3-Quinuclidinyl benzilate (agent BZ) toxicokinetics in rats.

3-Quinuclidinyl benzilate (BZ) ranks among incapacitating military warfare agents. It acts as a competitive inhibitor on muscarinic receptors leading to non-lethal mental impairment. The present study aimed to investigate toxicokinetics of BZ in rats. Moreover, BZ can be exploited to produce a pharmacological model of Alzheimer's disease; thus, this paper focuses mainly on the BZ distribution to the brain. Wistar rats were administered i.p. with BZ (2 and 10 mg/kg). The BZ concentration was determined using LC-MS/MS in plasma, urine, bile, brain, kidney and liver. The sample preparation was based on a solid phase extraction (liquids) or protein precipitation (organ homogenates). The plasma concentration peaked at 3 min (204.5 ± 55.4 and 2185.5 ± 465.4 ng/ml). The maximal concentration in the brain was reached several minutes later. Plasma elimination half-life was 67.9 ± 3.4 in the 2 mg/kg group and 96.6 ± 27.9 in the 10 mg/kg group. BZ concentrations remained steady in the brain, with slow elimination (t1/2 506.9 ± 359.5 min). Agent BZ is excreted mainly via the urine. Steady BZ concentration in the brain could explain the previously published duration of the significant impairment in passive avoidance tasks in rats after an injection of BZ.

Pharmacokinetics and efficacy of atropine sulfate/obidoxime chloride co-formulation against VX in a guinea pig model.

Nerve agent exposure is generally treated by an antidote formulation composed of a muscarinic antagonist, atropine sulfate (ATR), and a reactivator of acetylcholinesterase (AChE) such as pralidoxime, obidoxime (OBI), methoxime, trimedoxime or HI-6 and an anticonvulsant. Organophosphates (OPs) irreversibly inhibit AChE, the enzyme responsible for termination of acetylcholine signal transduction. Inhibition of AChE leads to overstimulation of the central and peripheral nervous system with convulsive seizures, respiratory distress and death as result. The present study evaluated the efficacy and pharmacokinetics (PK) of ATR/OBI following exposure to two different VX dose levels. The PK of ATR and OBI administered either as a single drug, combined treatment but separately injected, or administered as the ATR/OBI co-formulation, was determined in plasma of naïve guinea pigs and found to be similar for all formulations. Following subcutaneous VX exposure, ATR/OBI-treated animals showed significant improvement in survival rate and progression of clinical signs compared to untreated animals. Moreover, AChE activity after VX exposure in both blood and brain tissue was significantly higher in ATR/OBI-treated animals compared to vehicle-treated control. In conclusion, ATR/OBI has been proven to be efficacious against exposure to VX and there were no PK interactions between ATR and OBI when administered as a co-formulation.

Revefenacin, a Long-Acting Muscarinic Antagonist, Does Not Prolong QT Interval in Healthy Subjects: Results of a Placebo- and Positive-Controlled Thorough QT Study.

Revefenacin is a novel once-daily, lung-selective, long-acting muscarinic antagonist developed as a nebulized inhalation solution for the maintenance treatment of chronic obstructive pulmonary disease. In a randomized, 4-way crossover study, healthy subjects received a single inhaled dose of revefenacin 175 µg (therapeutic dose), revefenacin 700 µg (supratherapeutic dose), and placebo via standard jet nebulizer, and a single oral dose of moxifloxacin 400 mg (open-label) in separate treatment periods. Electrocardiograms were recorded, and pharmacokinetic samples were collected serially after dosing. The primary end point was the placebo-corrected change from baseline QT interval corrected for heart rate using Fridericia's formula, analyzed at each postdose time. Concentration-QTc modeling was also performed. Following administration of revefenacin 175  and 700 µg, placebo-corrected change from baseline QTcF (ΔΔQTcF) values were close to 0 at all times, with the largest mean ΔΔQTcF of 1.0 millisecond (95% confidence interval [CI], -1.2 to 3.1 milliseconds) 8 hours postdose and 1.0 millisecond (95%CI, -1.1 to 3.1 milliseconds) 1 hour postdose after inhalation of revefenacin 175 and 700 µg, respectively. Revefenacin did not have a clinically meaningful effect on heart rate (within ±5 beats per minute of placebo), or PR and QRS intervals (within ±3 and ±1 milliseconds of placebo, respectively). Using concentration-QTc modeling, an effect of revefenacin > 10 milliseconds can be excluded within the observed plasma concentration range of up to ≈3 ng/mL. Both doses of revefenacin were well tolerated. These results demonstrate that revefenacin does not prolong the QT interval.

Pharmacokinetic Drug-Drug Interactions Between Trospium Chloride and Ranitidine Substrates of Organic Cation Transporters in Healthy Human Subjects.

Trospium chloride, a muscarinic receptor blocker, is poorly absorbed with different rates from areas in the jejunum and the cecum/ascending colon. To evaluate whether organic cation transporter (OCT) 1, OCT2 and multidrug and toxin extrusion (MATE) 1 and MATE2-K are involved in pharmacokinetics, competitions with ranitidine, a probe inhibitor of the cation transporters, were evaluated in transfected HEK293 cells. Furthermore, a drug interaction study with trospium chloride after intravenous (2 mg) and oral dosing (30 mg) plus ranitidine (300 mg) was performed in 12 healthy subjects and evaluated by noncompartmental analysis and population pharmacokinetic modeling. Ranitidine inhibited OCT1, OCT2, MATE1, and MATE2-K with half maximal inhibitory concentration values of 186 ± 25 µM, 482 ± 105 µM, 134 ± 37 µM, and 35 ± 11 µM, respectively. In contrast to our hypothesis, coadministration of ranitidine did not significantly decrease oral absorption of trospium. Instead, renal clearance was lowered by ∼15% (530 ± 99 vs 460 ± 120 mL/min; P < .05). It is possible that ranitidine was not available in competitive concentrations at the major colonic absorption site, as the inhibitor is absorbed in the small intestine and undergoes degradation by microbiota. The renal effects apparently result from inhibition of MATE1 and/or MATE2-K by ranitidine as predicted by in vitro to in vivo extrapolation. However, all pharmacokinetic changes were not of clinical relevance for the drug with highly variable pharmacokinetics. Intravenous trospium significantly lowered mean absorption time and relative bioavailability of ranitidine, which was most likely caused by muscarinic receptor blocking effects on intestinal motility and water turnover.

Population Pharmacokinetic Analysis of Fluticasone Furoate/Umeclidinium Bromide/Vilanterol in Patients with Chronic Obstructive Pulmonary Disease.

BACKGROUND: Population pharmacokinetic methods were used to characterize the pharmacokinetics of fluticasone furoate (FF), umeclidinium (UMEC), and vilanterol (VI) in patients with chronic obstructive pulmonary disease (COPD) when administered as a fixed-dose combination via a single closed inhaler. METHODS: Plasma concentration data from three studies were analyzed using non-linear mixed-effects modeling in NONMEM®. RESULTS: The pooled dataset consisted of 2948, 2589, and 3331 FF, UMEC, and VI observations from 714, 622, and 817 patients with COPD, respectively. There were 41%, 13%, and 21% of observations below the quantification limit for FF, UMEC, and VI, respectively. The pharmacokinetics of FF, UMEC, and VI were all adequately described by a two-compartment model with first-order absorption. The following covariates were statistically significant, but none were considered to be clinically relevant. For FF, Japanese heritage and FF/VI treatment on apparent inhaled clearance (CL/F) with FF CL/F 35% lower in patients of Japanese heritage across all treatments and FF CL/F 42% higher in patients with COPD following FF/VI administration. This is in line with the product label. For UMEC, weight, age, and smoking status on CL/F and weight on apparent volume of distribution (V2/F) with every 10% increase in age from 60 years of age leading to approximately a 6% decrease in UMEC CL/F and every 10% increase in weight from 70 kg leading to approximately a 6% increase in UMEC CL/F and approximately an 8% increase in UMEC V2/F. For a subject with COPD who smoked, UMEC CL/F was 28% higher. For VI, weight on CL/F and smoking status on V2/F with an approximately 4% increase in VI CL/F for every 10% increase in weight from 70 kg, and for a subject with COPD who smoked, VI V2/F was 46% higher. The majority of these covariates have been previously identified in historical analyses. None of these effects were clinically relevant in terms of systemic exposures and do not warrant dose adjustment. CONCLUSIONS: All FF, UMEC, and VI plasma concentrations were well interspersed with historical data and were all adequately described by a two-compartment model with first-order absorption. There were no clinically relevant differences in FF, UMEC, or VI systemic exposures when administered as FF/UMEC/VI, FF/VI + UMEC, or the dual combinations FF/VI and/or UMEC/VI.

Influence of CYP2D6 genetic polymorphism on pharmacokinetics of active moiety of tolterodine.

Tolterodine is metabolized to an active 5-hydroxymethyl tolterodine (5-HMT) by CYP2D6. This study investigated the relationship between CYP2D6 genotypes and pharmacokinetics of tolterodine and its active metabolite in healthy Korean subjects. All volunteers were genotyped for CYP2D6 and divided into four different genotype groups (CYP2D6*wt/*wt [*wt = *1 or *2], CYP2D6*wt/*10, CYP2D6*10/*10, and CYP2D6*5/*10). Each subject received a single oral dose of tolterodine tartrate (2 mg) in single-dose phase of the study. After the single-dose phase of the study, the same subjects received a single oral dose of tolterodine tartrate (2 mg) once daily for 1 week during multiple-dose tolterodine administration phase. Plasma concentrations of tolterodine and 5-HMT were measured by using liquid chromatography-tandem mass spectrometry method. Our study demonstrated that plasma exposure of tolterodine in CYP2D6*10/*10 and CYP2D6*5/*10 group significantly increased, compared with CYP2D6*wt/*wt group (P < 0.001). The pharmacokinetic parameters of 5-HMT were not significantly different in relation to CYP2D6 genotype, as 5-HMT itself is also metabolized by CYP2D6. With regard to active moiety (tolterodine + 5-HMT), Cmax and AUC0-24 was significantly increased in CYP2D6*10/*10 group, compared with CYP2D6*wt/*wt group (P < 0.001). Thus, our study showed the pharmacokinetics of tolterodine and its active moiety was significantly different in relation to CYP2D6 genotype.

Investigation of molecular mobility of pressure-sensitive-adhesive in oxybutynin patch in vitro and in vivo: Effect of sorbitan monooleate on drug release and patch mechanical property.

The aim of present study was to develop an oxybutynin (OXY) transdermal patch with good permeation behavior and mechanical property. Special attention was paid to the effect of chemical enhancer on the molecular mobility of pressure sensitive adhesive (PSA) at molecular level. PSAs and permeation enhancers were investigated through in vitro experiment using rat skin. The optimized formulation was evaluated through pharmacokinetic study using rat. In addition, the molecular mechanism of sorbitan monooleate (Span® 80) in the improvement of PSA molecular mobility was investigated using FT-IR, molecular dynamics simulation, DSC and rheological study. As a result, the optimized formulation using amide PSA demonstrated good adhesion property. And the AUC0-t and Cmax of optimized patch were 6435.8 ±â€¯747.8 h ∗ ng/mL and 127.8 ±â€¯18.0 ng/mL, respectively, which had no significant difference with commercial product. Furthermore, the improvement of the PSA mobility by Span® 80 rather than the decrease of interaction between drug and PSA was the main factor that enhanced the release of OXY from patch. In conclusion, a drug-in-adhesive OXY patch was developed, and the effect of PSA molecular mobility increase on the enhancement of drug skin permeation was proposed at molecular level.

Randomized study of the effects of Aerochamber Plus® Flow-Vu® on the efficacy, pharmacokinetics and safety of glycopyrronium/formoterol fumarate dihydrate metered dose inhaler in patients with chronic obstructive pulmonary disease.

OBJECTIVES: This study compared the efficacy, pharmacokinetics (PK), and safety of GFF MDI (Bevespi Aerosphere®), a fixed-dose combination of glycopyrronium and formoterol fumarate dihydrate (14.4/10 µg) delivered by a metered dose inhaler (MDI) formulated using innovative co-suspension delivery technology, in patients with moderate-to-very severe chronic obstructive pulmonary disease (COPD) with and without the Aerochamber Plus® Flow-Vu® valved holding chamber (VHC). METHODS: In this multicenter, open-label, crossover, Phase III study (NCT02454959), patients were randomized to receive GFF MDI 14.4/10 µg (equivalent to glycopyrrolate/formoterol fumarate 18/9.6 µg) twice daily for 7 days with and without the VHC. The primary endpoint was forced expiratory volume in 1 s area under the curve from 0 to 12 h (FEV1 AUC0-12) on Day 8. Steady state PK parameters for glycopyrronium and formoterol (AUC0-12, peak concentration [Cmax] and time to peak concentration [tmax]) were estimated from 12-h plasma concentration time data on Day 8. Safety and tolerability were also assessed throughout. RESULTS: Eighty patients were randomized. On Day 8, the ratio (90% confidence interval [CI]) of least squares mean (LSM) FEV1 AUC0-12 for GFF MDI with VHC (LSM = 1538 mL; n = 67) versus without VHC (LSM = 1516 mL; n = 68) was 101.4% (100.1, 102.7). PK parameters were comparable overall with a slightly higher exposure to glycopyrronium with the VHC. The AUC0-12 geometric LSM ratio (90% CI) for GFF MDI with versus without VHC was 115.99% (99.74, 134.89) for glycopyrronium and 96.66% (86.69, 107.78) for formoterol. GFF MDI with and without VHC were well tolerated with a similar adverse event profile. CONCLUSIONS: The magnitude of bronchodilatory effect was similar with and without a VHC following GFF MDI treatment. This, together with the PK and safety profiles, supports the use of the VHC with GFF MDI for the maintenance treatment of COPD, which could be particularly useful for patients who have difficulty with the coordination of an MDI.

Pharmacokinetics of glycopyrronium/formoterol fumarate dihydrate delivered via metered dose inhaler using co-suspension delivery technology in patients with moderate-to-very severe COPD.

Purpose: The efficacy and tolerability of GFF MDI (Bevespi Aerosphere®), a fixed-dose combination of glycopyrronium (GP)/formoterol fumarate dihydrate (FF) 14.4/10 µg (equivalent to glycopyrrolate/formoterol fumarate 18/9.6 µg) delivered by metered dose inhaler (MDI) using innovative co-suspension delivery technology, has been investigated in a Phase III clinical trial program (NCT01854645, NCT01854658, NCT01970878) in patients with COPD. Here, we present findings from a pharmacokinetic (PK) sub-study of NCT01854645 (PINNACLE-1). Methods: PINNACLE-1 was a multicenter, randomized, double-blind, parallel-group, 24 wk chronic-dosing, placebo- and active-controlled study. The PK sub-study assessed the systemic accumulation of glycopyrronium and formoterol following administration of GFF MDI 14.4/10 µg, GP MDI 14.4 µg, or FF MDI 10 µg (all BID) for 12 wks. Plasma for PK analysis was collected for up to 12 h after dosing, on Day 1 and Week 12. Results: Of 2,103 patients randomized in PINNACLE-1, 292 participated in the PK sub-study. The plasma concentration-time profiles of glycopyrronium were similar following treatment with GFF MDI or GP MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 2.30-fold for glycopyrronium. The plasma concentration-time profiles of formoterol were similar following treatment with GFF MDI or FF MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 1.62-fold for formoterol. Conclusion: Overall, the results have characterized the accumulation of glycopyrronium and formoterol associated with GFF MDI, GP MDI, and FF MDI, and indicated that there were no meaningful PK interactions, whether drug-drug or due to formulation, between glycopyrronium and formoterol following treatment with GFF MDI formulated using co-suspension delivery technology.

A phase 2a randomized controlled study to evaluate the pharmacokinetic, safety, tolerability and clinical effect of topically applied Umeclidinium in subjects with primary axillary hyperhidrosis.

BACKGROUND: Hyperhidrosis is a common medical condition which can have a significant impact on quality of life. Umeclidinium (UMEC) is a long-acting muscarinic antagonist (LAMA) developed as a dermal formulation. OBJECTIVES: This 2-week, double-blind, randomized, vehicle-controlled study evaluated systemic exposure, safety and tolerability of topically administered UMEC in subjects with primary axillary hyperhidrosis. Clinical effect was a secondary objective, measured by gravimetry and the hyperhidrosis disease severity scale (HDSS). Vehicle was included to evaluate safety. METHODS: Twenty-three subjects were randomized to either 1.85% UMEC (N = 18) or vehicle (N = 5) once daily. RESULTS: Measurable plasma concentrations were observed in 78% of subjects after the treatment. Nine subjects (50%) on UMEC and two subjects (40%) on vehicle reported AEs, most commonly application site reactions. At Day 15, seven subjects (41%) in UMEC and two subjects (40%) in vehicle had at least a 50% reduction in sweat production. Eight subjects (47%) in UMEC and one subject (20%) in vehicle had at least a two-point reduction in HDSS. No comparisons of treatment arms were planned prospectively. CONCLUSIONS: The measurable exposure, acceptable safety and preliminary clinical activity observed in this proof-of-concept study suggest the potential clinical utility of topical UMEC in subjects with axillary hyperhidrosis.

Urinary Excretion Contributes to Long-Lasting Blockade of Bladder Muscarinic Receptors by Imidafenacin: Effect of Bilateral Ureteral Ligation.

Imidafenacin is a potent and selective antagonist of M1 and M3 muscarinic receptors that is safe, efficacious, and well tolerated for controlling the symptoms of overactive bladder (OAB). However, the precise mechanisms responsible for the bladder-selective pharmacological effects of this agent remain unclear. The in vivo pharmacologic effects of imidafenacin result from receptor occupancy. Therefore, the present study was performed to characterize in vivo muscarinic receptor binding by tritium-labeled imidafenacin with high specific activity ([3H]imidafenacin) in the bladder and other tissues of mice, and to clarify the mechanisms underlying selective binding of imidafenacin to bladder muscarinic receptors. After intravenous injection of [3H]imidafenacin, its binding to muscarinic receptors in the bladder and other tissues of mice was assessed by a radioligand binding assay. [3H]Imidafenacin showed a significantly longer duration of binding to muscarinic receptors in the bladder than in other tissues, and muscarinic receptor binding of [3H]imidafenacin was markedly suppressed in the bladder alone after bilateral ligation of the ureters. After intravenous injection, the [3H]imidafenacin concentration was markedly higher in the urine than in the plasma, suggesting that urinary excretion may contribute significantly to the selective and long-lasting binding of imidafenacin to bladder muscarinic receptors. These findings suggest that the intravesicular concentration of an antimuscarinic agent and its active metabolites may have a substantial influence on its pharmacological effect and duration of action in patients with OAB. In addition, factors that modulate urine production may influence the efficacy and safety of antimuscarinic agents.

Characterization of PCS1055, a novel muscarinic M4 receptor antagonist.

Identification of synthetic ligands selective for muscarinic receptor subtypes has been challenging due to the high sequence identity and structural homology among the five muscarinic acetylcholine receptors. Here, we report the pharmacological characterization of PCS1055, a novel muscarinic M4 receptor antagonist. PCS1055 inhibited radioligand [(3)H]-NMS binding to the M4 receptor with a Ki=6.5nM. Though the potency of PCS1055 is lower than that of pan-muscarinic antagonist atropine, it has better subtype selectivity over previously reported M4-selective reagents such as the muscarinic-peptide toxins (Karlsson et al., 1994; Santiago and Potter, 2001a) at the M1 subtype, and benzoxazine ligand PD102807 at the M3-subtype (Bohme et al., 2002). A detailed head-to-head comparison study using [(3)H]-NMS competitive binding assays characterizes the selectivity profiles of PCS1055 to that of other potent muscarinic-antagonist compounds PD102807, tropicamide, AF-DX-384, pirenzapine, and atropine. In addition to binding studies, the subtype specificity of PCS1055 is also demonstrated by functional receptor activation as readout by GTP-γ-[(35)S] binding. These GTP-γ-[(35)S] binding studies showed that PCS1055 exhibited 255-, 69.1-, 342- and >1000-fold greater inhibition of Oxo-M activity at the M4 versus the M1-, M2(-), M3-or M5 receptor subtypes, respectively. Schild analyses indicates that PCS1055 acts as a competitive antagonist to muscarinic M4 receptor, and confirms the affinity of the ligand to be low nanomolar, Kb=5.72nM. Therefore, PCS1055 represents a new M4-preferring antagonist that may be useful in elucidating the roles of M4 receptor signaling.

Concentration-QT analysis of the randomized, placebo- and moxifloxacin-controlled thorough QT study of umeclidinium monotherapy and umeclidinium/vilanterol combination in healthy subjects.

The long-acting muscarinic antagonist umeclidinium (UMEC) is approved as a once-daily monotherapy and in combination with the long-acting ß2 agonist vilanterol (VI) for chronic obstructive pulmonary disease. The objective of this analysis was to assess the relationship between observed plasma UMEC and/or VI concentrations and QT interval corrected using Fridericia's correction (QTcF). 103 subjects were enrolled and 86 (83 %) completed the study. Subjects were randomized to 4 of 5 repeat-dose treatments (days 1-10: n = 77 subjects received placebo, n = 76 UMEC 500 µg, n = 78 UMEC/VI 125/25 µg, or n = 76 UMEC/VI 500/100 µg; day 10: n = 74 oral tablet moxifloxacin 400 mg [positive control]). The concentration-QTcF interval relationship was examined using nonlinear mixed-effects methods. For UMEC, predicted QTcF interval prolongation (at observed geometric mean of maximum plasma concentrations) was -2.38 ms (90 % prediction interval [PI] -3.82, -0.85) with UMEC 500 µg and -0.50 ms (90 % PI -0.80, -0.18) and -2.01 ms (90 % PI -3.22, -0.72) with UMEC/VI 125/25 µg and 500/100 µg, respectively. For VI, estimates were 5.89 ms (90 % PI 4.89, 6.91) and 7.23 ms (90 % PI 5.88, 8.55) with UMEC/VI 125/25 µg and 500/100 µg, respectively. Combined additive mean effects were estimated for UMEC/VI 125/25 µg (5.39 ms [90 % PI 4.40, 6.47]) and 500/100 µg (5.22 ms [90 % PI 3.72, 6.80]). The model-predicted decrease with UMEC and increase with UMEC/VI combination in QTcF interval suggest that the QT effect is likely attributable to VI. These model-predicted results support those of previously-published traditional statistical analyses.

Pharmacokinetics of Glycopyrronium Following Repeated Once-Daily Inhalation in Healthy Chinese Subjects.

BACKGROUND AND OBJECTIVES: Glycopyrronium is a once-daily long-acting muscarinic antagonist for the maintenance treatment of patients with chronic obstructive pulmonary disease. This study assessed the pharmacokinetics of inhaled glycopyrronium 50 µg once-daily for 14 days in healthy Chinese subjects. METHODS: In this open-label study, 12 Chinese healthy subjects (six males and six females; mean age 23.1 years [range 18-26 years]) were enrolled and completed the study. Glycopyrronium in plasma was determined using validated liquid chromatography-mass spectrometry method with a lower limit of quantification of 1.5 pg/mL. Plasma pharmacokinetic parameters were determined on Day 1 after first dose and on Day 14 (steady state) after last dose using non-compartmental analysis. Trough pharmacokinetic samples (Days 5, 7, 10 and 12) were collected. Safety was also assessed. RESULTS: Glycopyrronium was rapidly absorbed into the systemic circulation after inhalation and its plasma concentrations decreased rapidly thereafter. Median time to reach maximum concentration (T max) was reached within 5 min after inhalation on both Days 1 and 14. Accumulation in the systemic exposure to glycopyrronium was observed from the time of first dose administration on Day 1 up to Day 14 and the observed accumulation ratio (R acc) values of area under the plasma drug concentration-time curve [AUC] from time 0 to 24 h post-dose (AUC0-24h) and maximum plasma drug concentration (C max) (Day 14/Day 1) were 2.77 and 1.59, respectively. The elimination half-life (T 1/2) was not reported. Mean effective half-life (T 1/2,acc) was 37.7 h. Pharmacokinetic steady state was reached after 5 days of daily dosing. One subject experienced dry mouth; otherwise glycopyrronium was well tolerated. CONCLUSIONS: Comparison of systemic exposure to glycopyrronium in Chinese versus the non-Chinese population did not indicate clinically relevant ethnic differences. Multiple inhaled doses of glycopyrronium were safe and well tolerated.

The pharmacokinetics of intraosseous atropine in hypovolemic swine.

OBJECTIVE: Compare the pharmacokinetics of atropine administered via the intravenous (IV), intramuscular (IM), and intraosseous (IO) routes in a normovolemic and hypovolemic swine model. DESIGN: Prospective, between subjects, experimental study. SETTING: Vivarium. SUBJECTS: Yorkshire-cross swine (N = 36). INTERVENTION: Atropine was administered via IV, IM, or IO routes to normovolemic and hypovolemic swine. Blood samples were drawn at regular intervals after atropine administration and analyzed for plasma atropine concentration. Pharmacokinetic parameters were obtained from modeling the plasma concentrations. MAIN OUTCOME MEASUREMENTS: Pharmacokinetic parameters, maximum concentration (Cmax) and time to maximum concentration (Tmax). RESULTS: The IV and IO groups in both the normovolemic and hypovolemic models reached peak plasma concentration immediately and had a very rapid distribution phase with no apparent absorption phase for the IO groups. Peak plasma concentration and time to reach peak concentration were both significantly lower for the IM groups. There was a significant increase in absorption time with IM administration in the hypovolemic model compared to the normovolemic model. CONCLUSION: The IO route is an effective method of administering atropine and is comparable to the IV route even under conditions of significant hemorrhage. Therapeutic levels of atropine may be delayed and possibly difficult to obtain via IM injection in the presence of hypovolemic shock.

Population Pharmacokinetics and Pharmacodynamics of GSK961081 (Batefenterol), a Muscarinic Antagonist and ß2-Agonist, in Moderate-to-Severe COPD Patients: Substudy of a Randomized Trial.

GSK961081 (batefenterol) is a novel bifunctional molecule composed of a muscarinic antagonist and a ß2-agonist. The aims of this substudy were (1) to characterize the population pharmacokinetics (PK) and pharmacodynamics (PD) of GSK961081 in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD); and (2) to investigate the relationship between systemic exposure to GSK961081 and key cardiac-related safety parameters. Three once-daily doses (100, 400, and 800 µg) and three twice-daily doses (100, 200, and 400 µg) of GSK961081 DISKUS were investigated. A two-compartment disposition PK model with first-order absorption adequately described the plasma GSK961081 concentration-time data. An empirical maximum-effects PD model adequately described the forced expiratory volume in 1 s (FEV1) response relationship with the covariate baseline FEV1 on day 1. No clear relationships between GSK961081 plasma drug levels and cardiac-related safety parameters were apparent. The PK and PD models will be used to guide the dose selection and development of GSK961081 in patients with COPD.

Comparing the cardiovascular therapeutic indices of glycopyrronium and tiotropium in an integrated rat pharmacokinetic, pharmacodynamic and safety model.

Long acting inhaled muscarinic receptor antagonists, such as tiotropium, are widely used as bronchodilator therapy for chronic obstructive pulmonary disease (COPD). Although this class of compounds is generally considered to be safe and well tolerated in COPD patients the cardiovascular safety of tiotropium has recently been questioned. We describe a rat in vivo model that allows the concurrent assessment of muscarinic antagonist potency, bronchodilator efficacy and a potential for side effects, and we use this model to compare tiotropium with NVA237 (glycopyrronium bromide), a recently approved inhaled muscarinic antagonist for COPD. Anaesthetized Brown Norway rats were dosed intratracheally at 1 or 6h prior to receiving increasing doses of intravenous methacholine. Changes in airway resistance and cardiovascular function were recorded and therapeutic indices were calculated against the ED50 values for the inhibition of methacholine-induced bronchoconstriction. At both time points studied, greater therapeutic indices for hypotension and bradycardia were observed with glycopyrronium (19.5 and 28.5 fold at 1h; >200 fold at 6h) than with tiotropium (1.5 and 4.2 fold at 1h; 4.6 and 5.5 fold at 6h). Pharmacokinetic, protein plasma binding and rat muscarinic receptor binding properties for both compounds were determined and used to generate an integrated model of systemic M2 muscarinic receptor occupancy, which predicted significantly higher M2 receptor blockade at ED50 doses with tiotropium than with glycopyrronium. In our preclinical model there was an improved safety profile for glycopyrronium when compared with tiotropium.

Modeling the heterogeneous intestinal absorption of propiverine extended-release.

Propiverine is a widely used antimuscarinic drug with bioavailability that is limited by intestinal first-pass extraction. To study the apparent heterogeneity in intestinal first-pass extraction, we performed a population analysis of oral concentration-time data measured after administration of an extended-release formulation of propiverine in ten healthy subjects. Using an inverse Gaussian function as input model, the assumption that the systemically available fraction increases as a sigmoidal function of time considerably improved the fit. The step-like increase in this fraction at time t=3.7h predicted by the model suggests that propiverine is predominantly absorbed in colon. A nearly perfect correlation was found between the estimates of bioavailability and mean dissolution time.

Study of pharmacokinetic interaction of paroxetine and roxithromycin on bencycloquidium bromide in healthy subjects.

PURPOSE: The aim of this study was to investigate the potential drug-drug interaction between Bencycloquidium bromide (BCQB) and paroxetine, and between BCQB and roxithromycin. METHODS: Two studies were conducted on healthy male Chinese volunteers. Study A was an open-label, two-period, one-sequence crossover study (n=21). Each participant received a single nasal spray dose of BCQB 180µg on day 1. After a 7-day wash-out period, subjects received 20mg of paroxetine from day 8 to 17, and were co-administered 20mg of paroxetine and BCQB 180µg on day 18. In study B, participants (n=12) were randomly assigned to two groups. In period I, group A received BCQB 180µg on day 1, followed by the same dose four times daily from day 4 to 10, then, on day 11 a single dose of 150mg roxithromycin with BCQB 180µg were co-administered. In parallel, group B received a single dose of roxithromycin 150mg on day 1, followed by 300mg of roxithromycin from day 4 to 10, then, on day 11 a single dose of BCQB 180µg with roxithromycin 300mg were co-administered. After a wash-out time of 7days the respective treatments of each group (A and B) were swapped in period II. Blood samples were collected for pharmacokinetic analysis. Statistical comparison of pharmacokinetic parameters was performed to identify a possible drug interaction between treatments. Tolerability was evaluated by recording adverse events. RESULTS: Study A: Geometric mean AUC0-36 for BCQB alone and co-administered with paroxetine were 474.3 and 631.3pgh/ml, respectively. The geometric mean ratio (GMR) of AUC0-36 was 1.33 (1.13-1.46), 90% C.Is, and was out the predefined bioequivalence interval (90% C.Is, 0.80-1.25). Geometric mean Cmax were 187.0 and 181.2pg/ml. Study B: The GMR of AUC0-36 was 0.98 (0.90-1.07), 90% C.Is for BCQB, and the GMR of AUC0-72 was 0.98 (0.87-1.11), 90% C.Is for roxithromycin. Both GMRs were within the predefined bioequivalence interval (90% C.Is, 0.80-1.25). Other pharmacokinetic parameters were within the predefined interval. No serious adverse events were reported and no significant clinical changes were observed in laboratory test results, vital signs and ECGs in any of the studies. All treatments were well tolerated. CONCLUSION: The co-administration of BCQB with paroxetine showed a moderate increase in BCQB exposure, but was not clinically relevant. Also, no drug interaction was found between BCQB and roxithromycin.

Efficacy and safety of nebulized glycopyrrolate for administration using a high efficiency nebulizer in patients with chronic obstructive pulmonary disease.

AIMS: To establish the dose-response for pharmacodynamics (bronchodilatation), safety and pharmacokinetics for a nebulized formulation of the long acting muscarinic antagonist glycopyrrolate (EP-101) with a high efficiency nebulizer in patients with chronic obstructive pulmonary disease (COPD). METHODS: Patients with moderate to severe COPD (GOLD II/III), with reversible lung function, were enrolled into this randomized, double-blind, placebo-controlled, six period crossover study (n = 42). Patients received single doses of EP-101 (12.5-400 µg) and placebo via a high efficiency nebulizer (eFlow® PARI nebulizer), with washout between treatments. Plasma pharmacokinetics were assessed in a subset of patients (n = 11). RESULTS: All treatments were well tolerated with similar adverse event rates reported with placebo and at all doses. There were no clinically relevant changes in heart rate, systolic and diastolic blood pressure or in ECG parameters including QTc interval. Following treatment with EP-101 at all doses there was a rapid bronchodilator response within 5 min. Significant improvements in mean change from baseline FEV1 at 24 h were reported at doses ≥ 50 µg compared with placebo, with a clear dose-response relationship. Mean changes in FEV1 were 0.10 l (95% CI 0.06, 0.14) and 0.12 l (95% CI 0.08, 0.16) for 100 µg and 200 µg, respectively. CONCLUSION: Single doses of EP-101 ranging from 12.5 µg to 400 µg were well tolerated. EP-101 delivered by high efficiency nebulizer device produced a rapid onset of bronchodilatation with clinically meaningful improvements in lung function maintained over a 24 h period at all doses >50 µg.