long-term use of PEG 3350 in patients with chronic constipation. Adapted from DiPalma JA et al.44 evacuation in more than 25% of defecations. Additionally, inclusion criteria required that subjects had on average fewer than 3 satisfactory bowel movements per week during a 14-day observation period. Study subjects received PEG 3350 as a single daily dose of 17 g or placebo for 6 months. Results from this study are summarized in Figure 7.44 PEG 3350 was more effective than placebo at improving the symptoms of chronic constipation over the 6-month trial. There were no significant differences in laboratory findings or adverse events between therapies. Similar results were observed when analyzed for differences due to gender, race, or age. In this study, PEG 3350 was found to be safe and effective for use in patients with chronic constipation for up to 6 months.44 Patient Dissatisfaction With Traditional Constipation and IBS-C Treatments Results of a study published earlier this year found that approximately 50% of patients with self-reported chronic constipation indicated that they were dissatisfied with traditional therapies (over-the-counter and prescription agents including fiber and bulking agents) in terms of their overall relief.45 Approximately two thirds of patients in this study believed that available agents are ineffective at relieving the multiple symptoms of constipation. Nearly three quarters thought that traditional agents had unpredictable results and were ineffective in relieving their bloating. Patients with IBS-C have abdominal pain or discomfort in addition to the symptoms of constipation.6 It follows then that patients with IBS-C will have a greater degree of impairment with regard to their symptoms and are likely to be more difficult to satisfy therapeutically. Lembo evaluated the frequency of adverse events experienced by 668 patients as a result of treatment of IBS-C and found that 99% of the patients had tried at least 1 medication for their gastrointestinal symptoms.46 On average, these patients had tried at least 4 different medications for their IBS-C symptoms, and 75% of them reported discontinuing use of these medications 20 VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE
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