William P. Forbes

Rifaximin Treatment in Hepatic Encephalopathy

BACKGROUND Hepatic encephalopathy is a chronically debilitating complication of hepatic cirrhosis. The efficacy of rifaximin, a minimally absorbed antibiotic, is well documented in the treatment of acute hepatic encephalopathy, but its efficacy for prevention of the disease has not been established. METHODS In this randomized, double-blind, placebo-controlled trial, we randomly assigned 299 patients who were in remission from recurrent hepatic encephalopathy resulting from chronic liver disease to receive either rifaximin, at a dose of 550 mg twice daily (140 patients), or placebo (159 patients) for 6 months. The primary efficacy end point was the time to the first breakthrough episode of hepatic encephalopathy. The key secondary end point was the time to the first hospitalization involving hepatic encephalopathy. RESULTS Rifaximin significantly reduced the risk of an episode of hepatic encephalopathy, as compared with placebo, over a 6-month period (hazard ratio with rifaximin, 0.42; 95% confidence interval [CI], 0.28 to 0.64; P<0.001). A breakthrough episode of hepatic encephalopathy occurred in 22.1% of patients in the rifaximin group, as compared with 45.9% of patients in the placebo group. A total of 13.6% of the patients in the rifaximin group had a hospitalization involving hepatic encephalopathy, as compared with 22.6% of patients in the placebo group, for a hazard ratio of 0.50 (95% CI, 0.29 to 0.87; P=0.01). More than 90% of patients received concomitant lactulose therapy. The incidence of adverse events reported during the study was similar in the two groups, as was the incidence of serious adverse events. CONCLUSIONS Over a 6-month period, treatment with rifaximin maintained remission from hepatic encephalopathy more effectively than did placebo. Rifaximin treatment also significantly reduced the risk of hospitalization involving hepatic encephalopathy. (ClinicalTrials.gov number, NCT00298038.)

Rifaximin Therapy for Patients with Irritable Bowel Syndrome without Constipation

BACKGROUND Evidence suggests that gut flora may play an important role in the pathophysiology of the irritable bowel syndrome (IBS). We evaluated rifaximin, a minimally absorbed antibiotic, as treatment for IBS. METHODS In two identically designed, phase 3, double-blind, placebo-controlled trials (TARGET 1 and TARGET 2), patients who had IBS without constipation were randomly assigned to either rifaximin at a dose of 550 mg or placebo, three times daily for 2 weeks, and were followed for an additional 10 weeks. The primary end point, the proportion of patients who had adequate relief of global IBS symptoms, and the key secondary end point, the proportion of patients who had adequate relief of IBS-related bloating, were assessed weekly. Adequate relief was defined as self-reported relief of symptoms for at least 2 of the first 4 weeks after treatment. Other secondary end points included the percentage of patients who had a response to treatment as assessed by daily self-ratings of global IBS symptoms and individual symptoms of bloating, abdominal pain, and stool consistency during the 4 weeks after treatment and during the entire 3 months of the study. RESULTS Significantly more patients in the rifaximin group than in the placebo group had adequate relief of global IBS symptoms during the first 4 weeks after treatment (40.8% vs. 31.2%, P=0.01, in TARGET 1; 40.6% vs. 32.2%, P=0.03, in TARGET 2; 40.7% vs. 31.7%, P<0.001, in the two studies combined). Similarly, more patients in the rifaximin group than in the placebo group had adequate relief of bloating (39.5% vs. 28.7%, P=0.005, in TARGET 1; 41.0% vs. 31.9%, P=0.02, in TARGET 2; 40.2% vs. 30.3%, P<0.001, in the two studies combined). In addition, significantly more patients in the rifaximin group had a response to treatment as assessed by daily ratings of IBS symptoms, bloating, abdominal pain, and stool consistency. The incidence of adverse events was similar in the two groups. CONCLUSIONS Among patients who had IBS without constipation, treatment with rifaximin for 2 weeks provided significant relief of IBS symptoms, bloating, abdominal pain, and loose or watery stools. (Funded by Salix Pharmaceuticals; ClinicalTrials.gov numbers, NCT00731679 and NCT00724126.).

A Comparison of Cilostazol and Pentoxifylline for Treating Intermittent Claudication

PURPOSE We performed a randomized, double-blind, placebo-controlled, multicenter trial to evaluate the relative efficacy and safety of cilostazol and pentoxifylline. PATIENTS AND METHODS We enrolled patients with moderate-to-severe claudication from 54 outpatient vascular clinics, including sites at Air Force, Veterans Affairs, tertiary care, and university medical centers in the United States. Of 922 consenting patients, 698 met the inclusion criteria and were randomly assigned to blinded treatment with either cilostazol (100 mg orally twice a day), pentoxifylline (400 mg orally 3 times a day), or placebo. We measured maximal walking distance with constant-speed, variable-grade treadmill testing at baseline and at 4, 8, 12, 16, 20, and 24 weeks. RESULTS Mean maximal walking distance of cilostazol-treated patients (n = 227) was significantly greater at every postbaseline visit compared with patients who received pentoxifylline (n = 232) or placebo (n = 239). After 24 weeks of treatment, mean maximal walking distance increased by a mean of 107 m (a mean percent increase of 54% from baseline) in the cilostazol group, significantly more than the 64-m improvement (a 30% mean percent increase) with pentoxifylline (P <0.001). The improvement with pentoxifylline was similar (P = 0.82) to that in the placebo group (65 m, a 34% mean percent increase). Deaths and serious adverse event rates were similar in each group. Side effects (including headache, palpitations, and diarrhea) were more common in the cilostazol-treated patients, but withdrawal rates were similar in the cilostazol (16%) and pentoxifylline (19%) groups. CONCLUSION Cilostazol was significantly better than pentoxifylline or placebo for increasing walking distances in patients with intermittent claudication, but was associated with a greater frequency of minor side effects. Pentoxifylline and placebo had similar effects.

Effect of cilostazol on walking distances in patients with intermittent claudication caused by peripheral vascular disease

PURPOSE This study evaluated the effects of cilostazol on walking distances in patients with intermittent claudication (IC) caused by peripheral arterial occlusive disease. METHODS The study was a multicenter, randomized, double-blind, placebo-controlled trial. Two hundred thirty-nine patients with IC were randomly assigned to receive cilostazol (100 mg b.i.d.) or a placebo for 16 weeks. All patients underwent serial, variable-grade, constant-speed treadmill testing. Absolute claudication distance (ACD), assessed at the end of the 12-hour dosing interval (trough), was the primary end point. Secondary end points included ACD assessed 3 to 4 hours after dosing (peak) and initial claudication distances (trough and peak). Functional status measures, including the Medical Outcomes Scale (SF-36) and Walking Impairment Questionnaire, were used to assess subjective changes over the 16-week treatment period. Ankle-brachial indexes were calculated from Doppler-measured systolic pressures at every visit with treadmill testing. RESULTS Patients treated with cilostazol demonstrated significant improvements over the placebo patients in ACD at all three time points tested after baseline (weeks 8, 12, and 16). Peak treadmill testing at weeks 8 and 12 also showed significant improvement in walking distances for cilostazol-treated patients over placebo-treated patients. At week 16, patients in the cilostazol group had a 96.4-meter (47%) increase in ACD compared with 31.4 meters (12.9%) for the placebo group (p < 0.001). In the SF-36, significant improvement was observed in the physical component subscale and the composite physical component score. In the Walking Impairment Questionnaire, improvements were significant in patient reports of walking speed and specific measures of walking difficulty. Ankle-brachial indexes improved in the cilostazol group (0.64 +/- 0.02 to 0.70 +/- 0.02) compared with the placebo group (0.68 +/- 0.02 to 0.69 +/- 0.02) (p < 0.0125). The most frequent adverse events were headache, abnormal stools (e.g. loose stools), diarrhea, and dizziness. CONCLUSIONS Cilostazol significantly increased ACD at all measured time points and initial claudication distances at most time points. This agent may represent a new treatment option for patients with intermittent claudication.

Meta-analysis of results from eight randomized, placebo-controlled trials on the effect of cilostazol on patients with intermittent claudication☆

We examined the effect of cilostazol, a type III phosphodiesterase inhibitor, on pain-free and maximal walking distance and quality of life measures. The present study examined adverse effects in 2,702 patients with stable, moderate to severe claudication enrolled in 8 randomized, double-blind, placebo-controlled trials. Treatment duration ranged from 12 to 24 weeks. Cilostazol therapy increased maximal and pain-free walking distances by 50% and 67%, respectively. In subgroup analysis, cilostazol increased pain-free and maximal walking distance similarly in men and women, in older (>/=65 years) and younger patients, and in patients with and without diabetes. Quality-of-life assessments revealed enhanced scores for physical well-being. Cilostazol-treated patients reported a higher incidence of headache, bowel complaints, and palpitations than patients given placebos. Cilostazol decreased triglycerides by 15.8% and increased high-density lipoprotein cholesterol by 12.8%, but there were no deleterious effects on any hematologic or serum markers. We conclude that cilostazol significantly increases walking distance and quality-of-life measures in patients with claudication without major adverse effects.

Effect of Cilostazol on treadmill walking, community-based walking ability, and health-related quality of life in patients with intermittent claudication due to peripheral arterial disease: Meta-analysis of six randomized controlled trials

OBJECTIVES: To assess whether cilostazol, a phosphodiesterase III inhibitor, improves treadmill and community‐based walking ability and health‐related quality of life (HQL) in patients with intermittent claudication resulting from peripheral arterial disease (PAD).

Rifaximin Is Safe and Well Tolerated for Long-term Maintenance of Remission From Overt Hepatic Encephalopathy

BACKGROUND & AIMS Rifaximin is a gut-selective, oral antimicrobial agent shown to reduce the recurrence of overt hepatic encephalopathy (HE) and HE-related hospitalizations in a 6-month, randomized, controlled trial (RCT). We performed a phase 3, open-label maintenance study to assess the safety and rate of hospitalization with long-term rifaximin use. METHODS We conducted a 24-month, open-label maintenance study of rifaximin (550 mg, twice daily) in patients with HE who participated in the previous RCT of rifaximin or new patients enrolled from March 2007 to December 2010. Safety was assessed (adverse events, clinical laboratory parameters) for the integrated population of all patients, who were given rifaximin 550 mg twice daily (all-rifaximin population, N = 392). Safety and hospitalization data were compared between the group given placebo in the original RCT (n = 159) and those given rifaximin (n = 140). RESULTS In the all-rifaximin population, the median exposure to rifaximin was 427.0 days (range, 2-1427 d), with 510.5 person-years of exposure. The profile and rate of adverse events with long-term rifaximin treatment were similar to those of the original RCT. There was no increase in the rate of infections, including with Clostridium difficile, or development of bacterial antibiotic resistance. Rates of hospitalizations with long-term rifaximin administration remained low: the HE-related hospitalization rate, normalized for exposure (0.21; all-rifaximin population), was similar to that of the rifaximin group in the original RCT (0.30), and lower than that for the placebo group (0.72). CONCLUSIONS Long-term treatment (≥24 mo) with rifaximin (550 mg, twice daily) appears to provide a continued reduction in the rate of HE-related and all-cause hospitalization, without an increased rate of adverse events. ClinicalTrials.gov number: NCT00686920.

Randomised clinical trial: rifaximin improves health-related quality of life in cirrhotic patients with hepatic encephalopathy – a double-blind placebo-controlled study

Aliment Pharmacol Ther 2011; 34: 853–861

A Randomized, Multicenter Study Comparing the Safety and Efficacy of Sodium Phosphate Tablets With 2L Polyethylene Glycol Solution Plus Bisacodyl Tablets for Colon Cleansing

OBJECTIVE:The safety and efficacy of NaP tablets have not been compared with 2L PEG lavage solution. A multicenter, investigator-blinded study was conducted to compare the colon-cleansing efficacy of a new NaP tablet formulation with that of 2L PEG solution plus bisacodyl tablets in adults undergoing colonoscopy.METHODS:A total of 481 patients were randomized to receive either 32 tablets (48 g) of NaP or 2L PEG solution plus 4 (20 mg) bisacodyl tablets. Quality of colon cleansing was assessed using a 4-point scale (1 = excellent, 2 = good, 3 = fair, and 4 = inadequate), and the primary efficacy end point was mean overall colon-cleansing score. Safety assessments included recording of adverse events and changes in biochemical tests and vital signs.RESULTS:A total of 411 patients were included in the efficacy analysis. The mean overall and ascending colon-cleansing scores for NaP tablets were significantly better than PEG plus bisacodyl (overall 1.5 vs 1.8, ascending 1.4 vs 1.8, P < 0.0001 for both). Patients treated with NaP tablets experienced significantly fewer adverse events (66% vs 82%, P = 0.0003) and gastrointestinal symptoms (64% vs 79%, P = 0.0001) compared with patients receiving PEG plus bisacodyl. Patients receiving NaP tablets were significantly less likely to experience abdominal distention, abdominal pain, and vomiting than patients receiving PEG plus bisacodyl (P < 0.0012). Transient fluctuations in laboratory parameters were observed in both treatment groups; however, the fluctuations were more common and of greater magnitude in the NaP group particularly in phosphorous, sodium, and potassium.CONCLUSION:The colon-cleansing efficacy of the new 32-tablet NaP dosing regimen in this study was found to be significantly better than the 2L PEG solution plus bisacodyl tablets regimen. The 32-tablet NaP dosing regimen was associated with fewer adverse events. As expected electrolyte shifts were more common and of greater magnitude in the NaP group compared with the PEG plus bisacodyl group; however, both treatment groups demonstrated significant changes in electrolytes and creatinine.

Development and Validation of a Biomarker for Diarrhea-Predominant Irritable Bowel Syndrome in Human Subjects

Diarrhea-predominant irritable bowel syndrome (IBS) is diagnosed through clinical criteria after excluding “organic” conditions, and can be precipitated by acute gastroenteritis. Cytolethal distending toxin B (CdtB) is produced by bacteria that cause acute gastroenteritis, and a post-infectious animal model demonstrates that host antibodies to CdtB cross-react with vinculin in the host gut, producing an IBS-like phenotype. Therefore, we assessed circulating anti-CdtB and anti-vinculin antibodies as biomarkers for D-IBS in human subjects. Subjects with D-IBS based on Rome criteria (n=2375) were recruited from a large-scale multicenter clinical trial for D-IBS (TARGET 3). Subjects with inflammatory bowel disease (IBD) (n=142), subjects with celiac disease (n=121), and healthy controls (n=43) were obtained for comparison. Subjects with IBD and celiac disease were recruited based on the presence of intestinal complaints and histologic confirmation of chronic inflammatory changes in the colon or small intestine. Subjects with celiac disease were also required to have an elevated tTG and biopsy. All subjects were aged between 18 and 65 years. Plasma levels of anti-CdtB and anti-vinculin antibodies were determined by ELISA, and compared between groups. Anti-CdtB titers were significantly higher in D-IBS subjects compared to IBD, healthy controls and celiac disease (P<0.001). Anti-vinculin titers were also significantly higher in IBS (P<0.001) compared to the other groups. The area-under-the-receiver operating curves (AUCs) were 0.81 and 0.62 for diagnosis of D-IBS against IBD for anti-CdtB and anti-vinculin, respectively. Both tests were less specific in differentiating IBS from celiac disease. Optimization demonstrated that for anti-CdtB (optical density≥2.80) the specificity, sensitivity and likelihood ratio were 91.6%, 43.7 and 5.2, respectively, and for anti-vinculin (OD≥1.68) were 83.8%, 32.6 and 2.0, respectively. These results confirm that anti-CdtB and anti-vinculin antibodies are elevated in D-IBS compared to non-IBS subjects. These biomarkers may be especially helpful in distinguishing D-IBS from IBD in the workup of chronic diarrhea.