Pharmacokinetics and tissue distribution of the anticholinergics tiotropium and ipratropium in the rat and dog

Pharmacokinetics and Tissue Distribution of Nasal Spray of a Novel Muscarinic Receptor Blocker, 101BHG-D01, in Dogs and Rats

BACKGROUND

101BHG-D01 is a novel selective anti-muscarinic (M) 3 receptor-blocking drug. 101BHGD01 nasal spray is intended to be used to relieve sneezing and runny nose symptoms caused by allergic rhinitis.

METHODS

In this study, we examined the plasma pharmacokinetics, tissue distribution, and major excretion mode of 101BHG-D01 in Beagle dogs and rats following nasal spray and intranasal administration, respectively, using HPLCMS/ MS.

RESULTS/DISCUSSION

We found that the pharmacokinetics of 101BHG-D01 was linear in dogs. 101BHG-D01 entered the bloodstream rapidly following nasal spray. Its plasma half-life was approximately 6 h and resided at least 24 h in the body. Moreover, 101BHG-D01 retained a significant amount in the nasal cavity. Finally, we found that 101BHGD01 was eliminated mainly in the form of stools in rats.

CONCLUSION

In conclusion, we provided pertinent reference information regarding the design and optimization of drug delivery regimens for clinical trials.

Cigarette smoke extract combined with lipopolysaccharide reduces OCTN1/2 expression in human alveolar epithelial cells in vitro and rat lung in vivo under inflammatory conditions

Organic cation transporter 1/2 (OCTN1/2) play important roles in the transport of drugs related to pulmonary inflammatory diseases. Nevertheless, the involvement of inflammation induced by cigarette smoke extract (CSE) combined with lipopolysaccharide (LPS) in the regulation of OCTN1/2 is not fully understood. In this study, CSE combined with LPS was used to establish inflammation models in vitro and in vivo. Our study found that the expression of OCTN1/2 was downregulated in rat lung in vivo and in a human alveolar cell line in vitro after treatment with CSE and LPS compared with the control group, while the expression of inflammatory factors was upregulated. After treatment with ipratropium bromide (IB) or dexamethasone (DEX), the expression of OCTN1/2 was upregulated compared with that in the CSE-LPS model group, while the expression of inflammatory factors was significantly downregulated. After administration of the NF-κB inhibitor PDTC on the basis of the inflammatory status, the expression of OCTN1/2 was upregulated in the treated group compared with the CSE-LPS model group, while the expression of phospho-p65, phospho-IκBα and inflammatory factors was significantly downregulated. We further added the NF-κB agonist HSP70 and found a result that the exact opposite of that observed with PDTC. Our findings show that CSE combined with LPS can downregulate the expression of OCTN1/2 under inflammatory conditions, and that the downregulation of OCTN1/2 expression may partially occur via the NF-κB signaling pathway.

An occupational exposure limit (OEL) approach to protect home healthcare workers exposed to common nebulized drugs

Home healthcare is a growing area of employment. Assessment of occupational health risks to home health care workers (HHCWs) is important because in many cases the unique characteristics of the home environment do not facilitate the level of exposure control afforded to caregivers in hospitals and other fixed patient care sites. This assessment is focused on health risks to HHCWs from exposure to pharmaceutical drugs used to treat asthma and other respiratory diseases, which are commonly administered to patients in aerosolized form via nebulizers. We developed risk-based exposure limits for workers in the form of occupational exposure limits (OEL) values for exposure to nebulized forms of the three most common drugs administered by this method: albuterol, ipratropium, and budesonide. The derived OEL for albuterol was 2 μg/day, for ipratropium was 30 μg/day, and for budesonide was 11 μg/day. These OELs were derived based on human effect data and adjusted for pharmacokinetic variability and areas of uncertainty relevant to the underlying data (human and non-human) available for each drug. The resulting OEL values provide an input to the occupational risk assessment process to allow for comparisons to HHCW exposure that will guide risk management and exposure control decisions.

The pharmacokinetics of orally administered butylscopolamine in greyhound dogs

The oral tablet formulation of butylscopolamine, which is available without prescription, is commonly used by trainers of racing greyhounds to treat functional urethral obstruction. As medication control of butylscopolamine is therefore required for such use to ensure the integrity of greyhound racing, an administration study was performed in six greyhounds to determine the pharmacokinetics of orally administered butylscopolamine. A single dose of one 10 mg butylscopolamine tablet was administered orally to simulate this use in greyhound racing. Blood, urine and faeces were collected at regular intervals from the greyhounds for up to 9 days and butylscopolamine concentrations determined. There was some, but very limited, absorption of butylscopolamine, with rapid elimination from plasma with a mean half-life of 2 hr. Urine concentrations initially declined in a similar manner to the plasma pharmacokinetics but then entered a much longer half-life of approximately 50 hr. Faecal concentrations declined to very low levels between 48 and 120 hr. The use of orally administered butylscopolamine for functional urethral obstruction in greyhounds is unjustified due to this very limited drug absorption. Medication control of butylscopolamine's antispasmodic effect on the digestive tract is possible by setting screening limits based on the urinary and faecal drug levels as determined in this study.

Experimental validation of a computationally-designed tiotropium membrane sensor

This work draws an analogy between theoretical and practical data for innocuous potentiometric sensor optimization.

Ultrasensitive sub-pg/ml determination of tiotropium bromide in human plasma by 2D-UHPLC–MS/MS: challenges and solutions

Background: To adequately support pharmacokinetic evaluations of tiotropium bromide in planned clinical studies. It was desirable to measure it with a LLOQ of sub pg/ml. Results: A sensitive bioanalytical method for the determination of tiotropium in human plasma sample was successfully developed and validated in the range of 0.2–100 pg/ml. The method was successfully applied to support two clinical studies of over 3000 samples. The overall incurred sample reanalysis passing rate was 93.7%. Conclusion: The combination of a dual stage liquid–liquid extraction and a 2D ultra-HPLC greatly reduced matrix effects and increased assay sensitivity. When developing effective ultrasensitive assays, it is imperative to balance the aspects related to sensitivity with those that will ensure assay ruggedness.

Stress-associated cardiovascular reaction masks heart rate dependence on physical load in mice

When tested on the treadmill mice do not display a graded increase of heart rate (HR), but rather a sharp shift of cardiovascular indices to high levels at the onset of locomotion. We hypothesized that under test conditions cardiovascular reaction to physical load in mice is masked with stress-associated HR increase. To test this hypothesis we monitored mean arterial pressure (MAP) and heart rate in C57BL/6 mice after exposure to stressful stimuli, during spontaneous locomotion in the open-field test, treadmill running or running in a wheel installed in the home cage. Mice were treated with β1-adrenoblocker atenolol (2mg/kg ip, A), cholinolytic ipratropium bromide (2mg/kg ip, I), combination of blockers (A+I), anxiolytic diazepam (5mg/kg ip, D) or saline (control trials, SAL). MAP and HR in mice increased sharply after handling, despite 3weeks of habituation to the procedure. Under stressful conditions of open field test cardiovascular parameters in mice were elevated and did not depend on movement speed. HR values did not differ in I and SAL groups and were reduced with A or A+I. HR was lower at rest in D pretreated mice. In the treadmill test HR increase over speeds of 6, 12 and 18m/min was roughly 1/7-1/10 of HR increase observed after placing the mice on the treadmill. HR could not be increased with cholinolytic (I), but was reduced after sympatholytic (A) or A+I treatment. Anxiolytic (D) reduced heart rate at lower speeds of movement and its overall effect was to unmask the dependency of HR on running speed. During voluntary running in non-stressful conditions of the home cage HR in mice linearly increased with increasing running speeds. We conclude that in test situations cardiovascular reactions in mice are governed predominantly by stress-associated sympathetic activation, rendering efforts to evaluate HR and MAP reactions to workload unreliable.

Dual-pharmacology muscarinic antagonist and β₂ agonist molecules for the treatment of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the world today. Bronchodilators, particularly muscarinic antagonists and β(2) agonists, are recommended for patients with moderate to severe COPD. Dual-pharmacology muscarinic antagonist- β(2) agonist (MABA) molecules present an exciting new approach to the treatment of COPD by combining muscarinic antagonism and β(2) agonism in a single entity. They have the potential to demonstrate additive or synergistic bronchodilation over either pharmacology alone. Due to this enticing prospect, several companies have now reported MABA discovery efforts through a conjugated/linked strategy with one candidate (GSK-961081) demonstrating clinical proof of concept. Several MABA crystal forms have been identified, satisfying the requirements for inhaled dosing devices. There are significant challenges in designing MABAs, but the potential to achieve enhanced bronchoprotection in patients and facilitate 'triple therapy' makes this an extremely important and exciting area of pharmaceutical research.

Inhaled long-acting muscarinic antagonists in chronic obstructive pulmonary disease

In 2002, the first long-acting muscarinic antagonist, tiotropium bromide (Spiriva®), was launched as a once-daily bronchodilating agent for the treatment of chronic obstructive pulmonary disease. Since then, there has been intense discovery research activity in this area and, currently, several alternative inhaled long-acting muscarinic antagonists are reported under clinical development by several pharmaceutical companies. This article will review the current inhaled development candidates, as well as literature reports of the most significant preclinical chemical series specifically designed as inhaled antimuscarinic agents.

Fine mapping the spatial distribution and concentration of unlabeled drugs within tissue micro-compartments using imaging mass spectrometry

Readouts that define the physiological distributions of drugs in tissues are an unmet challenge and at best imprecise, but are needed in order to understand both the pharmacokinetic and pharmacodynamic properties associated with efficacy. Here we demonstrate that it is feasible to follow the in vivo transport of unlabeled drugs within specific organ and tissue compartments on a platform that applies MALDI imaging mass spectrometry to tissue sections characterized with high definition histology. We have tracked and quantified the distribution of an inhaled reference compound, tiotropium, within the lungs of dosed rats, using systematic point by point MS and MS/MS sampling at 200 µm intervals. By comparing drug ion distribution patterns in adjacent tissue sections, we observed that within 15 min following exposure, tiotropium parent MS ions (mass-to-charge; m/z 392.1) and fragmented daughter MS/MS ions (m/z 170.1 and 152.1) were dispersed in a concentration gradient (80 fmol-5 pmol) away from the central airways into the lung parenchyma and pleura. These drug levels agreed well with amounts detected in lung compartments by chemical extraction. Moreover, the simultaneous global definition of molecular ion signatures localized within 2-D tissue space provides accurate assignment of ion identities within histological landmarks, providing context to dynamic biological processes occurring at sites of drug presence. Our results highlight an important emerging technology allowing specific high resolution identification of unlabeled drugs at sites of in vivo uptake and retention.

Determination of bencycloquidium bromide, a novel anticholinergic compound, in rat tissues by liquid chromatography-electrospray ionization mass spectrometry

First, a liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for quantification of bencycloquidium bromide (BCQB) in rat tissue homogenates was developed and validated, which would support investigation on drug distribution into tissues in animal models. 1-ethyl-bencycloquidium bromide was used as the internal standard (IS). Sample preparation in tissue homogenates was achieved by using solid phase extraction on a 3 mL C(18)-cartridge column. Chromatographic separation was analyzed on a Hanbon Lichrospher 5-C(18) column. The mobile phase consisted of methanol-40 mM ammonium acetate buffer-formic acid (75:25:0.25, v/v/v) which was pumped at 1.0 mL min(-1). BCQB was determined using electrospray ionization in a single quadrupole mass spectrometer. LC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 330.2 for BCQB and m/z 344.2 for the IS. The assay was linear from 3.015 ng mL(-1) to 301.5 ng mL(-1) of BCQB in rat tissue (liver, kidney, lung, trachea, heart, spleen, stomach, intestines, brain, muscle, testicle, ovary and fat) homogenates. The lower limit of quantification (LLOQ) was 3.015 ng mL(-1) of BCQB in all tissue homogenates. Acceptable precision and accuracy were obtained for concentrations over the entire standard curve ranges for tissue homogenates. The method was used to successfully quantify BCQB in rat tissue homogenates for a tissue distribution study of BCQB in rats after intranasal administration.

Effect of tiotropium bromide on the cardiovascular response to exercise in COPD

INTRODUCTION

Exercise limitation and exertional dyspnea are important symptoms of chronic obstructive pulmonary disease (COPD), which may be partially relieved by tiotropium. Although the mechanism of relief is multifactorial, improved dynamic ventilatory mechanics appear to be important. It is not however known whether tiotropium may also act by improving cardiovascular function during exercise.

METHODS

We conducted a randomized, placebo-controlled crossover study in 18 COPD subjects with a FEV(1) 40+/-3% predicted (mean+/-SEM). Subjects inhaled either tiotropium 18 microg or placebo once daily for 7-10 days then the other intervention for a further 7-10 days after a 35-day washout period. Subjects performed constant work rate cycle exercise at 75% of maximum after each treatment period. Heart rate, blood pressure, oxygen uptake, operating lung volumes and breathing pattern were measured.

RESULTS

Heart rate was 7 beats/min lower at rest and throughout exercise with tiotropium compared to placebo (p=0.001). Oxygen uptake was unchanged throughout exercise. Oxygen pulse on exercise was greater by 7.4% (p<0.01) and systolic blood pressure was lower by 7 mmHg (p=0.03). The cardiac rate pressure product was reduced by 7.6% (p<0.01) with tiotropium. Exercise endurance tended to be greater with tiotropium. Reduction in heart rate on exercise correlated with an increase in inspiratory reserve volume (r=-0.50, p=0.04).

CONCLUSION

Tiotropium may improve cardiac as well as pulmonary function during exercise in COPD. We suggest that this effect may be due, in part, to improved cardiopulmonary interaction as a result of mechanical unloading of the ventilatory muscles however further study is required.

Determination of bencycloquidium bromide in rat plasma by liquid chromatography–electrospray ionization-mass spectrometry

A liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) assay for the determination of bencycloquidium bromide (BCQB) in rat plasma was firstly developed and validated. After addition of 1-ethyl-bencycloquidium bromide as an internal standard (I.S.), the plasma samples were deproteinized with methanol and the supernatant was assayed by LC-ESI-MS. Chromatographic separation was achieved with a Hanbon Lichrospher 5-C18 column. The mobile phase consisted of methanol-40 mM ammonium acetate buffer-formic acid (75:25:0.25, v/v/v) and delivered at the flow rate of 1.0 ml/min. LC-ESI-MS was carried out on a single quadrupole mass spectrometer using electrospray ionization (ESI) and positive selected-ion monitoring (SIM). Target ions were monitored at [M](+)m/z 330.2 for BCQB and [M] (+)m/z 344.2 for I.S. Calibration curve was linear over the range of 3-1500 ng/ml. The lower limit of quantification (LLOQ) was 3.0 ng/ml. The intra- and inter-run relative standard deviations (R.S.D.%) of the assay were less than 7.1 and 12.3%, respectively. The accuracy determined at the concentrations of 3.0, 100.0, 500.0 and 1500 ng/ml for BCQB were within +/-15.0%. The established method has been applied successfully to study the pharmacokinetics of BCQB in rats after intranasal administration.

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 <or=7.34%. The method was successfully applied to a pharmacokinetic study of systemic absorption in healthy male volunteers given a single 18 microg inhaled dose.

Synthesis and Radiolabelling of Ipratropium and Tiotropium for Use as PET Ligands in the Study of Inhaled Drug Deposition

Ipratropium bromide [(1R,3r,5S,8r,2′RS)-3-(3′-hydroxy-2′-phenylpropionyloxy)-8-isopropyl-8-methyl-8-azabicyclo[3.2.1]octan-8-ium bromide] and tiotropium bromide [(1R,2R,4S,5S,7s)-7-[2′-hydroxy-2′,2′-di(thiophen-2′′-yl)acetoxy]-9,9-dimethyl-9-aza-3-oxatricyclo[3.3.1.02,4]nonan-9-ium bromide] are inhaled drugs used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma. Tertiary amine precursors have been synthesized and radiolabelled with carbon-11 by N-alkylation with [11C]CH3I. The [11C]ipratropium and [11C]tiotropium positron emission tomography (PET) ligands are obtained with high radiochemical purity, in 0.3 and 0.5% non-decay corrected yields based on [11C]CO2 at end-of-synthesis and specific activities of 11 and 18 GBq μmol−1, respectively, calculated at end-of-synthesis. These PET radioligands can be used in the study of inhaled drug deposition.