Toxicological and pharmacokinetic analysis at therapeutic dose of SRS27, an investigational anti-asthma agent

SRS27, an andrographolide analogue, had been proven to have therapeutic properties at a dose of 3 mg/kg in both in vitro and in vivo asthma models of our previous study. The present study focuses on the pharmacokinetic and toxicity profile of this compound to provide further evidence for the development of this compound as an anti-asthma agent. A simple pharmacokinetic study was performed in female BALB/c mice to measure blood plasma concentration of the compound at therapeutic dose. At a single dose of 3 mg/kg, SRS27 had a relatively short half-life but was able to achieve a concentration range of 13-19 μM that is related to its in vitro bioactivities. With regard to toxicity profile, SRS27 appears to be safe, as no histopathological changes were observed in the liver, kidneys and ovaries of SRS27-treated female BALB/c mice. In addition, there was no significant change in the mean body weight and organ weight of the animals in the SRS27-treated groups compared with the vehicle-treated control group at the end of the treatment. This fully supports the absence of any significant changes in peripheral blood leukocyte counts of SRS27-treated mice. Rewardingly, this acute toxicity study also revealed that SRS27 has a wide therapeutic window as no toxicity symptoms were detected with a dose up to 60 mg/kg daily when tested for 14 days. These results provide strong justification for further investigation of SRS27 as a potential new anti-asthma agent.

Pharmacokinetics of fluticasone propionate multidose, inhalation-driven, novel, dry powder inhaler versus a prevailing dry powder inhaler and a metered-dose inhaler

BACKGROUND

A novel inhalation-driven multidose dry powder inhaler (MDPI) that eliminates the need for the patient to coordinate device actuation with inhalation has been developed for delivery of inhaled asthma medications.

OBJECTIVE

To characterize the pharmacokinetics of single-dose fluticasone propionate (Fp) MDPI compared with single doses of Fp dry powder inhaler (DPI) and a metered-dose inhaler (MDI) in healthy subjects.

METHODS

This was a single-center, open-label, randomized, three-period crossover, single-dose pilot study in healthy adults ages 18 to 45 years. Eligible subjects (N = 18) were randomized to one of six treatment sequences that contained three treatment arms: Fp MDPI 400 μg/inhalation × two inhalations (800 μg total dose); Fp DPI 250 μg/inhalation × four (1000 μg total dose); and Fp MDI 220 μg/inhalation × four (880 μg total dose). Pharmacokinetics (area under concentration-versus-time curve [AUC], maximum plasma concentration [Cmax], time to Cmax [tmax], and elimination half-life [t½]), safety, and tolerability were assessed for each treatment.

RESULTS

Plasma Fp concentration-versus-time curves were comparable across treatments. Geometric mean AUC0-t and Cmax for Fp MDPI 800 μg were 19% and 18% higher, respectively, compared with Fp DPI 1000 μg, and 47% and 82% higher, respectively, compared with Fp MDI 880 μg. Median tmax (60.0-60.6 minutes) and median t1/2 (9.1-9.8 hours) were comparable across the three treatments. Single-dose Fp was well tolerated, with no new safety issues noted.

CONCLUSION

Single-dose administration of Fp MDPI 800 μg produced systemic exposure comparable with those for Fp DPI 1000 μg and Fp MDI 880 μg.

Pharmacological characterization of CRTh2 antagonist LAS191859: Long receptor residence time translates into long-lasting in vivo efficacy

The chemoattractant receptor-homologous molecule expressed on T-helper type 2 cells (CRTh2) is a G protein-coupled receptor expressed on the leukocytes most closely associated with asthma and allergy like eosinophils, mast cells, Th2-lymphocytes and basophils. At present it is clear that CRTh2 mediates most prostaglandin D2 (PGD2) pro-inflammatory effects and as a result antagonists for this receptor have reached asthma clinical studies showing a trend of lung function improvement. The challenge remains to identify compounds with improved clinical efficacy when administered once a day. Herein we described the pharmacological profile of LAS191859, a novel, potent and selective CRTh2 antagonist. In vitro evidence in GTPγS binding studies indicate that LAS191859 is a CRTh2 antagonist with activity in the low nanomolar range. This potency is also maintained in cellular assays performed with human eosinophils and whole blood. The main differentiation of LAS191859 vs other CRTh2 antagonists is in its receptor binding kinetics. LAS191859 has a residence time half-life of 21h at CRTh2 that translates into a long-lasting in vivo efficacy that is independent of plasma levels. We believe that the strategy behind this compound will allow optimal efficacy and posology for chronic asthma treatment.

Bioequivalence study of montelukast tablets in healthy Pakistani volunteers

Montelukast is a leukotrien receptor antagonist used for asthma treatment. Objective of this study was to evaluate the bioequivalence of two montelukast 10mg tablets, Innovator drug (Singulair) as reference and other locally manufactured drug (Montiget) in 12 healthy volunteers. It was randomized, single dose, two-period crossover study with 1 week washout period. Blood samples (4-5 ml) were collected before and after drug administration and plasma was separated for analysis. Concentrations of montelukast at different time intervals were determined by validated UV-HPLC method at 345nm wavelength. Bioequivalence was assessed by using non compartmental approach and also calculated the 90% confidence interval of the least-squared pharmacokinetic parameters (Cmax, AUC0-t and AUC0-OO). On average, Cmax, AUC0-t, AUC0-inf, was 2.35μg/mL, 1.28µg.h./ml, 1.67µg.h./ml, for innovator drug and 2.53μg/mL, 1.53µg.h./ml, 1.96µg.h./ml, for test drug, respectively. Confidence interval (90%) for Cmax, AUC0-t and AUC0-inf was 89-97%, 85-91% and 81-98% respectively. No statistical difference was found between the Cmax and AUC values of test and reference drugs. The confidence intervals for Cmax, AUC0-t and AUC0-OO are fully laid within the acceptable range of FDA (80-125%), thus two formulations are considered to be bioequivalent.

Effect of clarithromycin and fluconazole on the pharmacokinetics of montelukast in human volunteers

OBJECTIVE

Montelukast, a leukotriene receptor antagonist, is used in the treatment of asthma. The objective of the study reported here was to determine whether multiple doses of clarithromycin or fluconazole affect the pharmacokinetics of montelukast.

METHODS

This was a four-phase cross-over study with a washout period of 2 weeks between phases. In phase 1, 12 volunteers received a single oral dose of 10 mg montelukast. In phase 2, the volunteers received a single, oral dose of 1,000 mg clarithromycin once daily for 2 days, followed by, on day 3, a single oral dose of 10 mg montelukast co-administered with clarithromycin. In phase 3, a single oral dose of 50 mg fluconazole was given once daily for 6 days, followed by, on day 7, a single oral dose of 10 mg montelukast co-administered with 50 mg fluconazole. In the last phase (phase 4), a single oral dose of 150 mg fluconazole was given once daily for 6 days, followed by, on day 7, a single oral dose of 10 mg montelukast co-administered with 150 mg fluconazole. The plasma concentration of montelukast was measured by high performance liquid chromatography for 24 h.

RESULTS

Following clarithromycin co-administration, the area under the concentration-time curve from zero to infinity ( AUC(0-∞)) of montelukast increased by 144% [90% confidence interval (CI) 2.03-2.86]. The co-administration of a single oral dose of 150 and 50 mg fluconazole decreased the montelukast AUC(0-∞) by 30.7 (90% CI 0.53-0.81) and 38.8% (90% CI 0.57-0.69), respectively.

CONCLUSIONS

Clarithromycin increased the plasma concentrations of montelukast whereas fluconazole reduced the plasma concentrations of montelukast. The mechanism of the interaction is probably due to interference of the interacting drugs with transporters mediating the uptake of montelukast.

[An experimental serum pharmacological study on an application method in traditional Chinese medicine for treatment and prevention of asthma]

OBJECTIVE

To study the mechanism of herbal application along meridians for treatment and prevention of asthma by using serum pharmacological test to observe the effects of serum containing herbs against the constriction of tracheal spiral strips induced by acetylcholine chloride (Ach).

METHODS

Guinea pigs were randomly divided into normal control group, normal saline (NS) application group, aminophylline application group, aminophylline injection group, 1-day herb application group, 7-day herb application group and 14-day herb application group. Asthma was induced by Hutson's method in guinea pigs except the normal control group. Guinea pigs in herb application groups were treated by external application of a compound herbal medicine 60 min once every day. Guinea pigs in NS application group were treated by external application of NS. Guinea pigs in the two aminophylline-treated groups were treated by external application and intraperitoneal injection of aminophylline at a dose of 400 mg/kg, respectively. The guinea pigs were killed and the sera were obtained after 1-day, 7-day and 14-day treatment in the three herb application groups, 7-day treatment in the NS application group, the aminophylline application and injection groups, respectively. Serum pharmacological method was used to do the experiment, the effects of different sera on the constriction of tracheal strips were observed, and the constriction rates were calculated.

RESULT

The serum containing herbs had an effect in reducing the constriction of tracheal spiral strips induced by Ach, and the effect was similar to that of the serum obtained from the aminophylline injection group. The constriction rate of the tracheal spiral strips was decreased when herbal application treatment was prolonged within a period of time, and it became stable when herbal application treatment was between 7-14 days. The constriction of tracheal spiral strips induced by Ach could be reduced remarkably when it was previously treated by serum containing herbs.

CONCLUSION

The anti-acetylcholine function with a time-dependent effect is one of the mechanisms of herbal application treatment along meridians for asthma, and furthermore, herbal application treatment along meridians might be useful for preventing asthma.

Preparation of drug nanoparticle-containing microparticles using a 4-fluid nozzle spray drier for oral, pulmonary, and injection dosage forms

We prepared microparticles containing nanoparticles of water-insoluble pranlukast hemihydrate (PLH) using a 4-fluid nozzle spray drier. These particles were designed to improve the absorption of PLH and to allow delivery by oral, pulmonary, and injection routes. Mannitol (MAN) was used as a water-soluble carrier for the microparticles. We orally administered suspensions of PLH powder and PLH-MAN microparticles to rats. We also compared the in vitro aerosol performance of the PLH powder and PLH-MAN microparticles using a cascade impactor, and we compared the delivery of PLH by oral administration of PLH powder and pulmonary delivery of PLH-MAN microparticles at PLH/MAN ratios of 1:4 and 1:10. The absorption of PLH was markedly enhanced by pulmonary deliver of PLH-MAN composite microparticles. The area under the plasma concentration-time curve per dose for pulmonary administration of the 1:4 and 1:10 PLH-MAN microparticles was approximately 85- and 100-fold higher, respectively, than for oral administration of PLH powder. Also, we found that PLH rapidly disappeared from the plasma following injection of PLH aqueous solution or PLH-MAN microparticles dissolved in water. The PLH particles remaining after dissolution of MAN from the 1:10 PLH-MAN microparticles were 200 nm in diameter. Therefore, PLH particles may be captured immediately after injection by reticuloendothelial tissues such as the liver and spleen. This study demonstrated that it is possible to use the 4-fluid spray drier to prepare microparticles containing PLH nanoparticles that that improve drug absorption and can be administered by oral, pulmonary, and injection routes.

Pharmacokinetics of inhaled monodisperse beclomethasone as a function of particle size

AIMS

For optimal efficacy, antiasthma drugs should be delivered to the desired region in the airways. To date, the optimal particle size for steroids in adults is not known. The aim of the study was to evaluate the pulmonary bioavailability for inhaled beclomethasone dipropionate (BDP) aerosols of different particle sizes.

METHODS

In a randomized single-blind crossover trial, 10 mild asthmatic patients inhaled monodisperse BDP aerosols with mass median aerodynamic diameters (MMADs) of 1.5, 2.5 and 4.5 microm. Gastrointestinal absorption was blocked by activated charcoal. Plasma concentrations of 17-beclomethasone monopropionate (17-BMP) were measured by liquid chromatography plus mass spectrometry.

RESULTS

Aerosols with MMADs of 1.5 microm, 2.5 microm, and 4.5 microm gave mean maximum concentrations (C(max)) of 17-BMP of 475 pg ml(-1), 1300 pg ml(-1), and 1161 pg ml(-1), respectively. The area under the curve (AUC) values of 17-BMP for MMADs of 1.5 microm, 2.5 microm, and 4.5 microm were 825 pg ml(-1) h, 2629 pg ml(-1) h, and 2276 pg ml(-1) h, respectively. The mean terminal half-time of 17-BMP for all three aerosol sizes was around 1.5 h.

CONCLUSIONS

Monodisperse BDP aerosols with a MMAD of 1.5 microm gave two-three fold lower values for C(max) and AUC than those with MMADs of 2.5 and 4.5 microm.

Ciclesonide disposition and metabolism: pharmacokinetics, metabolism, and excretion in the mouse, rat, rabbit, and dog

The pharmacokinetics, metabolism, and excretion of ciclesonide, a novel and effective inhaled glucocorticoid for the treatment of asthma, were investigated after intravenous and oral administration of 14C-ciclesonide in the mouse, rat, rabbit, and dog. The pharmacokinetics of ciclesonide in all animal species were characterized by a low oral bioavailability (approximately 6% or less), a high clearance, and a large volume of distribution. The apparent terminal half-life of ciclesonide was short; the apparent terminal half-life of the active desisobutyryl-ciclesonide metabolite (des-CIC or M1) was longer and ranged from 2.4 to 6.9 hours in the 4 species. Metabolites derived from ciclesonide in serum (or plasma) and excreta samples from the 4 animal species were profiled and identified by LC/RAM/MS (liquid chromatography/radioactivity monitor/mass spectrometry). Ciclesonide was extensively metabolized to yield des-CIC, which was further metabolized to primarily yield hippuric acid and hydroxylated metabolites, namely, isomers of cyclohexane-monohydroxylated des-CIC and B-ring-monohydroxylated des-CIC. Greater than 90% of intravenous and oral 14C-ciclesonide doses were recovered in all species; the main elimination route was fecal/biliary. A comparison of in vitro and in vivo metabolite profiles between mice, rats, rabbits, and dogs with those from humans indicated that metabolic pathways for ciclesonide were qualitatively similar in humans and in the 4 animal species.

A mechanism-based binding model for the population pharmacokinetics and pharmacodynamics of omalizumab

AIM

Omalizumab, a humanized IgG monoclonal antibody that binds to human immunoglobulin E (IgE), interrupts the allergic cascade in asthmatic patients. The aim was to compare simultaneously drug exposure and IgE biomarker responses in Japanese and White patient populations.

METHODS

An instantaneous equilibrium drug-ligand binding and turnover population model was built from 202 Japanese patients. A posterior predictive evaluation for the steady-state distributions of omalizumab and IgE was then carried out against 531 White patients.

RESULTS

The mean parameters estimated from the Japanese patients were as follows: omalizumab clearance 7.32 +/- 0.153 ml h(-1), IgE clearance 71.0 +/- 4.68 ml h(-1) and the difference between that for omalizumab and the complex 5.86 +/- 0.920 ml h(-1), the volume of distribution for omalizumab and IgE 5900 +/- 107 ml, and that for the complex 3630 +/- 223 ml, the rate of IgE production 30.3 +/- 2.04 microg h(-1). Half-lives of IgG (23 days) and IgE (2.4 days) were close to previous reports. The dissociation constant for binding, 1.07 nM, was similar to in vitro values. Clearance and volume of distribution for omalizumab varied with bodyweight, whereas the clearance and rate of production of IgE were predicted accurately by baseline IgE. Overall, these covariates explained much of the interindividual variability.

CONCLUSIONS

The predictiveness of the Japanese model was confirmed by Monte-Carlo simulations for a White population, also providing evidence that the pharmacokinetics of omalizumab and IgE were similar in these two populations. Furthermore, the model enabled the estimation of not only omalizumab disposition parameters, but also the binding with and the rate of production, distribution and elimination of its target, IgE.

A reversed-phase high-performance liquid chromatographic method for the determination of zafirlukast in pharmaceutical formulations and human plasma

Zafirlukast (ZAF) is a leukotriene receptor antagonist used in the treatment of chronic asthma. In this study, a simple and sensitive reversed-phase, high-performance liquid chromatographic method was developed for the determination of ZAF in pharmaceutical formulations and human plasma. Piribedil was used as an internal standard. Analysis was carried out on a Nucleosil C18 100 A (150 mm x 4.6 mm id, 5 Vm) column with acetonitrile-pH 3.0 acetate buffer (70 + 30, v/v) as the mobile phase at a flow rate of 0.8 mL/min. The peak was detected by an ultraviolet detector set at a wavelength of 240 nm. The retention times were about 3.9 min for piribedil and 5.8 min for ZAF. The developed method was applied to the determination of ZAF in its pharmaceutical formulation and spiked human plasma. For quantification of ZAF in spiked plasma, proteins were precipitated with ethanol before chromatographic analysis. The calibration range was linear from 49.69-437.50 ng/mL in spiked plasma. The absolute recovery from spiked plasma was 98.73 +/- 0.42% at a concentration of 254.78 ng/mL of ZAF. No endogenous substances from plasma were found to interfere.

Preparation and in vitro/in vivo evaluation of nano-sized crystals for dissolution rate enhancement of ucb-35440-3, a highly dosed poorly water-soluble weak base

Ucb-35440-3 is a new drug entity under investigation at UCB S.A. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak base, shows poor solubility and dissolution characteristics. In rat, the low oral bioavailability (F < 10%) is largely due to poor absorption. In order to enhance the solubility and dissolution characteristics, formulation of ucb-35440-3 as nanocrystals has been achieved in this study. Nanoparticles were prepared using high pressure homogenization and were characterized in terms of size and morphology. In vitro dissolution characteristics were investigated and compared to the un-milled drug in order to verify the theoretical hypothesis on the benefit of increased surface area. In vivo pharmacokinetic evaluation of ucb-35440-3 nanoparticles was also carried out on rats. Crystalline state evaluation before and following particle size reduction was conducted through polarized light microscopy and PXRD to denote any possible transformation to an amorphous state during the homogenization process. Drug chemical stability was also assessed following homogenization. The dissolution rate increased significantly at pH 3.0, 5.0 and 6.5 for ucb-35440-3 nanoparticles. However, the pharmacokinetic profile obtained yielded lower systemic exposure than the un-milled compound (in fed state), this although being thought to be the consequence of the drug and formulation characteristics.

Plasma concentrations of inhaled corticosteroids in relation to airflow obstruction in asthma

AIMS

To compare the pharmacokinetic profiles of beclometasone, budesonide, fluticasone and mometasone following inhalation in patients with asthma, and explore the relationship between lung function and plasma drug concentrations.

METHODS

Thirty subjects with asthma and a forced expiratory volume in 1 s (FEV(1)) ranging from 36 to 138% predicted, inhaled 800 microg beclometasone, budesonide and mometasone and 1000 microg fluticasone in random order. Plasma drug concentrations were measured over 8 h and the relationship between the area under the plasma concentration-time curve (AUC(0-8)) and lung function was modelled using linear regression. Estimated AUC(0-8) values at 50 and 100% predicted FEV(1) were compared for each drug.

RESULTS

Pharmacokinetic profiles differed markedly between the drugs. Correlation coefficients for the relation between FEV(1)% predicted and AUC(0-8) values for beclometasone, budesonide, fluticasone and mometasone were 0.37 (P = 0.05), 0.33 (P = 0.08), 0.25 (P = 0.2) and 0.52 (P = 0.004), respectively, and estimated AUC(0-8) values were 1.3 [95% confidence interval (CI) 1.0, 1.8], 1.3 (95% CI 1.0, 1.8), 1.4 (95% CI 0.9, 2.2) and 2.2 (95% CI 1.3, 3.5) times higher for the four drugs, respectively, at 100 compared with 50% predicted FEV(1.)

CONCLUSION

The higher plasma concentrations of inhaled corticosteroids in patients with a higher FEV(1)% predicted suggests that, for any given dose, these patients will be at greater risk of developing adverse systemic effects with long-term use.

[Evaluation of the effect of inhaled glucocorticosteroids by morning cortisolemia]

The authors study the effect on adrenal function of a small dose of inhaled steroids in children with asthma. The study group consisting in 61 children treated with inhaled steroids (38 children treated with beclomethasone dipropionate and 23 treated with fluticasone propionate) who were compared with 17 controls (children with asthma treated with nonsteroidal therapy). In the study group, after 12 months of therapy morning cortisolemia was lower as compared with the values before the treatment. In children treated with beclomethasone the morning cortisol before therapy was 217.6 +/- 76.4 nmol/L and after therapy of 171.5 +/- 52 nmol/L (p < 0.077). In children treated with fluticasone initial cortisol was of 210.8 +/- 19.5 nmol/L and after treatment of 175.2 +/- 30.9 nmol/L (p < 0.027).

Effect of CYP2D6 genotype on flecainide pharmacokinetics in Japanese patients with supraventricular tachyarrhythmia

OBJECTIVE

To examine the effect of CYP2D6 genotype on the pharmacokinetics of flecainide, we conducted a population pharmacokinetic analysis of the data collected during routine therapeutic drug monitoring of Japanese patients with supraventricular tachyarrhythmia.

METHODS

Population analysis was performed on retrospective data from 58 patients with normal kidney and liver function treated with oral flecainide for supraventricular tachyarrhythmia. Serum concentrations of flecainide were determined by high-performance liquid chromatography. CYP2D6 genotyping for extensive metabolizer (EM), intermediate metabolizer (IM) and poor metabolizer (PM) alleles was conducted by allele-specific polymerase chain reaction (PCR) and stepdown PCR. WinNonMix was used to estimate oral clearance (CL/F) of flecainide with a one-compartment model for first-order absorption.

RESULTS

Body weight, age, sex, serum creatinine concentration (Scr), and CYP2D6 genotype influenced flecainide pharmacokinetics. The CL/F was affected by age (30% reduction in > or =70 years old) and sex (24% reduction in females). The ratios of CL/F for the five CYP2D6 genotypes were: 1.00 (EM/EM), 0.89 (EM/IM), 0.84 (EM/PM), 0.79 (IM/IM), 0.73 (IM/PM). A model including these five covariates reduced the interpatient variability of CL/F from 32.9% (base model) to 17.8%. Using a Bayesian method we estimated that the CL/F in IMs was significantly lower than in homozygous EMs (0.25+/-0.05 l h(-1) kg(-1) vs. 0.37+/-0.08 l h(-1) kg(-1), P<0.05) among male patients under 70 years old.

CONCLUSIONS

CYP2D6 genotype, even in IMs, as well as body weight, age, sex, and Scr influence flecainide pharmacokinetics in Japanese patients with supraventricular tachyarrhythmia.

Efficacy and safety of inhaled fluticasone propionate chlorofluorocarbon in 2- to 4-year-old patients with asthma: results of a double-blind, placebo-controlled study

BACKGROUND

Current asthma guidelines recommend inhaled glucocorticoids administered via pressurized metered-dose inhaler (MDI) with a holding chamber as the preferred therapy for young children with asthma.

OBJECTIVE

To evaluate the efficacy and safety of fluticasone propionate chlorofluorocarbon MDI use in preschool-aged children with asthma.

METHODS

Randomized, double-blind, placebo-controlled, parallel-group study of 332 children aged 24 to 47 months with asthma. Fluticasone propionate chlorofluorocarbon, 44 or 88 microg twice daily, or placebo (chlorofluorocarbon propellant alone) administered for 12 weeks via MDI with a valved holding chamber and an attached face mask. The primary efficacy measure was average change in 24-hour daily asthma symptom scores. Safety assessments included adverse events, 12-hour urinary cortisol excretion, and growth.

RESULTS

Treatment failure (ie, asthma exacerbation) occurred in approximately half as many fluticasone propionate-treated patients (13%-14%) as placebo-treated patients (24%). Compared with placebo users, patients treated with fluticasone propionate, 88 microg twice daily, had a 13% greater improvement in the mean proportion of symptom- and albuterol-free days (P = .02); asthma symptom scores and albuterol use were also significantly reduced. Patients treated with fluticasone propionate, 44 microg twice daily, had greater improvements than placebo-treated patients; however, differences did not reach statistical significance. At end point, the growth velocities of fluticasone propionate-treated patients were within the range of those of placebo-treated patients. No clinically relevant changes in 12-hour overnight urinary cortisol excretion were observed.

CONCLUSION

Compared with placebo use, fluticasone propionate, 88 microg administered twice daily, significantly reduced asthma exacerbations, asthma symptoms, and rescue albuterol use and was well tolerated, with no clinically relevant systemic effects, as measured by growth velocity or 12-hour urinary cortisol excretion levels.

Montelukast and zafirlukast do not affect the pharmacokinetics of the CYP2C8 substrate pioglitazone

OBJECTIVE

Pioglitazone, a thiazolidinedione antidiabetic drug, is metabolised mainly by the cytochrome P450 (CYP) 2C8 enzyme. The leukotriene receptor antagonists montelukast and zafirlukast have potently inhibited CYP2C8 activity and the metabolism of pioglitazone in vitro. Our objective was to determine whether montelukast and zafirlukast increase the plasma concentrations of pioglitazone in humans.

METHODS

In a randomised, double-blind crossover study with three phases and a washout period of 3 weeks, 12 healthy volunteers took either 10 mg montelukast once daily and placebo once daily, or 20 mg zafirlukast twice daily, or placebo twice daily, for 6 days. On day 3, they received a single oral dose of 15 mg pioglitazone. The plasma concentrations of pioglitazone and its metabolites M-IV, M-III, M-V and M-XI were measured for 96 h.

RESULTS

The total area under the plasma concentration-time curve of pioglitazone during the montelukast and zafirlukast phases was 101% (range 71-143%) and 103% (range 78-146%), respectively, of that during the placebo phase. Also, the peak plasma concentration and elimination half-life of pioglitazone remained unaffected by montelukast and zafirlukast. There were no statistically significant differences in the pharmacokinetics of any of the metabolites of pioglitazone between the phases.

CONCLUSIONS

Montelukast and zafirlukast do not increase the plasma concentrations of pioglitazone, indicating that their inhibitory effect on CYP2C8 is negligible in vivo, despite their strong inhibitory effect on CYP2C8 in vitro. The results highlight the importance of in vivo interaction studies and of the incorporation of relevant pharmacokinetic properties of drugs, including plasma protein binding data, to in vitro-in vivo interaction predictions.

Pharmacokinetic disposition of inhaled ciclesonide and its metabolite desisobutyryl-ciclesonide in healthy subjects and patients with asthma are similar

OBJECTIVE

To evaluate whether the inflammatory process and bronchial constriction associated with asthma influence the pulmonary distribution and airway penetration of inhaled ciclesonide by investigating the pharmacokinetics of ciclesonide and its active metabolite, desisobutyryl-ciclesonide (des-CIC) in patients with asthma and matched healthy subjects.

METHODS

12 patients with asthma (8 males, 4 females) and 12 healthy subjects matched for age, sex, height, and weight received a single inhaled dose of 1,280 microg (ex-actuator, equivalent to 1,600 microg ex-valve) ciclesonide by metered-dose inhaler in a parallel-group study. Timed blood samples were collected for measurement of serum concentrations of des-CIC and ciclesonide by liquid chromatography with tandem mass spectrometry.

RESULTS

There were no differences in the pharmacokinetics of des-CIC between healthy subjects and patients with asthma. Ratio analysis of the primary variable, the area under the concentration-time curve from time 0 to infinity (AUC(0 - inf)) showed equivalence for des-CIC in healthy subjects and patients with asthma, with a ratio of 1.003 (90% confidence interval between 0.815 and 1.234). The mean terminal half-life (t1/2) for des-CIC was also similar in patients with asthma (3.15 hours) and healthy subjects (3.33 hours). Furthermore, the pharmacokinetic parameter estimates for ciclesonide were comparable between the study groups.

CONCLUSION

After administration of a single dose of ciclesonide, the pharmacokinetic parameter estimates for des-CIC were equivalent between patients with mild-to-moderate asthma and healthy subjects, suggesting that there is comparable lung deposition and activation of ciclesonide in the 2 populations.

Spectrofluorometric determination of montelukast in dosage forms and spiked human plasma

The native fluorescence of montelukast has been studied under different experimental conditions. The highest fluorescence intensity was obtained in methanol at 390 nm using 340 nm for excitation. Surfactants and sensitizers had either a negative or a slightly positive effect on its fluorescence intensity. The fluorescence intensity-concentration plot was rectilinear over the range 0.125 to 5 microg/ml with a lower detection limit of 0.02 microg/ml (3.4 x 10(-8) M). Interference likely to be introduced from co-formulated drugs (such as loratadine) or co-administered drugs (such as verapamil, carbazepam, propranolol) or other common drugs, was studied. The method was successfully applied to the determination of the drug in tablets (pediatric tablets, chewable tablets and adult tablets). The mean % recoveries were in agreement with those provided by the manufacturer. The method was further applied to the in vitro determination of montelukast in spiked human plasma, the mean % recovery (n = 5) was 100.08 +/- 1.40.

A population pharmacokinetic model for montelukast disposition in adults and children

PURPOSE

The purpose was to develop a population pharmacokinetic model for montelukast after intravenous administration. Clinical trial simulations were conducted using the model developed to identify the lowest intravenous dose in 6- to 14-year-old children that would give montelukast systemic exposures that were comparable to those found to be associated with efficacy in adults.

METHODS

Two clinical studies were conducted where montelukast was administered intravenously as a 7-mg dose to adults and as a 3.5-mg dose to children aged 6 to 14 years. Model development included defining the base pharmacostatistical model and investigating the effects of demographic variables [age and total body weight (TBW)] on the structural parameters, using a nonlinear mixed effect modeling approach.

RESULTS

A linear three-compartment pharmacokinetic model was found to best describe the disposition of montelukast. Inclusion of TBW as a covariate caused a 35% and 63% decrease in the interindividual variabilities on clearance and central volume of distribution, respectively. Trial simulations suggested that a 5.25-mg intravenous dose of montelukast should be chosen in children aged 6 to 14 years.

CONCLUSIONS

The model developed can adequately describe the intravenous pharmacokinetics of montelukast and can be used as a useful tool for dose selection in pediatric subpopulations.

Comparison of the systemic pharmacodynamic effects and pharmacokinetics of salmeterol delivered by CFC propellant and non-CFC propellant metered dose inhalers in healthy subjects

This was a randomised, double-blind, placebo-controlled, cross-over study comparing the systemic pharmacodynamic effects (heart rate and serum potassium) and pharmacokinetics of salmeterol delivered by the non-CFC hydrofluoralkane (HFA) propellant 134a and the CFC propellant (propellant 11/12) metered dose inhalers (MDI) in healthy subjects. At the therapeutic dose (50 microg), salmeterol-mediated systemic pharmacodynamics were equivalent for the HFA and CFC MDIs. Higher doses of salmeterol (150 and 300 microg) produced dose-related beta-agonist pharmacodynamic effects irrespective of the propellant. However, these effects were lower with salmeterol HFA MDI than with the salmeterol CFC MDI at all dose levels. Overall, salmeterol Cmax and AUC(0-t) values were lower for salmeterol HFA compared with salmeterol CFC MDI. At the highest dose (300 microg), where a full pharmacokinetic profile was obtained, exposure to salmeterol delivered by the HFA MDI compared with the salmeterol CFC MDI was 27% and 30% lower for Cmax and AUC(0-t), respectively. Maximum plasma concentrations were generally seen in the first plasma samples taken 5 min after the start of dosing. Salmeterol HFA was well-tolerated. At supratherapeutic doses, adverse events were typical for high-dose salmeterol with fewer adverse events occurring with the HFA compared with the CFC formulation. These data indicate that the salmeterol HFA MDI would not be associated with a significantly different pharmacodynamic, safety and tolerability profile compared with the salmeterol CFC MDI.

An Automated Method for the Determination of Montelukast in Human Plasma Using Dual-Column HPLC Analysis and Peak Height Summation of the Parent Compound and Its Photodegradation Product

PURPOSE

To develop an assay to evaluate the bioequivalence of overcoated and marketed montelukast formulations, the former to be used for future blinded clinical studies.

METHODS

The method used automated 96-well sample preparation and dual-column HPLC analysis for increased throughput. Regression analysis was performed using the total peak height of montelukast and its photodegradent, a cis-ethenyl geometric isomer. This approach successfully compensated for montelukast's light sensitivity, allowing both clinical specimen handling and bioanalytical laboratory analysis to be conducted without extensive precautions being taken to protect samples from UV light. To ensure a molar equivalent fluorescence response between the cis (Z) and trans (E) isomers, the emission wavelength and detector attenuation were both increased just prior to the elution of the montelukast peak (i.e., the trans isomer), effectively dampening the response of the stronger fluorophore. Plasma proteins were precipitated using acetonitrile, and 50 microl of supernatant was injected onto an HPLC system consisting of two C18 analytical columns connected to a 10-port switching valve. Injections were overlapped on alternating columns allowing twice as many samples to be processed during each analytical run.

RESULTS

The calibration curve was linear from 5 to 2000 ng ml(-1). The inter-day and intra-day precision expressed as coefficient of variation (%CV), were 1.1-6.1% and 3.1-6.7%, respectively. The accuracy, reported as percentage bias, was less than or equal to +/-9.1%. The absolute recovery was determined to be 94.3% and 98.1% at 15 and 1500 ng ml(-1), respectively.

CONCLUSIONS

This assay represents a rapid, accurate, and sensitive method for the determination of montelukast in human plasma. The method has been successfully used to demonstrate the bioequivalence of the overcoated montelukast formulations to their equivalent marketed tablets.

Effect of food on pharmacokinetics of an inhaled drug: a case study with a VLA-4 antagonist, HMR1031

HMR1031 is a potent and specific antagonist of the integrin VLA-4 (alpha4beta1) binding to vascular cell adhesion molecule-1 (VCAM-1) and fibronectin. HMR1031 is an inhaled drug being developed for the treatment of asthma using an Ultrahaler dry-powder inhalation device. A pharmacoscintigraphic study of HMR1031 suggests a lung deposition of approximately 25% and gastrointestinal tract deposition of approximately 75%. Since oral absorption may be contributing to systemic plasma concentrations, the effect of food on HMR1031 was assessed. This was a single-dose (3 mg), open-label, randomized, two-way crossover (fasted vs. fed) study in 8 healthy male subjects. Blood samples were collected at predose and up to 24 hours postdose. Plasma concentrations were determined by the LC/MS/MS method. HMR1031 was rapidly absorbed, with median tmax values of 1.0 and 0.75 hours under fasted and fed conditions, respectively. Under fasted conditions, mean AUCinfinity and Cmax values were 16.4 ng x h/mL and 4.56 ng/mL, respectively. Under fed conditions, mean AUCinfinity and Cmax values decreased to 11.7 ng x h/mL and 2.81 ng/mL, respectively. The mean terminal elimination half-life (t1/2) for both treatment groups was similar (2.7 h). HMR1031 population estimates of the apparent clearance, apparent volume of distribution, and absorption rate were 225 L/h (4.1% coefficient of variation [CV]), 44.5 L (26% CV), and 0.340 h-1 (7.0% CV), respectively. Food is a significant covariate on clearance. These data suggest that food unexpectedly decreases the systemic exposure of inhaled HMR1031 by approximately 30%, probably due to increased liver blood flow and increased biliary excretion. This decrease in systemic exposure is unlikely to affect the topical effect of the drug but may result in increased variability in plasma pharmacokinetics. The disposition and food effect of HMR1031 can be described using mixed-effect modeling.

HPLC-radiometric determination of quinlukast in biological fluids

An analytical method for the analysis of a novel antiasthmatic drug quinlukast and its metabolites in the plasma, bile and urine was developed. For the analysis, the solid phase extraction method and the C(8) RP-HPLC with radiometric detection of the drug were used. This method enables a quantitative determination of the agent and all of its metabolites (even of those with an unknown structure) in a biological system. The procedure is, therefore, suitable both for the pharmacokinetic analysis of quinlukast and the determination of its elimination pathways.

A simple pharmacokinetic method to evaluate the pulmonary dose in clinical practice—analyses of inhaled sodium cromoglycate

When the expected effect of an inhaled drug is not achieved, the cause could be poor inhalation technique and consequently a low pulmonary dose. A simple in vivo test to evaluate the pulmonary dose would be a benefit. This study evaluates the relative and systemic bioavailability following inhalation of nebulized sodium cromoglycate (SCG) in healthy subjects. Blood samples were collected during 240 min and urine was collected in two portions, up to 6 h post-inhalation. Two exposures were performed and comparisons based on the quantification of drug in plasma and urine by a high-performance liquid chromatography (HPLC) procedure were done. In one of the exposures, a pulmonary function test was performed to study if an expected effect of increased absorption could be detected. There was a good correlation between the two exposures shown in the plasma concentrations, but not in the urine analyses. The forced exhaled volume manoeuvres were associated with a higher Cmax and plasma concentrations up to 60 min post-inhalation (P<0.01). This effect was not detected in the urine analyses. We conclude that this pharmacokinetic method with inhaled SCG and plasma analyses could be used to evaluate individual inhalation technique. The HPLC method used was rapid and had adequate sensitivity.

Pharmacokinetics of a novel anti-asthmatic, scoparone, in the rabbit serum assessed by a simple HPLC method

The pharmacokinetics of scoparone (Sco), an anti-asthmatic coumarin derivative extracted from the traditional Chinese herb "Yin Chen", was determined in rabbit plasma by a high performance liquid chromatography (HPLC) method which was newly developed using a Nova-Pak Silica C(18) column and a mobile phase of acetonitrile-water (20:80, v/v). After intravenous administration of Sco at a dose of 2.0 or 3.6 mg/kg, the time course of the plasma concentration of Sco was found to fit an open two-compartment model. AUC values increased, dose-dependently. Mean T(1/2) values showed that half-life was dosage independent. Distribution and elimination of Sco in rabbit plasma were both relatively rapid. These results indicate that Sco could be easily administrated by spray inhalers and is expected to have few associated side effects.

Technology evaluation: omalizumab, Genentech/Novartis/Tanox

Genentech, Novartis and Tanox have co-developed Genentech's anti-IgE humanized monoclonal antibody omalizumab for the treatment of allergic rhinitis and asthma. The antibody is currently undergoing phase II clinical trials for allergic rhinitis in Canada and phase III clinical trials for both indications in Japan. Omalizumab is at the pre-registration stage for both indications in the US, New Zealand, Switzerland and Western Europe, and is currently registered for both indications in Australia.

Comparison of the bioavailability and systemic effects of beclometasone dipropionate suspension for nebulization and beclometasone dipropionate via a metered-dose inhaler after single-dose administration in healthy male volunteers

Pharmacokinetic properties of a drug, and selection and correct usage of an appropriate delivery device, are factors that can affect the outcome of inhaled therapyThe use of nebulization can overcome problems that are associated with other delivery systems used for inhalation therapyThe objective of this open, randomized, single-dose study was to compare the systemic exposure and safety of beclometasone dipropionate (BDP) suspension for nebulization with BDP via metered-dose inhaler (MDI) in healthy subjects. Following a run-in period to assess basal 24-h serum cortisol levels and cortisol urinary excretion, 12 healthy males were administered BDP 1,600 microg given via MDI and were then randomized to receive a single dose of either 1,600 microg (n = 6) or 3,200 microg BDP (n = 6) suspension for nebulization given via a nebulizer Results with respect to systemic exposure to beclometasone-17-monopropionate (B17MP) (the active metabolite of BDP) and systemic effects on the hypothalamic-pituitary-adrenal (HPA) axis were determined by evaluation of a number of pharmacokinetic parameters for plasma B17MP and serum and urinary cortisol, respectively. A statistically significantly greater peak plasma concentration (Cmax) of B17MP was reported with BDP via MDI (1,587 pg ml(-1)) compared with BDP 1,600 microg (455 pg ml(-1)) and BDP 3,200 microg suspensions for nebulization (758 pg ml(-1)), and was achieved more rapidly (Tmax) (1.3 h, 3 h, and 2.5 h, respectively). In addition, elimination half-life (t 1/2(el)) was statistically significantly shorter with BDP via MDI (4.6 h) than with both dosages of BDP suspensions for nebulization (7.4 h and 6.3 h with 1600 microg and 3,200 microg, respectively), as was mean residence time (MRT) (5.4 h, 11.1 h, and 10.0 h, respectively). Total systemic exposure to B17MP (as determined by the area under the concentration-time curve: AUCinfinity) was comparable for BDP via MDI (6,883 pg ml(-1) h(-1)) and BDP 3,200 microg suspension for nebulization (8,201 pg ml(-1) h(-1)), but significantly greater than with BDP 1,600 microg suspension for nebulization (4,870 pg ml(-1); P < 0.05 vs BDP via MDI). All treatments were well tolerated, and no significant differences were found between them with respect to the serum or urinary cortisol pharmacokinetic parameters assessed. In conclusion, the results of this study demonstrate that BDP suspension for nebulization 3,200 microg given via a nebulizer and BDP 1,600 microg given via an MDI are equivalent in terms of systemic exposure to B17MP and systemic effects on the HPA axis, with BDP suspension for nebulization having a potentially more prolonged activity. It confirms that use of a double dose of BDP suspension for nebulization administered by nebulizer compared with BDP given via metered-dose inhalation is justified and poses no risk with regard to safety.

An Approach to Complete the Manual for Determination of Serum Pirmenol Levels

In order to complete TDM manual for pirmenol in Sapporo Medical Center NTT East, we developed HPLC method and pretreatment procedure for pirmenol samples obtained from patients. Serum (250 microliters) was alkalinized and pirmenol was extracted into n-hexane, and then the drug was again extracted into an acidic solvent, 0.044 M KH2PO4 (pH 2.6) including 0.5% triethylamine. The aqueous extract was used for quantitative determination of the drug by HPLC. The mobile phase consisted of the above acidic solvent-acetonitrile (5:1, v/v) was delivered at 45 degrees C with a flow rate of 1 ml/min through a 4.6 mm x 25 cm ODS-3, a reversed-phase column. Detection of pirmenol and the internal standard (disopyramide) was achieved at 263 nm. Pirmenol and disopyramide was eluted at 5 and 11 min, respectively. Assay limit (25 ng/ml) and accuracy of the analytical method were satisfactory for TDM of pirmenol. During the HPLC analysis of patient samples, no substances that interfered with pirmenol detection were found. It was shown that 1) hemolysis did not affect pirmenol assay at all, 2) pirmenol was stable in the blood samples for at least 24 h even if they were stood at room temperature, and 3) pirmenol was stable for at least 3 days in frozen serum but there significant decrease was observed in pirmenol concentration after 7 days.

Inhalation and deposition of nebulized sodium cromoglycate in two different particle size distributions in children with asthma

The relative deposition of two inhaled droplet size distributions of sodium cromoglycate produced by a Hudson Updraft II nebulizer was evaluated, using a setup modified from the proposed Comité Européen Normalisé (CEN) standard prEN 13544-1. The modified setup comprised an Andersen 296 impactor and a Spira Electro 2 dosimeter. The setup was characterized prior to use in children with sodium cromoglycate (SCG) and sodium fluoride as tracer aerosol. The main in vivo study was designed to allow nine children with a mean age of 10 years to inhale SCG aerosol at two different relative humidities (RH), a high RH (> 90%) and a low RH (13%), which in turn resulted in two different droplet size distributions. The nebulizer/dosimeter was set to provide 1-sec nebulization during 50 inhalations. Throughout the exposures, the children were instructed to inhale in a consistent manner with target tidal volumes (0.5 L) and inhalation flows (0.4 L/sec). Blood samples were taken at predefined time intervals, and the area under the curve (AUC) was calculated. A lung deposition program, TGLD2, was used to calculate the expected deposition, using the droplet sizes and inhalation parameters obtained during in vivo exposures. The in vivo monitoring of droplet size distribution during the exposure showed that the low, intermediate (room air), and high RHs gave a mean droplet size distribution with a mass median aerosol diameter (MMAD) of 1.2, 1.7, and 2.0 microm, respectively. The average tidal volume over all exposures was 0.51 +/- 0.12 L. The total deposition fraction was 33.4% of the estimated nebulizer output. A correlation was found between tidal volume and the calculated deposited fraction. The results indicate that there is a difference in total deposition, depending on the size of the droplet size distribution, with the larger droplet size distribution (MMAD, 2.0 microm) having a higher total deposition than the smaller droplet size distribution (MMAD, 1.2 microm). The deposition results were in good agreement with the deposition fractions estimated using the TGLD2 software for the inhalation parameters found in the study. The obtained study results can arise from differences in regional deposition, but may also be explained by differences in extrathoracic deposition.

Multiple-dose proportionality study of flunisolide hydrofluoroalkane

The hydrofluoroalkane (HFA) formulation of the inhaled corticosteroid flunisolide is a modification of the original chlorofluorocarbon formulation. HFA flunisolide substitutes an HFA for a chlorofluorocarbon propellant and uses a built-in spacer in its pressurized metered-dose inhaler. An open-label, randomized, three-way crossover, multiple-dose study evaluated the dose proportionality of three doses of flunisolide HFA. Twenty-one healthy volunteers received the following doses twice daily for 4.5 days: 85, 170, and 340 micrograms. Plasma levels of flunisolide and of the flunisolide metabolite 6 beta-OH flunisolide were measured after single- and multiple-dose administration. After a single dose, dose proportionality was observed across the three dose levels for peak plasma concentration (Cmax) and the area under the plasma concentration-time curve (AUC) up to both the time corresponding to the last measurable concentration (AUC0-tau) and the time to infinity (AUC0-infinity). After multiple doses, dose proportionality was observed for both Cmax and AUC at the medium and high doses. Predose plasma levels of flunisolide measured on day 4 were below the limit of detection. The elimination half-life of flunisolide ranged from 0.95 to 1.34 hours. After both single and multiple doses, dose proportionality was observed in dose-adjusted Cmax and AUC0-infinity for the inactive 6 beta-OH metabolite. HFA flunisolide was well tolerated. The lack of accumulation after repeated administration of HFA flunisolide suggests that the systemic exposure of flunisolide is low, which is a safety goal for inhaled corticosteroids.

Pharmacokinetic comparison of beclomethasone dipropionate extrafine aerosol from two inhaler devices in children with asthma

OBJECTIVE

The primary objective was to test the comparability of the pharmacokinetics of beclomethasone dipropionate (BDP) delivered from a pressurized extrafine solution formulation in two inhalation devices in children with asthma. One inhaler was actuated using the press and breathe (P&B) technique and the other was breath-actuated (AH); both inhalers used HFA-134a as propellant.

METHODS

Eighteen children aged between 9 years and 12 years entered and completed the study; written informed consent was obtained from all patients and their legal guardians. Each patient received, according to a randomized three-period crossover design, 200 microg BDP as four inhalations from 50 microg/actuation P&B, 200 microg BDP as four inhalations from 50 microg/actuation AH, and 400 microg BDP as four inhalations from 100 microg/actuation AH. Each patient was instructed on the proper use of each device once, at the screening visit. Patients self-administered all inhalations at the same time of day during the study without further coaching. Blood samples were collected for 24 h during each period to assay for the presence of BDP and metabolites. The log-transformed pharmacokinetic data were compared using a confidence-interval approach.

RESULTS

Almost all the BDP-derived material in the plasma was the active metabolite beclomethasone 17-monopropionate; pharmacokinetic analyses were only performed for this metabolite. The ratios each of the pharmacokinetic parameters maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC), between the AH and P&B inhaler devices, were 0.94 and 1.1, respectively, and the corresponding 95% confidence intervals demonstrated comparability of the devices. Dose proportionality of C(max) and AUC between the 200-microg and 400-microg doses was similarly shown. About twice as many inhalation errors occurred during the P&B administration as during the AH periods, but the incidence was still low and did not result in any change in pharmacokinetics.

CONCLUSION

The rate and extent of drug absorption was comparable from the P&B and AH inhaler devices in children with asthma. Dose proportionality was also observed.

Single-dose study to compare the pharmacokinetics of HFA flunisolide and CFC flunisolide

The hydrofluoroalkane (HFA) formulation of the inhaled corticosteroid flunisolide is a modification of the original chlorofluorocarbon (CFC) formulation. HFA flunisolide replaces CFC with an HFA propellant and uses a built-in spacer in its pressurized metered-dose inhaler. The average HFA flunisolide particle size is 1.2 microm compared with 3.8 microm for the CFC formulation. The smaller particle size improves lung targeting, allowing a reduction in the HFA flunisolide dose relative to CFC flunisolide while maintaining comparable efficacy. In a study of 12 healthy men, pharmacokinetic parameters were determined after single doses of 1000 microg CFC flunisolide delivered without a spacer, 340 microg HFA flunisolide delivered through a spacer, and 516 microg HFA flunisolide delivered without a spacer. A standard noncompartmental analysis of the concentration data was performed and mean (+/- S.D.) pharmacokinetic values were reported. Peak plasma concentrations (observed C(max)) were similar for the three treatments. Area under the curve up to the time corresponding to the last measurable concentration (AUC(0)(-)(tlast)) was similar for the CFC and HFA flunisolide, plus spacer groups (4.4 +/- 1.6 ng x h/mL and 5.0+/- 4.2 ng x h/mL, respectively); however, AUC(0)(-)(tlast) for the HFA flunisolide without spacer group was comparatively lower than for the CFC group (3.5 +/- 1.6 ng x h/mL). Observed C(max) and AUC(0)(-)(tlast) for 6 beta-OH flunisolide, the first-pass metabolite of flunisolide and an indicator of oropharyngeal deposition, were significantly higher in the CFC flunisolide group than in either HFA flunisolide group.

LC/MS/MS plasma assay for the peptidomimetic VLA4 antagonist I and its major active metabolite II: for treatment of asthma by inhalation

In vitro and in animals, I is a potent and specific peptidomimetic for the potential treatment of airway inflammation in the pathogenesis of asthma. Preclinical studies indicated extensive conversion of I to an active metabolite II, and thus, a very sensitive assay for I and II was needed to support an inhalation ascending-dose study in man. The LC/MS/MS plasma/urine assay method (1.0 ml of sample) involves the following: liquid-liquid extraction of acidified plasma into pentane-ethyl acetate (90:10 v/v); evaporation of the organic extract, reconstitution into methanol; addition of water to the methanolic extract and freezing. After thawing, the extract is centrifuged and the clear supernatant injected for chromatography. Extract is chromatographed on a YMC ODS-AM column (50 x 2.0 mm). For detection, a Sciex 365 LC/MS/MS with an electrospray inlet and used in the positive ion, multiple reaction monitoring mode was used to monitor precursor-->fragment ions of m/z 709-->594 for I and m/z 513-->380 for II. The plasma assay was linear over the concentration range of 0.1-100 ng/ml in plasma for I and II. Accuracy and precision for I ranged from 97.9 to 102.1% of nominal with a 0.84-10.65% CV; similarly for II, 98.0-101.7% and 1.39-9.28% CV, respectively. Extraction recovery averaged 63.7% for I and 64.9% for II. This general assay methodology may be applied to assay small acidic peptides and peptidomimetics from biological fluids by LC/MS/MS.

Flunisolide HFA vs flunisolide CFC: pharmacokinetic comparison in healthy volunteers

Two preparations of flunisolide, an inhaled corticosteroid, were compared in a parallel, multiple-dose study of 31 healthy volunteers. The new flunisolide preparation substitutes hydrofluoroalkane (HFA) for chlorofluorocarbon (CFC) as a propellant and incorporates a spacer into its pressurized metered-dose inhaler (pMDI). In this study, subjects were randomly assigned to receive flunisolide CFC 1000 microg bid; flunisolide HFA 170 microg bid; or flunisolide HFA 340 microg bid. Dosing was continued for 13.5 days. Plasma samples were analyzed after the first dose on day 1 and again after 13.5 days of treatment. No significant differences in day 1 dose-adjusted peak plasma concentrations (C(max)) were observed. Dose proportionality in C(max) and area under the concentration--time curves (AUC) was observed for the flunisolide HFA 170 and 340 microg bid groups on days 1 and 14. Day 1 mean dose-adjusted AUC was significantly greater in the flunisolide CFC 1000 microg bid group than in either flunisolide HFA group, indicating greater systemic availability of flunisolide CFC. Oral clearance and volume of distribution were significantly higher for flunisolide CFC than for flunisolide HFA. This may be due to greater oropharyngeal deposition by the flunisolide CFC formulation. Another indicator of greater flunisolide CFC oropharyngeal deposition was observed in C(max) and AUC(0--tlast) values for 6beta-OH flunisolide, the first-pass metabolite of flunisolide. The values of these pharmacokinetic parameters were significantly higher in the flunisolide CFC group than in the 340 microg bid flunisolide HFA group on days 1 and 14. However, this was not the case for cortisol values where flunisolide HFA accounted for less oropharyngeal deposition and more targeted delivery without adverse events. The study demonstrated that flunisolide HFA administered through a pMDI with built-in spacer was safe and well tolerated in healthy volunteers.

Sodium cromoglycate attenuates pulmonary inflammation without influencing bronchial responsiveness in healthy subjects exposed to organic dust

BACKGROUND

Inhalation of organic dust from a pig house induces airway inflammation and increases bronchial responsiveness to methacholine in healthy subjects.

OBJECTIVE

To study whether sodium cromoglycate influences the airway inflammatory reaction and the increase in airway responsiveness induced by inhalation of organic dust.

METHODS

Bronchoalveolar and nasal lavages, and bronchial methacholine challanges were performed and blood samples were drawn in 32 healthy subjects before and after exposure to dust in a pig farm. Sodium cromoglycate was inhaled (20 mg, twice a day) and administered intranasally (5.2 mg, twice a day) by 16 and a corresponding placebo was given to the other 16 healthy controls for two weeks prior to exposure.

RESULTS

Exposure induced a significant increase in inflammatory cells and soluble components (pro-inflammatory cytokines, inflammatory mediators) in bronchoalveolar and nasal lavage fluid in both groups. The increase in neutrophils, interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha as well as myeloperoxidase and soluble intracellular adhesion molecule (ICAM)-1 in bronchoalveolar lavage (BAL) fluid was significantly reduced by treatment with sodium cromoglycate. Although sodium cromoglycate inhalation largely influenced a variety of inflammatory indices in bronchoalveolar lavage fluid it had no effect on the increase in bronchial responsiveness to methacholine.

CONCLUSION

Sodium cromoglycate alters the airway inflammatory response to inhaled organic dust without influencing the dust-induced increase in bronchial responsiveness to methacholine.

Expedient liquid chromatographic method with fluorescence detection for montelukast sodium in micro-samples of plasma

This study describes an expedient assay for the analysis of the asthma medication, montelukast sodium (Singulair, MK-0476), in human plasma samples. After a simple extraction of the plasma, the drug and internal standard, quinine bisulfate, were measured by HPLC. The chromatographic system consisted of a single pump, a refrigerated autosampler, a C8 4-microm particle size radial compression cartridge at 40 degrees C and a fluorescence detector with the excitation and emission wavelengths set at 350 and 400 nm, respectively. The mobile phase which was delivered at 1.0 ml/min, was prepared by adding 200 ml of 0.025 M sodium acetate, pH adjusted to 4.0 with acetic acid, to 800 ml of acetonitrile, with 50 microl triethylamine. With a run time of only 10 min per sample, this assay had an overall recovery of >97% with a detection limit of 1 ng/ml. The inter- and intra-run relative standard deviations at 0.05, 0.2 and 1.0 microg/ml were all <9.2%, while the analytical recovery at the same concentrations were within 7.7% of the amount added.

Absorption kinetics after inhalation of fluticasone propionate via the Diskhaler, Diskus and metered-dose inhaler in healthy volunteers

OBJECTIVE

The aim of this analysis was to assess the rate and extent of systemic availability of inhaled fluticasone propionate (FP) from 2 dry powder systems (Diskhaler and Diskus) and a metered-dose inhaler (MDI) by deconvolution analysis.

METHODS

The inhalation devices were evaluated in 3 separate studies with identical protocols. 12 healthy male volunteers were randomised to receive FP given as a 1000 microg inhaled dose and 250 microg by intravenous infusion according to a double-blind double-dummy crossover design. The bioavailability of FP after inhalation represents absorption of the drug from the lungs, since the bioavailability of the swallowed portion of the inhaled dose is negligible.

RESULTS

When corrected for the bioavailability (of FP) achieved by each inhalation device, the rate of absorption of FP over the first 2 hours was rapid from all devices. The mean time for absorption of 50% of the bioavailable dose was 1.6, 2.4, and 2.2 hours for the Diskhaler, Diskus and MDI, respectively. Thereafter, absorption from each device was prolonged, with approximately 10% of the dose remaining in the lungs 12 hours after inhalation.

CONCLUSION

Irrespective of the inhalation device used, the prolonged absorption of FP into the systemic circulation indicates a long residence time in the lungs.

Systemic exposure to fluticasone propionate administered via metered-dose inhaler containing chlorofluorocarbon or hydrofluoroalkane propellant

OBJECTIVE

The pharmacokinetic profile of a single dose of inhaled fluticasone propionate (FP) administered via a metered-dose inhaler (MDI), containing either a chlorofluorocarbon (CFC) or hydrofluoroalkane (HFA) propellant was investigated in healthy volunteers.

METHODS

Two randomised, double-blind, crossover studies were conducted, each in 12 male volunteers. Both studies compared pharmacokinetic data after a single inhaled dose of FP 1000 microg from a MDI containing either CFC (CFC MDI) or HFA (HFA MDI) with a single intravenous dose of FP 250 microg.

RESULTS

The maximum plasma FP concentrations after inhalation via the 2 types of MDI were almost identical (0.56 and 0.54 microg/L for CFC MDI and HFA MDI, respectively); bioavailability values of inhaled FP from the 2 MDIs were also similar (geometric mean values: 26.4% via the CFC MDI and 28.6% via the HFA MDI). Inhalation of FP via both MDI formulations produced similar reductions in urinary cortisol excretion over 12 and 24 hours postdose.

CONCLUSION

The bioavailability values of FP after inhalation via a CFC MDI and an HFA MDI are similar. The 2 formulations deliver comparable amounts of FP, and systemic exposures to FP from the 2 devices, measured by urinary cortisol excretion, are not significantly different.

Pharmacokinetics of fluticasone propionate inhaled via the Diskhaler and Diskus powder devices in patients with mild-to-moderate asthma

OBJECTIVE

The aim of these studies was to compare the pharmacokinetics of inhaled fluticasone propionate (FP) after repeated administration via the Diskus or Diskhaler dry powder inhalers (DPIs) to patients with mild-to-moderate asthma.

METHODS

Both studies evaluated the pharmacokinetics of inhaled administration of FP via a DPI to patients with mild-to-moderate asthma, according to a randomised, double-blind, placebo-controlled design. In the first study, FP 100 microg or 500 microg was administered twice daily via the Diskhaler for 6 weeks and, in the second, FP 500 microg was administered via the Diskus or Diskhaler for 12 weeks.

RESULTS

In the first study, plasma FP concentrations could be detected consistently only with the higher dose; the lower dose produced concentrations close to or below the 0.025 microg/L quantification limit of the radioimmunoassay used. From detailed analysis of a subgroup of patients receiving the 500 microg dosage, steady-state plasma FP concentrations were attained within one week of commencing treatment. After 4 weeks, the maximum plasma FP concentration (Cmax) in this subgroup was 0.096 microg/L [95% confidence interval (CI) 0.066-0.141] and the area under the plasma FP concentration-time curve up to the last quantifiable concentration (AUClast) was 0.491 microg/L x h (95% CI: 0.256-0.940). The steady-state to single dose accumulation ratio for FP after twice-daily administration varied between patients: a ratio of approximately 1.7 was recorded after comparison of Cmax at week 4 and day 1. In the second study, the point estimate of the Diskus to Diskhaler ratio for Cmax in all patients was 0.91 (90% CI: 0.76-1.10) after 4 weeks' treatment. From a detailed analysis of a subgroup of patients, the corresponding ratio for AUClast at the same time point was 1.15 (90% CI: 0.69-1.94), indicating no significant difference in systemic exposure to FP between the 2 devices. Steady-state kinetics were achieved by week 1: the point estimate ratios of Cmax and AUClast at week 4 compared with week 1 were 0.88 (90% CI: 0.66-1.16) and 0.95 (90% CI: 0.66-1.36), respectively. Administration of FP via either DPI had no effect on plasma cortisol levels over the 12-hour postdose period.

CONCLUSION

In patients with asthma receiving repeated inhaled doses of FP, the systemic exposure (AUC) after inhalation from the Diskus was similar to that from the Diskhaler, with no difference between the DPIs in the effects on cortisol suppression. The 2 DPIs therefore have very similar pharmacokinetic profiles.

Comparison of the systemic availability of fluticasone propionate in healthy volunteers and patients with asthma

OBJECTIVES

The aim of this analysis was to compare the systemic exposure to inhaled fluticasone propionate (FP) after administration of either single or repeated dose regimens via dry powder and metered-dose inhalers in patients with asthma and healthy volunteers.

BACKGROUND

The pharmacokinetics of FP, a topically active glucocorticoid administered by inhalation for the treatment of asthma and rhinitis, are well characterised in healthy volunteers. As asthma is characterised by pathophysiological changes in the lung, it may be inappropriate to use data from studies in healthy volunteers to predict the deposition and absorption of FP in patients with asthma.

METHODS AND RESULTS

Pooled data from 13 pharmacokinetic studies showed that the systemic availability of FP (measured as area under the plasma FP concentration-time curve) after single or multiple administration by inhalation was 2 to 3 times lower in patients with asthma than in healthy volunteers. This observation correlated well with the systemic effects of FP in the 2 groups. Reduction in 24-hour urinary cortisol excretion after inhalation of FP (determined in 9 of the studies) was greater in healthy volunteers than in patients with asthma. The hypothalamic-pituitary-adrenal axis suppression caused by systemic exposure to FP in adults with asthma is therefore substantially less than that in healthy volunteers.

CONCLUSION

Differences in the deposition of FP in the lungs of patients with asthma, probably caused by obstructed inspiratory airflow, may explain this observation.

The relationship between systemic exposure to fluticasone propionate and cortisol reduction in healthy male volunteers

OBJECTIVE

The aim of this analysis was to assess the pharmacokinetic/pharmacodynamic relationship between systemic exposure to fluticasone propionate (FP) and reductions in the plasma cortisol level and urinary cortisol excretion.

METHODS

A total of 122 healthy male volunteers participating in 7 different studies received either oral (5 to 40 mg), inhaled (500 to 2000 microg) or intravenous (250 to 1000 g) single morning doses of FP or placebo. Data on systemic exposure to FP, expressed in terms of the area under the FP concentration-time curve up to 24 hours (AUC(24h,FP)) for the 3 different routes of administration were pooled, together with corresponding data on the 24-hour plasma cortisol level or urinary cortisol excretion. The data were used to develop a pharmacokinetic/pharmacodynamic model, from which parameter estimates and 95% confidence intervals (CI) for the estimates could be derived.

RESULTS

The intercept in the absence of drug (E0) was -0.5% (95% CI: -0.6, -0.3%) and the maximum drug-induced reduction in mean plasma cortisol levels (Emax) was 72% (95% CI: 64, 79%). The systemic exposure to FP that resulted in half the maximum possible reduction in plasma cortisol levels (AUC50) was 3.2 microg/L x h (95% CI: 2.8, 3.7 microg/L x h); this equates approximately to the plasma FP concentration obtained after administration of a 1000 microg inhaled dose. A similar relationship was seen between AUC50 and urinary cortisol excretion, although the variability in AUC50 for urinary cortisol was much greater than for plasma cortisol.

CONCLUSION

A pharmacokinetic/pharmacodynamic model has been established which relates systemic exposure to FP (after a single morning dose) to the percentage reduction in urinary or plasma cortisol. The relationship is independent of both dose and route of administration.

Bioavailability of orally administered micronised fluticasone propionate

OBJECTIVE

The aim of this study was to determine the absolute oral bioavailability of fluticasone propionate (FP) in healthy volunteers.

METHODS

A 3-period incomplete block crossover design was used. On separate occasions, 21 male volunteers received a single 250 microg intravenous dose of FP (n = 21) and twice daily oral doses of either micronised FP 0.1 mg (n = 9), 1 mg (n = 12), 10 mg (n = 11) or placebo (n = 9) for 4 days.

RESULTS

FP was not measurable in the plasma after twice daily oral administration of a 0.1 mg dose. FP concentrations just above the limit of quantification could be measured in only 5 volunteers, and only at some time points, after administration of FP 1 mg twice daily. At a dose of 10 mg twice daily the absolute oral bioavailability of the drug was <1% when a liquid chromatography-mass spectrometry assay was used to assess plasma concentrations. Only oral doses of FP 10 mg twice daily, 10 times greater than the recommended maximum inhaled dose, produced any detectable change in urinary cortisol excretion.

CONCLUSION

The results of this study confirm that oral absorption of FP into the systemic circulation is negligible. The swallowed portion of an inhaled dose of FP is unlikely to increase the systemic exposure to the drug, thus decreasing the likelihood of adverse systemic effects.

Comparative kinetics of metabolism of beclomethasone propionate esters in human lung homogenates and plasma

The systemic availability of inhaled beclomethasone dipropionate (BDP) is the net result of the absorption of the glucocorticoid from the lower respiratory and gastrointestinal tracts, and metabolism in the lung, plasma, and other sites. The metabolism kinetics of BDP and its active metabolite, beclomethasone 17-monopropionate (17-BMP), in human lung 1000 x g supernatant (HLu) and human plasma (HP) at 37 degrees C were compared. The effect of MgCl(2) and/or an NADPH-generating system on the decomposition of BDP and 17-BMP in HLu was also investigated. The concentrations of BDP and its metabolites were determined by HPLC with UV detection at 242 nm. Kinetics of decomposition of BDP and 17-BMP in HLu and HP were qualitatively and quantitatively different. The decomposition of BDP in HLu involved only hydrolysis. In comparison, three reactions are involved following incubation of BDP in HP; namely, hydrolysis, transesterification, and loss of hydrogen chloride. The hydrolysis of BDP and 17-BMP in HLu seem to be inhibited appreciably by MgCl(2) with the NADPH-generating system. Effective activation of BDP in HLu, in combination with transesterification of 17-BMP in HP, might favor a high ratio of local antiinflammatory activity to systemic side effects following inhalation of BDP.

From hydrofluoroalkane pressurized metered dose inhalers (pMDIs) and comparability with chlorofluorocarbon pMDIs

Fluticasone propionate pressurized metered dose inhalers (pMDIs) containing the hydrofluoroalkane (HFA) propellant, HFA 134a, are being developed to replace existing chlorofluorocarbon (CFC) pMDIs. This is part of the ongoing worldwide project to limit the damage to the earth's ozone layer. The in vivo performance and dose proportionality of fluticasone propionate HFA 134a pMDIs was examined for fluticasone propionate doses of 400, 1000 and 2000 microg using the 50, 125 and 250 microg strength pMDIs, respectively. The 125 and 250 microg strength HFA 134a pMDIs were compared with corresponding fluticasone propionate CFC pMDIs. Twenty-three healthy subjects participated in this single dose, randomized, five-way, cross-over study. Serial blood samples were collected 24 h post-dose to measure fluticasone propionate plasma concentrations. Twenty-four hour urinary-free cortisol was also measured before and after dosing. A dose-proportional increase in plasma fluticasone propionate concentrations was observed with increasing dose for the HFA 134a pMDIs. This was associated with a dose-related decrease in urinary cortisol excretion. Similar or lower fluticasone propionate systemic exposure was observed with the HFA 134a pMDIs compared to the corresponding CFC inhalers. The differences in systemic exposure observed for the HFA 134a and CFC pMDIs were too small to produce a differential effect on urinary cortisol excretion. Since fluticasone propionate has negligible oral bioavailability, the systemic exposure, which arises only from pulmonary absorption, is a measure of lung deposition. There was a good correlation between the in vitro fine particle mass produced by the different strengths and types of pMDI and the systemic exposure to fluticasone propionate. Therefore, the fluticasone propionate HFA 134a pMDI is an acceptable pharmaceutical alternative to the current CFC pMDI, producing similar lung deposition and no increase in systemic exposure at microgram equivalent doses.

Binding of glucocorticoids to human nasal tissue in vitro

BACKGROUND

Intranasal application of glucocorticoids is an efficacious treatment of allergic rhinitis and some cases of nonallergic rhinitis. However, no data on binding of glucocorticoids to nasal tissue are available. Pronounced binding of the compound to the target tissue is favorable as it might serve as a local deposit delivering the glucocorticoid to specific receptors and it slows down the efflux of the compound into systemic circulation.

METHODS

Human nasal tissue was incubated with fluticasone propionate, budesonide, flunisolide and beclomethasone-17-monopropionate. Kinetics of binding and redistribution of the tissue-bound fraction into human plasma was monitored.

RESULTS

Binding of glucocorticoids to human nasal tissue was fast and highest for the lipophilic fluticasone propionate, followed by beclomethasone-17-monopropionate. Also, highest concentrations of these lipophilic glucocorticoids remained in nasal tissue after equilibration of drug-saturated tissue with plasma.

CONCLUSIONS

Lipophilic compounds exhibit a high tissue binding and retention which is an important property of topically applied glucocorticoids. It is the basis for prolonged action and low concentration of the compound in systemic circulation.

Trace-level quantitation of iralukast in human plasma by microbore liquid chromatography/tandem mass spectrometry

Iralukast (CGP 45715A) is a potent peptido-leukotriene antagonist that is active in various in vitro and animal models for the treatment of asthma. An analytical challenge was to develop a sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with a lower limit of quantitation (LLOQ) of 10 pg/mL for the analysis of iralukast when administered at low doses during clinical trials. Several issues had to be addressed in order to devise a LC/MS/MS assay for the above compound. First, iralukast appeared to be light sensitive and unstable at room temperature under acidic conditions. Second, a LLOQ of 10 pg/mL was needed to support several clinical trials. Third, positive electrospray ionization of iralukast did not yield the necessary sensitivity required for studies in humans. Consequently, LC/MS/MS conditions were optimized for the negative ion mode of detection. Fourth, sample preparation steps proved to be critical to reduce the possibility of microbore HPLC column (50 mm x 1.0 mm i.d.) obstruction, chromatographic deterioration, and matrix-mediated electrospray ion suppression. While our validated method addressed the above challenges, its major drawback was limited sample throughput capability. Nonetheless, plasma concentration-time profiles for patients with moderate asthma after oral administration of 200, 500, 1000, and 5000 microgram/kg/day of iralukast were successfully obtained.

Plasma concentrations of disodium cromoglycate after various inhalation methods in healthy subjects

AIMS

To compare the plasma concentrations of disodium cromoglycate (DSCG) following various inhalation procedures in healthy volunteers.

METHODS

Nine healthy subjects inhaled 2 mg of aerosol, 20 mg of nebuliser solution only, 20 mg of nebuliser solution mixed with isotonic saline, or 20 mg of nebuliser solution mixed with saline and procaterol, a beta2-adenoceptor agonist, on separate occasions 2-3 weeks apart. Plasma concentrations of DSCG were determined by high-performance liquid chromatography (h.p.l.c.).

RESULTS

The peak plasma concentrations of DSCG were 1.5+/-0.7 (range 0.4-2.4) ng ml-1 in the aerosol group, 8.8+/-6.2 (range 5.3-19.9) ng ml-1 in the nebuliser solution only group, 17.2+/-16.3 (range 5.0-38.6) ng ml-1 in the nebuliser solution plus isotonic saline group, and 24.5+/-11. 9 (range 10.2-44.9) ng ml-1 in the nebuliser solution plus saline and procaterol group. Thus subjects who used the nebuliser had markedly higher plasma concentrations of DSCG than subjects who used the aerosol inhaler.

CONCLUSIONS

These findings may have important implications for the evaluation of inhalation treatment with DSCG for bronchial asthma.

Determination of the glucocorticoid fluticasone propionate in plasma by automated solid-phase extraction and liquid chromatography-tandem mass spectrometry

A sensitive, robust and high throughput mass spectrometry based method is described for the determination of the glucocorticoid fluticasone propionate in plasma. The method employs solid-phase extraction in 96 well microtitre plate format which has been automated by means of a custom built Zymark robotic system. The extracts are analysed by liquid chromatography-tandem mass spectrometry using thermally and pneumatically assisted electrospray ionisation and selected reaction monitoring. The method is both accurate and precise with both intra- and inter-assay precision (C.V.) of less than <6%. The method provides a lower limit of quantification of 20 pg/ml from 0.5 ml of human plasma, sufficient to monitor systemic concentrations of inhaled fluticasone propionate at therapeutic doses.

Determination of montelukast sodium in human plasma by column-switching high-performance liquid chromatography with fluorescence detection

MK-0476 (montelukast sodium) is a potent and selective cysteinyl leukotriene receptor antagonist that is being investigated in the treatment of asthma. A simple and sensitive method for the determination of MK-0476 in human plasma was developed using column-switching high-performance liquid chromatography (HPLC) with fluorescence detection. A plasma sample was injected directly onto the HPLC system consisting of a pre-column (Capcell pak MF) and an analytical column (Capcell pak C18) which were connected with a six-port switching valve. The column eluate was monitored with a fluorescence detector (excitation at 350 nm; emission at 400 nm). The calibration curve was linear in a concentration range of 1-500 ng ml(-1) for MK-0476 in human plasma. The intra-day coefficients of variation of all concentrations within the range was less than 9.2%, and the intra-day accuracy values were between 97.2 and 114.6%. This method was used to measure the plasma concentration of MK-0476 following oral administration of the drug in humans.