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

Central and peripheral lung deposition of fluticasone propionate dry powder inhaler formulations in humans characterized by population pharmacokinetics

This study aimed to gain an in-depth understanding of the pulmonary fate of three experimental fluticasone propionate (FP) dry powder inhaler formulations which differed in mass median aerodynamic diameters (MMAD; A-4.5 µm, B-3.8 µm and C-3.7 µm; total single dose: 500 µg). Systemic disposition parameter estimates were obtained from published pharmacokinetic data after intravenous dosing to improve robustness. A biphasic pulmonary absorption model, with mucociliary clearance from the slower absorption compartment, and three systemic disposition compartments was most suitable. Rapid absorption, presumably from peripheral lung, had half-lives of 6.9 to 14.6 min. The peripherally deposited dose (12.6 µg) was significantly smaller for formulation A-4.5 µm than for the other formulations (38.7 and 39.3 µg for B-3.8 µm and C-3.7 µm). The slow absorption half-lives ranged from 6.86 to 9.13 h and were presumably associated with more central lung regions, where mucociliary clearance removed approximately half of the centrally deposited dose. Simulation-estimation studies showed that a biphasic absorption model could be reliably identified and that parameter estimates were unbiased and reasonably precise. Bioequivalence assessment of population pharmacokinetics derived central and peripheral lung doses suggested that formulation A-4.5 µm lacked bioequivalence compared to the other formulations both for central and peripheral doses. In contrast, the other fomulations were bioequivalent. Overall, population pharmacokinetics holds promise to provide important insights into the pulmonary fate of inhalation drugs, which are not available from non-compartmental analysis. This supports the assessment of the pulmonary bioequivalence of fluticasone propionate inhaled formulations through pharmacokinetic approaches, and may be helpful for discussions on evaluating alternatives to clinical endpoint studies.

Randomised clinical trial: the safety and tolerability of fluticasone propionate orally disintegrating tablets versus placebo for eosinophilic oesophagitis

BACKGROUND

APT-1011, a fluticasone propionate orally disintegrating tablet formulation, is under investigation for the treatment of eosinophilic oesophagitis (EoE).

AIMS

To evaluate the safety and tolerability of APT-1011 administered to patients with EoE and to assess the effect on clinical symptoms of EoE, endoscopic appearance and oesophageal eosinophilia.

METHODS

A randomised, double-blind, placebo-controlled, multicentre, phase 1b/2a study was conducted at seven medical centres in the US to evaluate the safety and tolerability of APT-1011 over 8 weeks in adults and adolescents with EoE. Participants were randomised to placebo (n = 8), 1.5 mg APT-1011 BID (n = 8) or 3.0 mg APT-1011 QD (n = 8). Safety and tolerability were assessed as the primary outcome; histologic and endoscopic measures were assessed as exploratory outcomes.

RESULTS

There were no deaths, serious treatment-emergent adverse events (TEAEs), severe TEAEs or discontinuations from the study related to a TEAE. In one participant randomised to 1.5 mg APT-1011 BID, a reduction in cortisol was observed, but without evidence of adrenal insufficiency. Compared with placebo, treatment with APT-1011 resulted in greater reductions in oesophageal eosinophil counts, EoE Endoscopic Reference Score, patient global assessment and symptom-based EoE activity index from baseline to end of treatment (Week 8).

CONCLUSIONS

APT-1011 was safe and well tolerated in adolescents and adults with EoE. Exploratory efficacy outcomes demonstrated improvement in histologic and endoscopic findings as well evidence of symptom improvement. The results of this study support the continued development of APT-1011 for the treatment of EoE (NCT-01386112).

Effect of Food Intake and Body Position on the Pharmacokinetics of Swallowed APT-1011, a Fluticasone Orally Disintegrating Tablet, in Healthy Adult Volunteers

Eosinophilic esophagitis is a common atopic disease of the esophagus. APT-1011 is an orally disintegrating tablet formulation of fluticasone propionate under development for the treatment of eosinophilic esophagitis. The objective of this study was to evaluate the pharmacokinetics, safety, and tolerability of APT-1011 under fed or fasted conditions in the morning (am) or at bedtime (hs) in the supine position. The study was a randomized, single-dose, 3-way, crossover design in healthy adult volunteers. In each study period participants received 2 3-mg orally disintegrating APT-1011 tablets. Serial plasma samples were collected before dosing and up to 72 hours after each dose. Twenty-two participants completed the study. The fluticasone propionate peak concentration (C_max ) ranged from 5.97 to 200 pg/mL. Compared with am-fasted dosing, am-fed dosing was associated with a modestly higher C_max (∼21%) but lower net exposure (area under the concentration-time curve ∼56% difference) and shorter time to reach C_max (T_max ) (T_max fasted = 10 hours, fed = 5 hours). Dosing at hs resulted in an 18% and 32% decrease in C_max relative to am-fasted and am-fed conditions, respectively. Dosing at hs led to an exposure that was higher than am-fed but lower than am-fasted dosing. T_max with hs dosing (14 hours) was later than that with am dosing (T_max fasted = 10 hours, fed = 5 hours). Adverse events were mild. There is low systemic exposure of fluticasone propionate with APT-1011. The rate of absorption was increased with a high-fat meal but decreased with hs dosing, suggesting the potential for longer dwell times in the esophagus.

Estimation of Fraction Dissolved After Intratracheal Delivery of a Potent Janus Kinase Inhibitor, iJAK-001, with Low Solubility in Rat and Sheep: Impact of Preclinical PKPD on Inhaled Human Dose Projection

Background: A highly potent pan-Janus kinase (JAK) inhibitor with excellent kinome selectivity was developed for topical delivery to treat severe asthma. This poorly soluble drug discovery candidate, iJAK-001, is expected to exhibit long duration of JAK/STAT pathway inhibition at low doses in asthmatics because of depot effect after dry powder inhalation. Human dose projection for inhaled molecules with low aqueous solubility remains to be a daunting challenge because of several limitations: (1) bioanalytical measurement of dissolved fraction after inhalation of solid particles is uncertain; (2) distribution of these particles is not homogenous in the lung; (3) in vitro solubility measurements to estimate fraction dissolved may not be a reflection of local surface lung concentration; (4) lack of a surrogate biomarker of lung target engagement, and (5) invasive procedure needed to sample human lung tissue in the clinic. Methods: We leveraged in silico, in vitro, and in vivo tools preclinically and found significant differences in lung to plasma partition ratio when iJAK-001 was given intravenously (IV) or intratracheally in a solution-based formulation versus that in suspension, as well as pharmacodynamic response in preclinical asthma models when delivered systemically via IV infusion versus inhaled. Results and Conclusion: The combined results from above suggest that caution must be exercised using either lung or plasma exposure for human dose projection. Instead, using the local inhibitor concentration estimate based on delivery efficiency, dose, fraction absorbed, and rate of absorption normalized by lung (cardiac) blood flow may be more appropriate for dose projection.

Between-Batch Pharmacokinetic Variability Inflates Type I Error Rate in Conventional Bioequivalence Trials: A Randomized Advair Diskus Clinical Trial

We previously demonstrated pharmacokinetic differences among manufacturing batches of a US Food and Drug Administration (FDA)-approved dry powder inhalation product (Advair Diskus 100/50) large enough to establish between-batch bio-inequivalence. Here, we provide independent confirmation of pharmacokinetic bio-inequivalence among Advair Diskus 100/50 batches, and quantify residual and between-batch variance component magnitudes. These variance estimates are used to consider the type I error rate of the FDA's current two-way crossover design recommendation. When between-batch pharmacokinetic variability is substantial, the conventional two-way crossover design cannot accomplish the objectives of FDA's statistical bioequivalence test (i.e., cannot accurately estimate the test/reference ratio and associated confidence interval). The two-way crossover, which ignores between-batch pharmacokinetic variability, yields an artificially narrow confidence interval on the product comparison. The unavoidable consequence is type I error rate inflation, to ∼25%, when between-batch pharmacokinetic variability is nonzero. This risk of a false bioequivalence conclusion is substantially higher than asserted by regulators as acceptable consumer risk (5%).

Inhaled corticosteroids: potency, dose equivalence and therapeutic index

Glucocorticosteroids are a group of structurally related molecules that includes natural hormones and synthetic drugs with a wide range of anti-inflammatory potencies. For synthetic corticosteroid analogues it is commonly assumed that the therapeutic index cannot be improved by increasing their glucocorticoid receptor binding affinity. The validity of this assumption, particularly for inhaled corticosteroids, has not been fully explored. Inhaled corticosteroids exert their anti-inflammatory activity locally in the airways, and hence this can be dissociated from their potential to cause systemic adverse effects. The molecular structural features that increase glucocorticoid receptor binding affinity and selectivity drive topical anti-inflammatory activity. However, in addition, these structural modifications also result in physicochemical and pharmacokinetic changes that can enhance targeting to the airways and reduce systemic exposure. As a consequence, potency and therapeutic index can be correlated. However, this consideration is not reflected in asthma treatment guidelines that classify inhaled corticosteroid formulations as low-, mid- and high dose, and imbed a simple dose equivalence approach where potency is not considered to affect the therapeutic index. This article describes the relationship between potency and therapeutic index, and concludes that higher potency can potentially improve the therapeutic index. Therefore, both efficacy and safety should be considered when classifying inhaled corticosteroid regimens in terms of dose equivalence. The historical approach to dose equivalence in asthma treatment guidelines is not appropriate for the wider range of molecules, potencies and device/formulations now available. A more robust method is needed that incorporates pharmacological principles.

The effect of ketoconazole on the pharmacokinetics and pharmacodynamics of inhaled fluticasone furoate and vilanterol trifenatate in healthy subjects

AIM

To investigate the effects of the cytochrome P450 3A4 (CYP3A4) inhibitor ketoconazole on the pharmacokinetics (PK) and pharmacodynamics of fluticasone furoate (FF) and vilanterol trifenatate (VI).

METHODS

Two double-blind, randomized, placebo-controlled, two-way crossover studies in healthy subjects. In study 1, subjects received single doses of ketoconazole (400 mg) or placebo on days 1-6, with a single dose of inhaled VI (25 μg) on day 5. Pharmacodynamic and PK data were obtained up to 48 h following the VI dose. In study 2, subjects received once daily ketoconazole (400 mg) or placebo for 11 days, with FF/VI (200/25 μg) for the final 7 days. Pharmacodynamic and PK data were obtained up to 48 h following the day 11 dose.

RESULTS

In study 1, there was no effect of co-administration of ketoconazole and VI on pharmacodynamic or PK parameters. In study 2, co-administration of ketoconazole and FF/VI had no effect on 0-4 h maximal heart rate or minimal blood potassium {treatment difference [90% confidence interval (CI)] -0.6 beats min(-1) (-5.8, 4.5) and 0.04 mmol l(-1) (-0.03, 0.11), respectively}, whilst there was a 27% decrease in 24 h weighted mean serum cortisol [treatment ratio (90% CI) 0.73 (0.62, 0.86)]. Co-administration of ketoconazole increased [percentage change (90% CI)] FF area under the curve (0-24) and maximal plasma concentration by 36% (16, 59) and 33% (12, 58), respectively, and VI area under the curve (0-t') and maximal plasma concentration by 65% (38, 97) and 22% (8, 38), respectively.

CONCLUSION

Co-administration of FF/VI or VI with ketoconazole resulted in a less than twofold increase in systemic exposure to FF and VI. There was no increase in β-agonist systemic pharmacodynamic effects, while serum cortisol was decreased by 27%. Co-administration of FF/VI with strong CYP3A4 inhibitors has the potential to increase systemic exposure to both fluticasone furoate and vilanterol, which could lead to an increase in the potential for adverse reactions.

Detection of fluticasone propionate in horse plasma and urine following inhaled administration

Fluticasone propionate (FP) is an anti-inflammatory agent with topical and inhaled applications commonly used in the treatment of asthma in steroid-dependent individuals. The drug is used in racehorses to treat Inflammatory Airway Disease; this work was performed in order to advise on its use and detect potential misuse close to racing. Methods were developed for the extraction and analysis of FP from horse plasma and a carboxylic acid metabolite (FP-17βCOOH) from horse urine. The methods utilize ultra high performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) in order to detect the extremely low concentrations of analyte present in both matrices. The developed methods were used to analyse plasma and urine samples collected following inhaled administration of FP to six thoroughbred horses. FP was detected in plasma for a minimum of 72 h post-administration and FP-17βCOOH was detected in urine for approximately 18 h post-administration. The results show that it is possible to detect FP in the horse following inhaled administration.

Pharmacokinetic and pharmacodynamic properties of inhaled beclometasone dipropionate delivered via hydrofluoroalkane-containing devices

Inhaled corticosteroids have a key role in the treatment of asthma and chronic obstructive pulmonary disease. In recent times, beclometasone dipropionate has been reformulated in pressurised metered dose inhalers (pMDIs), using hydrofluoroalkanes (HFAs) as a propellant. Extensive toxicological testing has shown that HFA-propellants are well tolerated. Among the reformulated beclometasone dipropionate-containing pMDIs, only the characteristics of the two Qvar formulations have been thoroughly explored. Compared to the reference beclometasone dipropionate formulation, the mass median aerodynamic diameter of the Qvar formulations are substantially smaller (1.1 vs 4.0 microm), whereas that of Modulite averages 2.6 microm. Scintigraphic and pharmacokinetic studies indicate a higher lung deposition for both the Qvar and the Beclazone formulations, compared with reference beclometasone dipropionate formulation. Since the 2- to 3-fold increase in pulmonary deposition results in a 2.6- to 3-fold difference in relative efficacy for Qvar, half the dose of the reference beclometasone dipropionate formulation has been currently recommended in adult patients with asthma, a recommendation that is supported by a large number of clinical trials. Conversely, the design of the studies conducted to compare the efficacy of Qvar with fluticasone propionate and budesonide does not allow establishing their equivalence on a milligram per milligram basis. Good studies on the bioequivalence between the reference beclometasone dipropionate formulation and the Modulite or Beclazone formulations are not available.

Potential effects of fluticasone propionate on bone mineral density in patients with asthma: a 2-year randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the effects of treatment with fluticasone propionate vs placebo on bone, hypothalamic-pituitary-adrenal (HPA) axis function, and the eyes in patients with asthma.

PATIENTS AND METHODS

This randomized, double-blind, placebo-controlled study of 160 patients with asthma who had minimal previous exposure to corticosteroids was conducted from July 1994 through June 1997. Patients received fluticasone at 88 microg twice daily, fluticasone at 440 microg twice daily, or placebo twice daily for 2 years. Bone mineral density (BMD) was evaluated every 6 months by lumbar spine, proximal femur, and total body scans. Measurements of HPA axis function and ophthalmic evaluations were conducted at similar intervals.

RESULTS

Among the 3 groups, no significant differences were observed in BMD at week 104 (at any anatomical site). Mean percent change from baseline in the lumbar spine was less than 1% for all 3 groups. At all time points, HPA axis function was similar in the 88-microg fluticasone group compared with the placebo group. For mean change from baseline in corticotropin-stimulated peak cortisol (P = .003 and P = .02 at weeks 24 and 52, respectively) and area under the stimulated plasma cortisol vs time curve (P = .002 and P = .02 at weeks 24 and 52, respectively), statistically significant reductions from baseline were observed in the 440-microg fluticasone group compared with the placebo group. These reductions of 10% to 13% from baseline were not accompanied by other signs of systemic effect and did not persist with continued treatment (at weeks 76 and 104). No important ocular changes were observed.

CONCLUSION

Long-term treatment with 88 microg of fluticasone twice daily was comparable to placebo in all skeletal, ophthalmic, and HPA axis function assessments. Treatment with fluticasone at 440 microg twice daily resulted in no significant effects on BMD and a statistically significant but not clinically important temporary reduction in cortisol production.

Adrenal function as assessed by low-dose adrenocorticotropin hormone test before and after switching from inhaled beclomethasone dipropionate to inhaled fluticasone propionate

Low-dose adrenocorticotropin hormone (ACTH) tests (0.5 microg/L 73 m2) were done before and after switching from inhaled beclomethasone dipropionate to inhaled fluticasone propionate in 12 patients 33-77 years old who had mild-to-severe asthma to compare the effects of these drugs on adrenal function. Low-dose ACTH tests were performed after the subjects had received inhaled beclomethasone dipropionate (200-900 microg/day) for at least 12 wk. Treatment was then switched to inhaled fluticasone propionate (200-600 microg/day) for at least 12 wk, and a second low-dose ACTH test was done. Pulmonary function was assessed on the basis of peak expiratory flow rate (PEFR, % of predicted value). After switching treatment, the daily dose of inhaled corticosteroid decreased by about 40%. Basal serum cortisol and ACTH levels were similar with both treatments. The adrenal response, as assessed by incremental rise in the serum cortisol level (peak minus basal) after ACTH challenge, improved significantly (5.6-7.9 microg/dL, p < 0.01) after switching to fluticasone. All three patients who had lower serum cortisol levels during beclomethasone treatment than during fluticasone treatment showed improvement in both the peak cortisol level and the incremental rise in cortisol. Mean morning and evening PEFRs significantly increased after switching from beclomethasone to fluticasone (morning: 71.2 to 76.0%, p < 0.01; evening: 67.3 to 72.1%, both p < 0.05). The diurnal variation of PEFR significantly decreased from 10.9% to 8.3% after switching treatment (p < 0.01). We conclude that switching from beclomethasone to fluticasone reduces the risk of adrenal dysfunction associated with inhaled steroids and improves pulmonary function.

The use of a physiologically based pharmacokinetic model to evaluate deconvolution measurements of systemic absorption

BACKGROUND

An unknown input function can be determined by deconvolution using the systemic bolus input function (r) determined using an experimental input of duration ranging from a few seconds to many minutes. The quantitative relation between the duration of the input and the accuracy of r is unknown. Although a large number of deconvolution procedures have been described, these routines are not available in a convenient software package.

METHODS

Four deconvolution methods are implemented in a new, user-friendly software program (PKQuest, http://www.pkquest.com). Three of these methods are characterized by input parameters that are adjusted by the user to provide the "best" fit. A new approach is used to determine these parameters, based on the assumption that the input can be approximated by a gamma distribution. Deconvolution methodologies are evaluated using data generated from a physiologically based pharmacokinetic model (PBPK).

RESULTS AND CONCLUSIONS

The 11-compartment PBPK model is accurately described by either a 2 or 3-exponential function, depending on whether or not there is significant tissue binding. For an accurate estimate of r the first venous sample should be at or before the end of the constant infusion and a long (10 minute) constant infusion is preferable to a bolus injection. For noisy data, a gamma distribution deconvolution provides the best result if the input has the form of a gamma distribution. For other input functions, good results are obtained using deconvolution methods based on modeling the input with either a B-spline or uniform dense set of time points.

Methods used to assess pulmonary deposition and absorption of drugs

The assessment of pulmonary drug absorption and deposition is becoming increasingly important in drug development. Absorption information can be used to maximize pulmonary selectivity, to screen drug candidates and to help evaluate the bioequivalence of generic inhalation products. Several methods are available to investigate pulmonary drug absorption and deposition, ranging from in vitro experiments to in vivo pharmacokinetic and pharmacodynamic analyses. In combination, these methods can indicate the fate of an inhaled drug.