Prolonged remission from hepatic encephalopathy with rifaximin: results of a placebo crossover analysis

BACKGROUND

Rifaximin therapy reduced risk of hepatic encephalopathy (HE) recurrence and HE-related hospitalisations during a 6-month, randomised, placebo-controlled trial (RCT) and a 24-month open-label maintenance (OLM) study. However, the impact of crossover from placebo to rifaximin therapy is unclear.

AIM

To study the impact of crossing over from placebo to rifaximin treatment on breakthrough HE and hospitalisation rates using a within-subjects design.

METHODS

Adults with cirrhosis and history of overt HE episodes, currently in HE remission, received placebo during the RCT and crossed over to rifaximin 550 mg twice daily during the OLM study. Rate of breakthrough overt HE episodes, hospitalisations and incidence and rate of adverse events (AEs) were analysed during RCT and first 6 months of OLM.

RESULTS

Of 82 patients randomised to placebo in the RCT who crossed over to the OLM study, 39 experienced an HE episode during the RCT compared with 14 during the OLM study (P < 0.0001). Significantly lower rates of HE events were observed with rifaximin treatment compared with placebo treatment (P < 0.0001). Rates of HE-related hospitalisation were numerically lower during rifaximin treatment compared with placebo treatment, although not significant. Rates of most common AEs, serious AEs and infection-related AEs were similar between the two treatments.

CONCLUSIONS

This analysis confirms the repeatability of results from the RCT on safety and efficacy of rifaximin 550 mg twice daily in reducing the risk of hepatic encephalopathy recurrence, and suggests these findings are translatable outside of a rigorous, controlled trial setting.

A retrospective analysis: the development of patient reported outcome measures for the assessment of Crohn's disease activity

BACKGROUND

The Crohn's Disease Activity Index (CDAI) is a measure of disease activity based on symptoms, signs and a laboratory test. The US Food and Drug Administration has indicated that patient reported outcomes (PROs) should be the primary outcome in randomised controlled trials for Crohn's disease (CD).

AIM

As no validated PRO exists for CD, to investigate whether CDAI diary card items could be modified for this purpose.

METHODS

Data from a trial of rifaximin-extended intestinal release were used to identify cut-points for stool frequency, pain and general well-being using receiver operating characteristic curves with CDAI <150 as criterion. The operating properties of 2- and 3-item PRO were evaluated using data from a trial of methotrexate in CD. Regression analysis determined PRO2 and PRO3 scores that correspond to CDAI-defined thresholds of 150, 220 and 450 and changes of 50, 70 and 100 points.

RESULTS

Optimum cut-points for CDAI remission were mean daily stool frequency ≤1.5, abdominal pain ≤1, and general well-being score of ≤1 (areas under the ROC curve 0.79, 0.91 and 0.89, respectively). The effect estimates were similar using 2- and 3-item PROs or CDAI. PRO2 and PRO3 values corresponding to CDAI scores of 150, 220 and 450 points were 8, 14, 34 and 13, 22, 53. The corresponding values for CDAI changes of 50, 70 and 100, were 2, 5, 8 and 5, 9, 14. Responsiveness to change was similar for both PROs.

CONCLUSION

Patient reported outcomes derived from CDAI diary items may be appropriate for use in clinical trials for CD.

Safety and tolerability of rifaximin for the treatment of irritable bowel syndrome without constipation: a pooled analysis of randomised, double-blind, placebo-controlled trials

BACKGROUND

The efficacy of rifaximin, a nonsystemic, gut-targeted antibiotic for reducing non-constipation-predominant irritable bowel syndrome (non-C IBS) symptoms, has been demonstrated in one phase 2b and two phase 3 randomised, double-blind, placebo-controlled trials, but detailed data about rifaximin safety and tolerability during treatment and subsequent follow-up periods are lacking.

AIM

To assess and determine the frequency of rifaximin and placebo adverse events (AEs) in phase 2b and phase 3 non-C IBS trials.

METHODS

A post hoc pooled safety analysis of the phase 2b (rifaximin 275, 550, and 1100 mg twice daily for 2 weeks; 550 mg twice daily for 4 weeks) and phase 3 (rifaximin 550 mg three times daily for 2 weeks) studies was performed. Data on treatment and post-treatment AEs were collected. Patients were followed up for 12 weeks and 10 weeks post-treatment in the phase 2b and phase 3 trials, respectively.

RESULTS

Patients receiving rifaximin (n = 1103) and placebo (n = 829) had a similar incidence of drug-related AEs (12.1% vs. 10.7%), serious AEs (1.5% vs. 2.2%), drug-related AEs resulting in study discontinuation (0.8% vs. 0.8%), gastrointestinal-associated AEs (12.2% vs. 12.2%) and infection-associated AEs (8.5% vs. 9.5%). There were no cases of Clostridium difficile colitis or deaths.

CONCLUSIONS

The safety and tolerability profile of rifaximin during treatment and post-treatment was comparable to placebo. Future research should define the safety and tolerability profile, including risk of C. difficile colitis and microbial antibiotic resistance, with repeated courses of rifaximin in patients with non-constipation-predominant irritable bowel syndrome (ClinicalTrials.gov: NCT00269412, NCT00731679, and NCT00724126).

Mesalazine granules 1.5 g once-daily maintain remission in patients with ulcerative colitis who switch from other 5-ASA formulations: a pooled analysis from two randomised controlled trials

BACKGROUND

Mesalazine (mesalamine) granules (MG) were shown to be effective for the maintenance of remission of ulcerative colitis (UC) in two double-blind placebo-controlled trials.

AIM

To evaluate the efficacy of once-daily MG for maintenance of remission in patients with UC who switched from other 5-aminosalicylic acid (5-ASA) formulations.

METHODS

Data from two independent multicenter, randomised, double-blind, placebo-controlled, 6-month trials evaluating patients with UC in remission were combined for analysis of a subpopulation of patients who switched from other 5-ASA formulations to MG 1.5 g or placebo upon randomisation. The primary endpoint was the percentage of patients who remained relapse-free at Month 6 or end of treatment. Relapse was defined as a Sutherland Disease Activity Index (SDAI) rectal bleeding score ≥1 and mucosal appearance score ≥2, a UC flare or medication used to treat a UC flare.

RESULTS

Of the 487 patients who received 5-ASA maintenance therapy at enrolment, 322 were in the MG group and 165 were in the placebo group. The percentage of patients who remained relapse-free (based on Sutherland Disease Activity Index scores) after 6 months was significantly higher with MG than placebo (78.3% vs. 58.8%, P < 0.001). Rectal bleeding, stool frequency and the physician's rating of disease activity remained unchanged after 6 months in a higher percentage of patients using MG compared with those on placebo (P < 0.004 for each endpoint).

CONCLUSION

Mesalazine granules 1.5 g once-daily is effective for maintenance of remission in UC patients who switch from other 5-ASA formulations. ClinicalTrials.gov identifiers NCT00744016, NCT00767728.

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

BACKGROUND

Hepatic encephalopathy (HE) is a brain disorder that often results from cirrhosis due to viral hepatitis, metabolic and alcohol-related liver disease, and is characterised by cognitive, psychiatric and motor impairments. Recurrent bouts of overt HE negatively impact daily functioning and quality of life.

AIM

To evaluate the effect of rifaximin on health-related quality of life (HRQL) in cirrhotic patients with HE.

METHODS

Patients with cirrhosis in remission from HE (Conn score = 0 or 1) and a documented history of recurrent HE episodes (≥2 within 6 months of screening) were randomised to rifaximin 550 mg twice daily (N = 101) or placebo (N = 118) for 6 months. Concomitant lactulose was permitted during the study. The Chronic Liver Disease Questionnaire (CLDQ) was administered every 4 weeks, and time for occurrence of HE breakthrough was recorded. A longitudinal analysis using time-weighted averages of the CLDQ scores normalised by days on study therapy was used to evaluate the effect of treatment on HRQL, and between HE outcomes (HE recurrence, yes/no) irrespective of treatment.

RESULTS

The time-weighted averages of the overall CLDQ score and each domain score were significantly higher in the rifaximin group vs. placebo (P-values ranged from 0.0087 to 0.0436); and were significantly lower in patients who experienced HE breakthrough compared to those who remained in remission (P-values were <0.0001).

CONCLUSION

Rifaximin significantly improved HRQL in patients with cirrhosis and recurrent hepatic encephalopathy. A lower HRQL may predict recurrence of hepatic encephalopathy.

Clinical trial: once-daily mesalamine granules for maintenance of remission of ulcerative colitis - a 6-month placebo-controlled trial

BACKGROUND

Ulcerative colitis (UC) is a chronic relapsing and remitting idiopathic inflammatory bowel disorder.

AIM

To evaluate once-daily mesalamine (mesalazine) granules (MG) for maintenance of remission of UC.

METHODS

Randomized, double-blind, placebo-controlled trial of patients (n=209 MG, n=96 placebo) with UC in remission [revised Sutherland Disease Activity Index (SDAI) rectal bleeding=0, mucosal appearance <2] who took MG 1.5 g or placebo once-daily for up to 6 months. Primary efficacy endpoint: the percentage of patients who remained relapse-free at month 6/end of treatment. Relapse was defined as SDAI rectal bleeding score ≥1 and a mucosal appearance score ≥2, a UC flare, or initiation of medication to treat a UC flare.

RESULTS

The percentage of relapse-free patients at month 6/end of treatment was higher with MG than placebo (78.9% vs. 58.3%, P < 0.001) in the intent-to-treat analysis. Significant differences (P ≤ 0.025) favouring MG were observed for most secondary endpoints including improvement in rectal bleeding, physician's disease activity rating, stool frequency, the SDAI at month 6/end of treatment, patients classified as a treatment success and relapse-free duration. The incidence of adverse events was similar between groups.

CONCLUSIONS

Once-daily mesalamine (mesalazine) was effective in maintaining remission of UC for 6 months.

Clinical trial: sodium phosphate tablets are preferred and better tolerated by patients compared to polyethylene glycol solution plus bisacodyl tablets for bowel preparation

BACKGROUND

Patient acceptance of bowel preparation can affect colon cancer screening compliance. Aim To compare patient acceptance, preference and tolerability of 32-sodium phosphate tablets vs. 2L polyethylene glycol solution plus 4 bisacodyl tablets for bowel preparation.

METHODS

A prospective, randomized, investigator-blinded, multicentre trial was performed. Results were based on responses to a patient questionnaire.

RESULTS

411 patients (205 sodium phosphate; 206 polyethylene glycol plus bisacodyl) completed the study preparation and patient questionnaire prior to colonoscopy. More patients receiving sodium phosphate vs. polyethylene glycol plus bisacodyl found it easy to take (77% vs. 42%), reported it to be without taste (47% vs. 6%), found it easy to take with respect to volume of liquid prescribed (72% vs. 27%) and indicated they would take the same preparation again in the future (96% vs. 74%, P < 0.0001 for all). Fewer patients receiving sodium phosphate vs. polyethylene glycol plus bisacodyl had to take time off work or change ordinary activities to take the study preparation (18% vs. 52%, P < 0.0001). Nausea, vomiting, bloating and abdominal pain were reported less frequently with sodium phosphate (P < 0.0013).

CONCLUSION

The 32-tablet sodium phosphate dosing regimen was easier to take and better tolerated, when compared to 2L polyethylene glycol plus bisacodyl tablets for bowel preparation.

Effects of cilostazol on resting ankle pressures and exercise-induced ischemia in patients with intermittent claudication

During exercise, patients with intermittent claudication (IC) have decreased limb arterial blood pressure that recovers during rest. A novel method for assessing dynamic recovery of function is measurement of the hemodynamic response after exercise. Cilostazol (Pletal), a new agent for the treatment of IC, increases walking distance and may decrease ischemic burden. The objective of this study was to assess the effect of cilostazol versus placebo on hemodynamic measurements after exercise-induced ischemia in patients with IC. Two double-blind, placebo-controlled studies with similar inclusion/exclusion criteria and duration (24 weeks) were pooled. Patients walked on a treadmill at 2.0 miles/h (3.2 km/h) on a 12.5% grade until the claudication-limited maximal walking distance (MWD) was reached. Anterior and posterior tibial pressures were measured with Doppler ultrasound at baseline and at 1, 5, and 9 min during recovery. Area under the curve (AUC), a measure of the time course of recovery of systolic pressure after exercise-induced ischemia, and ankle-brachial index (ABI) were calculated and compared using analysis of variance (ANOVA). All three treatment groups (308 patients randomized to cilostazol 100 mg bid, 303 to cilostazol 50 mg bid, and 299 to placebo) had similar baseline characteristics. Mean post-exercise AUC for cilostazol 100 mg and 50 mg bid versus placebo increased by 0.31 (p = 0.001) and 0.26 (p = 0.004), respectively. Mean resting ABI increased by 0.03 (p = 0.0039) and 0.04 (p = 0.0001) in the cilostazol 100 mg and 50 mg bid groups, respectively. In conclusion, following 24 weeks of treatment, cilostazol increased the ABI at rest and improved the recovery time of ankle pressures post-exercise.

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.

Cilostazol pharmacokinetics after single and multiple oral doses in healthy males and patients with intermittent claudication resulting from peripheral arterial disease

OBJECTIVE

To study the pharmacokinetics of cilostazol following single oral administration of 50 to 200 mg in healthy young males, and after repeated oral administration of 100 mg every 12 hours to patients with peripheral arterial disease (PAD).

DESIGN

The healthy male single dose study was a single-centre, randomised sequence, open-label, incomplete block, 3-period, 4-treatment, crossover design. The patient study was a single-centre, multiple dose, open-label study.

STUDY PARTICIPANTS

20 healthy nonsmoking male volunteers were enrolled and successfully completed the single dose study. 26 patients (21 males, 5 females) with intermittent claudication resulting from PAD were enrolled and completed the single/multiple dose study.

MAIN OUTCOME MEASURES

Noncompartmental pharmacokinetic parameters, the area under the plasma concentration-time curve from zero to the time of last measurable plasma concentration, and maximum plasma concentration.

RESULTS

Peak plasma concentrations of cilostazol occurred about 3 hours after drug administration and then declined biexponentially with concentrations detectable (> 20 micrograms/L) in the plasma for at least 36 hours postdose. The apparent elimination half-life of cilostazol (approximately 11 hours) was similar after a single dose or after multiple doses, with steady state being reached within 4 days. Cilostazol accumulated 1.7-fold following multiple dose administration. The apparent volume of distribution (Vz/F; 2.76 L/kg) suggested extensive distribution of cilostazol in the tissues. The oral clearance of cilostazol (CL/F; 0.18 L/h/kg) was much lower than liver blood flow, indicating a low extraction ratio drug, and hence low probability of a significant first-pass effect. None of the administered doses were recovered in the urine as unchanged cilostazol, suggesting that metabolism, rather than urinary excretion, is the major elimination route. Following single oral doses of 50 to 200 mg, the plasma concentrations of cilostazol and its metabolites increased less than proportionally to the dose. The pharmacokinetics of cilostazol in normal healthy volunteers are predictive of those in patients with PAD. Single oral doses of 50 to 200 mg cilostazol as well as 100 mg cilostazol every 12 hours were well tolerated.

CONCLUSION

The plasma concentration of cilostazol and its metabolites increased less than proportionally with increasing doses. The relatively low plasma clearance and high volume of distribution of cilostazol suggest a low first-pass effect and extensive distribution. The pharmacokinetics of cilostazol in normal volunteers is predictive of that in patients with PAD. Cilostazol was well tolerated in healthy volunteers and patients with intermittent claudication resulting from PAD.

Relative bioavailability and effects of a high fat meal on single dose cilostazol pharmacokinetics

OBJECTIVES

The objectives of this research were to (1) assess the relative bioavailability following administration of a 100 mg cilostazol suspension versus 100 mg tablet; (2) assess dosage form equivalency (2 x 50 mg compared with 1 x 100 mg); (3) compare the relative bioavailability following a single 50 mg dose of cilostazol administered as an ethanolic solution versus a 50 mg tablet; and (4) determine the effects of high fat diet on the pharmacokinetics of cilostazol following a single dose of 100 mg cilostazol in the fed or fasted state. Results were compiled from 3 separate studies to address these objectives.

DESIGN

All studies involved healthy adult males receiving single oral doses of cilostazol in the fed or fasted state. The fed state consisted of administering cilostazol after ingestion of a high fat meal. One study compared the relative bioavailability of 100 mg suspension and 2 x 50 mg tablet versus 100 mg tablet in a randomised crossover design. The study involving administration of a 50 mg cilostazol ethanolic solution was a single treatment study. The effects of food on the pharmacokinetics of cilostazol after administration of 100 mg cilostazol in the fed or fasted state as well as the pharmacokinetic profile following administration of a single 50 mg oral dose of cilostazol were assessed in a randomised crossover design.

STUDY PARTICIPANTS

All participants were healthy nonsmoking males aged between 19 and 48 years whose bodyweight was within 15% of ideal bodyweight.

MAIN OUTCOME MEASURES

Noncompartmental pharmacokinetic parameters were determined for each study participant.

RESULTS

The area under the plasma concentration-time curve (AUC) parameters were within the 80 to 125% criterion for bioequivalence for the cilostazol and its primary metabolite, OPC-13015. The maximum observed plasma concentrations (Cmax) for these formulations were not equivalent and indicated that the absorption of cilostazol from a suspension is more rapid than from a tablet. The apparent terminal half-lives (t1/2z) of cilostazol and OPC-13015 were shorter after administration of the suspension compared with the tablet. Cmax and AUC following administration of a single 50 mg cilostazol tablet were approximately 80% of that from the same dose administered as an ethanolic solution. The t1/2z of cilostazol decreased from 15.5 hours after a tablet to 2.5 hours after an ethanolic solution. Upon coadministration with a high fat meal, the Cmax of cilostazol increased 90% and AUC infinity increased 25% (p < 0.05). The t1/2z decreased from 15.1 +/- 14.5 hours (mean +/- SD) in the fasted state to 5.4 +/- 2.0 hours in the fed state. Single oral doses of 50 and 100 mg cilostazol were well tolerated.

CONCLUSIONS

The relative bioavailability of the 100 mg cilostazol tablet versus an oral 100 mg cilostazol suspension is 100%. The 2 x 50 mg and 1 x 100 mg tablets are considered to be bioequivalent. The absorption following administration of 50 mg cilostazol ethanolic solution is faster and appears to be greater than that after administration of the 50 mg tablet. Coadministration of food increases the rate and extent of cilostazol absorption. The oral pharmacokinetics of cilostazol and metabolites are absorption-rate limited. The significant differences in the t1/2z observed when comparing cilostazol tablet, suspension, and solution as well as the effects of food suggest 'flip-flop' pharmacokinetics.

Effect of hepatic impairment on the pharmacokinetics of a single dose of cilostazol

OBJECTIVE

The pharmacokinetic profiles of cilostazol and its metabolites following a single oral dose of cilostazol 100 mg were compared between individuals with impaired and normal liver function.

DESIGN

The study was conducted as a single-centre, open-label, single dose pharmacokinetic and tolerability trial.

STUDY PARTICIPANTS

12 patients with impaired and compensated liver function were compared with 12 volunteers with normal liver function. Participants in each group were matched for gender, age and weight. Of the 12 patients with hepatic impairment examined in this study, 10 had mild impairment (Child-Pugh class A) and 2 had moderate impairment (Child-Pugh class B).

MAIN OUTCOME MEASURES

Blood and urine were collected up to 144 hours after drug administration. Pharmacokinetics were determined by noncompartmental methods.

RESULTS

Protein binding did not differ between the groups (95.2% healthy volunteers, 94.6% hepatically impaired patients). Mean +/- SD unbound oral clearance of cilostazol decreased by 8.6% because of hepatic impairment (3380 +/- 1400 ml/min in healthy volunteers, 3260 +/- 2030 ml/min in hepatically impaired patients). Total urinary excretion of metabolites was significantly higher in healthy volunteers (26 vs 17% of dose). Overall, the pharmacokinetics of cilostazol and its metabolites, OPC-13213 and OPC-13015, were not substantially different in those with mild and moderate hepatic disease compared with values in healthy volunteers. Except for terminal-phase disposition half-life and apparent terminal-phase volume of distribution for cilostazol, the ratios of geometric means of pharmacokinetic parameters for plasma cilostazol, OPC-13213 and OPC-13015 in those with hepatic impairment versus healthy volunteers were close to 100%.

CONCLUSIONS

Based on the results of the pharmacokinetic analysis, dose adjustment in patients with mild hepatic impairment is not necessary. However, caution should be exercised when cilostazol is administered to patients with moderate or severe hepatic impairment.

Effects of CYP3A inhibition on the metabolism of cilostazol

OBJECTIVE

In vitro results suggest that cilostazol is metabolised by cytochrome P450 (CYP) isoforms 1A2, 2D6, 3A and 2C19. This study investigated the role of CYP3A inhibition on the metabolism of cilostazol.

DESIGN

The study was conducted as a single-centre, open-label, nonrandomised, 2-period, crossover pharmacokinetic trial. A single dose of cilostazol 100 mg was administered orally on days 1 and 15. Erythromycin (150 mg orally 3 times daily) was administered on days 8 to 20. 14C-erythromycin (3 microns Ci) was administered intravenously on days 1 and 15 one hour before cilostazol administration to determine baseline and the inhibitory effect of erythromycin treatment on CYP3A activity.

STUDY PARTICIPANTS

16 healthy nonsmoking male volunteers.

MAIN OUTCOME MEASURES

Serial blood and pooled urine samples were collected before and after cilostazol administration to quantitate cilostazol and its metabolites. Serial exhalation samples were collected after intravenous 14C-erythromycin administration and radioactivity was quantitated by scintillation counting. Pharmacokinetics were determined by noncompartmental methods and compared before and after erythromycin administration. Tolerability assessments included adverse events, laboratory tests, vital signs and electrocardiographs.

RESULTS

Following erythromycin coadministration, cilostazol maximum plasma concentration (Cmax), area under the plasma concentration-time curve at time t (AUCt), and area under the curve from zero to infinity (AUC infinity) increased significantly by 47, 87, and 73%, respectively, and an approximately 50% reduction in unbound clearance was observed for the major circulating metabolite of cilostazol, OPC-13015. Cmax decreased significantly (p < 0.001) by 24%, while AUCt increased by 8%; this increase was not significant. For the second major metabolite, OPC-13213, the Cmax and AUCt increased by 29 and 141%, respectively (p < 0.001).

CONCLUSIONS

In vivo results are in agreement with previous in vitro human microsome studies, indicating that cilostazol is metabolised to OPC-13015 via CYP3A. In addition, OPC-13213 concentrations increased after inhibition of CYP3A because of inhibition of sequential metabolism of OPC-13213 via CYP3A. A starting dose for cilostazol of 50 mg twice daily should be considered during coadministration of inhibitors of CYP3A.

Interaction potential and tolerability of the coadministration of cilostazol and aspirin

OBJECTIVE

This study evaluated the effects of repeated oral drug administration with cilostazol alone and with aspirin (acetylsalicylic acid) on platelet aggregation, coagulation and bleeding time as well as the cilostazol-aspirin pharmacokinetic interaction in healthy males.

DESIGN

This was a randomised, double-blind, placebo-controlled, crossover study. Participants received either cilostazol 100 mg or placebo twice a day for 10 days; aspirin 325 mg/day was coadministered for the last 5 days. After a 14-day washout period, participants received the alternative treatment.

STUDY PARTICIPANTS

12 healthy male volunteers were enrolled.

MAIN OUTCOME MEASURES

Differences in bleeding times, platelet aggregation, prothrombin time (PT) and activated partial thromboplastin time (aPTT) between cilostazol with aspirin and cilostazol alone. Noncompartmental pharmacokinetic parameters were determined for each study participant.

RESULTS

Cilostazol, with or without aspirin, caused no changes in PT, aPTT or bleeding time. There was a 23 to 35% increase in inhibition of ADP-induced ex vivo platelet aggregation by cilostazol plus aspirin when compared with aspirin alone. There was no additive or synergistic effect on arachidonic acid-induced platelet aggregation. Statistically significant but clinically insignificant increases in the area under the plasma concentration-time curve to the last measurable plasma concentration and trough concentrations of cilostazol and its metabolites (OPC-13015 and OPC-13213) occurred after aspirin coadministration, with no differences observed in the maximum plasma concentration Drug-related adverse events were generally mild, the most frequent being headache.

CONCLUSIONS

Cilostazol and aspirin coadministration did not cause clinically significant changes in PT, aPTT, bleeding time, platelet aggregation or plasma concentrations of cilostazol and its 2 active metabolites. Cilostazol was generally well tolerated with or without aspirin.

Effect of renal impairment on the pharmacokinetics of cilostazol and its metabolites

OBJECTIVE

The pharmacokinetics of cilostazol were studied in patients with mild, moderate and severe renal impairment and in healthy volunteers after administration of 50 mg single and multiple doses of cilostazol.

DESIGN

This was an open-label, single and multiple dose study administering 50 mg cilostazol every 12 hours to healthy volunteers and patients with varying degrees of renal impairment.

PARTICIPANTS

6 normal volunteers [creatinine clearance (CLCR) > or = 90 ml/min]; 6 patients with mild (CLCR 50 to 89 ml/min), 5 with moderate (CLCR 26 to 49 ml/min) and 6 with severe (CLCR 5 to 25 ml/min) renal impairment.

OUTCOME MEASURES

Noncompartmental pharmacokinetic parameters were determined for each study participant.

RESULTS

At steady state, in the severe renal disease group, cilostazol and OPC-13015 peak concentrations (Cmax) were 29 and 41% lower and the areas under the concentration-time curve over the dosage interval (AUC tau) 39 and 47% lower than in the healthy volunteers. Cmax and AUC tau of OPC-13213 were significantly higher, 173 and 209%, respectively, than those in the healthy volunteers. The accumulation ratios were not significantly different between the various renal function groups for cilostazol and its metabolites. The estimated pharmacological activity of cilostazol and its metabolites was similar between the normal volunteers and those with severe renal impairment.

CONCLUSIONS

A dosage reduction in renally impaired patients is not supported by the pharmacokinetics of cilostazol and its metabolites in this patient group.

A new pharmacological treatment for intermittent claudication: results of a randomized, multicenter trial

BACKGROUND

Effective medication is limited for the relief of intermittent claudication, a common manifestation of arterial occlusive disease. Cilostazol is a potent inhibitor of platelet aggregation with vasodilation effects.

OBJECTIVE

To evaluate the safety and efficacy of cilostazol for the treatment of intermittent claudication.

METHODS

Thirty-seven outpatient vascular medicine clinics at regional tertiary and university hospitals in the United States participated in this multicenter, randomized, double-blind, placebo-controlled, parallel trial. Of the 663 screened volunteer patients with leg discomfort, a total of 516 men and women 40 years or older with a diagnosis of moderately severe chronic, stable, symptomatic intermittent claudication were randomized to receive cilostazol, 100 mg, cilostazol, 50 mg, or placebo twice a day orally for 24 weeks. Outcome measures included pain-free and maximal walking distances via treadmill testing, patient-based quality-of-life measures, global assessments by patient and physician, and cardiovascular morbidity and all-cause mortality survival analysis.

RESULTS

The clinical and statistical superiority of active treatment over placebo was evident as early as week 4, with continued improvement at all subsequent time points. After 24 weeks, patients who received cilostazol, 100 mg, twice a day had a 51% geometric mean improvement in maximal walking distance (P<.001 vs placebo); those who received cilostazol, 50 mg, twice a day had a 38% geometric mean improvement in maximal walking distance (P<.001 vs placebo). These percentages translate into an arithmetic mean increase in distance walked, from 129.7 m at baseline to 258.8 m at week 24 for the cilostazol, 100 mg, group, and from 131.5 to 198.8 m for the cilostazol, 50 mg, group. Geometric mean change for pain-free walking distance increased by 59% (P<.001) and 48% (P<.001), respectively, in the cilostazol, 100 mg, and cilostazol, 50 mg, groups. These results were corroborated by the results of subjective quality-of-life assessments, functional status, and global evaluations. Headache, abnormal stool samples or diarrhea, dizziness, and palpitations were the most commonly reported potentially drug-related adverse events and were self-limited. A total of 75 patients (14.5%) withdrew because of any adverse event, which was equally distributed between all 3 treatment groups. Similarly, there were no differences between groups in the incidence of combined cardiovascular morbidity or all-cause mortality.

CONCLUSION

Compared with placebo, long-term use of cilostazol, 100 mg or 50 mg, twice a day significantly improves walking distances in patients with intermittent claudication.

Effect of the novel antiplatelet agent cilostazol on plasma lipoproteins in patients with intermittent claudication

Cilostazol is an antiplatelet agent and vasodilator marketed in Japan for treatment of ischemic symptoms of peripheral vascular disease. It is currently being evaluated in the United States for treatment of symptomatic intermittent claudication (IC). Cilostazol has been shown to improve walking distance in patients with IC. In addition to its reported vasodilator and antiplatelet effects, cilostazol has been proposed to have beneficial effects on plasma lipoproteins. We examined the effect of cilostazol versus placebo on plasma lipoproteins in 189 patients with IC. After 12 weeks of therapy with 100 mg cilostazol BID, plasma triglycerides decreased 15% (P<0.001). Cilostazol also increased plasma high density lipoprotein cholesterol (HDL-C) (10%) and apolipoprotein (apo) A1 (5.7%) significantly (P<0.001 and P<0.01, respectively). Both HDL3 and HDL2 subfractions were increased by cilostazol; however, the greatest percentage increase was observed in HDL2. Individuals with baseline hypertriglyceridemia (>140 mg/dL) experienced the greatest changes in both HDL-C and triglycerides with cilostazol treatment. In that subset of patients, HDL-C was increased 12.2% and triglycerides were decreased 23%. With cilostazol, there was a trend (3%) toward decreased apoB as well as increased apoA1, resulting in a significant (9.8%, P<0.002) increase in the apoA1 to apoB ratio. Low density lipoprotein cholesterol and lipoprotein(a) concentrations were unaffected. Cilostazol treatment resulted in a 35% increase in treadmill walking time (P=0.0015) and a 9.03% increase in ankle-brachial index (P<0.001). These results indicate that in addition to improving the symptoms of IC, cilostazol also favorably modifies plasma lipoproteins in patients with peripheral arterial disease. The mechanism of this effect is currently unknown.

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.

Pharmacokinetics of multiple-dose oral cilostazol in middle-age and elderly men and women

Cilostazol is being developed for the treatment of intermittent claudication due to peripheral arterial disease (PAD). This study was conducted to investigate the effects of age and gender on the pharmacokinetics of cilostazol after multiple-dose administration. It was an open label, multiple-dose study of cilostazol administered to male and female subjects 50 years of age and older at a dose of 100 mg (oral tablet) twice daily for 7 days. Equal numbers of healthy male and female (7 per group), nonsmoking subjects stratified into age groups of 50 to 59 years, 60 to 69 years, and 70 years or older were enrolled. Serial plasma samples were obtained. Data were analyzed by model-independent methods. Cilostazol was absorbed at a moderate rate, with peak plasma concentrations occurring at an overall mean of 2.4 hours after administration. Cilostazol is extensively bound (95%), primarily to albumin. A trend toward increasing cilostazol free fraction with age was observed in the male subjects, which was explained by a decrease in plasma albumin concentration with age. Differences in plasma protein binding between age and gender groups (less than 15%) are not expected to have any clinical significance. Plasma cilostazol concentrations reached steady state by day 4. The pharmacokinetic characteristics of cilostazol were not affected by age or gender.

The effectiveness of labetalol compared to hydrochlorothiazide in hypertensive black patients

Labetalol and hydrochlorothiazide (HCTZ) were compared for their efficacy in controlling hypertension of blacks in a prospective, double-blind study. Sixty-one adult patients with mild to moderate hypertension (standing diastolic blood pressure greater than or equal to 95 mm Hg and less than or equal to 114 mm Hg) were randomly selected to receive either labetalol 100 mg twice daily (n = 30) or HCTZ 25 mg twice daily (n = 31). The study was divided into two phases: a 4-week placebo run-in phase, during which all previous antihypertensive medication was discontinued, and a 12-week drug treatment phase. Labetalol and HCTZ doses were titrated to 400 mg twice and 50 mg twice daily, respectively, during the first 6 weeks of the drug treatment phase for those patients not achieving blood pressure control (standing diastolic blood pressure less than 90 mm Hg and a decrease of 10 mm Hg from baseline) on initial dosages. By the end of the 12 weeks of drug administration, patients on labetalol experienced a mean decrease of 10 mm Hg in standing diastolic blood pressure compared to a mean decrease of 10.1 mm Hg in patients on HCTZ. No differences were observed between the two treatment groups in reductions of either standing blood pressure or heart rate. While 19 of 30 patients on labetalol (63%) achieved blood pressure control at some point during the study with a mean daily dose of 568 mg, 18 of 31 (58%) HCTZ-treated patients achieved control with a mean daily dose of 72 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of milrinone in the management of congestive heart failure

Milrinone is a bipyridine derivative with positive inotropic and vasodilating properties. The intravenous form of the drug has been approved by the Food and Drug Administration (FDA) for short-term management of congestive heart failure (CHF). The FDA has requested additional mortality data prior to approval of the oral form. Milrinone produces positive inotropic and vasodilating effects through unknown mechanisms, and causes a dose-dependent increase in cardiac index and a decrease in systemic vascular resistance and pulmonary capillary wedge pressure. It is extensively absorbed following oral administration with an elimination half-life of approximately 1.5-2 hours and a corresponding duration of action of 3-6 hours. Its major route of elimination is renal (83 percent). The intravenous dose is 50 micrograms/kg given over ten minutes, followed by a maintenance infusion of 0.375-0.75 micrograms/kg/min titrated to the desired hemodynamic response. The average effective oral dosage is 7.5-10 mg four to six times daily. Milrinone is most effective in the short-term management of CHF where the majority (60-80 percent) of patients have symptomatic and hemodynamic improvement as well as increases in exercise duration. However, many patients do not derive long-term benefit from milrinone therapy. Available evidence suggests that milrinone does not arrest the natural progression of CHF, and some investigators feel it may actually worsen CHF and shorten patients' length of survival. Milrinone has been generally well tolerated with a low risk of major organ toxicity. The most common adverse reactions with intravenous milrinone include ventricular arrhythmias (12 percent) and supraventricular arrhythmias (4 percent).(ABSTRACT TRUNCATED AT 250 WORDS)