Maternal paracetamol intake and fetal ductus arteriosus constriction/closure: comprehensive signal evaluation using the Austin Bradford Hill criteria.

PURPOSE: Acetaminophen (APAP) is available over-the-counter and widely regarded as safe for use in pregnancy. APAP has been used to close a persistently patent ductus arteriosus. Fetal constriction/closure of the ductus arteriosus (FCCDA), of public health interest given the drug's widespread use during pregnancy, is being monitored globally, including by the European Medicines Agency Pharmacovigilance Risk Assessment Committee. Our objective was to share a comprehensive signal evaluation of FCCDA with in utero APAP exposure to determine if the totality of evidence is sufficiently more consistent with one of the following two possibilities: (1) APAP never contributes to FCCDA (null hypothesis or HO) versus (2) APAP may in some cases be at least a contributory cause of in utero DA narrowing (alternative hypothesis or HA) to justify risk communication. METHODS: To assess the relative support for HO versus HA, we synthesize and interpret within an Austin Bradford Hill criteria framework a comprehensive, cross-disciplinary set of published information and de novo analysis, including toxicology, epidemiology, clinical pharmacology, and clinical and quantitative pharmacovigilance analysis of spontaneous reports. RESULTS: While residual uncertainty remains, the totality of information is more compatible with HA than H0, to the extent that it is reasonably possible that APAP may sometimes be at least a contributory cause of FCCDA. CONCLUSION: It is reasonably possible that APAP may sometimes be at least a contributory cause of FCCDA, and this should therefore be communicated to stakeholders. TRIAL REGISTRATION: CLINICALTRIALS. GOV REGISTRATION: NOT APPLICABLE.

Pharmacokinetics, Safety, and Clinical Outcomes of Omadacycline in Women with Cystitis: Results from a Phase 1b Study.

Omadacycline, an aminomethylcycline antibiotic, is approved as once-daily intravenous (i.v.) and oral (p.o.) monotherapy for acute bacterial skin and skin structure infections and for community-acquired bacterial pneumonia, and it is under development for treatment of urinary tract infection (UTI). This is a phase 1b, randomized, open-label study of omadacycline in women with cystitis (defined as UTI symptoms and a positive urine leukocyte esterase test). Patients received omadacycline for 5 days (group 1: 200 mg intravenously on day 1, then 300 mg orally every 24 h [q24h]; group 2: 300 mg orally every 12 h [q12h] on day 1, then 300 mg orally q24h; group 3: 450 mg orally q12h on day 1, then 450 mg orally q24h). Blood and urine samples were collected over 5 days. Investigator-assessed clinical response was determined at end of treatment (EOT; day 6) and posttreatment evaluation (PTE; 5 to 9 days after last dosing). A total of 31 women were treated. At steady state (day 5), the range of mean omadacycline urine concentrations over 24 h across the groups was 17.94 to 48.12 µg/ml. The most common treatment-emergent adverse events were gastrointestinal (including nausea [60% to 73%] and vomiting [20% to 40%]) and were generally mild and transient. Investigator-determined clinical success was observed in 94% and 84% of patients at EOT and PTE, respectively, with similar results across groups. A favorable microbiological response at PTE was observed in 78% of patients who had a baseline pathogen. Omadacycline is partially excreted in urine and appears to be safe and well tolerated. These preliminary results indicate that omadacycline warrants further evaluation in larger controlled UTI studies.

Safety and Pharmacokinetics of the Aminomethylcycline Antibiotic Omadacycline Administered to Healthy Subjects in Oral Multiple-Dose Regimens.

Omadacycline, a first-in-class aminomethylcycline antibiotic, is related to tetracyclines but is structurally modified to circumvent mechanisms of resistance to tetracyclines. Omadacycline demonstrates potent activity against a broad range of pathogens, including drug-resistant strains, and is in late-stage development for treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. Previous studies support an intravenous-to-oral transition regimen with 300-mg once-daily oral dosing. This phase 1 study investigated the pharmacokinetics and safety/tolerability of multiple oral omadacycline doses higher than 300 mg. Using a 3-period crossover design, healthy adults were randomized to receive oral omadacycline at 300, 450, and 600 mg in variable sequence (n = 26) or placebo (n = 7) once daily for 5 consecutive days per period. In plasma, omadacycline maximum concentration and total exposure increased with increasing dose but were less than dose proportional. The kinetics of omadacycline plasma accumulation were similar between dose levels; exposure on day 5 was ∼50% higher than that on day 1. Omadacycline plasma concentrations on day 1 of 450-mg dosing were similar to those on day 5 of 300-mg dosing. All doses were generally well tolerated, but the 600-mg dose was associated with more gastrointestinal adverse events.

Pharmacokinetics and Safety of Omadacycline in Subjects with Impaired Renal Function.

Many antibiotics require dose adjustments in patients with renal impairment and/or in those undergoing hemodialysis. Omadacycline, the first aminomethylcycline antibiotic in late-stage clinical development, displays activity against a broad spectrum of bacterial pathogens, including drug-resistant strains. Data from completed phase 3 studies of omadacycline for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) showed intravenous (i.v.) to once-daily oral omadacycline to be clinically effective and well tolerated. To determine if the dosing of omadacycline should be adjusted in patients with impaired renal function, a phase 1 study examining the pharmacokinetics (PK) and safety of i.v. omadacycline (100 mg) was conducted in subjects with end-stage renal disease (ESRD) on stable hemodialysis (n = 8) and in matched healthy subjects (n = 8). i.v. administration of omadacycline produced similar plasma concentration-time profiles in subjects with ESRD and healthy subjects. Further, in subjects with ESRD, similar values of the PK parameters were observed when omadacycline was administered i.v. after or before dialysis. The mean area under the concentration-time curve from time zero extrapolated to infinity in plasma was 10.30 µg · h/ml when omadacycline was administered to ESRD subjects after dialysis, 10.20 µg · h/ml when omadacycline was administered to ESRD subjects before dialysis, and 9.76 µg · h/ml when omadacycline was administered to healthy subjects. The mean maximum observed concentration of omadacycline in plasma in ESRD subjects was 1.88 µg/ml when it was administered after dialysis and 2.33 µg/ml when it was administered before dialysis, and in healthy subjects it was 1.92 µg/ml. The 100-mg i.v. dose of omadacycline was generally safe and well tolerated in both ESRD and healthy subjects. This study demonstrates that no dose adjustment is necessary for omadacycline in patients with impaired renal function or on days when patients are receiving hemodialysis.

Cerebrovascular response to an acute bout of low-volume high-intensity interval exercise and recovery in young healthy adults.

High-intensity interval exercise (HIIT) is performed widely. However, there is a gap in knowledge regarding the acute cerebrovascular response to low-volume HIIT. Our objective was to characterize the middle cerebral artery blood velocity (MCAv) response during an acute bout of low-volume HIIT in young healthy adults. We hypothesized that MCAv would decrease below the baseline (BL), 1) during HIIT, 2) immediately following HIIT, and 3) 30 min after HIIT. As a secondary objective, we investigated sex differences in the MCAv response during HIIT. Twenty-four young healthy adults completed HIIT [12 males, age = 25 (SD = 2)]. HIIT included 10 min of 1-min high intensity (∼70% estimated maximal Watts) and active recovery (10% estimated maximal Watts) intervals on a recumbent stepper. MCAv, mean arterial pressure (MAP), heart rate (HR), and end-tidal carbon dioxide ([Formula: see text]) were recorded at BL, during HIIT, immediately following HIIT, and 30 min after HIIT. Contrary to our hypothesis, MCAv remained above BL during HIIT. MCAv peaked at minute 3 then decreased concomitantly with [Formula: see text]. MCAv was lower than BL immediately following HIIT (P < 0.001). Thirty minutes after HIIT, MCAv returned to BL (P = 0.47). Compared with men, women had a higher MCAv at BL (P = 0.001), during HIIT (P = 0.009), immediately following HIIT (P = 0.004), and 30 min after HIIT (P = 0.001). MCAv did not decrease below BL during low-volume HIIT. However, MCAv decreased below BL immediately following HIIT and returned to resting values 30 min after HIIT. MCAv also differed between sexes.NEW & NOTEWORTHY We are the first, to our knowledge, to characterize the cerebrovascular and hemodynamic response to low-volume high-intensity interval exercise (HIIT, 1-min intervals) in young healthy adults. Middle cerebral artery blood velocity (MCAv) decreased during the HIIT bout and rebounded during active recovery. Women demonstrated a significantly higher resting MCAv than men and the difference remained during HIIT. Here, we report a novel protocol and characterized the MCAv response during an acute bout of low-volume HIIT.

Chronic hyperglycemia before acute ischemic stroke impairs the bilateral cerebrovascular response to exercise during the subacute recovery period.

BACKGROUND AND PURPOSE: Chronic hyperglycemia contributes to cerebrovascular dysfunction by damaging blood vessels. Poor glucose control has been tied to impairments in cerebral blood flow, which may be particularly detrimental for people recovering from major cerebrovascular events such as acute ischemic stroke. In this secondary analysis, we explore for the first time the connection between chronic hyperglycemia before acute stroke and the cerebrovascular response (CVR) to exercise 3 and 6 month into the subacute recovery period. METHODS: We recorded middle cerebral artery velocity (MCAv) using transcranial Doppler ultrasound bilaterally at rest and during moderate-intensity exercise in stroke patients at 3 (n = 19) and 6 (n = 12) months post-stroke. We calculated CVR as the difference between MCAv during steady-state exercise and resting MCAv. We obtained hemoglobin A1c levels (HbA1c; a measure of blood glucose over the prior 3 months) from the electronic medical record (EMR) and divided participants by HbA1c greater or less than 7%. RESULTS: Participants with high HbA1c (>7%) at the time of acute stroke had significantly lower CVR to exercise for both the stroke-affected (p = .009) and non-affected (p = .007) hemispheres at 3 months post-stroke. These differences remained significant at 6 months post-stroke (stroke-affected, p = .008; non-affected, p = .016). CONCLUSIONS: Patients with chronic hyperglycemia before acute ischemic stroke demonstrated impaired cerebrovascular function during exercise months into the subacute recovery period. These findings highlight the importance of maintaining tight glucose control to reduce morbidity and improve recovery post-stroke and could have implications for understanding cerebrovascular pathophysiology.

The Effect of Verapamil, a P-gp Inhibitor, on the Pharmacokinetics, Safety, and Tolerability of Omadacycline in Healthy Adults: A Phase I, Open-Label, Single-Sequence Study.

BACKGROUND: Omadacycline is a semisynthetic aminomethylcycline antibacterial derived from the tetracycline class. It is approved in the USA to treat adults with acute bacterial skin and skin-structure infections and community-acquired bacterial pneumonia. OBJECTIVES: This phase I, open-label study evaluated the effect of a potential drug-drug interaction of verapamil-a known P-glycoprotein (P-gp) inhibitor-with omadacycline on the pharmacokinetic profile of omadacycline in healthy adults. The safety and tolerability of omadacycline taken alone and in combination with verapamil were also evaluated. METHODS: A single oral dose of 240 mg verapamil extended release (ER) was given 2 h prior to a single oral dose of 300 mg omadacycline. RESULTS: Ten (83.3%) of the 12 participants enrolled in the study completed the study, and all enrolled participants were included in the safety and pharmacokinetic populations. An increase of 14-25% in systemic exposure to omadacycline was seen when administered following a single oral dose of 240 mg verapamil ER compared with omadacycline alone, as measured by the area under the concentration-time curve (AUC) from time 0 to 24 h after dosing (AUC0-24), from time 0 to the last quantifiable concentration (AUC0-t), from time 0 extrapolated to infinity (AUC0-inf), and by maximum (peak) observed plasma concentration (Cmax). Treatment-emergent adverse events were reported by one participant (nausea and headache). CONCLUSIONS: These findings suggest that, if given with a known P-gp inhibitor, dose adjustment of oral omadacycline is not warranted based on small increases in absorption and systemic exposure. No safety signals were identified.

Pilot Study to Characterize Middle Cerebral Artery Dynamic Response to an Acute Bout of Moderate Intensity Exercise at 3- and 6-Months Poststroke.

Background The primary aim of this study was to characterize the middle cerebral artery blood velocity (MCAv) dynamic response to an acute bout of exercise in humans at 3- and 6-months poststroke. As a secondary objective, we grouped individuals according to the MCAv dynamic response to the exercise bout as responder or nonresponder. We tested whether physical activity, aerobic fitness, and exercise mean arterial blood pressure differed between groups. Methods and Results Transcranial Doppler ultrasound measured MCAv during a 90-second baseline followed by a 6-minute moderate intensity exercise bout. Heart rate, mean arterial blood pressure, and end-tidal CO2 were additional variables of interest. The MCAv dynamic response variables included the following: baseline, time delay, amplitude, and time constant. Linear mixed model revealed no significant differences in our selected outcomes between 3- and 6-months poststroke. Individuals characterized as responders demonstrated a faster time delay, higher amplitude, and reported higher levels of physical activity and aerobic fitness when compared with the nonresponders. No between-group differences were identified for baseline, time constant, or exercise mean arterial blood pressure. In the nonresponders, we observed an immediate rise in MCAv following exercise onset followed by an immediate decline to near baseline values, while the responders showed an exponential rise until steady state was reached. Conclusions The MCAv dynamic response profile has the potential to provide valuable information during an acute exercise bout following stroke. Individuals with a greater MCAv response to the exercise stimulus reported statin use and regular participation in exercise.

Middle cerebral artery velocity dynamic response profile during exercise is attenuated following multiple ischemic strokes: a case report.

Blood flow regulation is impaired in people with stroke. However, the time course of change in middle cerebral artery velocity (MCAv) following repeated stroke at rest and during exercise remains unknown. In this case study, we provide novel characterization of the dynamic kinetic MCAv response profile to moderate-intensity exercise before and after repeated ischemic MCA stroke. The initial stroke occurred in the left MCA. At 3 months poststroke, left MCAv amplitude (Amp) was ~50% lower than the right. At the 6-month follow-up visit, MCAv Amp declined in both MCA with the left MCAv Amp ~50% lower than the right MCAv Amp. Following a second right MCA stroke, we report further decline in Amp for the left MCA. At the 3- and 6-month visit following the second stroke, the left MCAv Amp declined further (~10%). The right MCAv Amp dramatically decreased by 81.3% when compared to the initial study visit. The MCAv kinetic analysis revealed a marked impairment in the cerebrovascular response to exercise following stroke. We discuss potential pathophysiological mechanisms contributing to poststroke cerebrovascular dysfunction and the need to test therapeutic interventions (such as exercise) that might attenuate cerebrovascular decline in people following stroke.

A phase I, single and fractionated, ascending-dose study evaluating the safety, pharmacokinetics, pharmacodynamics, and immunogenicity of an erythropoietin mimetic antibody fusion protein (CNTO 528) in healthy male subjects.

The erythropoietin mimetic antibody fusion protein CNTO 528 was developed as a novel antibody fusion protein by constructing an active hematopoietic peptide onto an IgG1-based scaffold. This resulted in a molecule with a long circulating half-life and a prolonged effect of stimulating reticulocyte production and hemoglobin (Hgb) synthesis. To assess the safety, pharmacokinetics, and pharmacodynamics of CNTO 528, the authors gave 44 adult healthy male subjects single or fractionated doses of intravenous CNTO 528 or placebo. CNTO 528 was generally well tolerated. The maximum observed concentration (Cmax) and the area under the concentration versus time curve (AUC) increased in an approximately dose-dependent manner between the 0.09-mg/kg and 0.9-mg/kg doses. The maximum effect on the reticulocyte response occurred approximately 8 to 9 days after administration. A median increase in Hgb (> or =1 g/dL above baseline) was achieved 9 to 10 days after administration, with a maximum effect between 19 and 26 days. Two subjects in the 0.9-mg/kg dose group had elevated Hgb concentrations requiring phlebotomy. In this first-in-human study, CNTO 528 was well tolerated and effective in elevating and maintaining Hgb by at least 1 g/dL following a single intravenous administration, which suggests that an erythropoietin mimetic molecule, such as CNTO 528, may be an effective therapy for patients with anemia.

Effect of Food on the Bioavailability of Omadacycline in Healthy Participants.

Omadacycline is a first-in-class aminomethylcycline antibiotic being evaluated in phase 3 studies as oral and intravenous monotherapy for bacterial infections. This was a phase 1, randomized, open-label, 4-period, crossover study that evaluated the effect of food consumption on the bioavailability of omadacycline. Healthy participant were randomized to 1 of 4 sequences, which included the following predose conditions in different orders (A) ≥6-hour fast, (B) high-fat, nondairy meal 4 hours before dosing, (C) high-fat, nondairy meal 2 hours before dosing, and (D) high-fat meal containing dairy 2 hours before dosing. Participants received a single 300-mg oral dose of omadacycline during each treatment period; periods were separated by ≥5 days. Blood samples for pharmacokinetic (PK) analysis were collected over 24 hours after each dose, and safety assessments were performed during each treatment period. Least-squares mean and 90% confidence intervals were compared for fed state vs fasted state. Thirty-one participants were included in the PK analysis. Fasted AUC0-∞ , AUC0-t , and AUC0-24 were 10.2, 7.2, and 7.2 µg·h/mL, respectively, and Cmax was 0.6 µg/mL. Compared with a fasted dose, bioavailability was reduced by 15% to 17% by a nondairy meal 4 hours before dosing, 40% to 42% by a nondairy meal 2 hours before dosing, and 59% to 63% for a dairy meal 2 hours before dosing. Two participants experienced adverse events (mild nausea, mild somnolence). A 300-mg oral dose of omadacycline administered within 2 to 4 hours after food had reduced bioavailability compared with the fasted state. Oral omadacycline should be administered in a fasted state.

Phase I study of BMS-214662, a farnesyl transferase inhibitor in patients with acute leukemias and high-risk myelodysplastic syndromes.

PURPOSE: To investigate the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD) of BMS-214662, a farnesyl transferase (FTase) inhibitor, in patients with acute leukemias and high-risk myelodysplastic syndromes (MDS). PATIENTS AND METHODS: Patients with relapsed or refractory acute leukemias or MDS, or previously untreated but poor candidates for chemotherapy, were included in this phase I study with a 3 + 3 dose escalation design. BMS-214662 was administered as a 1-hour bolus once weekly at doses of 42 to 157 mg/m2. Once the MTD was identified, the schedule was changed to a 24-hour continuous infusion once weekly (starting dose, 300 mg/m2). RESULTS: Thirty patients were treated at a dose of 42 (n = 1), 56 (n = 3), 84 (n = 3), 118 (n = 13), 157 (n = 6) or 300 mg/m2 (n = 4). DLT occurred in 3 patients at 157 mg/m2, including nausea, vomiting, diarrhea, hypokalemia and cardiovascular problems. No DLT occurred with 24-hour continuous infusion. MTD with a 1-hour infusion was 118 mg/m2, with no MTD identified with the 24-hour infusion. Plasma concentrations of BMS-214662 correlated with the dose. Inhibition of FTase activity of approximately 60% occurred after the infusion with recovery to near baseline after 24 hours. Five patients had evidence of antileukemia activity, including two with complete remission with incomplete platelet recovery, one with hematologic improvement, and two with morphologic leukemia-free state. CONCLUSION: BMS-214662 is well tolerated at doses of up to 118 mg/m2 as a 1-hour infusion. The toxicity profile and efficacy may be improved with prolonged exposure. Further investigation of this agent in leukemia is warranted.

Evaluation of the Pharmacokinetics of Single- and Multiple-dose Buprenorphine Buccal Film in Healthy Volunteers.

PURPOSE: Buprenorphine, a partial µ-receptor agonist, is approved for the management of moderate to severe pain, but it has low oral bioavailability. Two open-label studies were performed to determine the pharmacokinetic profile of buprenorphine from buccal film formulations of buprenorphine. METHODS: Both studies enrolled healthy volunteers, aged 18 to 55 years, who received concurrent oral naltrexone to reduce adverse events (AEs); subjects with a history or evidence of substance abuse or current use of any product affecting cytochrome P450 3A4 activity were excluded. The first study (n = 25) was a 5-period crossover trial with 4 single doses (75 and 300 and 300 and 1200 µg) of 2 formulations (F14 and F24) of buccal buprenorphine (BBUP) and a 300-µg intravenous dose of buprenorphine with a 7-day washout between periods. In the second study, each subject (n = 10) received 6 doses of 4 BBUP strengths (60, 120, 180, and 240 µg BID) in a dose-escalation design. Plasma concentrations of buprenorphine and norbuprenorphine were assayed, and pharmacokinetics were summarized with descriptive statistics and analyzed by using a linear mixed effects model (single-dose study). AEs were recorded. FINDINGS: In the single-dose study, the 2 formulations exhibited comparable bioavailability of 46% to 51% that was independent of dose, with a single buprenorphine peak concentration from each BBUP dose occurring at 2.5 to 3 hours. The mean buprenorphine Cmax across the doses ranged from 0.17 ng/mL for the 75-µg dose to 1.43 ng/mL for the 1200-µg dose. AUC0-∞, AUC0-last, and Cmax were proportional to the dose of BBUP administered. Cmax of norbuprenorphine after BBUP administration was approximately one tenth that of buprenorphine Cmax. In the multiple-dose study, steady state was reached within 3 days of BID dosing. There was a linear increase in exposure across the dose range from 60 to 240 µg BID. Treatment-emergent AEs in both studies were consistent with those reported with opiate administration to healthy volunteers. IMPLICATIONS: The absolute bioavailability of BBUP was 46% to 51% across a 16-fold dose range, with dose-proportional increases in systemic exposure. Apparent steady-state conditions occurred within 3 days of dosing. These pharmacokinetic results suggest that therapeutic buprenorphine plasma concentrations can be obtained with BBUP across a wide dose range in a shorter time than other (eg, transdermal) dosage forms.

Differentiating the Effect of an Opioid Agonist on Cardiac Repolarization From µ-Receptor-mediated, Indirect Effects on the QT Interval: A Randomized, 3-way Crossover Study in Healthy Subjects.

PURPOSE: A thorough QT study was conducted in healthy subjects to evaluate the effect of buprenorphine hydrochloride administered through a buccal soluble film under coverage of naltrexone to block confounding, secondary QT effects. METHODS: Healthy subjects were enrolled in a randomized, partially blinded, 4-way crossover designed study. Subjects received buprenorphine 3 mg with naltrexone, naltrexone alone (with placebo films), placebo (placebo films and placebo naltrexone), and open-label moxifloxacin 400 mg with placebo naltrexone in separate in-house treatment periods. Naltrexone treatment (50 mg) was initiated 12 hours before buprenorphine and was given every 12 hours for a total of 4 doses. ECG data were extracted from a continuous recording predose and serially after dosing on the treatment day. ECG intervals were measured at a central ECG laboratory by using the high-precision QT technique. The QT interval was corrected for heart rate with Fridericia's formula (QTcF), and change-from-predose baseline QTcF (∆QTcF) was analyzed by using a mixed effect model. FINDINGS: Fifty-eight subjects (35 males) with a mean age of 32 were enrolled into the study. Treatment with buprenorphine 3 mg resulted in a small QT effect with the largest mean naltrexone-corrected ∆QTcF reaching 5.8 msec at 8 hours' postdosing (upper bound of the 90% CI below 10 msec). Exposure response analysis with a linear model demonstrated a significant linear relationship between plasma levels and naltrexone-corrected ∆QTcF, with an estimated mean slope of 0.65 msec per nanogram/milliliter (90% CI, 0.22 to 1.08). Using the exposure response model, an effect on ∆QTcF of 4.5 msec (2.80 to 6.12) can be predicted at the observed geometric peak plasma level after administration of the 3-mg buprenorphine dose in this study (3.6 ng/mL [3.33 to 3.98]). Naltrexone alone did not have a relevant effect on the QTcF interval. IMPLICATIONS: The present study showed that buprenorphine plasma levels up to 5 ng/mL had no effect on the QTc above the level of clinical concern.

Structure-based design of novel guanidine/benzamidine mimics: potent and orally bioavailable factor Xa inhibitors as novel anticoagulants.

As part of an ongoing effort to prepare orally active factor Xa inhibitors using structure-based drug design techniques and molecular recognition principles, a systematic study has been performed on the pharmacokinetic profile resulting from replacing the benzamidine in the P1 position with less basic benzamidine mimics or neutral residues. It is demonstrated that lowering the pK(a) of the P1 ligand resulted in compounds (3-benzylamine, 15a; 1-aminoisoquinoline, 24a; 3-aminobenzisoxazole, 23a; 3-phenylcarboxamide, 22b; and 4-methoxyphenyl, 22a) with improved pharmacokinetic features mainly as a result of decreased clearance, increased volume of distribution, and enhanced oral absorption. This work resulted in a series of potent and orally bioavailable factor Xa inhibitors that ultimately led to the discovery of SQ311, 24a. SQ311, which utilizes a 1-aminoisoquinoline as the P1 ligand, inhibits factor Xa with a K(i) of 0.33 nM and demonstrates both good in vivo antithrombotic efficacy and oral bioavailability.

A subcutaneous octreotide hydrogel implant for the treatment of acromegaly.

OBJECTIVE: To evaluate the pharmacokinetics, efficacy, and safety of a subcutaneous octreotide hydrogel implant in patients with acromegaly. METHODS: In 2 phase II open-label randomized studies, patients aged ≥ 18 years with confirmed acromegaly and octreotide responsiveness received one or two 52 mg hydrated implants (52 mg study) or a hydrated or nonhydrated 84 mg implant (84 mg study) inserted subcutaneously in the upper arm. Implants were removed after 6 months. The 84 mg study assessed pharmacokinetics in patients with undetectable baseline octreotide concentrations. Both studies assessed efficacy (serum growth hormone [GH], insulin-like growth factor 1 [IGF-1]) and safety (adverse events, physical examination, clinical chemistry). RESULTS: Eleven patients received 1 (n = 5) or 2 (n = 6) 52 mg implants; 34 received a hydrated (n = 17 [safety]; n = 16 [efficacy analysis]) or nonhydrated (n = 17) 84 mg implant. With the nonhydrated versus hydrated 84 mg implant, mean maximum serum concentration (Cmax) and mean area under the drug concentration versus time curve from time 0 to 6 months were decreased (P = 0.002 and P = 0.03, respectively) and mean time to Cmax was increased (P = 0.002). In both studies, IGF-1 and GH declined in month 1 and were significantly suppressed during the 6-month treatment versus baseline (P<0.001). With the 52 mg and 84 mg implants, respectively, 3 of 11 patients (27%) and 17 of 33 patients (52%) achieved IGF-1 normalization and 8 of 11 patients (73%) and 13 of 33 patients (39%) exhibited GH <2.5 ng/mL; 9 of 11 patients (82%) and 11 of 34 patients (32%) experienced treatment-related adverse events, which were mainly gastrointestinal. CONCLUSION: Octreotide hydrogel implants were well tolerated and maintained stable octreotide release and suppression of IGF-1 and GH over 6 months.

Pharmacokinetics and pharmacodynamics of the erythropoietin Mimetibody construct CNTO 528 in healthy subjects.

BACKGROUND AND OBJECTIVE: Anaemia is a serious comorbidity that is common in patients with renal failure or cancer. CNTO 528 is the first Mimetibody developed to mimic the effects of erythropoietin (EPO), a hormone that stimulates the production of red blood cells (RBCs). The objective of this study was to develop a pharmacokinetic and pharmacodynamic model for CNTO 528 in healthy male subjects. METHODS: A pharmacokinetic/pharmacodynamic model for CNTO 528 was developed to describe the serum concentration versus time profile and the pharmacological responses of percentage of reticulocytes, total RBC counts and haemoglobin concentration after a single intravenous administration of CNTO 528 at 0.03, 0.09, 0.3 and 0.9 mg/kg in 24 healthy subjects. An open, linear, two-compartment model was used to characterize the pharmacokinetic parameters of CNTO 528. A catenary cell production and lifespan loss model was used to fit the pharmacodynamic data, yielding estimates of drug potency (SC(50)), efficacy (S(max)) and other pharmacodynamic parameters. Bootstrap and posterior predictive checks (PPC) were used to evaluate the model. RESULTS: Administration of CNTO 528 stimulated the production of reticulocytes, RBCs and haemoglobin. CNTO 528 exhibits a half-life of 141 hours, or approximately 5.9 days. The SC(50) was estimated to be 0.37 mg/L, indicating that low serum CNTO 528 concentration was sufficient to produce pharmacological effects. Compared with historical controls, CNTO 528 S(max) appears to be 2-fold higher than recombinant human EPO. Bootstrap analysis and PPCs confirmed the accuracy and precision in the parameter estimates and the adequacy of the model to describe the CNTO 528 pharmacokinetics and pharmacodynamics. CONCLUSION: The mechanistic population model was suitable to characterize the pharmacokinetics and pharmacodynamics of intravenously administered CNTO 528 in healthy subjects. This qualified model is deemed appropriate to conduct clinical trial simulations and to support the decision-making process for dose selection in studies of EPO-stimulating agents.

N-in-1 dosing pharmacokinetics in drug discovery: experience, theoretical and practical considerations.

N-in-1 (or cassette) dosing pharmacokinetics (PK) has been used in drug discovery for rapid assessment of PK properties of new chemical entities. However, because of potential for drug-drug interactions this procedure is still controversial. This study was to retrospectively evaluate the N-in-1 dosing approach in drug discovery with an emphasis on the potential for drug-drug interactions. The systemic clearance, volume of distribution, oral bioavailability, and renal excretion of the 31 lead compounds in rats, dogs or chimpanzees were significantly correlated between the N-in-1 dosing and discrete studies with r values of 0.69, 0.91, 0.53, and 0.83 (p < 0.005 for all), respectively. PK parameters for 11 quality control compounds which were involved in 194 N-in-1 studies for screening approximately 1000 compounds had coefficient of variations of less than 70%. The intrinsic microsomal clearances generated from the N-in-1 and discrete incubations were nearly identical (r = 0.97, p < 0.0001). The intrinsic clearances of quality control compound from the N-in-1 incubations were consistent with its discrete CL(int) estimate (cv: 5.4%). Therefore, N-in-1 dosing is a useful approach in drug discovery to quickly obtain initial PK estimates. Potential drug-drug interactions that result in confounding PK estimates do not occur as frequently as expected.

Pharmacokinetics and pharmacodynamics of DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)), a potent and selective inhibitor of tumor necrosis factor alpha-converting enzyme in rodents, dogs, chimpanzees, and humans.

DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)) is a potent and selective inhibitor of tumor necrosis factor (TNF)-alpha-converting enzyme (TACE). It significantly inhibits lipopolysaccharide-induced soluble TNF-alpha production in blood from rodents, chimpanzee, and human, with IC(50) values ranging from 17 to 100 nM. In rodent models of endotoxemia, DPC 333 inhibited the production of TNF-alpha in a dose-dependent manner, with an oral ED(50) ranging from 1.1 to 6.1 mg/kg. Oral dosing of DPC 333 at 5.5 mg/kg daily for 2 weeks in a rat collagen antibody-induced arthritis model suppressed the maximal response by approximately 50%. DPC 333 was distributed widely to tissues including the synovium, the site of action for antiarthritic drugs. Pharmacokinetic and pharmacodynamic studies in chimpanzee revealed a systemic clearance of 0.4 l/h/kg, a V(ss) of 0.6 l/kg, an oral bioavailability of 17%, and an ex vivo IC(50) for the suppression of TNF-alpha production of 55 nM (n = 1). In a phase I clinical trial with male volunteers after single escalating doses of oral DPC 333, the terminal half-life was between 3 and 6 h and the ex vivo IC(50) for suppressing TNF-alpha production was 113 nM. Measurement of the suppression of TNF-alpha production ex vivo may serve as a good biomarker in evaluating the therapeutic efficacy of TACE inhibitors. Overall, the pharmacological profiles of DPC 333 support the notion that suppression of TNF-alpha with TACE inhibitors like DPC 333 may provide a novel approach in the treatment of various inflammatory diseases including rheumatoid arthritis, via control of excessive TNF-alpha production.