Validation of a sensitive and specific LC-MS/MS method and application to evaluate the systemic exposure and bioavailability of glycopyrrolate via different drug delivery approaches/devices.

A specific and sensitive LC-MS/MS method using d3 -glycopyrrolate as the internal standard (IS) was developed for the quantitative determination of glycopyrrolate (GLY) in human plasma over a concentration range of 4.00-2000 pg/ml. The GLY and IS were extracted using a solid-phase extraction cartridge, then eluted with 0.5% formic acid in 70:30 acetonitrile-water. The eluate was directly injected into an Agilent Pursuit 5PFP column for analysis using an isocratic mobile phase of 50:50 A:B at a flow-rate of 0.500 ml/min (A, 10 mm ammonium acetate in 1% formic acid; B, methanol). The MS detection was in positive mode by monitoring m/z 318.3 → 116.1 (GLY) and 321.3 → 119.1 (IS). The method validation showed the linearity of r2 ≥ 0.9960, intra-/inter-run precisions of ≤11.1% coefficient of variation and accuracies ranging from -2.5 to 12.8% relative error for all levels of quality control samples. This method was successfully employed to support a clinical study to compare absorption and bioavailability of GLY administered by a Magnair® eFlow nebulizer to a Seebri® Breezhaler® with/without a charcoal blockade of gastric absorption. By comparison with intravenous administration, respective bioavailabilities of ~15% for GLY/Magnair and ~22% for the Seebri Breezhaler were found. The bioanalytical reliability was also demonstrated by satisfactory incurred sample reanalysis performance.

Pharmacokinetics, pharmacodynamics and safety of a novel extrafine BDP/FF/GB combination delivered via metered-dose inhaler in healthy Chinese subjects.

BACKGROUND: BDP/FF/GB pMDI is a novel triple fixed-dose combination of extra-fine inhalation aerosol beclomethasone dipropionate (BDP)/formoterol fumarate (FF)/glycopyrronium bromide (GB). Limited data on the pharmacokinetic (PK) and pharmacodynamic (PD) properties of BDP/FF/GB fixed-dose combination in healthy subjects was available. PURPOSES: This study aimed to evaluate the pharmacokinetics, pharmacodynamics and safety of BDP/FF/GB pMDI in healthy Chinese subjects. METHODS: This is an open-label, parallel-group, randomized, single and multiple dose study. In the single dose group, subjects received single supra-therapeutic inhaled dose of BDP/FF/GB pMDI (BDP/FF/GB 400/24/50 µg). In the multiple dose group, subjects received therapeutic inhaled dose of BDP/FF/GB pMDI (BDP/FF/GB 200/12/25 µg), twice daily, for 7 consecutive days. Plasma BDP, B17MP, formoterol and GB were determined by a validated ultra performance liquid chromatography method with tandem mass spectrometric detection (UPLC/MS-MS). Heart rate (HR), QTcF, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were evaluated as the surrogate indicators of pharmacodynamic effects. RESULTS: A total of 24 subjects were randomized and 22 (11 in each group) completed the study. The dose adjusted pharmacokinetic profiles of BDP, beclomethasone-17-monopropionate (B17MP, the most active metabolite of BDP), formoterol and GB were overall similar in therapeutic and supra- therapeutic dose group, showing dose proportional increase of the systemic exposure to BDP, B17MP, formoterol and GB. The pharmacodynamic variables were within the normal range and showed no significant difference between the two groups. All the treatment-emergent adverse events (TEAEs) were mild and no severe TEAE was reported. CONCLUSIONS: Dose adjusted PK profiles were similar between therapeutic and supra-therapeutic dose for all compounds, nearly dose proportional systemic exposure to B17MP, formoterol and GB after BDP/FF/GB pMDI administration in healthy Chinese subjects. BDP/FF/GB pMDI was safe and well tolerated in healthy Chinese subjects. The PK profiles were comparable to previously published data from Western European healthy Caucasian subjects.

Pharmacokinetics of budesonide/glycopyrrolate/formoterol fumarate metered dose inhaler formulated using co-suspension delivery technology after single and chronic dosing in patients with COPD.

BACKGROUND: Budesonide/glycopyrrolate/formoterol fumarate metered dose inhaler (BGF MDI), formulated using co-suspension delivery technology, is a triple fixed-dose combination in late-stage clinical development for chronic obstructive pulmonary disease (COPD). METHODS: We conducted two studies to characterize the pharmacokinetic (PK) profile of BGF MDI in patients with COPD: (i) a phase I, open-label, single and chronic (7-day) dosing study (NCT03250182) with one treatment arm (BGF MDI 320/18/9.6 µg); and (ii) a PK sub-study of KRONOS (NCT02497001), a phase III, randomized, double-blind study in which patients received 24 weeks' treatment with BGF MDI 320/18/9.6 µg, glycopyrrolate/formoterol fumarate (GFF) MDI 18/9.6 µg, budesonide/formoterol fumarate (BFF) MDI 320/9.6 µg, or budesonide/formoterol fumarate dry powder inhaler (BUD/FORM DPI) 320/9 µg. PK parameters in both studies included maximum observed plasma concentration (Cmax) and area under the plasma concentration-time curve from 0 to 12h (AUC0-12). RESULTS: In the phase I PK study (30 patients), budesonide and glycopyrronium Cmax were comparable after single and chronic dosing of BGF MDI (accumulation ratio [RAC] 95% and 107%, respectively) whereas Cmax for formoterol was slightly higher after chronic dosing (RAC 116%). AUC0-12 for budesonide, glycopyrronium, and formoterol were higher following chronic versus single dosing, with an RAC of 126%, 179%, and 143%, respectively. After 7 days' dosing, AUC0-12 and Cmax for all three components of BGF MDI were similar to those in the KRONOS PK sub-study (202 patients) at Week 24. In the latter sub-study, Cmax and AUC0-12 at Week 24 were generally comparable across treatments for budesonide (geometric mean ratios [GMR] of 96%-109% for BGF MDI vs BFF MDI or BUD/FORM DPI), glycopyrronium (GMR of 88%-100% for BGF MDI vs GFF MDI), and formoterol (GMR of 80%-113% for BGF MDI vs GFF MDI or BFF MDI). CONCLUSIONS: Steady-state PK parameters of budesonide, glycopyrronium, and formoterol were similar after 7 days' dosing in the phase I PK study and after 24 weeks in the KRONOS PK sub-study. Systemic exposure to budesonide, glycopyrronium, and formoterol was generally comparable across treatments in the KRONOS PK sub-study, suggesting no meaningful drug-drug or within-formulation PK interactions.

Identification of Major Esterase Involved in Hydrolysis of Soft Anticholinergic (2R3'R-SGM) Designed From Glycopyrrolate in Human and Rat Tissues.

The glycopyrrolate soft analog, SGM, designed to be easily hydrolyzed into the significantly less active zwitterionic metabolite, SGa, typifies soft drug that reduces systemic side effects (a problem often seen with traditional anticholinergics) following local administration. In this study, hydrolysis of 2R3'R-SGM, the highest pharmacologically active stereoisomer of SGM, was investigated in human and rat tissues. In both species, 2R3'R-SGM was metabolized to 2R3'R-SGa in plasma but was stable in liver and intestine. The half-life of 2R3'R-SGM was found to be 16.9 min and 9.8 min in human and rat plasma, respectively. The enzyme inhibition and stimulation experiments showed that plasma paraoxonase 1 (PON1) is responsible for the hydrolysis of 2R3'R-SGM in humans and rats. The PON1-mediated hydrolysis of 2R3'R-SGM was confirmed in the lipoprotein-rich fractions of human plasma. As PON1 is naturally attached to high-density lipoprotein, it might be absent in topical tissues where 2R3'R-SGM is applied, supporting its local stability and efficacy. The metabolic behavior of 2R3'R-SGM indicates that it is an ideal soft drug to be detoxified as soon as it moves into systemic circulation. Furthermore, the similarity of 2R3'R-SGM metabolism in humans and rats showed that the rat is a suitable animal for preclinical study.

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.

Dispersive micro-solid-phase extraction combined with online preconcentration by capillary electrophoresis for the determination of glycopyrrolate stereoisomers in rat plasma.

A simple and sensitive analytical method for four isomers of glycopyrrolate in rat plasma was developed using cation-selective exhaustive injection-sweeping cyclodextrin-modified electrokinetic chromatography (CSEI-Sweeping-CDEKC) for online enrichment combined with dispersive micro-solid-phase extraction pretreatment. The CSEI-Sweeping-CDEKC was conducted on an uncoated fused silica capillary (40.2 cm × 75 µm) with an applied voltage of -20 kV. The electrophoretic analysis was carried out in 30 mM phosphate solution at pH 2.0 containing 20 mg/mL sulfated-ß-cyclodextrin and 5% acetonitrile. Under these optimized conditions, the detection limit for racemic glycopyrrolate was found to be 2.0 ng/mL and this method could increase 495-fold detection sensitivity compared with the traditional injection method. Additionally, the parameters that affected the extraction efficiency of dispersive micro-solid-phase extraction were also examined systematically. The glycopyrrolate isomers in rat plasma samples as low as 0.0625 µg/mL were able to be separated and detected by capillary electrophoresis with the aid of CSEI-sweeping. The findings of this study show that the dispersive micro-solid-phase extraction pretreatment coupled with CSEI-Sweeping-CDEKC is a rapid and convenient method for analyzing glycopyrrolate isomers in rat plasma.

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.

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.

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.

Pharmacokinetics and pharmacodynamics of glycopyrrolate following a continuous-rate infusion in the horse.

Glycopyrrolate (GLY) is an antimuscarinic agent that is used in humans and domestic animals primarily to reduce respiratory tract secretions during anesthesia and to reverse intra-operative bradycardia. Although GLY is used routinely in veterinary patients, there is limited information regarding its pharmacokinetic (PK) and pharmacodynamic (PD) properties in domestic animals, and an improved understanding of the plasma concentration-effect relationship in racehorses is warranted. To accomplish this, we characterize the pharmacokinetic-pharmacodynamic (PK-PD) actions of GLY during and after a 2-h constant-rate intravenous infusion (4 µg/kg/h) and evaluate potential PK-PD models for cardiac stimulation in adult horses. Measurements of plasma GLY concentrations, heart and respiration rates, and frequency of bowel movements were performed in six Thoroughbred horses. The time course for GLY disposition in plasma followed a tri-exponential equation characterized by rapid disappearance of GLY from blood followed by a prolonged terminal phase. Physiological monitoring revealed significant (P < 0.01) increases in heart (>70 bpm) and respiratory rates accompanied by a marked and sustained delay in the frequency of bowel movements (1.1 ± 0.2 h [saline group] vs. 6.0 ± 2.0 h [GLY group]). Two of six horses showed signs of colic during the 8-h observation period after the end of the GLY infusion, but were treated and recovered without further complications. The relationship between plasma GLY concentration and heart rate exhibited counterclockwise hysteresis that was adequately described using an effect compartment.

Validation of a liquid chromatography-tandem mass spectrometry method for quantification of glycopyrrolate in horse plasma.

A rapid, sensitive, and specific ultra-high-performance liquid chromatography with heated electrospray ionization-tandem mass spectrometry (UHPLC-HESI-MS-MS) method to detect and quantify glycopyrrolate in horse plasma has been developed and validated. We also determined glycopyrrolate in plasma after oral and intravenous administration of clinically relevant doses to Thoroughbred horses. Calibration was accomplished by weighted, linear regression analysis using a deuterated analogue of glycopyrrolate as internal standard (IS). Glycopyrrolate (GLY) and the IS (GLY-d(3)) were isolated from plasma matrices via weak cation exchange using a simple solid-phase extraction technique. Chromatographic analysis was achieved by reversed-phase UHPLC on a C(18) Acquity™ column. Extracts were analyzed in positive electrospray ionization mode and precursor and product ions were detected and quantified by MS-MS using a triple-stage quadrupole (TSQ) instrument. The method was characterized by a linear range of 0.125-25 pg/mL (R(2) > 0.998), a lower limit of quantification of 0.125 pg/mL and a lower limit of detection of 0.025 pg/mL. Recovery of GLY ranged from 78% to 96%, and intra- and interbatch precision were 3.3-14.4%CV and 3.4-14.4%CV, respectively. Glycopyrrolate was stable in plasma for up to 170 days at -80°C, through three freeze/thaw cycles, and for up to 48 h after extraction under 20°C autosampler conditions.

Quantitative determination of glycopyrrolate in human plasma by liquid chromatography-electrospray ionization mass spectrometry: the use of a volatile ion-pairing agent during both liquid-liquid extraction and liquid chromatography.

The work presented here deals with the development of a quantitative tool for the determination of the quaternary ammonium anticholinergic glycopyrrolate in human plasma samples. Mepenzolate was used as an internal standard. The plasma samples were subjected to a suitable sample clean-up consisting of a simple and relatively fast, two step liquid-liquid ion-pair extraction procedure. The chromatography, using the same volatile ion-pair reagent heptafluorobutyric acid (HFBA), takes only 10 min. Relative standard deviation of retention times was never above 2.26% (n=36). The method was fully validated based on the US FDA Bioanalytical Method Validation Guidance for Industry. As such, a quantitative ESI-LC-MS(/MS) (TOF mass spectrometry) method was optimized for the absolute quantification of glycopyrrolate in human plasma in a concentration range from 0.101 to 101 ng/mL using a quadratic calibration function (R(2)=0.9995), y=-2.21 x 10(-4) (+/-3.93 x 10(-5))xx(2)+5.85 x 10(-2) (+/-5.27 x 10(-3))xx+4.08 x 10(-3) (+/-4.82 x 10(-4)). For the three QC concentrations (QC(1) 0.252, QC(2) 2.52, and QC(3) 25.2ng/mL) and the LLOQ (0.101 ng/mL), total precision was under 20% (18.0% (n=6) at the LLOQ) and maximum accuracy was 112% (88.9% for the LLOQ, n=6). Absolute matrix effect (maximum 133%+/-9.59, n=3), absolute recovery (better than 41.8%+/-2.22, n=3), relative (inter-subject) matrix effect (maximum 10.9%+/-1.45, n=4) and process efficiency (better than 45.2%+/-5.74, n=3) too were assessed at the 3 QC concentrations.

Pharmacokinetic-pharmacodynamic model for the anticholinergic effect of glycopyrrolate.

OBJECTIVE: The purpose of this study was to develop and test a pharmacokinetic-pharmacodynamic (PK-PD) model for the anticholinergic effect of glycopyrrolate in eight healthy male volunteers. METHODS: First, arterial drug concentration (Cp) data after a single intravenous (i.v.) bolus injection (5 micrograms/kg) were individually fitted to a three-compartment PK model. Second, the effect of a 2-h glycopyrrolate i.v. infusion (5 micrograms/kg/h) on the mean R-R interval (RRI) and the Hayano index of the high frequency variability of RRI (HF CCV) was modelled using an effect-compartment, inhibitory sigmoidal Emax model, with the individual PK parameters from the first part as constants. Third, the developed model was tested using a computer-driven infusion which aimed at two ascending steady-state effect-site concentrations (Ce) at 1-h intervals, corresponding to 20% and 80% of the maximal effect (Emax) observed in the second part. RESULTS: Modeling of the HF CCV data yielded the following mean (+/- SD) estimates: concentration at 50% of Emax (EC50), 2.46 +/- 0.58 ng/ml, equilibration half-time (t1/2 ke0), 42.5 +/- 7.7 min, and sigmoidicity factor (gamma), 7.26 +/- 2.82. The corresponding values for RRI data were 2.79 +/- 0.52 ng/ml, 58.3 +/- 17.2 min, and 4.75 +/- 1.56. During the computer-controlled two-step infusion (performed using HF CCV as the effect variable), the measured Cp approached the targeted Ce in most of the subjects, while the observed effect appeared to surpass the targeted levels. CONCLUSION: Although we were able to develop individual PK-PD models for glycopyrrolate, maintaining a stable anticholinergic effect in the computer-driven infusion appeared to be difficult. This is probably due to intra-individual variability in the PK-PD parameters and the extremely steep concentration-effect relationship of glycopyrrolate.

Pharmacokinetics and oral bioavailability of glycopyrrolate in children.

Based on plasma levels determined with a radioreceptor assay and following a single oral (50 micrograms/kg) and intravenous (5 micrograms/kg) administration of glycopyrrolate in six healthy children operated twice during a several weeks period, a negligible and variable oral bioavailability was found (3.3; 1.3-13.3%) (median;range). No significant changes in heart rate after oral or intravenous administration of the drug could be seen. Oral glycopyrrolate appears to have no place in paediatric premedication.

Pharmacokinetics of glycopyrrolate in children.

STUDY OBJECTIVE: To investigate the pharmacokinetics of glycopyrrolate in children. DESIGN: Open study with three parallel groups. SETTING: Pediatric surgery department at a university hospital. PATIENTS: 26 healthy ASA physical status I children undergoing minor surgery. INTERVENTIONS: Patients were assigned to 1 of 3 groups: under 1 year of age (Group 1, n = 8), between 1 and 3 years of age (Group 2, n = 7), and over 3 years of age (Group 3, n = 11). Glycopyrrolate 5 micrograms/kg was given as a single intravenous (i.v.) injection before induction of general anesthesia. Blood samples (for determination of drug concentrations in plasma) were collected via venous cannula inserted into the contralateral antecubital vein. MEASUREMENTS AND MAIN RESULTS: ECG was observed continuously, blood pressure was measured with an automatic noninvasive device, and blood samples were taken just before and at 2, 4, 6, 10, 15, 30, 60, 120, 180, 240, 360, and 480 minutes after injection of glycopyrrolate. Glycopyrrolate concentrations in plasma were determined with a radioreceptor assay. The only significant difference in the pharmacokinetic parameters was the shortened elimination half-life in patients between 1 and 3 years of age. Glycopyrrolate 5 micrograms/kg i.v. did not cause any significant alterations in heart rate. CONCLUSIONS: There were no significant changes in the distribution volume or clearance of glycopyrrolate in children of different ages. The shortened elimination half-life in children between 1 and 3 years of age is of minor clinical importance.

Pharmacokinetics of glycopyrronium in uraemic patients.

We studied the pharmacokinetics of glycopyrronium in 11 uraemic patients undergoing cadaveric renal transplantation and in seven ASA I control patients undergoing general surgery. Glycopyrronium 4 micrograms kg-1 was given i.v. before induction of anaesthesia. Blood and urine samples were collected for up to 24 h for measurement of glycopyrronium concentrations using a radioreceptor assay. Volume of distribution in the elimination phase (V beta) was similar in both groups, the elimination half-life (T1/2 beta) was longer (P < 0.05), area under the plasma concentration-time curve (AUC) larger (P < 0.01) and plasma clearance (CI) smaller (P < 0.01) in the uraemic patients. In 3 h, mean 0.7 (range 0-3)% and 50 (21-82)% of glycopyrronium was excreted in the urine in the uraemic and healthy patients, respectively (P < 0.001). The 24-h renal excretion was 7 (0-25)% in uraemic and 65 (30-99)% in control patients (P < 0.001). We conclude that the elimination of glycopyrronium is severely impaired in uraemic patients.

Radioreceptor assay for pharmacokinetic studies of glycopyrrolate.

A sensitive radioreceptor assay for the determination of glycopyrrolate concentrations in human plasma, urine and cerebrospinal fluid (CSF) is described. The applicability of the assay for kinetic studies in human was studied by determining the plasma concentrations and the renal excretion in three gynaecological surgical patients, who received 8 micrograms/kg of glycopyrrolate as a premedication intramuscularly. Tritiated N-methyl scopolamine was used to label the muscarinic cholinergic receptors in the membrane preparation obtained from the rat brain. The limit of detection of the assay was 70 ng/l in plasma, 2 micrograms/l in urine and 140 ng/l in CSF. There was no evidence of cross-reactivity of glycopyrrolate derivatives in clinical concentrations. A very rapid absorption was found with a mean maximum plasma concentration (Cmax) of 14.26 (range 12.02-16.97) micrograms/l and mean Tmax (time to Cmax) of 13.3 (range 10-15) min. and almost 50% of the dose administered was excreted into the urine within 3 hr. The CSF levels of glycopyrrolate were under detection limit. It is concluded that the sensitivity of the method is sufficient for pharmacokinetic studies of glycopyrrolate after therapeutic dosing.

Pharmacokinetics of glycopyrronium in parturients.

A sensitive radioreceptor assay was used to determine the pharmacokinetics of glycopyrronium 6 micrograms/kg after intramuscular (deltoid muscle) administration in eight Caesarean section patients. A fast absorption rate was found with a mean maximum plasma concentration (Cmax) of 6.3 (SD 1.5) ng/ml, a mean time to Cmax (Tmax) of 10.0 (3.8) minutes and the elimination half-life (t1) of 33.4 (1.92). The respective AUC0-8 h value was 5.61 (1.27) hours ng/ml. This dose produced a significant increase in the maternal heart rate after 10 minutes (p less than 0.05) and an antisialogogue effect after 30 minutes (p less than 0.05) of the drug injection. Almost half of drug (48.3%) was excreted into the urine within 3 hours. There were no measurable levels of glycopyrronium in the lumbar cerebrospinal fluid (CSF) after 60 minutes of drug injection. The concentrations of glycopyrronium in the umbilical venous (0.28 (0.25) ng/ml) and in the umbilical arterial (0.18 (0.11) ng/ml) plasma after 86 minutes of drug injection were low and clinically insignificant, as was the case in the amniotic fluid (0.15 (0.08) ng/ml).