Towards clinical adherence monitoring of oral endocrine breast cancer therapies by LC-HRMS-method development, validation, comparison of four sample matrices, and proof of concept

Oral endocrine therapies (OET) for breast cancer treatment need to be taken over a long period of time and are associated with considerable side effects. Therefore, adherence to OET is an important issue and of high clinical significance for breast cancer patients' caregivers. We hypothesized that a new bioanalytical strategy based on liquid chromatography and high-resolution mass spectrometry might be suitable for unbiased adherence monitoring (AM) of OET. Four different biomatrices (plasma, urine, finger prick blood by volumetric absorptive microsampling (VAMS), oral fluid (OF)) were evaluated regarding their suitability for AM of the OET abemaciclib, anastrozole, exemestane, letrozole, palbociclib, ribociclib, tamoxifen, and endoxifen. An analytical method was developed and validated according to international recommendations. The analytical procedures were successfully validated in all sample matrices for most analytes, even meeting requirements for therapeutic drug monitoring. Chromatographic separation of analytes was achieved in less than 10 min and limits of quantification ranged from 1 to 1000 ng/mL. The analysis of 25 matching patient samples showed that AM of OET is possible using all four matrices with the exception of, e.g., letrozole and exemestane in OF. We were able to show that unbiased bioanalytical AM of OET was possible using different biomatrices with distinct restrictions. Sample collection of VAMS was difficult in most cases due to circulatory restraints and peripheral neuropathy in fingers and OF sampling was hampered by dry mouth syndrome in some cases. Although parent compounds could be detected in most of the urine samples, metabolites should be included when analyzing urine or OF. Plasma is currently the most suitable matrix due to available reference concentrations.

Validation of a rapid and sensitive LC-MS/MS method for determination of exemestane and its metabolites, 17β-hydroxyexemestane and 17β-hydroxyexemestane-17-O-β-D-glucuronide: application to human pharmacokinetics study

A novel, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the evaluation of exemestane pharmacokinetics and its metabolites, 17β-dihydroexemestane (active metabolite) and 17β-dihydroexemestane-17-O-β-D-glucuronide (inactive metabolite) in human plasma. Their respective D3 isotopes were used as internal standards. Chromatographic separation of analytes was achieved using Thermo Fisher BDS Hypersil C18 analytic HPLC column (100 × 2.1 mm, 5 μm). The mobile phase was delivered at a rate of 0.5 mL/min by gradient elution with 0.1 % aqueous formic acid and acetonitrile. The column effluents were detected by API 4000 triple quadrupole mass spectrometer using electrospray ionisation (ESI) and monitored by multiple reaction monitoring (MRM) in positive mode. Mass transitions 297 > 121 m/z, 300 > 121 m/z, 299 > 135 m/z, 302 > 135 m/z, 475 > 281 m/z, and 478 > 284 m/z were monitored for exemestane, exemestane-d3, 17β-dihydroexemestane, 17β-dihydroexemestane-d3, 17β-dihydroexemestane-17-O-β-D-glucuronide, and 17β-dihydroexemestane-17-O-β-D-glucuronide-d3 respectively. The assay demonstrated linear ranges of 0.4 – 40.0 ng/mL, for exemestane; and 0.2 – 15.0 ng/mL, for 17β-dihydroexemestane and 17β-dihydroexemestane-17-O-β-D-glucuronide, with coefficient of determination (r²) of > 0.998. The precision (coefficient of variation) were ≤10.7%, 7.7% and 9.5% and the accuracies ranged from 88.8 to 103.1% for exemestane, 98.5 to 106.1% for 17β-dihydroexemestane and 92.0 to 103.2% for 17β-dihydroexemestane-17-O-β-D-glucuronide. The method was successfully applied to a pharmacokinetics/dynamics study in breast cancer patients receiving exemestane 25mg daily orally. For a representative patient, 20.7% of exemestane in plasma was converted into 17β-dihydroexemestane and 29.0% of 17β-dihydroexemestane was inactivated as 17β-dihydroexemestane-17-O-β-D-glucuronide 24 hours after ingestion of exemestane, suggesting that altered 17-dihydroexemestane glucuronidation may play an important role in determining effect of exemestane against breast cancer cells.

Intranasal Loteprednol Etabonate in Healthy Male Subjects: Pharmacokinetics and Effects on Endogenous Cortisol

Loteprednol etabonate (LE) is a glucocorticoid soft drug that is currently in development for intranasal use. The main objectives of this study were to examine the pharmacokinetics and potential effects on systemic cortisol of two intranasal suspension formulations of LE and to compare these findings with placebo and fluticasone propionate (FP, Flonase) control treatments. In this randomized, double-blind (except for FP), parallel-group study (n = 8/group), all subjects received for 14 days once daily in the morning two puffs of the following nasal spray formulations into each nostril: LE 0.1% (400 microg/day), LE 0.2% (800 microg/day), FP 0.05% (200 microg/day), and placebo. Drug trough levels were determined on days 1, 5, 12, 13, and 14, and a full pharmacokinetic profile was established on day 14, and 24-hour serum cortisol profiles were assessed prior to treatment (i.e., at baseline) and after the last dose. All subjects completed the protocol without treatment-emergent adverse findings. All formulations were rapidly absorbed (t(max) less than 1 h). The rather short mean terminal half-lives of 2.2 +/- 1.5 hours and 1.8 +/- 1.0 hours for LE 400 microg and LE 800 microg, respectively, and 4.2 +/- 1.8 hours for the 200-microg FP treatment explained the lack of any accumulation. Mean peak concentrations (C(max)) were 139 +/- 57 pg/mL with LE 400 microg and 164 +/- 54 pg/mL with LE 800 microg and thus fairly independent from dose. The 200-microg FP treatment resulted in a C(max) of only 15.5 +/- 5.9 pg/mL. Mean measured AUC(0-t) values (193 +/- 87 pg/h/mL(-1), 300 +/- 183 pg/h/mL(-1), and 40 +/- 34 pg/h/mL(-1) for LE 400 microg, LE 800 microg, and FP 200 microg, respectively) showed high variability and suggested nonlinear pharmacokinetics for the LE formulations, indicative of a less complete systemic uptake of LE from the 0.2% concentration. None of the treatments (LE 400 microg, LE 800 microg, and FP 200 microg) showed evidence for serum cortisol suppression when compared with placebo, respectively. The uptake and systemic exposure appears less complete from the 0.2% LE concentration, which principally favors this formulation for further clinical development.

Detection, synthesis and characterization of metabolites of steroid hormones conjugated with cysteine

The occurrence of several polyunsaturated testosterone related compounds (including 4,6-androstadien-3,17-dione and 4,6-androstadien-17β-ol-3-one) in urine after alkaline treatment of the sample has been recently reported. Although several experiments seem to indicate that they are testosterone metabolites, their origin is still unknown. In this study, it is demonstrated that these metabolites are produced from the degradation of cysteine conjugates. Several testosterone metabolites conjugated with cysteine have been synthesized and characterized by NMR techniques. Their detection in human urine has been performed by LC-MS/MS. The acquisition of several transitions in the SRM mode and the comparison between ion ratios and retention times allowed for the unequivocal confirmation of the presence of cysteine conjugates in urine. The analysis of urine samples collected after testosterone administration confirmed that synthesized cysteine conjugates are testosterone metabolites. The fact that these conjugates result in polyunsaturated compounds in urine after alkaline treatment was demonstrated by fraction collection and alkaline treatment of each fraction. Besides, the presence of these metabolites was also confirmed in human plasma. The formation of these metabolites implies an unreported metabolic biotransformation: 6,7-dehydrogenation as phase I metabolism followed by conjugation with glutathione and subsequent transformation to cysteine conjugates. Finally, the existence of similar metabolites for cortisol and progesterone was also confirmed by LC-MS/MS indicating that the presented metabolic pathway is not exclusively active in androgens, but common to progestagens and glucocorticoids.

A liquid chromatography-tandem mass spectrometry method for the simultaneous determination of exemestane and its metabolite 17-dihydroexemestane in human plasma

A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantitation of exemestane (Exe) and its main metabolite 17-dihydroexemestane (DhExe) in human plasma. The analytes were extracted by protein precipitation with acetonitrile, containing stable 13C-labelled Exe (13C3-Exe) as internal standard, and measured by LC-MS/MS. The best chromatographic separation of the analytes from the interferences was achieved by using a Phenyl column operating under isocratic regime conditions. The total chromatographic runtime was 5.0 min and the elution of Exe and DhExe occurred at 2.5 min and 2.9 min, respectively. Quantitation was performed by employing the positive electrospray ionization (ESI) technique and multiple reaction monitoring mode (MRM). The monitored precursor to product-ion transitions for Exe, DhExe and 13C3-Exe internal standard were m/z 297.0 --> 120.8, m/z 299.1 --> 134.9 and m/z 300.0 --> 123.2, respectively. The lower limit of quantitation (LLOQ) was 0.1 ng/ml for DhExe and 0.2 ng/ml for Exe. The method was linear up to 36-51 ng/ml with r2 > or = 0.998. The intra- and inter-assay precision were < or = 7.7% and 5.1% for Exe and < or = 8.1 and 4.9% for DhExe while deviations from nominal values were in the 1.5-13.2% and - 9.0-5.8% ranges for Exe and DhExe, respectively. The analytical method resulted robust and suitable for pharmacokinetic monitoring of Exe and its main metabolite during adjuvant therapy in patients with breast cancer.

Integrated analytical approach in veal calves administered the anabolic androgenic steroids boldenone and boldione: urine and plasma kinetic profile and changes in plasma protein expression

Surveillance of illegal use of steroids hormones in cattle breeding is a key issue to preserve human health. To this purpose, an integrated approach has been developed for the analysis of plasma and urine from calves treated orally with a single dose of a combination of the androgenic steroids boldenone and boldione. A quantitative estimation of steroid hormones was obtained by LC-APCI-Q-MS/MS analysis of plasma and urine samples obtained at various times up to 36 and 24 h after treatment, respectively. These experiments demonstrated that boldione was never found, while boldenone alpha- and beta-epimers were detected in plasma and urine only within 2 and 24 h after drug administration, respectively. Parallel proteomic analysis of plasma samples was obtained by combined 2-DE, MALDI-TOF-MS and muLC-ESI-IT-MS/MS procedures. A specific protein, poorly represented in normal plasma samples collected before treatment, was found upregulated even 36 h after hormone treatment. Extensive mass mapping experiments proved this component as an N-terminal truncated form of apolipoprotein A1 (ApoA1), a protein involved in cholesterol transport. The expression profile of ApoA1 analysed by Western blot analysis confirmed a significant and time dependent increase of this ApoA1 fragment. Then, provided that further experiments performed with a growth-promoting schedule will confirm these preliminary findings, truncated ApoA1 may be proposed as a candidate biomarker for steroid boldenone and possibly other anabolic androgens misuse in cattle veal calves, when no traces of hormones are detectable in plasma or urine.

Plasma concentrations of fluticasone propionate and budesonide following inhalation: effect of induced bronchoconstriction

AIMS

To determine whether and to what extent bronchoconstriction affects plasma concentrations of fluticasone and budesonide following inhalation.

METHODS

Twenty people with mild asthma inhaled 1000 microg fluticasone (Accuhaler) plus 800 microg budesonide (Turbohaler) on two visits. On one occasion, prior to drug inhalation, FEV(1) was decreased by at least 25% using inhaled methacholine. Plasma drug concentrations were measured for each drug over 5 h and area under the plasma concentration-time curve (AUC(0,5 h)) compared between visits.

RESULTS

The mean difference in FEV(1) prior to drug inhalation on the 2 days was 33%. AUC(0,5 h) values for fluticasone and budesonide were lower by a median of 60% (IQR 36-75) and 29% (IQR 2-44), respectively, when administered following bronchoconstriction; the reduction was greater for fluticasone than for budesonide, P = 0.007.

CONCLUSIONS

The lower plasma concentrations of fluticasone and, to a lesser extent, budesonide seen when the drugs were inhaled following induced bronchoconstriction, is likely to reflect variations that will occur with fluctuations in airway caliber in asthma.

Absolute Bioavailability of Intranasal Fluticasone Furoate in Healthy Subjects

BACKGROUND

Fluticasone furoate (drug code GW685698) is an enhanced-affinity glucocorticoid that has been developed for the treatment of allergic rhinitis.

OBJECTIVES

The objectives of this study were to estimate the absolute bioavailability of fluticasone furoate nasal spray and to describe the intranasal (IN) and IV pharmacokinetics of fluticasone furoate in healthy subjects.

METHODS

This was a single-center, randomized, open label, 2-period crossover study. Healthy male and female subjects were randomized to receive supra-therapeutic doses of fluticasone furoate 880 microg IN qSh for 10 doses in 1 treatment period, and a single IV dose of 250 pg fluticasone furoate given as an infusion over 20 minutes in the other treatment period. Each treatment period was separated by a 4- to 5-day washout period. Blood sampling was carried out over 8 hours following the final IN dose and 24 hours following the IV dose to determine plasma fluticasone furoate concentrations. Plasma samples were analyzed for fluticasone furoate using online solid-phase extraction with high-performance liquid chromatography with tandem mass-spectrometric detection. The lower limit of quantification was 10 pg/mL. The sample size was based primarily on logistical considerations. Sample-size sensitivity was assessed by estimating the 90% CI for the absolute bioavailability of IN fluticasone furoate, based on different estimated bioavailabilities and within-subject SDs. The following pharmacokinetic parameters were derived: IN administration: AUC from time 0 to the end of the dosing interval (AUC(0-tau)), AUC(0-t), C(max), and T(max); IV administration: AUC(0-infinity), AUC(0-t), t(1/2), C(max), T(max), total systemic clearance, and volume of distribution at steady state.

RESULTS

A total of 16 subjects were included in the study. Their mean age was 27.8 years (range, 19-45 years), and their mean body weight was 72.84 kg (range, 55.3-97.2 kg). The geometric mean AUC(0-tau) for 880 microg IN was 74.9 pg x mL/h and geometric mean AUC(0-infinity) for 250 microg IV was 4259 pg x mL/h. The geometric mean of the absolute bioavailability of fluticasone furoate nasal spray in these healthy subjects was 0.50% (90% CI, 0.34%-0.74%). The administration of large doses by the IN route did not elicit clinical concern. Three (19%) of 16 subjects reported adverse events (AEs) during the IN administration period, with 2 subjects experiencing dizziness and 1, toothache. Five (31%) subjects reported AEs during the IV administration period, with 3 subjects experiencing infusion-site or IV catheter-related events; 1 subject, dizziness; and 1 subject, headache.

CONCLUSIONS

The geometric mean of the absolute bioavailability of fluticasone furoate 880 microg IN qSh for 10 doses in these healthy subjects was low--0.50%.

Efficacy and safety of fluticasone propionate hydrofluoroalkane inhalation aerosol in pre-school-age children with asthma: a randomized, double-blind, placebo-controlled study

OBJECTIVE

To evaluate the efficacy and tolerability of fluticasone propionate (FP) hydrofluoroalkane (HFA) in children age 1 to < 4 years with asthma.

STUDY DESIGN

Children were assigned (2:1) to receive FP HFA 88 mug (n = 239) or placebo HFA (n = 120) twice daily through a metered-dose inhaler with a valved holding chamber and attached facemask for 12 weeks. The primary efficacy measure was mean percent change from baseline to endpoint in 24-hour daily (composite of daytime and nighttime) asthma symptom scores.

RESULTS

The FP-treated children had significantly greater (P < or = .05) reductions in 24-hour daily asthma symptom scores (-53.9% vs -44.1%) and nighttime symptom scores over the entire treatment period compared with the placebo group. Daytime asthma symptom scores and albuterol use were slightly more decreased with FP than with placebo; however, the differences were not statistically significant. Increases in the percentage of symptom-free days were comparable. The percentage of patients who experienced at least 1 adverse event was similar in the 2 groups. Baseline median urinary cortisol excretion values were comparable between the groups, and there was little change from baseline at endpoint. FP plasma concentrations demonstrated that systemic exposure was low.

CONCLUSIONS

FP HFA 88 mug twice daily was effective and well tolerated in pre-school-age children with asthma.

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.

Short polystyrene monolith-fritted micro-liquid chromatography columns for rapid isocratic analysis of pharmaceuticals direct from plasma

The manufacture of micro-HPLC columns with combined stationary phases, a body of 3.5-microm XTerra-C18 particles, and poly(styrene-divinylbenzene) (PS-DVB) frits is described in detail. The efficiency of the columns was assessed by rapid separation of neutral and acid compound mixtures. Direct analysis of some pharmaceuticals in plasma resulted in lower limits of detection (LOD) for salmeterol xinofate of 12.5 nanograms on-column.

Fluticasone propionate hydrofluoroalkane inhalation aerosol in patients receiving inhaled corticosteroids

BACKGROUND

Inhaled corticosteroids (ICSs) delivered by metered-dose inhalers that contain chlorofluorocarbon propellants are being discontinued because of the harmful effects of chlorofluorocarbon on the ozone layer. Therefore, some metered-dose inhaler products are being reformulated with "ozone-friendly" hydrofluoroalkane propellants.

OBJECTIVE

To evaluate treatment with fluticasone propionate hydrofluoroalkane inhalation aerosol, 88, 220, and 440 microg twice daily, vs placebo in patients with asthma receiving an ICS.

METHODS

Randomized, double-blind, parallel-group, 12-week study.

RESULTS

Mean morning predose percent predicted forced expiratory volume in 1 second increased by 2.2%, 3.2%, and 4.6% in the fluticasone propionate, 88-, 220-, and 440-microg twice-daily, groups, respectively, compared with an 8.3% decrease for placebo (P < .001 vs placebo for all groups). Secondary pulmonary function end points and asthma symptoms showed similar improvements compared with placebo. Discontinuation from the study due to lack of efficacy was 50% in the placebo group and 11%, 10%, and 6% in the fluticasone propionate, 88-, 220-, and 440-microg twice-daily, groups, respectively. At week 12, the probability of remaining in the study was 0.89, 0.90, and 0.94 for the fluticasone propionate, 88-, 220-, and 440-microg twice-daily, groups, respectively, vs 0.45 for the placebo group (P < .001 for all). Changes in 24-hour urinary cortisol excretion rates were similar among treatment groups.

CONCLUSIONS

Fluticasone propionate hydrofluoroalkane, previously shown to be a clinically suitable alternative to fluticasone propionate chlorofluorocarbon, was effective and well tolerated. The ability to switch from fluticasone propionate chlorofluorocarbon and other chlorofluorocarbon-containing ICSs to fluticasone propionate hydrofluoroalkane without sacrificing asthma control or tolerability will facilitate a smooth transition to this nonchlorofluorocarbon-containing medicinal.

Fluticasone propionate plasma concentration and systemic effect: effect of delivery device and duration of administration

BACKGROUND

Inhaled corticosteroids are the preferred therapy in persistent asthma. Dry powder inhalers (DPIs) generate a larger particle size compared with metered-dose inhalers (MDIs), which affects pulmonary deposition, bioavailability, and subsequent systemic effects of fluticasone propionate (fluticasone).

OBJECTIVE

To examine the relationship of fluticasone pharmacokinetics and cortisol suppression for 2 fluticasone formulations (DPI and MDI) administered in adults over 1-week and 6-week treatment periods.

METHODS

Two previous studies conducted in adults by the Asthma Clinical Research Network examined relative efficacy and systemic effect of fluticasone from MDI and DPI. Sample sets (n=33) were analyzed for fluticasone after administration of 352 microg from the MDI, and 400 microg from the DPI formulation, twice daily, after a 1-week treatment period. The second study's sample sets (n=9) were analyzed for fluticasone after 6 weeks therapy at 352 microg twice daily from the MDI formulation, allowing achievement of steady state.

RESULTS

ANOVA revealed a significant trend of increasing fluticasone area under the curve from 0 to time t (AUC(0-->t)) when comparing DPI with MDI for 1 week with MDI for 6 weeks (P<.0001). Similarly, ANOVA revealed increasing cortisol suppression between these groups (P=.007). Linear regression demonstrated that increasing fluticasone AUC(0-->t) was significantly correlated with cortisol suppression (P<.0001; r(2)=0.41). MDI for 6 weeks showed increasing fluticasone AUC (P=.0008, t test) compared with MDI for 1 week, suggesting accumulation.

CONCLUSION

Fluticasone plasma concentrations are significantly greater after MDI compared with DPI, and cortisol suppression is associated with fluticasone plasma concentrations. Accumulation of fluticasone concentrations suggests that time to steady state exceeds 1 week of treatment with MDI.

Interpretation of absorption rate data for inhaled fluticasone propionate obtained in compartmental pharmacokinetic modeling

OBJECTIVE

Reports characterizing the pharmacokinetics of inhaled fluticasone propionate (FP) using compartmental approaches have suggested that the absorption of FP into the systemic circulation is rapid with a half-life of approximately 10 min. We believe that this is a classical case of misassignment of the pharmacokinetic parameter estimates, a problem often encountered while modeling pharmacokinetic data. The objective of this study was to illustrate and analyze this problem using actual blood level data of FP obtained in 14 healthy subjects.

MATERIALS AND METHODS

Serum concentration-time data of FP were obtained from a double-blind, randomized study involving single and multiple twice-daily inhalations of 500 microg via a dry powder device, Diskus. The profiles were fitted using one- and two-compartment pharmacokinetic models with first order absorption. Various permutations of the resulting exponential rate constants were analyzed to determine the combination that was most consistent with the underlying physical process.

RESULTS

The two-compartment body model with first order absorption gave excellent fits for the observed FP concentrations after both single and multiple dosing. Even though peak levels were reached relatively early (30 - 90 min) after inhalation, the combination that most appropriately described the underlying process was alpha > Ka > beta, i.e. slow absorption, rapid distribution and slower elimination kinetics. The absorption, distribution and elimination half-lives resulted to be 3.8 h, 9.9 min and 13.6 h, respectively, consistent with the high lipophilicity and sustained dissolution characteristics observed in vitro.

CONCLUSIONS

Analysis of FP pharmacokinetics after inhalation represents a classical case of potential misassignment of the exponential rate constants, which if ignored, could lead to erroneous interpretations regarding the underlying process. The study also elucidates the pitfall of using t(max) to calculate absorption rate.

Molecular pharmacology and antitumor activity of PX-866, a novel inhibitor of phosphoinositide-3-kinase signaling

We have developed biologically stable semisynthetic viridins as inhibitors of phosphoinositide (PtdIns)-3-kinases. The most active compound was PX-866 (acetic acid (1S,4E,10R,11R,13S,14R)-[4-diallylaminomethylene-6-hydroxy-1-methoxymethyl-10,13-dimethyl-3,7,17-trioxo-1,3,4,7,10,11,12,13,14,15,16,17-dodecahydro-2-oxa-cyclopenta[a]phenanthren-11-yl ester), which inhibited purified PtdIns-3-kinase with an IC50 of 0.1 nmol/L and PtdIns-3-kinase signaling measured by phospho-Ser473-Akt levels in HT-29 colon cancer cells with an IC50 of 20 nmol/L. PX-866 administered to mice at 10 mg/kg inhibited phospho-Ser473-Akt in HT-29 colon tumor xenografts up to 80% with recovery taking >48 hours after p.o. administration but more rapidly after i.v. or i.p. administration. PX-866 was eliminated from mouse plasma with a half-life of 18 minutes and a clearance of 360 mL/min/kg following i.v. administration and, when administered i.p. or p.o., showed first-pass metabolism with sequential N-deallylation. Synthetic standards of the N-deallylated metabolites of PX-866 inhibited PtdIns-3-kinase at low nanomolar per liter concentrations. PX-866 exhibited in vivo antitumor activity against s.c. OvCar-3 human ovarian cancer and A-549 human lung cancer xenografts in immunodeficient mice with log cell kills up to 1.2. PX-866 also increased the antitumor activity of cisplatin against A-549 xenografts and radiation treatment against OvCar-3 xenografts. The results show that PX-866 is a biologically stable broad-spectrum PtdIns-3-kinase inhibitor with good pharmacokinetics that causes prolonged inhibition of PtdIns-3-kinase signaling in human tumor xenografts. PX-866 exhibits single agent in vivo antitumor activity and increases the antitumor effects of cisplatin and radiation treatment.

Effect of fluticasone propionate nasal spray on bioavailability of intranasal hydromorphone hydrochloride in patients with allergic rhinitis

STUDY OBJECTIVE

To investigate the effect of the nasal corticosteroid fluticasone propionate on the bioavailability and pharmacokinetics of single-dose intranasal hydromorphone hydrochloride in patients with allergic rhinitis.

DESIGN

Randomized, three-way, crossover pharmacokinetic study.

SETTING

University clinical research unit.

PATIENTS

Twelve patients with allergic rhinitis.

INTERVENTION

Hydromorphone hydrochloride 2.0 mg was administered by intravenous infusion (treatment A), intranasal spray without allergic rhinitis treatment (treatment B), and intranasal spray after 6 days of fluticasone propionate (treatment C). Blood samples were collected serially from 0-16 hours.

MEASUREMENTS AND MAIN RESULTS

Pharmacokinetic parameters were determined by noncompartmental methods. An analysis of variance (ANOVA) model was used for statistical analysis. Mean (% coefficient of variation) absolute bioavailability of intranasal hydromorphone was 51.9% (28.2) and 46.9% (30.3) in patients with allergic rhinitis with and without treatment with fluticasone propionate, respectively. Mean maximum concentration (Cmax) values were 3.02 and 3.56 ng/ml, respectively. No statistical differences in Cmax and area under the concentration versus time curve were detected between intranasal treatments. Bioavailability values for both intranasal treatments were lower than those in healthy volunteers (57%). Median time to Cmax (Tmax) values were significantly different (p=0.02) for treatments B and C (15 and 30 min, respectively) using rank-transformed Tmax for ANOVA. Adverse effects were consistent with known effects of hydromorphone administered by other routes, with the exception of bad taste after intranasal administration.

CONCLUSION

Hydromorphone was rapidly absorbed after nasal administration, with maximum concentrations occurring for most subjects within 30 minutes. Allergic rhinitis may affect pain management strategies for intranasal hydromorphone, with a delay in onset of action for patients treated with fluticasone propionate.

A novel specific bioassay for the determination of glucocorticoid bioavailability in human serum

OBJECTIVE

Some patients develop side-effects even on relatively low doses of topically administered glucocorticoids (GCs), while others appear to be less sensitive to GCs. We have developed and validated a bioassay which can measure glucocorticoid bioavailability directly from small amounts of human serum to help elucidate underlying mechanisms.

METHODS

We have stably transfected the human embryonic kidney cell line HEK293 with a plasmid expressing the glucocorticoid receptor, and a plasmid containing the luciferase gene preceded by three concatenated steroid response elements, bringing luciferase expression under control of the liganded glucocorticoid receptor.

RESULTS

The assay, with an intra- and interassay coefficient of variance (CV) better than 10%, showed the expected difference in potency between different GCs (fluticasone propionate > budesonide > dexamethasone > hydrocortisone). No cross-reactivity was detected with other steroid hormones such as progesterone, testosterone and oestradiol. The bioassay easily detects the rise and subsequent fall of bioavailable GCs in human serum following ingestion of only 0.5 mg dexamethasone, and clearly reflects the diurnal cortisol rhythm. Moreover, systemic availability following inhalation of 2 x 250 micro g fluticasone propionate using a pressure dose inhaler could be demonstrated.

CONCLUSIONS

This assay can be used to determine levels of bioavailable GCs in serum, both endogenous and administered, and thus may help in optimizing treatment regimens. The small amount of serum needed to perform an analysis makes this assay applicable even to infants.

Pharmacokinetics and systemic effects of inhaled fluticasone propionate in chronic obstructive pulmonary disease

AIMS

We have previously shown that the systemic exposure to inhaled fluticasone propionate (FP) is reduced in asthmatics compared with healthy subjects. We have now compared its pharmacokinetics in patients suffering from chronic obstructive pulmonary disease (COPD, n = 10) and matched healthy subjects (n = 13).

METHODS

A double-blind, randomized, cross-over study design was used. Plasma FP and serum cortisol were measured for 12 h after subjects received hydrofluoroalkane FP 1000 microg day-1 inhaled (via an MDI and spacer) for 7 days and following a single 1000- microg intravenous dose.

RESULTS

The pharmacokinetics differed in the two groups. After inhalation, geometric least square means were significantly lower in the COPD group for the plasma AUC (1961 vs 2996 pg ml-1 h-1 for COPD and controls, respectively; P = 0.03) and the Cmax (235 vs 421 pg ml-1 for COPD and controls, respectively; P = 0.03). Suppression of serum cortisol concentration over 12 h was greater in healthy controls. Weighted mean serum cortisol concentration (nmol l-1) in healthy subjects and COPD was 93 and 170, respectively (P = 0.03). The intravenous pharmacokinetic parameters for FP were comparable in the two groups, resulting in similar suppression of serum cortisol.

CONCLUSIONS

We conclude that the altered pharmacokinetics of inhaled fluticasone propionate in COPD caused less hypothalamic-pituitary-adrenal suppression than in healthy controls. This is further evidence that the systemic effects of inhaled corticosteroids should be assessed in patients and not healthy subjects.

Plasma concentrations of fluticasone propionate and budesonide following inhalation from dry powder inhalers by healthy and asthmatic subjects

BACKGROUND

All currently available inhaled corticosteroids reach the systemic circulation and have the potential to produce adverse effects with long term use. This risk is often assessed by measuring the effect of different inhaled corticosteroids on the hypothalamic-pituitary-adrenal (HPA) axis in healthy subjects. Absorption of fluticasone propionate and its effects on the HPA axis are greater in healthy subjects than in subjects with moderately severe asthma, but we have failed to show any difference in morning budesonide plasma levels or systemic effects between healthy and asthmatic subjects following inhalation of budesonide. To provide more information on the absorption of fluticasone propionate and budesonide, we have compared the plasma levels of both drugs over 8 hours in healthy and asthmatic subjects.

METHODS

The area under the plasma concentration-time curves (AUC) and the maximum concentration (Cmax) of fluticasone propionate and budesonide after a single inhaled dose of each drug were compared in 12 healthy control subjects and 12 subjects with moderately severe asthma.

RESULTS

Peak plasma levels of budesonide occurred much earlier and were approximately 20-fold higher than those of fluticasone propionate in both healthy and asthmatic subjects. The AUC and Cmax for fluticasone propionate were lower by 307 (95% CI 62 to 522) pg/ml/h or 43% (p=0.02) and 52 (95% CI -11 to 115) pg/ml or 39% (p=0.1) in subjects with asthma compared with healthy control subjects. In contrast, the AUC and Cmax for budesonide were almost identical between the two groups (mean differences 826 (95% CI -1493 to 3143) pg/ml/h (p=0.5) and 157 (95% CI -1026 to 1339) pg/ml (p=0.8).

CONCLUSIONS

Following inhalation, healthy subjects have higher plasma levels of fluticasone propionate than subjects with asthma whereas budesonide plasma levels are similar in the two groups of subjects. Comparing the systemic effects of budesonide and fluticasone propionate in healthy subjects is unlikely to be relevant to subjects with asthma.

Differences in inhaled fluticasone bioavailability between holding chambers in children with asthma

STUDY OBJECTIVE

To determine if differences between holding chambers in previous in vitro aerosol studies would agree with the bioavailability of inhaled fluticasone propionate between the same holding chambers in children with asthma.

DESIGN

Double-blind, randomized, crossover study

SETTING

University of Florida Clinical Research Center.

PATIENTS

Eight children (aged 5-9 yrs) with stable asthma.

INTERVENTION

Under observation, the children inhaled two 110-microg puffs of fluticasone twice/day through the InspirEase or E-Z Spacer holding chamber.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected at baseline and then at 0.5, 1, 1.5, 2, 4, and 6 hours after the last dose of fluticasone. Primary outcome measures were peak fluticasone steady-state plasma concentration (Cmax) and area under the fluticasone plasma concentration-time curve from 0-6 hours (AUC0-6). The fluticasone plasma concentrations were determined by high-performance liquid chromatography-mass spectrometric assay. Mean +/- SD Cmax from InspirEase (245 +/- 77 pg/ml) was 18% higher than that after E-Z Spacer (199 +/- 58 pg/ml, p < 0.05). Mean +/- SD AUC0-6 from InspirEase (1103 +/- 305 pg x hr(-1) x ml(-1) was 22% higher than that delivered from E-Z Spacer (863 +/- 258 pg x hr(-1) x ml(-1), p = 0.06).

CONCLUSION

Differences in inhaled fluticasone bioavailability between these holding chambers in children with asthma corroborate differences reported in earlier in vitro aerosol studies.

Pharmacokinetics and systemic activity of fluticasone via Diskus and pMDI, and of budesonide via Turbuhaler

AIMS

To determine the basal pharmacokinetics, lung uptake and plasma cortisol suppression for two commonly prescribed inhaled corticosteroids.

METHODS

Twenty-one subjects (13 healthy and 8 mild asthmatic patients) received fluticasone propionate via a chlorofluorocarbon-propelled pressurized metered-dose inhaler (pMDI) (healthy subjects only) and Diskus and budesonide via Turbuhaler, 1000 microg twice daily for 7 days. Intravenous doses (200 microg) of both compounds were used as references. Plasma concentrations of fluticasone and budesonide were determined during 48 h by liquid chromatography plus tandem mass spectrometry (LC-MS-MS). Plasma concentrations of cortisol were determined by LC-MS every second hour for 24 h at baseline, and following each treatment.

RESULTS

The volume of distribution was found to be larger and the elimination half-life and mean absorption time longer for fluticasone than for budesonide. The systemic availability of budesonide via Turbuhaler (39%) was significantly higher than that of fluticasone via Diskus (13%) (ratio 3.0 [2.5, 3.6] with 95% confidence interval [CI]), and via pMDI (21%) (ratio 1.8 [1.3, 2.3]). In addition, at steady state the systemic availability of fluticasone via pMDI was significantly higher than via Diskus (ratio 1.6 [1.1, 2.2]). The lung deposition of budesonide via Turbuhaler was 2.2-fold [1.7, 2.9] higher than that of fluticasone pMDI and 3.4-fold [2.8, 4.0] higher than that of fluticasone Diskus. In addition, the lung deposition of fluticasone via pMDI was 1.5-fold [1.1, 2.9] higher than that via the Diskus inhaler. Plasma cortisol (24 h) was significantly reduced vs baseline for all three treatments. The cortisol concentration vs baseline was 12% for fluticasone pMDI, which was significantly lower (ratio 0.32 [0.24, 0.42]) than that for fluticasone Diskus (39%), and for budesonide Turbuhaler (46%) (ratio 0.27 [0.21, 0.37]). The plasma cortisol concentration did not differ significantly between treatments with fluticasone Diskus and budesonide Turbuhaler (ratio 0.87 [0.65; 1.15]).

CONCLUSIONS

Budesonide and fluticasone differ in their pharmacokinetic properties in that although clearance is the same, the rate of uptake and elimination is slower for fluticasone. Despite a significantly higher pulmonary availability of budesonide via Turbuhaler, the plasma cortisol suppression is less than that of fluticasone via pMDI and similar to that of fluticasone via Diskus. There is no indication of any difference between healthy subjects and mild asthmatic patients in the pharmacokinetics and plasma cortisol suppression of fluticasone and budesonide.

Quantification of epimeric budesonide and fluticasone propionate in human plasma by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

A highly sensitive and selective liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry assay was developed and validated for simultaneous determination of epimeric budesonide (BUD) and fluticasone propionate (FP) in plasma. The drugs were isolated from human plasma using C18 solid-phase extraction cartridges, and epimeric BUD was acetylated with a mixture of 12.5% acetic anhydride and 12.5% triethylamine in acetonitrile to form the 21-acetyl derivatives following the solid-phase extraction. Deuterium-labelled BUD acetate with an isotopic purity >99% was synthesized and used as the internal standard. The assay was linear over the ranges 0.05-10.0 ng/ml for epimeric BUD, and 0.02-4.0 ng/ml for FP. The inter- and intra-day relative standard deviations were <14.3% in the assay concentration range.

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.

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.

LC-MS-MS determination of exemestane in human plasma with heated nebulizer interface following solid-phase extraction in the 96 well plate format

A sensitive, specific and rapid analytical method for the quantitation of exemestane (EXE) in human plasma has been developed. EXE, 6-methylen-androsta-1,4-diene-3,17-dione, is an orally active irreversible steroidal aromatase inhibitor used for the therapy of metastatic postmenopausal breast cancer, with estrogen-dependent pathological conditions. The method involves extraction of EXE from human plasma by solid phase extraction using C2 endcapped sorbent in the 96 well plate format (50 mg/2 ml). After conditioning of the sorbent with 1 ml of acetonitrile (x2) the plates were rinsed with 1 ml of water (x2). The prepared samples (0.5 ml plasma, spiked with [13C3] EXE as internal standard (IS) and diluted with 0.5 ml water) were loaded and drawn through the plate with a minimum of vacuum. The plates were then washed with 1 ml acetonitrile:water (10:90) followed by a drying step for 30 min at full vacuum. Elution was by 0.15 ml of 0.1% trifluoracetic acid in acetonitrile (x2) under a minimum of vacuum. Aliquots of 80 microl were finally injected into the LC-MS-MS system. A Zorbax SB C8 column (4.6 x 150 mm, 5 microm) was used to perform the chromatographic separation; the mobile phase was 100% acetonitrile. MS detection used the heated nebulizer interface, with multiple reaction monitoring (MRM) (297-->121 m/z for EXE and 300-->123 m/z for IS) operated in positive ion mode. A weighed linear regression analysis (weighing factor 1/x2) was used to calculate EXE concentration in standard and unknown samples. The method was fully validated in the concentration range 0.05-25 ng ml(-1).

A sensitive LC-MS/MS method for the quantification of fluticasone propionate in human plasma

A sensitive and selective LC-(APCI) MS/MS method capable of quantifying fluticasone propionate (FP) at levels down to 10 pg ml(-1) in human plasma is reported. The method was validated over a linear range from 10 to 1000 pg ml(-1) using a previously published solid-phase extraction procedure with a 13C3-labeled internal standard. The inter and intra batch precision (coefficient of variation) and accuracy (% bias) of the quality controls samples (20, 25, 50, 100, 200, 500 and 1000 pg ml(-1)) were less than 15 and 11%, respectively. The method is robust, rapid (analysis time of 2 min), selective and hence is ideally suited for pharmacokinetic investigations involving inhalation of therapeutic doses of FP.

An improved method for the determination of fluticasone propionate in human plasma

Therapeutic monitoring of the potent, highly lipophilic glucocorticoid, fluticasone propionate (FP), was initially performed by a radioimmunoassay method. However an improved method with a lower limit of quantitation (LLOQ) of at least 25 pg per ml (pg/ml(-1)) was needed to measure the low levels of FP present in human plasma following inhalation administration of doses in the range 50-250 microg twice daily. A sensitive and specific liquid chromatographic, tandem mass spectrometric method (LC-MS/MS) with automated solid phase extraction (SPE) was developed and validated. Fluticasone propionate was extracted from plasma using Bond Elut C18 cartridges and analysed using reverse-phase chromatography with atmospheric pressure chemical ionisation followed by selective reaction monitoring. The method used a 13C-labelled internal standard and was validated over a concentration range of 25-500 pg/ml(-1). The method was shown to be specific, sensitive and reliable in the analysis of clinical samples. The main advantages of this method over the radioimmunoassay method previously used were improved sensitivity, specificity, ease of sample preparation and shortened analysis time.

Cannulation in situ of equine umbilicus. Identification by gas chromatography-mass spectrometry (GC-MS) of differences in steroid content between arterial and venous supplies to and from the placental surface

Equine umbilicus was cannulated in utero and a series of cord plasma samples removed for analysis. After steroid extraction and derivatisation, gas chromatographic-mass spectrometric (GC-MS) analysis demonstrated large differences in steroid content between the plasma samples obtained from the umbilical artery and vein, the blood supplies leading to and from the placental surface, respectively. 3Beta-hydroxy-5,7-androstadien-17-one, dehydroepiandrosterone, pregnenolone, 3beta-hydroxy-5alpha-pregnan-20-one, 5-pregnene-3beta,20beta-diol and 5beta-pregnane-3beta,20beta-diol were identified as major constituents in extracts from umbilical arterial plasma samples, mostly as unconjugated steroids. Together with 5alpha-pregnane-3,20-dione, these steroids were identified in extracts from umbilical venous plasma samples but at significantly reduced levels to those determined in arterial plasma samples. Oestradiol-17alpha, dihydroequilin-17alpha and dihydroequilenin-17alpha were identified in extracts (mostly sulphate-conjugated) from both umbilical arterial and venous plasma samples, much larger amounts being detected in the plasma sampled from, rather than to, the placental surface. Equilin, equilenin, oestrone, oestradiol-17beta, dihydroequilin-17beta and dihydroequilenin-17beta were not detected in the present studies. Isomers of 5(10)-oestrene-3,17beta-diol together with 5(10),7-oestradiene-3,17beta-diol and its possible oxidative artifact, 5(10),7,9-oestratriene-3,17beta-diol, were tentatively identified only in sulphate-conjugated extracts from umbilical venous plasma samples. No glucuronic acid-conjugated steroids could be detected. The implications of this work in the elucidation of the biosynthetic pathways leading to both the formation of oestrogens and C18 neutral steroids at the placental surface are discussed.

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.

Failure to detect systemic levels, and effects of loteprednol etabonate and its metabolite, PJ-91, following chronic ocular administration

The objective of this study was to determine the systemic exposure to loteprednol etabonate (LE) following its chronic, ocular instillation. This was a randomized, double-masked, placebo controlled, single center trial in 14 normal volunteers. Subjects were randomly assigned to receive either LE (n=10) or placebo (n=4) and instructed to instill one drop into each eye 8 times daily on Days 0 and 1 and four times daily on Days 2 through 42. Blood levels of loteprednol etabonate (LE) and its major metabolite PJ-91 (delta1 cortienic acid etabonate) in plasma, and circulating plasma cortisol levels were measured during the study. Plasma levels of LE or PJ-91 were below the level of quantitation (1 ng/mL) for all subjects in both treatment groups. Plasma cortisol levels were all within the normal range. Chronic exposure to LE at a concentration and frequency equal to or greater than the intended therapeutic dose does not result in detectable systemic levels or hypothalamic pituitary axis suppression.

Pharmacokinetic and pharmacodynamic evaluation of fluticasone propionate after inhaled administration

OBJECTIVE

To evaluate the pharmacokinetic and systemic pharmacodynamic properties of inhaled fluticasone propionate (FP).

METHODS

Single doses of 0.25, 0.5, 1.0 and 3.0 mg FP were administered to groups of six healthy subjects. Serum concentration profiles of FP were monitored over 24 h by means of high-performance liquid chromatography/mass spectrometry (HPLC/MS-MS). Systemic pharmacodynamic effects were evaluated by measuring endogenous serum cortisol and circulating white blood cells, and analyzed with previously developed integrated pharmacokinetic/pharmacodynamic (PK/PD) models.

RESULTS

FP showed a dose-independent terminal half-life with a mean (SD) of 6.0 (0.7) h. Maximum serum concentrations occurred 1.0 (0.5) h after administration, ranging from 90 pg.ml(-1) for the 0.25 mg dose to 400 pg.ml(-1) for the 3.0 mg dose. This, together with an estimated mean absorption time of nearly 5 h and a known oral bioavailability of less than 1%, indicates prolonged residence at and slow absorption from the lungs. In the investigated dose range, the cumulative systemic effect was dose-dependent for both markers of pharmacodynamic activity. For doses of 0.25, 0.50, 1.0 and 3.0 mg FP, the PK/PD-based cumulative systemic-effect parameters were 159, 186, 257 and 372% .h for lymphocyte suppression, 107, 186, 202 and 348% .h for granulocyte induction and 23.6%, 33.8%, 51.0% and 73.6% for cortisol reduction, respectively. The time courses of lymphocytes, granulocytes and endogenous cortisol could be sufficiently characterized with the applied PK/PD models. The measured in vivo EC50 values, 30 pg.ml(-1) and 7.3 pg.ml(-1) for white blood cells and cortisol, respectively, were in good agreement with predictions based on the in vitro relative receptor affinity of FP.

CONCLUSION

After inhalation, FP follows linear pharmacokinetics and exhibits dose-dependent systemic pharmacodynamic effects that can be described by PK/PD modeling.

Postnatal decline in gonadal secretion of dehydroepiandrosterone and 3 beta-hydroxyandrosta-5,7-dien-17-one in the newborn foal

Dehydroepiandrosterone (DHEA) and 3 beta-hydroxyandrosta-5,7-dien-17-one (7-dehydro-DHEA) are secreted in large quantities by the remarkably hypertrophied fetal gonads of both sexes in the pregnant mare. Their secretion serves as the fetal component of a feto-placental unit for oestrogen production in equine pregnancies. They are secreted in large amounts but show a decline in late pregnancy when the fetal gonads regress and levels of oestrogens in the mare fall as a consequence. We have examined the levels of these precursor steroids in the newborn foal in the first days after birth. DHEA and 7-dehydro-DHEA were measured in peripheral plasma in a direct RIA with a DHEA antibody which cross-reacts with 7-dehydro DHEA (> 150%). Subsequent studies were performed with solid-phase extraction, separation of unconjugated from conjugated steroids, and HPLC fractionation followed by RIA. Detection on HPLC at 254 and 280 nm was compared with results from RIA. It was concluded that DHEA is the major steroid produced by the gonads at birth. The concentrations are highly variable in the first day of postnatal life (70.45 +/- 63.06 ng/ml, n = 52) and decline rapidly to < 2 ng/ml (n = 6) at 96 h after birth. At this time the sulphate form is also seen, with an increasing ratio of DHEAS/DHEA as the value for total DHEA falls. The mechanism and significance of the apparent abrupt decline in gonadal steroidogenesis in the newborn foal remain unknown.

A sensitive method for the quantification of fluticasone propionate in human plasma by high-performance liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry

A highly sensitive and selective method has been developed for the quantification of fluticasone propionate (FP) in human plasma. The drug was isolated from human plasma using C18 solid-phase extraction cartridges. The analysis was based on high-performance liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry (HPLC/APCI/MS), using the 22R epimer of budesonide (BUD) acetate, synthesised using acetic anhydride, as internal standard. The mass spectrometer was operated in APCI mode with selected ions at tune masses of 473.2 and 501.2 m/z, corresponding to the MH+ of acetylated (22R)BUD and FP, respectively. The mobile phase used was a mixture of 50% ethanol in water with a flow rate of 0.45 ml min-1. The system was optimised by tuning the capillary and tube lens with a concentrated solution of FP. The recovery of FP from human plasma was 86.3%. Linearity of response was obtained over the concentration range 0.2-4.0 ng ml-1. The intra-assay and inter-assay variability were 6.3 and 2.9%, respectively. The lower limit of quantification was 0.2 ng ml-1 when a solid-phase extraction preceded the HPLC/APCI/MS.

Efficacy of inhaled fluticasone propionate in asthma results from topical and not from systemic activity

The objective of this study was to determine whether the therapeutic benefits of inhaled fluticasone propionate are mediated through topical or systemic effects. Two hundred seventy-four patients with asthma receiving beclomethasone dipropionate or triamcinolone acetonide during a 2-wk, single-blind, run-in period were randomized to inhaled fluticasone propionate powder 100 or 500 micrograms twice daily, oral fluticasone propionate 20 mg once daily, or placebo during a 6-wk treatment period. Patients receiving inhaled fluticasone propionate had a significantly greater probability of remaining in the study over time compared with patients receiving oral fluticasone propionate or placebo (p = 0.001). FEV1 and PEF rates at end point were significantly higher with inhaled fluticasone propionate treatment regimens than with oral fluticasone propionate (with the exception of PEF rates for inhaled fluticasone propionate 100 micrograms) or placebo treatments (p < or = 0.004). Systemic exposure to fluticasone propionate as assessed by trough plasma concentrations and/or 12-hr plasma concentration area under the curve analyses (AUC12) was higher with the oral fluticasone propionate than with the two inhaled fluticasone propionate treatment groups. The results of this study suggest that the therapeutic benefits of inhaled fluticasone propionate are mediated through topical effects in the lungs and not through systemic effects.

A radioimmunoassay for the determination of tipredane in human plasma

A sensitive method for the determination of tipredane in human plasma has been developed. Prior to radioimmunoassay, proteins are removed from plasma by precipitation with acetonitrile. A [125I]iodohistamide derivative of tipredane is used as a heterogeneous radioligand. The primary antiserum is raised in sheep against a tipredane (O-carboxymethyl) oxime-bovine serum albumin conjugate. Donkey anti-sheep IgG antiserum is used as the secondary antiserum in a double antibody separation procedure. The limit of quantification of the method is 1 ng ml-1 for 500 microliters of plasma. There is no significant interference from either established or putative metabolites of tipredane, endogenous steroids or a wide range of other drugs. The assay was used to determine the concentrations of tipredane in plasma samples collected in pilot clinical studies.

Dynamic modeling of cortisol reduction after inhaled administration of fluticasone propionate

Fluticasone propionate (FP) is a new corticosteroid that has been developed for the treatment of asthma. The compound has a very high receptor affinity, 18 times that of dexamethasone. After inhalation, FP is systemically available because of inhaled bioavailability. In healthy subjects this may lead to measurable systemic effects, such as cortisol reduction. A clinical study was conducted in 12 healthy volunteers to determine the systemic effects after inhaled administration of single 500-micrograms, 1,000-micrograms, and 2,000-micrograms doses of FP. Blood samples were collected over a 24-hour period after administration. Concentrations of FP and cortisol were measured in plasma by immunoassay. Cortisol reduction was chosen as the pharmacodynamic parameter. A novel linear release rate model was used to parameterize the cortisol data. The pharmacokinetics of FP were linear over the dose range studied. The cortisol release parameters were determined from baseline data (before drug administration). Based on these results, the E50 values for cortisol reduction were then determined for each dose of FP. The average E50 was 0.134 ng/mL for total FP concentrations and 0.013 ng/mL for unbound FP concentrations; these results were not dose dependent. These in vivo pharmacodynamic values measured in healthy subjects are in good agreement with the relatively high receptor affinity of FP.

Pharmacokinetics of intravenous fluticasone propionate in healthy subjects

1. Fluticasone propionate (FP) is a potent glucocorticoid used in the treatment of asthma. Prior to reporting the pharmacokinetics following the inhaled and oral routes, the pharmacokinetics need to be established following intravenous dosing. The present study determines the intravenous pharmacokinetics of FP, using non-compartmental analysis, in healthy male subjects over the 250 to 1000 micrograms dose range. 2. The pharmacokinetics of FP can be regarded as being linear over this dosing range. FP was extensively distributed within the body (Vss 3181), rapidly cleared (CL 1.1 l min-1) with a terminal elimination half-life of 7.8 h and a mean residence time of 4.9 h. 3. In order that future pharmacokinetic/pharmacodynamic and other modelling can be carried out, the plasma concentration-time profiles were parameterized using a model based on sums of exponentials, the appropriateness of this model was justified as the secondary kinetic parameters from the model were similar to those obtained using non-compartmental analysis.

Fluticasone propionate: topical or systemic effects?

Intranasal corticosteroids have been shown to be more effective than oral antihistamines for the treatment of seasonal allergic rhinitis. However, there are some who question whether intranasally administered corticosteroids should be used due to potential systemic effects. Fluticasone propionate, a potent corticosteroid with high specificity for the glucocorticoid receptor, is available as an aqueous nasal spray for the treatment of allergic rhinitis. To determine whether the efficacy of fluticasone propionate aqueous nasal spray (FPANS) was due to direct topical effects on the nasal mucosa or to indirect systemic effects following absorption from the nasal mucosa or from the swallowed portion of an intranasal dose, FPANS 200 micrograms once daily was compared with oral fluticasone propionate 5 mg or 10 mg once daily or placebo for 2 weeks in patients with seasonal allergic rhinitis. These oral dosages were chosen to yield low but consistent plasma fluticasone propionate concentrations. Both clinician- and patient-rated scores for nasal obstruction, rhinorrhoea, sneezing, and nasal itching were significantly lower in the intranasal fluticasone propionate group compared with both oral fluticasone propionate groups. A separate placebo-controlled study was conducted in patients with perennial rhinitis to determine if administration of FPANS 200 micrograms once daily for 1 year was associated with adverse systemic effects. At the 1-year assessment, there were no significant effects on bone mineral density or on biochemical markers of bone turnover. Similarly, there was no evidence of posterior subcapsular cataracts nor of glaucoma. Furthermore, there were no significant effects on hypothalamic-pituitary adrenal axis function as assessed by plasma cortisol and 24-h urinary cortisol response to the 6-h cosyntropin stimulation test. These data confirm that the efficacy of FPANS for the treatment of allergic rhinitis results from direct topical effects, thus reducing the likelihood of adverse systemic effects.

Pharmacokinetics and absolute bioavailability of epristeride in healthy male subjects

The objective of the current investigation was to describe the pharmacokinetics and absolute oral bioavailability of epristeride. Twelve healthy male subjects (mean (SD) age, 27 (6.2) years) received a single oral dose of 5 mg and an intravenous infusion of 4.5 mg over 30 min in a crossover fashion. Blood samples were obtained over 72h for the determination of epristeride plasma concentrations using a sensitive high-performance liquid chromatography assay. The lower limit of quantification was 5 ng mL-1. Pharmacokinetic analysis of the plasma concentration-time data was performed by both non-compartmental and compartmental methods. Absolute bioavailability was determined using dose-normalized AUC values following oral and intravenous administration. Epristeride plasma concentrations declined in a biexponential fashion with secondary peaks evident around 24 h in a majority of subjects following both routes of administration. Maximal plasma concentrations were typically achieved approximately 4 h after oral dosing. The mean apparent terminal elimination half-life estimates were similar following intravenous and oral administration and were 27.3 and 26.2 h, respectively. The mean plasma clearance and steady-state volume of distribution were 0.33 (0.09) mL min-1 kg-1 and 0.54 (0.17) L kg-1, respectively. The mean absolute bioavailability was 93% (95% CI: 84%, 104%). Following compartmental analysis of the intravenous data, the mean (SD) lambda 1 and lambda 2 half-life estimates were 2.74 (0.48) and 31.8 (19.5) h, respectively. The % AUC associated with the lambda 2 exponential phase was approximately 68%. This long half-life allows for once-daily dosing of epristeride.

Determination of exemestane, a new aromatase inhibitor, in plasma by high-performance liquid chromatography with ultraviolet detection

A sensitive and selective high-performance liquid chromatographic method for the determination of 6-methylen-androsta-1,4-diene-3,17-dione (exemestane) and its 17-dihydro metabolite in human plasma has been developed. The analytes and internal standard (Norgestrel) were extracted from plasma samples with a methylene chloride-iso-octane mixture; the organic phase was dried and the residue was reconstituted with an acetonitrile-water mixture, then analyzed by reversed-phase liquid chromatography. Quantification was achieved by ultraviolet detection of the eluate. The linearity, precision and accuracy of the method were evaluated. No interference from the constituents of human blank plasma was observed. The lower limit of quantification was 10 ng/ml plasma. The suitability of the method for in vivo samples was checked by analysis of plasma samples drawn from healthy male volunteers who had received a 200-mg single oral dose of the test compound.