Cold Flow Evaluation in Transdermal Drug Delivery Systems by Measuring the Width of the Oozed Adhesive.

The objective of this study was to develop a simpler and more practical quantitative evaluation method of cold flow (CF) in transdermal drug delivery systems (TDDSs). CF was forcibly induced by loading a weight on a punched-out sample (bisoprolol and tulobuterol tapes). When the extent of CF was analyzed using the area of oozed adhesive as following a previously reported method, the CF profiles were looked different between the samples 12 mm in diameter subjected to a 0.5-kg weight and samples 24 mm in diameter subjected to a 2.0-kg weight despite an equal load per unit area (4.42 g/mm2). The width of oozed adhesive around the original sample was suggested to be an index that properly describes the relationship between the load per unit area and the extent of CF. Further, it was clarified that the average CF width over the entire circumference of the sample was the same whether the samples were round or square as long as the sample area and load were the same. We also observed a linear relationship between the CF width and the aspect ratio of oval and rectangular samples. These results indicated that the CF properties of typical TDDS products lacking CF-proof processing at the edges could be determined by testing samples cut from the product rather than the whole TDDS patch. The proposed width measuring method was simple and useful for optimizing the composition of the adhesive and for testing the quality of the product.

Enantioselective disposition of clenbuterol in rats.

Clenbuterol is a long-acting ß2-adrenoceptor agonist and bronchodilator that is used for the treatment of asthma, but the desired activities reside almost exclusively in the (-)-R-enantiomer. This study examined enantioselectivity in the disposition of clenbuterol following administration of clenbuterol racemate to rats. Concentrations of clenbuterol enantiomers in plasma, urine and bile were determined by LC-MS/MS assay with a Chirobiotic T column. This method was confirmed to show high sensitivity, specificity and precision, and clenbuterol enantiomers in 0.1 ml volumes of plasma were precisely quantified at concentrations as low as 0.25 ng/ml. The pharmacokinetic profiles of clenbuterol enantiomers following intravenous and intraduodenal administration of clenbuterol racemate (2 mg/kg) in rats were significantly different. The distribution volume of (-)-R-clenbuterol (9.17 l/kg) was significantly higher than that of (+)-S-clenbuterol (4.14 l/kg). The total body clearance of (-)-R-clenbuterol (13.5 ml/min/kg) was significantly higher than that of the (+)-S-enantiomer (11.5 ml/min/kg). An in situ absorption study in jejunal loops showed no difference in the residual amount between the (-)-R- and (+)-S-enantiomers. Urinary clearance was the same for the two enantiomers, but biliary excretion of (-)-R-clenbuterol was higher than that of the (+)-S-enantiomer. The fractions of free (non-protein-bound) (-)-R- and (+)-S-clenbuterol in rat plasma were 48.8% and 33.1%, respectively. These results indicated that there are differences in the distribution and excretion of the clenbuterol enantiomers, and these may be predominantly due to enantioselective protein binding.

Comparison of ractopamine residue depletion from internal tissues.

The aim of the study was to compare residue depletion of ractopamine HCl as a ß-adrenergic agonist that promotes muscle growth of animals, from internal tissues on days after its repeat administration to animals. The experiment was carried out in 38 albino guinea pigs. Treated animals (n = 30) were orally administered ractopamine HCl in a dose of 3.5 mg/kg body mass per day for 7 consecutive days. On days 1, 10, 20 and 30 of drug discontinuation, animals were randomly sacrificed and the liver, kidney, lung, heart, muscle, spleen and fat samples were collected. In all matrices, ractopamine concentration was determined using validated enzyme-linked immunosorbent assay (ELISA) as a quantitative screening method. The highest ractopamine concentration was recorded on day 1 in the lungs (55.80 ± 15.62 µg/kg), followed by the kidney (21.85 ± 3.91 µg/kg), spleen (12.59 ± 1.95 µg/kg), fat (10.17 ± 5.02 µg/kg), heart (9.73 ± 0.22 µg/kg), liver (5.58 ± 2.09 µg/kg), and lowest in muscle (2.21 ± 1.02 µg/kg). Ractopamine residues were detected in the lungs in the period of 30 days after withdrawal in significantly higher concentrations in comparison to other investigated matrices, suggesting that depletion of ractopamine from the lungs occurs at a much slower rate than its depletion from other internal tissues.

Use of mirabegron in treating overactive bladder.

The lack of an alternative to antimuscarinics has led to the search for new drug targets for overactive bladder (OAB) symptoms. The presence of ß-3 adrenoreceptors in the bladder has been confirmed, and they are known to have a role in bladder relaxation. Targeting these receptors improves bladder compliance on filling and increases bladder capacity. MEDLINE literature search on efficacy and safety of mirabegron was performed. The US Food and Drug Administration Web site, clinicaltrials.gov, and controlled-trials.com online trial registries were searched for English-language articles containing the term "mirabegron". Finally, abstracts from recent International scientific meetings were searched for randomised controlled trials (RCTs). Studies show that mirabegron reduces the number of micturitions and incontinence episodes in a 24-h period compared with placebo. Dry mouth and gastrointestinal disturbances are the most common side effects, but these have been rated as mild to moderate. A small rise in mean heart rate and blood pressure has been shown. Further investigations are ongoing and results are awaited. Although mirabegron is metabolised by CYP2D6, it is also thought to inhibit the activity of this enzyme. Therefore, potential drug interactions with other CYP2D6 substrates need to be further studied. Mirabegron is a promising alternative to antimuscarinics. Further information on its long-term use in terms of efficacy, safety, and tolerability is awaited.

Blood-to-muscle distribution and urinary excretion of higenamine in rats.

Higenamine is a ß2 -agonist that has been prohibited in sports by the World Anti-Doping Agency. Higenamine could potentially promote anabolism and lipolysis; however, its crucial pharmacokinetics data, particularly muscle distribution, remain unavailable. The present study aims to investigate the blood-to-muscle distribution as well as the urinary excretion of higenamine in laboratory rats. In the first experiment, the microdialysis technique was employed to continuously measure free, protein-unbound concentrations in blood and muscle for 90 min (sampling at a 5-min interval) after rats received IV infusion of higenamine. The mean half-lives of higenamine in blood and muscle were 17.9 and 19.0 min, respectively. The blood-to-muscle distribution ratio (AUCmuscle /AUCblood ) of higenamine was estimated to be 22%. In the second experiment, rats were orally administered with a single-dose higenamine, and their urine samples were profiled at a 12-h interval for up to 48 h. Results showed only a small portion of total consumption (1.44%, ranging 0.71%-2.50%) was excreted in the urine. Among these time points, about 43% cumulative amount of higenamine was eliminated within the first 12 h. Our data suggested that one-quarter of the unbound higenamine rapidly penetrates from the vessels into muscle, distributes to the interstitial fluid, then eliminates from the rat in a short span of time. The muscle tissue is likely to have a low binding affinity for higenamine, and renal excretion plays a minor role in its elimination. Together, our findings provide valuable pharmacokinetics data that may gain deeper insights into higenamine's role in skeletal muscle functions.

Randomised trial of epinephrine dose and flush volume in term newborn lambs.

OBJECTIVES: Neonatal resuscitation guidelines recommend 0.5-1 mL saline flush following 0.01-0.03 mg/kg of epinephrine via low umbilical venous catheter for persistent bradycardia despite effective positive pressure ventilation (PPV) and chest compressions (CC). We evaluated the effects of 1 mL vs 3 mL/kg flush volumes and 0.01 vs 0.03 mg/kg doses on return of spontaneous circulation (ROSC) and epinephrine pharmacokinetics in lambs with cardiac arrest. DESIGN: Forty term lambs in cardiac arrest were randomised to receive 0.01 or 0.03 mg/kg epinephrine followed by 1 mL or 3 mL/kg flush after effective PPV and CC. Epinephrine (with 1 mL flush) was repeated every 3 min until ROSC or until 20 min. Haemodynamics, blood gases and plasma epinephrine concentrations were monitored. RESULTS: Ten lambs had ROSC before epinephrine administration and 2 died during instrumentation. Among 28 lambs that received epinephrine, 2/6 in 0.01 mg/kg-1 mL flush, 3/6 in 0.01 mg/kg-3 mL/kg flush, 5/7 in 0.03 mg/kg-1 mL flush and 9/9 in 0.03 mg/kg-3 mL/kg flush achieved ROSC (p=0.02). ROSC was five times faster with 0.03 mg/kg epinephrine compared with 0.01 mg/kg (adjusted HR (95% CI) 5.08 (1.7 to 15.25)) and three times faster with 3 mL/kg flush compared with 1 mL flush (3.5 (1.27 to 9.71)). Plasma epinephrine concentrations were higher with 0.01 mg/kg-3 mL/kg flush (adjusted geometric mean ratio 6.0 (1.4 to 25.7)), 0.03 mg/kg-1 mL flush (11.3 (2.1 to 60.3)) and 0.03 mg/kg-3 mL/kg flush (11.0 (2.2 to 55.3)) compared with 0.01 mg/kg-1 mL flush. CONCLUSIONS: 0.03 mg/kg epinephrine dose with 3 mL/kg flush volume is associated with the highest ROSC rate, increases peak plasma epinephrine concentrations and hastens time to ROSC. Clinical trials evaluating optimal epinephrine dose and flush volume are warranted.

Medication Discontinuation in Adults With COPD Discharged From the Hospital: A Population-Based Cohort Study.

BACKGROUND: Patients admitted to the hospital with COPD are commonly managed with inhaled short-acting bronchodilators, sometimes in lieu of the long-acting bronchodilators they take as outpatients. If held on admission, these long-acting inhalers should be re-initiated upon discharge; however, health-care transitions sometimes result in unintentional discontinuation. RESEARCH QUESTION: What is the risk of unintentional discontinuation of long-acting muscarinic antagonist (LAMA) and long-acting beta-agonist and inhaled corticosteroid (LABA-ICS) combination medications following hospital discharge in older adults with COPD? STUDY DESIGN AND METHODS: A retrospective cohort study was conducted by using health administrative data from 2004 to 2016 from Ontario, Canada. Adults with COPD aged ≥ 66 years who had filled prescriptions for a LAMA or LABA-ICS continuously for ≥ 1 year were included. Log-binomial regression models were used to determine risk of medication discontinuation following hospitalization in each medication cohort. RESULTS: Of the 27,613 hospitalization discharges included in this study, medications were discontinued 1,466 times. Among 78,953 patients with COPD continuously taking a LAMA or LABA-ICS, those hospitalized had a higher risk of having medications being discontinued than those who remained in the community (adjusted risk ratios of 1.50 [95% CI, 1.34-1.67; P < .001] and 1.62 [95% CI, 1.39, 1.90; P < .001] for LAMA and LABA-ICS, respectively). Crude rates of discontinuation for people taking LAMAs were 5.2% in the hospitalization group and 3.3% in the community group; for people taking LABA-ICS, these rates were 5.5% in the hospitalization group and 3.1% in the community group. INTERPRETATION: In an observational study of highly compliant patients with COPD, hospitalization was associated with an increased risk of long-acting inhaler discontinuation. These Results suggest a likely larger discontinuation problem among less adherent patients and should be confirmed and quantified in a prospective cohort of patients with COPD and average compliance. Quality improvement efforts should focus on safe transitions and patient medication reconciliation following discharge.

Detection of urine and blood clenbuterol following short-term oral administration in the horse.

BACKGROUND AND AIM: The pharmacokinetics of clenbuterol in equine urine and blood was investigated. MATERIAL AND METHODS: Urine and blood samples were collected following 3-day multiple oral administrations. The samples were examined using enzyme-linked immunosorbent assay and further confirmed by solid phase extraction and capillary electrophoresis. RESULTS: Urinary clenbuterol was detectable until day 14 after the last dose. The urinary excretion of clenbuterol was characterized by a biphasic pattern. The half-lives of the bi-exponential elimination (t(1/2alpha) and t(1/2beta)) for urinary clenbuterol were about 12.1 and 48 hours. After a single oral administration (4 microg/kg) of clenbuterol, the half-life of serum clenbuterol was approximately 11.4 hours.

The bioavailability and airway clearance of the steroid component of budesonide/formoterol and salmeterol/fluticasone after inhaled administration in patients with COPD and healthy subjects: a randomized controlled trial.

BACKGROUND: Airway absorption and bioavailability of inhaled corticosteroids (ICSs) may be influenced by differences in pharmacokinetic properties such as lipophilicity and patient characteristics such as lung function. This study aimed to further investigate and clarify the distribution of budesonide and fluticasone in patients with severe chronic obstructive pulmonary disease (COPD) by measuring the systemic availability and sputum concentration of budesonide and fluticasone, administered via combination inhalers with the respective long-acting beta2-agonists, formoterol and salmeterol. METHODS: This was a randomized, double-blind, double-dummy, two-way crossover, multicenter study. Following a run-in period, 28 patients with severe COPD (mean age 65 years, mean forced expiratory volume in 1 second [FEV1] 37.5% predicted normal) and 27 healthy subjects (mean age 31 years, FEV1 103.3% predicted normal) received two single-dose treatments of budesonide/formoterol (400/12 microg) and salmeterol/fluticasone (50/500 microg), separated by a 4-14-day washout period. ICS concentrations were measured over 10 hours post-inhalation in plasma in all subjects, and over 6 hours in spontaneously expectorated sputum in COPD patients. The primary end point was the area under the curve (AUC) of budesonide and fluticasone plasma concentrations in COPD patients relative to healthy subjects. RESULTS: Mean plasma AUC values were lower in COPD patients versus healthy subjects for budesonide (3.07 microM x hr versus 6.21 microM x hr) and fluticasone (0.84 microM x hr versus 1.50 microM x hr), and the dose-adjusted AUC (geometric mean) ratios in healthy subjects and patients with severe COPD for plasma budesonide and fluticasone were similar (2.02 versus 1.80; primary end point). In COPD patients, the Tmax and the mean residence time in the systemic circulation were shorter for budesonide versus fluticasone (15.5 min versus 50.8 min and 4.41 hrs versus 12.78 hrs, respectively) and Cmax was higher (1.08 microM versus 0.09 microM). The amount of expectorated fluticasone (percentage of estimated lung-deposited dose) in sputum over 6 hours was significantly higher versus budesonide (ratio 5.21; p = 0.006). Both treatments were well tolerated. CONCLUSION: The relative systemic availabilities of budesonide and fluticasone between patients with severe COPD and healthy subjects were similar. In patients with COPD, a larger fraction of fluticasone was expectorated in the sputum as compared with budesonide. TRIAL REGISTRATION: Trial registration number NCT00379028.

Pharmacokinetics of ritodrine diastereomers in patients pregnant with singletons and twins.

OBJECTIVE: The chiral pharmacokinetics and pharmacodynamics of ritodrine in patients pregnant with singletons and twins were investigated to determine the optimal use of ritodrine. METHODS: Eight and 20 patients with threatened preterm delivery of singletons and twins, respectively, were infused with ritodrine diastereomers. Serum concentrations of the drug were then measured using a newly developed method of chiral high-performance liquid chromatography. RESULTS: Almost double the dosage of racemic ritodrine was required to prolong pregnancies with twins compared with those of singletons (2.20 +/- 1.06 vs. 1.24 +/- 0.36 microg/min per kilogram; p < 0.0001). The mean ratios of (-)-ritodrine to (+)-ritodrine in singleton and twin pregnancies were 1.17 +/- 0.10 and 1.16 +/- 0.10, respectively. However, the serum concentration and dosage ratio (C/D ratio) of (-)-ritodrine as significantly higher than that of (+)-ritodrine (p < 0.0001), whereas the clearance of (-)-ritodrine was significantly lower than that of (+)-ritodrine (p < 0.0001). A comparison of the gestation period (weeks) and diastereomer clearance did not reveal significant regression in the total analysis of the data obtained from singleton and twin pregnancies. CONCLUSION: These results indicate that the clinical effectiveness of ritodrine diastereomers should be evaluated and that administration guidelines should be established based upon serum concentrations so that ritodrine can be more effectively administered to pregnant patients carrying either singletons or twins.

Accumulation of the beta(2)-adrenergic agonist clenbuterol in mouse dark hair.

The aim of the present study was to evaluate the suitability of dark hair as a matrix for determination of the beta(2)-adrenergic agonist clenbuterol residues using previously validated enzyme-linked immunosorbent assay (ELISA) as a screening method for its quantitative determination. The experimental group of mice (n = 60) were treated with two different anabolic dosages of clenbuterol for 15 days, whereas the control group of animals (n = 30) was left completely untreated. Hair samples were collected on days 0, 5, 10, and 15 of treatment. Validation of the ELISA analytical procedure showed good recovery (mean recovery 74%) with an acceptable intra-assay variation in individual measurements for all hair samples to which 5, 10, and 50 ng/g clenbuterol were added (CV < 10%). Low blank levels of clenbuterol (2.4 +/- 0.6 ng/g) were measured in hair of untreated mice, whereas significantly higher clenbuterol concentrations rising proportionally with the time of treatment were recorded in hair of mice treated with lower (6.5 mg/kg body mass) and higher (12.5 mg/kg body mass) dose of clenbuterol. The peak hair concentration of clenbuterol measured on the last day of treatment (day 15) was 1553.9 +/- 140.1 ng/g and 6248.3 +/- 589.4 ng/g in the lower and higher dose group, respectively. Study results clearly indicated dark hair as a pigmented tissue to have a high accumulation potential for clenbuterol residues, thus being the target matrix of choice for detection of clenbuterol abuse as an anabolic in meat production.

Comparative bioavailability study of two salbutamol tablets in healthy adult volunteers.

This study was carried out to compare the rate and extent of absorption of a generic salbutamol in oral dosage form (Brethmol, 4 mg) with the proprietary equivalent product (Ventolin, 4 mg), in healthy adult subjects, under fasting conditions. The study was a single dose, randomized, two way crossover study with a four-week washout period. It involved 22 healthy volunteers who received a single dose (4 mg) of the test and the reference products after an overnight fast of at least 10 hours. Blood samples were collected at pre-dose and a serial of 14 samples were collected from each of the subject from 1 h until 48 h post-dose. Plasma concentrations of salbutamol were analyzed using GCMS method. The mean AUC(0-yen) values were 91.26 and 96.45 h.ng/ml for reference and test product, respectively. The mean C(max) values were 12.26 and 12.38 ng/ml and the mean t(max) values were 2.80 and 2.33 hours for reference and test product, respectively. Analysis of variance showed that the 90% confidence intervals on the relative difference of the ratio for the AUC(0-yen) and the C(max) for the test and reference products were contained within the bioequivalence limit (80 - 125%) (C(max): 89.8 - 110.5% and AUC(0-yen): 91.6 - 121.5%). There was no statistically significant difference for the t(max) between the test and reference formulations (p = 0.30). The test formulation was found to be bioequivalent to the reference formulation with regard to AUC(0-yen) and C(max). There was no statistically significant difference in Brethmol and Ventolin t(max). In conclusion, Brethmol and Ventolin are bioequivalent in healthy subjects.

Terbutaline lessens protein fluxes across the alveolo-capillary barrier during high-volume ventilation.

OBJECTIVE: To evaluate whether a beta2-adrenergic agonist may reduce acute alveolo-capillary barrier alterations during high-volume ventilation. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: A total of 48 male Wistar rats. INTERVENTIONS: A zone of alveolar flooding was produced by liquid instillation in a distal airway. Proteins in the instilled solution were traced with 99mTc-albumin. 111In, which binds to transferrin, was injected into the systemic circulation. Terbutaline was administered in the instilled solution or intra-peritoneally. Conventional ventilation was applied for 30 min followed by different ventilation strategies for 90 min: conventional ventilation, high-volume ventilation with or without 6 cmH2O PEEP. MEASUREMENTS AND MAIN RESULTS: Protein fluxes across the alveolar and microvascular barriers were evaluated by scintigraphy. High-volume ventilation resulted in immediate leakage of 99mTc-albumin from alveolar spaces and increased pulmonary uptake of systemic 111In-transferrin. Terbutaline in the instilled solution and PEEP lessened alveolar 99mTc-albumin leakage and pulmonary 111In-transferrin uptake due to high-volume ventilation, whereas terbutaline given intra-peritoneally only lessened 111In-transferrin uptake. Terbutaline in the instilled solution also lessened the increase in lung wet-to-dry weight ratio due to high-volume ventilation. CONCLUSIONS: Terbutaline reduces protein fluxes across the alveolar epithelial and pulmonary microvascular barriers during high-volume ventilation in vivo. The route of administration may be important.

Pharmacokinetics of budesonide and formoterol administered via 1 pressurized metered-dose inhaler in patients with asthma and COPD.

In 3 open-label studies, the systemic bioavailability of budesonide and formoterol administered via pressurized metered-dose inhaler (pMDI) or dry powder inhaler (DPI) formulations was evaluated in asthma (24 children, 55 adults) or chronic obstructive pulmonary disease (COPD; n = 26) patients. Treatments were administered at doses high enough to estimate pharmacokinetic parameters reliably. Two of the studies included an experimental budesonide pMDI formulation. In study 1 (asthma, adults), budesonide area under the curve (AUC) was 32% and 31% lower and maximal budesonide concentration (C(max)) 45% and 56% lower after budesonide/formoterol pMDI and budesonide pMDI versus budesonide DPI. Formoterol AUC and C(max) were 13% and 39% lower after budesonide/formoterol pMDI versus formoterol DPI. In study 2 (asthma, children), budesonide AUC and C(max) were 27% and 41% lower after budesonide/formoterol pMDI versus budesonide DPI + formoterol DPI. In study 3 (COPD/asthma, adults), budesonide AUC and C(max) were similar and formoterol AUC and C(max) 18% and 22% greater after budesonide/formoterol pMDI versus budesonide pMDI + formoterol DPI (COPD). Budesonide and formoterol AUC were 12% and 15% higher in COPD versus asthma patients. In conclusion, systemic exposure generally is similar or lower with budesonide/formoterol pMDI versus combination therapy via separate DPIs or monotherapy and comparable between asthma and COPD patients.

The discovery of adamantyl-derived, inhaled, long acting beta(2)-adrenoreceptor agonists.

The design and profile of a series of adamantyl-containing long acting beta(2)-adrenoreceptor agonists are described. An optimal pharmacokinetic profile of low oral bioavailability was combined with a strong pharmacology profile when assessed using a guinea pig trachea tissue model. A focus was then placed on developing a robust synthetic route to ensure rapid delivery of material for clinical trials.

Determination of ritodrine in human plasma by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

A simple and sensitive HPLC/MS/MS method was developed and evaluated to determine the concentration of ritodrine (RTD) in human plasma. Liquid-liquid extraction with ethyl acetate was employed as the sample preparation method. The structural analogue salbutamol was selected as the internal standard (IS). The liquid chromatography was performed on a Hanbon Sci. & Tech. Lichrospher CN (150 mm x 4.6 mm, i.d., 5 microm) column (Hanbon, China) at 20 degrees C. A mixture of 0.03% acetic acid and methanol (50:50, v/v) was used as isocratic mobile phase to give the retention time 3.60 min for ritodrine and 2.94 min for salbutamol. Selected reaction monitoring (SRM) in positive ionization mode was employed for mass detection. The calibration functions were linear over the concentration range 0.39-100 ng mL(-1). The intra- and inter-day precision of the method were less than 15%. The lower limit of quantification was 0.39 ng mL(-1). The method had been found to be suitable for application to a pharmacokinetic study after oral administration of 20mg ritodrine hydrochloride tablet to 18 healthy female volunteers. The half-life is 2.54+/-0.67 h.

A non-parametric method to analyse time-course of effect in the absence of pharmacokinetic data: application to inhaled bronchodilators.

In spite of the extensive use of long-acting beta(2)-agonist (LABA) bronchodilators in asthma, the actual mechanism of their in vivo duration of action is not well understood, primarily due to limitations of standard pharmacokinetic-pharmacodynamic (PKPD) analysis methodologies. We have developed a novel method of analysing lung efficacy vs. time profiles for LABAs that can be used to provide comparative information on the lung PK. We hypothesised that for compounds that do not differ in their PK at the site of PD action, but differ in their in vivo potencies, the relationship between the area under the effect curve (AUEC) and the observed maximum effect (OME) at different doses is described by the same sigmoid curve. We have illustrated this property for standard PKPD models by obtaining analytical solution and through simulations. Anaesthetised dog in vivo effect vs. time profiles were gathered for six inhaled LABA candidates that differ in their in vitro potencies. Neither lung nor systemic PK was available for any compound. Analysis of the AUEC vs. OME data, derived from the efficacy profiles, using nonlinear mixed effects modelling indicated that for four compounds, the observed differences in in vivo duration of action was due to differences in their in vivo potencies and not because of lung PK differences. Therefore, it was concluded that for these compounds, characterisation of lung PK was unlikely to differentiate their PKPD characteristics. Thus, the proposed approach helped focus resources during translational research leading to lead candidate selection.

HPLC-electrospray mass spectrometric assay for the determination of (R,R)-fenoterol in rat plasma.

A fast and specific liquid chromatography-mass spectrometry method for the determination of (R,R)-fenoterol ((R,R)-Fen) in rat plasma has been developed and validated. (R,R)-Fen was extracted from 125 microl of plasma using solid phase extraction and analyzed on Atlantis HILIC Silica 3 microm column. The mobile phase was composed of acetonitrile:ammonium acetate (pH 4.1; 20mM) (85:15, v/v), at a flow rate of 0.2 ml/min. The lower limit of detection (LLOD) was 2 ng/ml . The procedure was validated and applied to the analysis of plasma samples from rats previously administered (R,R)-Fen in an intravenous bolus.

Characterization of monolithic matrix patch system containing tulobuterol.

The aim of this study was to investigate the effect of the functional groups in acrylic adhesive on tulobuterol uptake, release rate and permeation rate across rat dorsal skin. In addition, the relationship between these parameters was identified in order to formulate the monolithic matrix patch system. Seven acrylate pressure sensitive adhesives were used in this study with three different functional groups as follows: (1) no functionality (DT-4098), (2) hydroxyl group (DT-2287, DT-2510, DT-2525, DT-2516), and (3) carboxyl group (DT-2353, DT-2852). Tulobuterol-uptake in PSA was determined by the drug-uptake method. The amount of tulobuterol-uptake in acrylic polymers with a carboxyl group was higher than those in acrylate pressure sensitive adhesives with either a hydroxyl group or a nonfunctional group. The release rate of tulobuterol from the monolithic patches was evaluated and DT-2353 and DT-2852, which contained a carboxyl group, showed lower release rates of tulobuterol than the other acrylate pressure sensitive adhesives. The skin permeation of tulobuterol was investigated using excised rat dorsal skin and the permeation rate of tulobuterol from DT-2353 and DT-2852 was also lower than the other acrylate pressure sensitive adhesives. Taking into consideration the relationship between all the parameters, pressure sensitive adhesives can be categorized into two groups: those containing a carboxylic acid functional group and those containing a non-carboxylic group. These results indicate that there was an interaction between the secondary amino group of tulobuterol and the carboxyl group of the acrylate polymer. Therefore, we suggest that a drug's chemical structure and functional groups in pressure sensitive adhesives must be considered in order to formulate a transdermal patch system.

Analysis for higenamine in urine by means of ultra-high-performance liquid chromatography-tandem mass spectrometry: Interpretation of results.

Higenamine (Norcoclaurine) is a very popular substance in Chinese medicine and is present in many plants. The substance may be also found in supplements or nutrients, consumption of which may result in violation of anti-doping rules. Higenamine is prohibited in sport at all times and included in Class S3 (ß-2-agonists) of the World Anti-Doping Agency (WADA) 2017 Prohibited List. The presence of higenamine in urine samples at concentrations greater than or equal to 10 ng/mL constitutes an adverse analytical finding (AAF). This work presents a new metabolite of higenamine in urine sample which was identified by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were prepared according to 2 protocols - a Dilute and Shoot (DaS) approach and a method involving acid hydrolysis and double liquid-liquid extraction (LLE). To meet the requirements typical for a confirmatory analysis, the screening procedure was further developed. In samples prepared by the DaS method, 2 peaks were observed; the earlier one was specific for higenamine and the later one unknown. MS scan analysis showed mass about 80 Da higher than that of higenamine. In turn, in samples prepared in accordance with the protocol involving hydrolysis, an increase in the area under peak for higenamine was observed, while the second peak was absent. It seems that the described strategy of detection of higenamine in urine avoids false negative results.