Population Exposure-Response Modeling of Naloxegol in Patients With Noncancer-Related Pain and Opioid-Induced Constipation.

Naloxegol is a polyethylene glycol derivative of naloxone approved in the US as a once-daily oral treatment for opioid-induced constipation (OIC) in adults with chronic noncancer pain. Population exposure-response models were constructed based on data from two phase III studies comprising 1,331 adults with noncancer pain and OIC. In order to characterize the protocol-defined naloxegol responder rate, the number of daily spontaneous bowel movements (SBMs) was characterized by a longitudinal ordinal nonlinear mixed-effects logistic regression dose-response model, and the incidence of diary entry discontinuation was described by a time-to-event model. The mean number of SBMs per week increased with increasing naloxegol dose. The predicted placebo-adjusted responder rates (90% confidence interval) were 10.4% (4.6-13.4%) and 11.1% (4.8-14.4%) for naloxegol 12.5 and 25 mg/day, respectively. Model-predicted response to naloxegol was influenced by the baseline SBM frequency and characteristics of the opioid treatment.

Simulation and Prediction of the Drug-Drug Interaction Potential of Naloxegol by Physiologically Based Pharmacokinetic Modeling.

Naloxegol, a peripherally acting µ-opioid receptor antagonist for the treatment of opioid-induced constipation, is a substrate for cytochrome P450 (CYP) 3A4/3A5 and the P-glycoprotein (P-gp) transporter. By integrating in silico, preclinical, and clinical pharmacokinetic (PK) findings, minimal and full physiologically based pharmacokinetic (PBPK) models were developed to predict the drug-drug interaction (DDI) potential for naloxegol. The models reasonably predicted the observed changes in naloxegol exposure with ketoconazole (increase of 13.1-fold predicted vs. 12.9-fold observed), diltiazem (increase of 2.8-fold predicted vs. 3.4-fold observed), rifampin (reduction of 76% predicted vs. 89% observed), and quinidine (increase of 1.2-fold predicted vs. 1.4-fold observed). The moderate CYP3A4 inducer efavirenz was predicted to reduce naloxegol exposure by ∼50%, whereas weak CYP3A inhibitors were predicted to minimally affect exposure. In summary, the PBPK models reasonably estimated interactions with various CYP3A modulators and can be used to guide dosing in clinical practice when naloxegol is coadministered with such agents.

Randomised clinical trial: the long-term safety and tolerability of naloxegol in patients with pain and opioid-induced constipation.

BACKGROUND: Opioid-induced constipation (OIC) is a common adverse effect of opioid therapy. AIM: To evaluate the long-term safety and tolerability of naloxegol, an oral, peripherally acting µ-opioid receptor antagonist (PAMORA), in patients with noncancer pain and OIC. METHODS: A 52-week, multicenter, open-label, randomised, parallel-group phase 3 study was conducted in out-patients taking 30-1000 morphine-equivalent units per day for ≥4 weeks. Patients were randomised 2:1 to receive naloxegol 25 mg/day or usual-care (UC; investigator-chosen laxative regimen) treatment for OIC. RESULTS: The safety set comprised 804 patients (naloxegol, n = 534; UC, n = 270). Mean exposure duration was 268 days with naloxegol and 297 days with UC. Frequency of adverse events (AEs) was 81.8% with naloxegol and 72.2% with UC. Treatment-emergent AEs occurring more frequently for naloxegol vs. UC were abdominal pain (17.8% vs. 3.3%), diarrhoea (12.9% vs. 5.9%), nausea (9.4% vs. 4.1%), headache (9.0% vs. 4.8%), flatulence (6.9% vs. 1.1%) and upper abdominal pain (5.1% vs. 1.1%). Most naloxegol-emergent gastrointestinal AEs occurred early, resolving during or after naloxegol discontinuation and were mild or moderate in severity; 11 patients discontinued due to diarrhoea and nine patients owing to abdominal pain. Pain scores and mean daily opioid doses remained stable throughout the study; no attributable opioid withdrawal AEs were observed. Two patients in each group had an adjudicated major adverse cardiovascular event unrelated to study drug; no AEs were reported nor adjudicated as bowel perforations. CONCLUSION: In patients with noncancer pain and opioid-induced constipation, naloxegol 25 mg/day up to 52 weeks was generally safe and well tolerated.

Clinical trial: the incidence of NSAID-associated endoscopic gastric ulcers in patients treated with PN 400 (naproxen plus esomeprazole magnesium) vs. enteric-coated naproxen alone.

BACKGROUND: Gastroprotective co-therapy may reduce the risk of nonsteroidal anti-inflammatory drug (NSAID)-associated gastric ulcers, but adherence is suboptimal. AIM: To compare the incidence of gastric ulcers with PN 400 [enteric-coated (EC) naproxen 500 mg and immediate-release esomeprazole 20 mg], or EC naproxen. METHODS: Two randomized, double-blind, multicentre studies (PN400-301, PN400-302). Patients [stratified by low-dose aspirin (< or =325 mg) use] aged > or =50 years or 18-49 years with a history of ulcer, received PN 400 BID (301, n = 218; 302, n = 210) or EC naproxen 500 mg BID (301, n = 216; 302, n = 210) for 6 months. The primary endpoint was the cumulative incidence of endoscopic gastric ulcers. RESULTS: The cumulative incidence of gastric ulcers was significantly lower with PN 400 vs. EC naproxen (301: 4.1% vs. 23.1%, P < 0.001; 302: 7.1% vs. 24.3%, P < 0.001). PN 400 was associated with a lower combined incidence of gastric ulcers vs. EC naproxen in low-dose aspirin users (n = 201) (3.0% vs. 28.4%, P < 0.001) and non-users (n = 653) (6.4% vs. 22.2%, P < 0.001). The incidence of, and discontinuations due to, upper gastrointestinal (UGI) AEs was significantly lower with PN 400 relative to EC naproxen (P < 0.01, both studies). CONCLUSIONS: PN 400 significantly reduces the incidence of gastric ulcers, regardless of low-dose aspirin use, in at-risk patients, and is associated with improved UGI tolerability relative to EC naproxen (ClinicalTrials.gov, NCT00527782).

Clinical trial: evaluation of gastric acid suppression with three doses of immediate-release esomeprazole in the fixed-dose combination of PN 400 (naproxen/esomeprazole magnesium) compared with naproxen 500 mg and enteric-coated esomeprazole 20 mg: a randomized, open-label, Phase I study in healthy volunteers.

BACKGROUND: PN 400 is a fixed-dose combination formulated to provide sequential delivery of immediate-release (IR) esomeprazole and enteric-coated (EC) naproxen. AIM: To evaluate gastric acid suppression with three doses of esomeprazole in PN 400 compared with EC esomeprazole 20 mg. METHODS: In this Phase I, randomized, open-label study, 28 healthy adults received PN 400 b.d. (naproxen 500 mg plus esomeprazole 10, 20 and 30 mg) and non-EC naproxen 500 mg b.d. plus EC esomeprazole 20 mg o.d., each for 9 days in a crossover fashion. The primary endpoint was percentage of time on day 9 that intragastric pH was >4.0; secondary endpoints included pharmacokinetics and safety. RESULTS: Day 9 percentage of time where intragastric pH was >4.0 was 76.5%, 71.4%, 40.9% and 56.9% [corrected] for PN 400 containing 30, 20 and 10 mg esomeprazole, and naproxen plus esomeprazole 20 mg respectively. This was significantly greater for PN 400 containing 30 and 20 mg esomeprazole vs. naproxen plus esomeprazole 20 mg (95% CI: 13.0-26.0 and 7.8-20.7 respectively). The pharmacokinetics of PN 400 were consistent with its formulation. No serious adverse events occurred. CONCLUSION: PN 400 containing 20 mg esomeprazole was the lowest dose to achieve gastric acid suppression comparable to EC esomeprazole 20 mg and was selected for further evaluation.

Intravenous esomeprazole pharmacodynamics in critically ill patients.

OBJECTIVE: A widely held belief contends that food-induced proton pump activation is important for optimal proton pump inhibitor-induced inhibition of gastric acid secretion. This study was undertaken to assess intragastric acid control with intravenous (IV) esomeprazole in critically ill patients. RESEARCH DESIGN AND METHODS: This open-label, single-arm, exploratory trial was conducted at five university or regional hospital intensive care units in the US. Adult patients admitted to an intensive care unit who required mechanical ventilation and had at least one additional risk factor for stress-induced ulcer received twice-daily IV esomeprazole 40 mg for 48 hours and could continue for another 24 hours if no prepyloric enteral feedings were planned. CLINICAL TRIAL REGISTRATION: D9612L00107; ClinicalTrials.gov Identifier NCT00428701. MAIN OUTCOME MEASURES: The primary efficacy variable was the linear-interpolated percentage of time intragastric pH was > or =4 during 24-48 hours. Secondary efficacy variables included the interpolated percentage of time intragastric pH was > or =4 during 0-24, 0-48, and 48-72 hours, the percentage of gastric aspirates collected with pH > or =4 during 0-24, 24-48, 0-48, and 48-72 hours, and time to stable pH > or =4. Safety was assessed based on adverse events (AEs), physical examinations, vital signs, laboratory tests, and electrocardiograms. RESULTS: Forty-five patients were enrolled (one was excluded because of previous partial gastrectomy). Interpolated mean percentage time pH > or =4 was 88.8%, 80.7%, and 83.5% for 24-48, 0-24, and 0-48 hours, respectively. For 0-72 hours, > or =78% of gastric aspirates had pH > or =4. Median time to stable pH was 1 hour (95% confidence interval: 0.67, 2.00). Treatment was well tolerated, with no evidence of gastrointestinal bleeding. A total of 75 AEs occurred in 34 patients, none considered treatment related. CONCLUSIONS: In this noncontrolled exploratory study, twice-daily IV esomeprazole 40 mg rapidly decreased intragastric acidity and effectively maintained pH >/=4 during 0-72 hours in fasting, critically ill, mechanically ventilated patients at high risk for stress ulcers.

Intravenous esomeprazole 40 mg vs. intravenous lansoprazole 30 mg for controlling intragastric acidity in healthy adults.

BACKGROUND: Intravenous (IV) formulations of proton pump inhibitors are effective for patients in whom oral therapy is not appropriate. AIM: To compare IV esomeprazole and IV lansoprazole for the control of intragastric pH. METHODS: In this open-label crossover study, healthy, Helicobacter pylori-negative adults were randomized to one of two treatment sequences, each consisting of two 5-day dosing periods of IV esomeprazole 40 mg or IV lansoprazole 30 mg. Twenty-four-hour intragastric pH monitoring was conducted on days 1 and 5 of each dosing period. RESULTS: On days 1 and 5, intragastric pH was >4.0 significantly longer with esomeprazole than lansoprazole (least-squares means: day 1, 40.0% vs. 33.6%; day 5, 61.9% vs. 45.4%; both P < 0.0001). During the first 4 h of pH monitoring, intragastric pH was >4.0 significantly longer on days 1 and 5 with esomeprazole than lansoprazole (P < 0.0001). Kaplan-Meier estimates of median hours to stable pH >4.0 were 4.92 for esomeprazole and 5.75 for lansoprazole (P = 0.0014 for test on Gehan scores). CONCLUSION: In healthy adults, IV esomeprazole 40 mg controlled intragastric acidity faster and more effectively than IV lansoprazole 30 mg.

Relationship between intragastric acid control and healing status in the treatment of moderate to severe erosive oesophagitis.

AIM: To assess the relationship between the percentage of time intragastric pH >4.0 and healing of erosive oesophagitis. METHODS: In this proof-of-concept study, adults with endoscopically verified Los Angeles grade C or grade D erosive oesophagitis were randomly assigned to oral esomeprazole 10 or 40 mg once daily for 4 weeks. On day 5, patients underwent 24-h pH monitoring. At 4 weeks, erosive oesophagitis healing status was endoscopically assessed. Investigators scored gastro-oesophageal reflux disease symptoms on a 4-point scale [none to severe (0-3)] before and 4 weeks after treatment. The percentage of time intragastric pH was >4.0 and healing status were correlated and tested for significance using a Spearman rank correlation (r). RESULTS: 103 patients had evaluable data (mean age, 48.7 years; 65% men). Mean percentages of time with intragastric pH >4.0 on day 5 in patients with healed and unhealed erosive oesophagitis were 61% and 42%, respectively (P = 0.0002), indicating that erosive oesophagitis healing rates were positively related to the percentage of time intragastric pH was >4.0. Greater intragastric acid control correlated with lower final daytime and night-time heartburn and acid regurgitation symptom scores (r = -0.029, -0.029 and -0.021; P = 0.003, 0.003 and 0.032, respectively). CONCLUSION: A positive relationship between intragastric acid control and erosive oesophagitis healing was demonstrated.

Comparison of the effects of intravenously and orally administered esomeprazole on acid output in patients with symptoms of gastro-oesophageal reflux disease.

BACKGROUND: Intravenous esomeprazole may be beneficial for patients who cannot take oral medications. AIM: To compare intravenous esomeprazole with oral esomeprazole for effects on maximal acid output during pentagastrin stimulation in patients with gastro-oesophageal reflux disease symptoms. METHODS: In four separate open-label, randomized, two-way crossover studies, adult patients were administered esomeprazole 20 or 40 mg once daily either orally or intravenously (by 15-min infusion or 3-min injection) for 10 days and switched to the other formulation with no washout period. Basal acid output and maximal acid output were measured on days 11, 13 and 21. RESULTS: In the four studies (total of 183 patients), least-squares mean maximal acid output ranged from 3.0 to 4.1 mmol/h after intravenous esomeprazole 40 or 20 mg and from 2.2 to 3.3 mmol/h after oral esomeprazole 20 or 40 mg. Differences between formulations were small and not statistically significant but did not meet the prospectively defined criterion for non-inferiority of the intravenous formulation. Median basal acid output values ranged from 0.04 to 0.27 mmol/h after intravenous administration and from 0.05 to 0.25 mmol/h after oral esomeprazole. CONCLUSIONS: Intravenous esomeprazole is an acceptable alternative to the oral formulation for treatment of up to 10 days of duration.

Efficacy of esomeprazole 40 mg vs. lansoprazole 30 mg for healing moderate to severe erosive oesophagitis.

BACKGROUND: Secondary analyses from previous studies indicated that esomeprazole was more effective than lansoprazole and omeprazole in healing moderate or severe (Los Angeles grades C or D) erosive oesophagitis (EE). AIM: To compare prospectively healing rates with esomeprazole vs. lansoprazole in patients with moderate to severe EE. METHODS: In this multicentre, randomized, double-blind, parallel-group trial, adult patients with endoscopically confirmed moderate or severe EE received esomeprazole 40 mg (n = 498) or lansoprazole 30 mg (n = 501) once daily for up to 8 weeks. The primary end point was EE healing through week 8. Secondary assessments included investigator-assessed resolution of symptoms and safety and tolerability. RESULTS: Time to healing was significantly different (P = 0.007), favouring esomeprazole. Estimated healing rates at week 8 were 82.4% with esomeprazole 40 mg and 77.5% with lansoprazole 30 mg. Heartburn resolved at week 4 in 72% and 64% of patients who received esomeprazole and lansoprazole, respectively (P = 0.005). Control of other GERD symptoms was similar between treatments. Both treatments were well tolerated. CONCLUSIONS: With 8 weeks' treatment, esomeprazole 40 mg once daily heals moderate to severe EE faster and in more patients, and resolves heartburn in more patients after 4 weeks of treatment, than lansoprazole 30 mg once daily.

Intragastric acid suppression and pharmacokinetics of twice-daily esomeprazole: a randomized, three-way crossover study.

BACKGROUND: Patients with refractory gastro-oesophageal reflux disease, extra-oesophageal reflux symptoms, Barrett's oesophagus, or Zollinger-Ellison syndrome may require greater acid suppression than that obtained with once-daily esomeprazole. AIM: To assess gastric acid suppression (determined by intragastric pH) and pharmacokinetics of twice-daily vs. once-daily esomeprazole. METHODS: In a randomized, double-blind, three-way crossover study, healthy subjects received esomeprazole 40 mg once daily, 20 mg twice daily, or 40 mg twice daily for five consecutive days. Twenty-four-hour continuous ambulatory intragastric pH was recorded on day 5. RESULTS: Esomeprazole 40 mg twice daily provided a mean of 19.2 h with intragastric pH > 4.0 (80.1% of a 24-h time period; 95% confidence interval 74.5-85.7%) vs. 14.2 h with 40 mg once daily (59.2%; 95% CI 53.7-64.7%) and 17.5 h with 20 mg twice daily (73.0%; 95% confidence interval 67.4-78.5%) in 25 subjects. Intragastric pH was maintained >4.0 for a similar percentage of time during active and sleeping periods for all doses. CONCLUSIONS: Esomeprazole 40 mg twice daily provides significantly greater acid suppression (number of hours in a 24-h period with pH > 4.0) than once-daily dosing and may be a reasonable consideration for patients requiring greater acid suppression for acid-related disease.

Esomeprazole administered through a nasogastric tube provides bioavailability similar to oral dosing.

AIM: To determine if nasogastric tube administration of the enteric-coated pellets from an opened esomeprazole capsule provides bioavailability similar to oral dosing with the intact capsule. METHODS: A randomized, single-centre, open-label, two-period crossover pharmacokinetic study consisting of two 5-day dosing periods separated by a 7- to 14-day washout period was conducted. Healthy subjects between the ages of 18 and 50 years received esomeprazole 40 mg once daily either orally as an intact capsule, or as a suspension of the enteric-coated pellets from an opened capsule in water through a nasogastric tube. RESULTS: In 47 evaluable subjects, the 90% confidence intervals were 0.87-1.08 and 0.93-1.25 for the geometric mean of the ratio of nasogastric tube administration relative to administration of the intact capsule for the area under the plasma concentration-time curve and for maximum plasma concentration, respectively, on day 1, demonstrating bioequivalence. Oral and nasogastric administration also demonstrated similar bioavailabilities on day 5. Esomeprazole was well tolerated regardless of the mode of administration. CONCLUSIONS: Nasogastric tube administration of the enteric-coated pellets from an opened esomeprazole 40 mg capsule provides bioavailability similar to oral dosing. Administration of the contents of an opened esomeprazole 40 mg capsule in water through a nasogastric tube is a practical alternative for patients with feeding tubes who require effective gastric acid suppression, but cannot swallow an oral preparation.

Focus of signet ring cell carcinoma in an adenoma of the sigmoid colon.

A case of a pedunculated adenomatous polyp of the sigmoid colon was found to have a primary focus of signet ring cell carcinoma. Histologic examination of the medium-sized polyp was consistent with an adenoma to carcinoma sequence for signet ring cell carcinoma of the colon, similar to that for the common adenocarcinomas.

High prevalence of chronic gastrointestinal symptoms in a National Guard Unit of Persian Gulf veterans.

OBJECTIVES: To determine the prevalence and spectrum of GI complaints in a group of Persian Gulf veterans (PGV) and to compare these data to a group of veterans (controls) from the same unit who were not deployed to the Persian Gulf region. METHODS: A 68-item survey was distributed to 136 members of a single National Guard Unit. The survey asked the veterans to rate the frequency of GI symptoms before, during, and after the Persian Gulf war had concluded. The participants were also asked to rate frequency of 10 non-GI symptoms at the time of this survey. RESULTS: Fifty-seven PGV and 44 nondeployed veterans participated in the survey. Before the Persian Gulf war, both PGV and control groups reported low frequencies of GI symptoms. A majority of the PGV experienced GI symptoms during their deployment to the Gulf region, which persisted after their return to the United States. There were many significant differences observed between the two groups in frequency of both GI and non-GI symptoms. The greatest differences seen were for excessive gas, loose or greater than three stools per day, incomplete rectal evacuation, and abdominal pain. CONCLUSIONS: A high prevalence of chronic GI symptoms exists in this group of PGV and is significantly greater than a group of controls. The most prevalent chronic GI symptoms are those that have been associated with functional GI disorders. However, the abrupt onset and clustering in this group suggests that nonfunctional etiologies may be contributing factors.

Ca2+-mediated degradation of central nervous system (CNS) proteins: topographic and species variation.

Incubation of homogenates of rat, rabbit, and bovine spinal cord and of bovine brain white and gray matter in the presence of calcium (5 mM) produced an extensive degradation of the neurofilament triplet proteins (NFP; 200 K, 150 K, and 69 K). The breakdown products of the NFPs were identified by immunoblot. The glial fibrillary acidic protein (GFAP), microtubular proteins (MTP), and myelin proteins were also degraded. The 150 K NFP was more susceptible than the other NFPs. The extent of calcium-mediated degradation was slightly greater with rat spinal cord than the others. Bovine brain white matter had more activity than gray, which had no appreciable degradative activity. The breakdown was prevented by both EGTA and leupeptin but a similar concentration of MgCl2 (5 mM) had no effect. These results suggest that NFPs are degraded by a Ca2+-activated neutral proteinase in the central nervous system (CNS) of several species. The lesser activity in gray matter suggests that the enzyme is enriched in axons, myelin, and/or oligodendroglial cells.

Purification of a calcium-activated neutral proteinase from bovine brain.

A calcium-activated neutral proteinase (CANP) resolved into three components has been partially purified from bovine brain. The method of isolation has resulted in 22,000, 7,100, and 8,000-fold purification for CANP I, II and III respectively. All three fractions require Ca2+ for activation. The characterization of the purified CANP I has shown that it is activated by 250 microM Ca2+ and the enzyme loses its activity when incubated in the presence of Ca2+ without substrate. Mg2+ is ineffective. The enzyme degrades neurofilament triplet proteins, tubulin and casein efficiently. The myelin basic protein is hydrolyzed after longer incubation. Bovine serum albumin and histones are unaffected. The enzyme is active at pH 5.5 to 9.0 with optimum between pH 7.5 and 8.5. It has a Km of 1.8 X 10(-7) M for the 69,000 dalton neurofilament protein. The enzyme is inhibited by sulphydryl blocking reagents and also by EGTA, leupeptin and E-64c. The SDS-PAGE analysis of the enzyme fractions has shown a major band at 66-68,000 daltons and two minor bands at 60,000 and 48-50,000 daltons for CANP I; a major band at 48-50,000 daltons and a minor band at 30-32,000 daltons for CANP II and a predominant doublet at 30-32,000 daltons with a minor band at 48-50,000 daltons for CANP III. The degradation of neurofilament proteins suggests that the CANP(s) may be involved in the turnover of these proteins.

Kallikrein content of rat pancreatic acinar cells or islets by direct radioimmunoassay.

Recent reports have suggested that kallikreins may enzymatically convert proinsulin to insulin. The quantity of rat pancreatic kallikrein in isolated Islets of Langerhans, acinar cells and in whole pancreatic extracts was measured by direct radioimmunoassay and bioassay. Immunoreactive kallikrein content in acinar cells was 813 +/- 111 ng/mg protein (mean +/- S.E.M.). In whole pancreatic homogenates, it was 1303 +/- 213 ng/mg protein. Appreciable quantities of the enzyme were not detected in islets. Kallikrein activity as measured with a rat uterine bioassay had similar distribution. Because of the localization of kallikrein, it is unlikely that the enzyme is involved in the in vivo conversion of proinsulin to insulin.