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.

Local and systemic effects of inhaled AZD9164 compared with tiotropium in patients with COPD.

There is still a need for new agents which improve upon the therapeutic index of tiotropium, the current standard of care for many patients with chronic obstructive pulmonary disease (COPD). We examined in patients with COPD the efficacy of single doses of AZD9164, an M(3)-selective muscarinic antagonist, to identify an appropriate dose-range for future studies. COPD patients (n = 28) inhaled AZD9164 (100, 400 and 1200 µg), tiotropium (18 µg) and placebo at 5 study centre visits (Clinicaltrials.gov identifier NCT00939211). The effects of these test drugs on average (E(av)), peak (E(max)) and trough (E(22-26)) forced expiratory volume in one second (FEV(1)) were assessed, as were systemically-mediated effects and the safety and exposure of single doses of AZD9164. AZD9164 100, 400 and 1200 µg caused increases in FEV(1) to peak effects of 12, 17 and 12% above baseline respectively, following an initial transient and dose-related fall in FEV(1) and associated increase in mild respiratory symptoms such as cough. Bronchodilation was maintained overnight, with minimal FEV(1) decline. AZD9164 400 and 1200 µg produced larger effects than tiotropium on E(22-26) (p < 0.05; both doses) while AZD9164 400 µg also had larger effects on E(max) (p = 0.001) and E(av) (p < 0.05). There were no serious adverse events and statistically significant systemic effects were observed only with AZD9164 1200 µg. AZD9164 may improve upon the therapeutic index of tiotropium, increasing the magnitude and duration of lung function improvements without increasing systemically-mediated adverse events. The initial bronchoconstrictor effect of AZD9164 requires further investigation.

Pharmacokinetics and tolerability (Study 1) with particular reference to ocular safety (Study 2) of tiotropium Respimat soft mist inhaler: findings from two dose-ranging studies in healthy men.

Data are presented from two randomized, double-blind, placebo-controlled studies in which the tolerability of tiotropium Respimat Soft MistTM Inhaler (SMI), a new-generation, propellant-free device for use in COPD, and the ocular safety oftiotropium were examined. In Study 1, 36 healthy males received tiotropium 8, 16, or 32 microg (n = 9/dose) or placebo (n = 3/dose level), administered once daily via Respimat SMI for 14 days. Safety and pharmacokinetics were evaluated. In Study 2, 48 healthy males received tiotropium 0.02, 0.04, 0.08, 0.16, 0.28, or 0.40 microg (n = 6/dose) or placebo (n = 2/dose level), applied as two drops to one eye (the highest dose was a significant multiple of a percentage of the proposed Respimat SMI clinical dose that could be inadvertently deposited in the eye). Ocular parameters were measured over 24 hours. Tiotropium Respimat SMI at doses up to 32 microg was well tolerated in Study 1; typical dose-dependent anticholinergic adverse events of mild-to-moderate intensity were observed. In Study 2, ocular tiotropium administration did not affect pupil diameter, pupillary reflex, intraocular pressure, or accommodation. Tiotropium Respimat SMI was well tolerated. Inadvertent ocular exposure to tiotropium up to 0.40 g is unlikely to result in ocular adverse effects.

Sensitive HPLC-ESI-MS method for the determination of tiotropium in human plasma.

A sensitive high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) assay is established for the determination of tiotropium in human plasma using benzyltriethylammonium chloride as the internal standard (IS). After being treated with C(18) cartridges, plasma samples are separated by HPLC on a reversed-phase C(18) column with a mobile phase of 40mM ammonium acetate buffer-methanol (56:44, v/v). Tiotropium is determined in a single-quadrupole MS. HPLC-ESI-MS is performed in the selected ion monitoring mode using target ions at m/z 392.0 for tiotropium and m/z 192.3 for the IS. The calibration curve is linear over the range 1.5-30 pg/mL. The intra- and inter-assay variability values are less than 10.1% and 13.6%, respectively. The mean plasma extraction recovery of tiotropium is 92.3 +/- 5.0%. The method has been successfully applied to studying the pharmacokinetics of tiotropium in healthy Chinese volunteers.

Liquid chromatography-electrospray ionization ion trap mass spectrometry for analysis of in vivo and in vitro metabolites of scopolamine in rats.

In vivo and in vitro metabolism of scopolamine is investigated using a highly specific and sensitive liquid chromatography-mass spectrometry (LC-MSn) method. Feces, urine, and plasma samples are collected individually after ingestion of 55 mg/kg scopolamine by healthy rats. Rat feces and urine samples are cleaned up by a liquid-liquid extraction and a solid-phase extraction procedure (C18 cartridges), respectively. Methanol is added to rat plasma samples to precipitate plasma proteins. Scopolamine is incubated with homogenized liver and intestinal flora of rats in vitro, respectively. The metabolites in the incubating solution are extracted with ethyl acetate. Then these pretreated samples are injected into a reversed-phase C18 column with mobile phase of methanol-ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70:30, v/v) and detected by an on-line MSn system. Identification and structural elucidation of the metabolites are performed by comparing their changes in molecular masses (DeltaM), retention-times and full scan MSn spectra with those of the parent drug. The results reveal that at least 8 metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, hydroxyscopolamine, and hydroxyscopolamine N-oxide) and the parent drug exist in feces after administering 55 mg/kg scopolamine to healthy rats. Three new metabolites (tetrahydroxyscopolamine, trihydroxy-methoxyscopolamine, and dihydroxy-dimethoxyscopolamine) are identified in rat urine. Seven metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, and hydroxyscopolamine) and the parent drug are detected in rat plasma. Only 1 hydrolyzed metabolite (scopine) is found in the rat intestinal flora incubation mixture, and 2 metabolites (aposcopolamine and norscopolamine) are identified in the homogenized liver incubation mixture.

Highly sensitive assay for tiotropium, a quaternary ammonium, in human plasma by high-performance liquid chromatography/tandem mass spectrometry.

Tiotropium bromide, a long-acting inhaled bronchodilator analogous to ipratropium bromide, is currently undergoing development for the treatment of chronic obstructive pulmonary disease. To evaluate its systemic absorption in humans, we have developed a rapid and sensitive method for its determination in human plasma based on high-performance liquid chromatography with tandem mass spectrometric detection (HPLC/MS/MS). Reversed-phase chromatography of tiotropium and the internal standard clenbuterol was carried out using acetonitrile/10 mM ammonium acetate (1% formic acid) 40:60 as mobile phase in a run time of 3.0 min. The sample preparation involved deproteination with acetonitrile, extraction into dichloromethane and back-extraction into hydrochloric acid. The assay was linear over the concentration range 0.500-50.0 pg/mL with intra- and inter-day precision (as relative standard deviation) both

Structural elucidation of in vivo and in vitro metabolites of anisodine by liquid chromatography-tandem mass spectrometry.

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESIMSn) was employed to investigate the in vivo and in vitro metabolism of anisodine. Feces, urine and plasma samples were collected after ingestion of 20 mg anisodine to healthy rats. Feces and urine samples were cleaned up by liquid-liquid extraction and solid-phase extraction procedures (C18 cartridges), respectively. Methanol was added to plasma samples to precipitate plasma proteins. Anisodine was incubated with homogenized liver and intestinal flora of rats in vitro, respectively, followed by extraction with ethyl acetate. LC-MSn was used for the separation and identification of the metabolites using C18 column with mobile phase of methanol/0.01% triethylamine solution (2 mM, adjusted to pH 3.5 with formic acid) (60:40, v/v). The results revealed that five metabolites (norscopine, scopine, alpha-hydroxytropic acid, noranisodine and hydroxyanisodine) and the parent drug existed in feces. Three new metabolites (dimethoxyanisodine, tetrahydroxyanisodine and trihydroxy-methoxyanisodine) were identified in urine. Four metabolites (norscopine, scopine, hydroxyanisodine and anisodine N-oxide) and the parent drug were detected in plasma. Two hydrolyzed metabolites (scopine and alpha-hydroxytropic acid) were found in rat intestinal flora incubation mixture, and two metabolites (aponoranisodine and anisodine N-oxide) were identified in homogenized liver incubation mixture.

A rapid and sensitive liquid chromatography/positive ion tandem mass spectrometry method for the determination of cimetropium in human plasma by liquid-liquid extraction.

We have developed and validated a simple detection system with high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometry (ESI-MS/MS) for determining cimetropium levels in human plasma using scopolamine butyl bromide as an internal standard (I.S.). The acquisition was performed in the multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 357.9 > 103.1 for cimetropium and m/z 359.9 > 103.1 for butyl-scopolamine. The method involves a simple single-step liquid-liquid extraction with dichloromethane. The analyte was chromatographed on an YMC C18 reversed-phase chromatographic column by isocratic elution with 10 mM ammonium formate buffer-methanol (19:81, v/v; adjusted to pH 4.0 with formic acid). The results were linear over the studied range (0.2-100 ng ml(-1)), with r2 = 1.0000, and the total analysis time for each run was 2 min. Intra- and interassay precisions were 0.70-8.54% and 1.08-4.85%, respectively, and intra- and interassay accuracies were 97.56-108.23% and 97.48-103.91%, respectively. The lower limit of quantification (LLOQ) was 0.2 ng ml(-1). At this concentration, mean intra- and interassay precisions were 8.54% and 4.85%, respectively, and mean intra- and interassay accuracies were 97.56% and 98.91%, respectively. The mean recovery ranged from 62.71 +/- 4.06 to 64.23 +/- 2.32%. Cimetropium was found to be stable in plasma samples under typical storage and processing conditions. The devised assay was successfully applied to a pharmacokinetic study of cimetropium bromide administered as a single oral dose (150 mg) to healthy volunteers.

Pharmacokinetics of intravenous, single-dose tiotropium in subjects with different degrees of renal impairment.

Tiotropium, a new potent anticholinergic bronchodilator, is excreted mainly by the kidney. To investigate the pharmacokinetics of tiotropium in renal impairment, the authors evaluated the pharmacokinetics and safety after administration of a single dose of intravenous tiotropium 4.8 microg, given as an infusion over 15 minutes in subjects with normal renal function and a wide range of renal impairment based on measured creatinine clearance (normal: > 80 mL/min, n = 6; mild impairment: > 50-80 mL/min, n = 5; moderate impairment: 30-50 mL/min, n = 7; severe impairment: < 30 mL/min, n =6). As expected for a drug excreted predominantly in unchanged form by the kidneys, tiotropium plasma concentrations increased as renal impairment worsened, with mean values of 55.5 (16.2 percent geometric coefficient of variation [%gCV]), 77.1 (20.1 %gCV), 101 (29.8 %gCV), and 108 (27.3 %gCV) pgh/mL for AUC(0-4h) in the normal renal function and the mild, moderate, and severe renal impairment groups, respectively. The percentage of tiotropium dose excreted unchanged in the urine decreased from 60.1% of dose (17.7 %gCV) to 59.3% (14.4 %gCV), 39.9% (34.5 %gCV), and 37.4% (10.2 %gCV) in the normal renal function and the mild, moderate, and severe renal impairment groups, respectively. Plasma protein binding of tiotropium did not significantly change in the renal-impaired subjects. Two subjects with normal renal function experienced headache 10 hours after the infusion, which was mild and transient. No adverse events occurred in subjects with renal impairment. There were no clinically relevant changes in blood pressure, pulse rate, 12-lead ECG, physical examination, hematology, or clinical chemistry, compared with baseline values, in any subject after intravenous administration of tiotropium. Tiotropium should only be used in patients with moderate to severe renal insufficiency if the potential benefit outweighs the potential risks.

Tiotropium (Spiriva): mechanistical considerations and clinical profile in obstructive lung disease.

Inhaled antimuscarinics, often called anticholinergics in clinical medicine, are established as first line bronchodilators in COPD. Tiotropium has been developed as a new generation antimuscarinic following ipratropium. Tiotropium is a specific, highly potent antimuscarinic, demonstrating very slow dissociation from muscarinic receptors. Dissociation from M2-receptors is faster than from M3 or M1, which in functional in vitro studies, appeared as kinetic receptor subtype selectivity of M3 and M1 over M2. The high potency and slow receptor dissociation found its clinical correlate in significant and long lasting bronchodilatation and bronchoprotection in patients with COPD and asthma. In asthma, protection against methacholine challenge exceeded the study period of 48 hours. In COPD, bronchodilatation of about 80% of the plateau was demonstrated after the first dose. Following chronic once daily inhalation for 28 days, the improvement in pulmonary function was sustained and there was a further increase in peak effects, but more importantly a rising baseline, achieving steady state within 2 weeks. Tiotropium achieves very stable long lasting effects with comparatively low variation of bronchodilatation between peak and trough (the level before the next administration). Stable 24 hour effectiveness profiles the compound as the first once daily bronchodilator. Clinical correlates of kinetic receptor subtype selective blockade remain to be shown. Plasma levels of tiotropium at trough are in the low pg/ml range and are unlikely to explain the sustained effectiveness in the airways. Slow dissociation from muscarinic receptors is likely to be responsible for the long duration of action.

Different effects of atropine and cimetropium bromide on gastric emptying of liquids and antroduodenal motor activity in man.

Atropine (1 mg intravenously) and a new antimuscarinic compound, cimetropium bromide (5 mg intravenously), as well as placebo (physiological saline) were tested for their effects on gastric emptying and antroduodenal motility in healthy humans. In a first single-blind cross-over study, the emptying rate was assessed in 12 subjects by measuring paracetamol absorption. In a second single-blind parallel-group study, antroduodenal motor activity was measured in 20 subjects through four perfused open tip catheters with orifices positioned in the antroduodenal region. Atropine, unlike cimetropium bromide, significantly delayed gastric emptying. Antral and duodenal motility index was reduced significantly by atropine, but not by cimetropium bromide. Heart rate significantly increased only after atropine. Three subjects taking atropine complained of dry mouth and one of blurred vision. In conclusion, the results of these studies show that atropine, unlike cimetropium bromide, strongly inhibits gastric emptying of liquids and reduces antroduodenal motor activity in man.

[3H]N-methylscopolamine binding to muscarinic receptors in human peripheral blood lymphocytes: characterization, localization on T-lymphocyte subsets and age-dependent changes.

The properties of the binding of the muscarinic receptor ligands, [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]N-methylscopolamine ([3H]NMS) in human mononuclear cells were compared. The binding of [3H]QNB showed a high, non-specific component and lack of saturability in both intact mononuclear cells and preparations of lysed mononuclear cell membranes. Conversely the specific binding of [3H]NMS had a high affinity and was saturable at concentrations greater than 30 nM in both intact and broken cells. Classical muscarinic receptor antagonists displaced specific binding of [3H]NMS binding according to the law of mass action, while displacement curves for pirenzepine and muscarinic agonists were very shallow (nH less than 1), suggesting the presence of more than one subtype of muscarinic receptor on mononuclear cell membranes. Binding studies with [3H]NMS to purified mononuclear cell subpopulations demonstrated that muscarinic binding sites were mainly localized on thymus-derived (T) lymphocytes and large granule lymphocytes. Moreover evidence is presented of an age-dependent increase of the density of muscarinic binding sites on T-lymphocytes. The results are discussed in terms of the usefulness of the binding of [3H]NMS in studying the physiological function of muscarinic receptors on human T-lymphocytes and their possible changes in patients with neurological diseases.

A sensitive radioreceptor assay for determining scopolamine concentrations in plasma and urine.

A sensitive and reliable procedure for the quantitation of low picogram levels of scopolamine in plasma and urine is described. The method consists of two steps, a preparative extraction step using C18 columns (Sep-Pak), followed by an analytical quantitation step involving a muscarinic radioreceptor assay. The extraction efficiency of the C18 columns was 85-95% for both plasma and urine over a wide concentration range. When [3H]methyl scopolamine is used as a tracer, the assay can detect picogram concentrations (greater than 25 pg) of scopolamine (base) in plasma and urine. The applicability of the procedure for therapeutic drug monitoring of scopolamine was demonstrated by using the method to determine plasma levels in humans after transdermal administration.

Discontinuous oral absorption of cimetropium bromide, a new antispasmodic drug.

The pharmacokinetic profiles of cimetropium bromide, after either intravenous injection of 10 mg or oral ingestion of 200 mg, were determined in eight healthy volunteers. After intravenous administration, the plasma levels and urinary excretion indicated that the drug is distributed and eliminated at a rapid rate (terminal half-life, 50 +/- 8 min) and that urinary excretion is not the exclusive route of elimination (46 +/- 2%) of the administered dose). After oral administration, a low percentage of the drug is absorbed (1-4% of the administered dose), however, the amount is sufficient for therapeutic effect. The absorption is discontinuous, with two distinct phases, and ends abruptly during the second phase.

[Biochemical studies with oxitropium bromide. 1. Pharmacokinetics and metabolism in the rat and dog]. / Biochemische Untersuchungen mit Oxitropiumbromid. 1. Pharmakokinetik und Metabolismus in Ratte und Hund.

The bronchospasmolytic drug (8r)-6 beta, 7 beta-epoxy-8-ethyl-3 alpha-[(-)-tropoyloxy]-1 alpha H, 5 alpha H-tropanium bromide (oxitropium bromide, Ba 253 BR, Ventilat) was tested pharmacokinetically as a 14C labelled substance in rats and dogs. Following oral administration low concentrations of radioactivity persisting over several hours were measured in the blood of dogs and rats. The active ingredient which can be separated from the metabolites by thin layer chromatography and quantified via the radioactivity reaches a maximum in the rat plasma after 1 to 2 h; it is then eliminated from the blood with a half-life of approx. 4 h. Following intravenous administration the radioactivity measured directly (active ingredient + metabolites) is distributed rapidly into the tissue of the rat and the dog. The distribution phase is followed by a relatively fast elimination phase ending in the terminal elimination phase approx. 1 h after administration. Rats and dogs eliminate the radioactivity mainly with the feces after oral administration, whereas following intravenous administration the rat eliminates about half with the feces and half via the kidneys. Biliary excretion of the rat is 12% after oral and 14% after intravenous administration. The rat absorbs 14% and the dog 28% of dose. Five metabolites have been demonstrated in the urine of the rat and the dog. Metabolism takes place exclusively in the tropaic acid part of the molecule and by hydrolysis of the compound.

[Biochemical studies with oxitropium bromide. 2. Pharmacokinetics and metabolism in humans]. / Biochemische Untersuchungen mit Oxitropiumbromid. 2. Pharmakokinetik und Metabolismus im Menschen.

The present paper reports on the human pharmacokinetics of (8r)-6 beta, 7 beta-epoxy-8-ethyl-3 alpha-/(-)-tropoyloxy/-1 alpha H, 5 alpha H-tropanium bromide (oxitropium bromide, Ba 253 BR, Ventilat) after intravenous and oral administration as well as following inhalation. The 14C-labelled substance was used. The concentrations of radioactivity measured in the plasma after i.v. administration show a biphasic course, a rapid alpha phase and a terminal phase (t 1/2 = 1.5 h). Once the alpha phase has passed the radioactivity concentrations measured after i.v. administration of 1 mg are comparable with those after 20 mg administered orally. The concentration course after inhalation corresponds essentially to the course after oral administration of lower doses. The cumulative renal excretion of the radioactivity is 68-78% for i.v. administration, 13% for oral administration, and 10% for inhalation. 7% (i.v.), 77% (p.o.) and 88% (inhalation) is excreted in the faeces. Oxitropium bromide is rapidly hydrolysed after oral administration. As little as 4 h later only 2-3% of intact active ingredient is found, whereas there is 85% of the hydrolysed product in the urine. A similar distribution pattern is observed in urine samples taken later. Some other metabolites are also recorded in minimal quantities. After i.v. administration, too, the hydrolysed product is excreted as the main component.

Absorption of morphine, butylscopolamine, mecamylamine and phenobarbitone from the small intestine of the triparanol-treated rat in situ.

The absorption of three basic drugs (morphine, butylscopolamine and mecamylamine) and an acidic drug (phenobarbitone) from the rat small intestine in situ was investigated by using a single perfusion technique. The effect of intestinal damage on absorption was studied by treating rats with triparanol 25-50 mg/kg every 24 h for three weeks. Treatment with triparanol decreased the cholesterol concentration in the intestinal wall. The absorption of morphine and mecamylamine was increased by treatment with triparanol, whereas the absorption of butylscopolamine was decreased and that of phenobarbitone remained unaltered. Treatment with triparanol decreased the concentration of mecamylamine in the intestinal wall, but the concentrations of other drugs were unchanged. When comparing the present in situ and previous in vitro results the decreased absorption of butylscopolamine after triparanol in situ was opposite to the finding in vitro. The increased absorption of morphine and unaltered absorption of phenobarbitone were in accordance with the finding in vitro. In situ the absorption of mecamylamine was increased, although in vitro it was unchanged. The structural damage, differences in composition of the intestinal wall and intestinal blood flow are supposed to be the reasons for changes in absorption.