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

The Pharmacokinetics of Inhaled Drugs

The pharmacokinetic (PK) profile of a drug after inhalation may differ quite markedly from that seen after dosing by other routes of administration. Drugs may be administered to the lung to elicit a local action or as a portal for systemic delivery of the drug to its site of action elsewhere in the body. Some knowledge of PK is important for both locally- and systemically-acting drugs. For a systemically-acting drug, the plasma concentration-time profile shares some similarities with drug given by the oral or intravenous routes, since the plasma concentrations (after the distribution phase) will be in equilibrium with concentrations at the site of action. For a locally-acting drug, however, the plasma concentrations reflect its fate after it has been absorbed and removed from the airways, and not what is available to its site of action in the lung. Consequently, those typical PK parameters which are determined from plasma concentration measurements, e.g., area under the curve (AUC), Cmax, tmax and post-peak t1/2 may provide information on the deposition and absorption of drugs from the lung; however, the information from these parameters becomes more complicated to decipher for those drugs which are locally-acting in the lung. Additionally, the plasma concentration profile for both locally- and systemically-acting drugs will not only reflect drug absorbed from the lung but also that absorbed from the gastrointestinal (GI) tract from the portion of the dose which is swallowed. This absorption from the GI tract adds a further complication to the interpretation of plasma concentrations, particularly for locally-acting drugs. The influence of physiological and pathological factors needs to be considered in the absorption of some inhaled drugs. The absorption of some hydrophilic drugs is influenced by the inspiratory maneuver used during initial inhalation of the drug, and at later times after deposition. Similarly, the effects of smoking have been shown to increase lung permeability and increase the absorption of certain hydrophilic drugs. The effects of different disease states of the lung have less defined influences on absorption into the systemic circulation.

Equivalent Systemic Exposure to Fluticasone Propionate/Salmeterol Following Single Inhaled Doses from Advair Diskus and Wixela Inhub: Results of Three Pharmacokinetic Bioequivalence Studies

Background: Wixela® Inhub® was developed to deliver inhaled fluticasone propionate/salmeterol (FP/S) combination as a substitutable generic equivalent to Advair® Diskus®. These studies aimed to confirm the pharmacokinetic bioequivalence (BE) of FP/S after single doses of Wixela Inhub (test [T]) and Advair Diskus (reference [R]). Methods: Three open-label, randomized, two-way crossover, single-dose studies in healthy subjects (N = 66 each) compared the systemic exposure of FP and salmeterol after inhalation from three dose strengths of FP/S (100/50, 250/50, or 500/50 μg) delivered from T and R. Primary BE endpoints were the area under the plasma concentration-time curve from time = 0 to the last measurable concentration (AUC(0-t)) and the maximum observed plasma concentration (Cmax) for both FP and S. The BE acceptance criteria specified that the 90% confidence intervals (CIs) of the geometric mean T/R ratios for AUC(0-t) and Cmax can be contained within 0.80-1.25 for both FP and salmeterol. Results: Wixela Inhub met the acceptance criteria for BE for FP and salmeterol at each dose strength. Estimated AUC(0-t) and Cmax geometric mean ratios (T/R [90% CI]) for FP were, respectively, 1.04 (1.00-1.08) and 0.92 (0.87-0.96) for 100/50 μg FP/S, 1.07 (1.02-1.13) and 1.01 (0.95-1.07) for 250/50 μg, and 0.97 (0.92, 1.00) and 0.90 (0.86-0.93) for 500/50 μg. Estimated AUC(0-t) and Cmax ratios for salmeterol were, respectively, 1.08 (1.04-1.11) and 1.00 (0.94-1.04) for 100/50 μg FP/S, 1.03 (0.99-1.07) and 0.93 (0.87-1.00) for 250/50 μg, and 1.00 (0.96-1.04) and 0.86 (0.81-0.91) for 500/50 μg. FP/S at all doses via both T and R was comparably well tolerated. Conclusions: Wixela Inhub was bioequivalent to Advair Diskus at all three dose strengths for both FP and S, providing direct evidence of equivalent systemic safety and indirect evidence for equivalent pulmonary deposition.

A Randomized Comparison of the Pharmacokinetics and Bioavailability of Fluticasone Propionate Delivered via Xhance Exhalation Delivery System Versus Flonase Nasal Spray and Flovent HFA Inhalational Aerosol

PURPOSE

The exhalation delivery system with fluticasone propionate (Xhance®) has been shown to deliver drug substantially more broadly in the nasal cavity (particularly into superior/posterior regions), with less off-target loss of drug to drip-out and swallowing, than conventional nasal sprays. This open-label study evaluated the systemic bioavailability of Xhance® by comparing the pharmacokinetic (PK) properties of a single dose of fluticasone from 3 products administering the drug using 3 different devices: Xhance®, Flonase® (fluticasone propionate inhalational nasal spray), and Flovent® HFA (fluticasone propionate inhalational aerosol).

METHODS

This open-label study was conducted in 2 parts. Study part 1 compared systemic exposure with a single dose of Xhance® 186 or 372 μg versus Flonase® 400 μg (3-way, 3-treatment, 3-sequence, randomized crossover in healthy subjects; n = 90). A separate study, part 2, under the same umbrella protocol, compared systemic exposure with Xhance® 372 μg versus Flovent® HFA 440 μg (2-way, 2-treatment, 2-sequence, randomized crossover in patients with mild to moderate asthma; n = 30).

FINDINGS

With Xhance® 186 μg, the geometric least squares mean (LSM) C_max was higher than with Flonase® 400 μg (16.02 vs 11.66 pg/mL, respectively; geometric mean ratio [GMR], 137.42%) and the geometric LSM AUC_0-∞ values were similar (97.30 vs 99.61 pg · h/mL; GMR, 97.78%). With Xhance® 372 μg, the geometric LSM C_max and AUC_0-∞ were higher than with Flonase® 400 μg (C_max, 23.50 vs 11.66 pg/mL [GMR, 201.53%]; AUC_0-∞, 146.61 vs 99.61 pg · h/mL [GMR, 147.19%]). In part 2, the geometric LSM C_max and AUC_0-∞ values were lower with Xhance® 372 μg than with Flovent® HFA 440 μg (C_max, 25.28 vs 40.02 pg/mL [GMR, 63.18%]; AUC_0-∞, 205.78 vs 415.16 pg · h/mL [GMR, 49.57%]).

IMPLICATIONS

Similar intranasal doses of Xhance® (372 μg) and Flonase® (400 μg) are clearly not bioequivalent. Systemic exposure is very low with all products. Systemic exposure is higher with Xhance® than with Flonase® and substantially lower than with Flovent® HFA 440 μg and, based on dose normalization, Flovent® HFA 220 μg. ClincalTrials.gov identifier: NCT02266927.

Batch-to-batch pharmacokinetic variability confounds current bioequivalence regulations: A dry powder inhaler randomized clinical trial

Current pharmacokinetic (PK) bioequivalence guidelines do not account for batch‐to‐batch variability in study design or analysis. Here we evaluate the magnitude of batch‐to‐batch PK variability for Advair Diskus 100/50. Single doses of fluticasone propionate and salmeterol combinations were administered by oral inhalation to healthy subjects in a randomized clinical crossover study comparing three different batches purchased from the market, with one batch replicated across two treatment periods. All pairwise comparisons between different batches failed the PK bioequivalence statistical test, demonstrating substantial PK differences between batches that were large enough to demonstrate bio‐inequivalence in some cases. In contrast, between‐replicate PK bioequivalence was demonstrated for the replicated batch. Between‐batch variance was ∼40–70% of the estimated residual error. This large additional source of variability necessitates re‐evaluation of bioequivalence assessment criteria to yield a result that is both generalizable and consistent with the principles of type I and type II error rate control.

Pharmacokinetics, Safety, and Tolerability of a New Fluticasone Propionate Multidose Dry Powder Inhaler Compared With Fluticasone Propionate Diskus(®) in Healthy Adults

BACKGROUND

Fluticasone propionate (Fp) is an inhaled corticosteroid with well-established safety and efficacy profiles. This study evaluated the systemic pharmacokinetics of Fp inhaled from a novel, inhalation-driven multidose dry powder inhaler (MDPI) that does not require coordination of actuation with inhalation.

METHODS

This was a single-center, open-label, randomized, 3-period crossover, single-dose study in healthy Japanese and Caucasian subjects aged 20-45 years, inclusive. Subjects were randomized to one of six treatment sequences including combinations of four inhalations of Fp MDPI 100 μg (400 μg total dose), Fp MDPI 200 μg (800 μg total dose), and Fp Diskus(®) 100 μg (400 μg total dose). The primary objective was to assess pharmacokinetics (maximum plasma concentration [Cmax] and area under concentration-vs.-time curve [AUC]) for each treatment. Safety and tolerability were also assessed.

RESULTS

Thirty subjects (15 Caucasian, 15 Japanese) met entry criteria and were randomized; all 30 subjects completed the study. At the inhaled Fp total doses evaluated (400 and 800 μg), the shapes of plasma concentration-vs.-time curves and systemic exposure (AUC0-t and Cmax) were similar in Japanese and Caucasian subjects. Geometric mean ratios (Japanese/Caucasian) for AUC0-t ranged from 1.11 to 1.15, and for Cmax ranged from 0.90 to 1.05, with no substantial differences between ethnic groups. In both ethnic groups, and in the combined population, systemic exposure (AUC0-t and Cmax) was highest for Fp MDPI 800 μg, followed by Fp MDPI 400 μg, and last by Fp Diskus 400 μg. No clinical laboratory, vital signs, or physical examination findings were considered clinically significant.

CONCLUSIONS

Systemic exposure following inhaled single doses of Fp was comparable in healthy adult Japanese and Caucasian subjects for each total dose and inhaler. The new MDPI provided more efficient drug delivery than Diskus, suggesting that Fp MDPI may provide similar clinical efficacy at a lower inhaled dose compared with Diskus. Single-dose inhaled Fp (400-800 μg) was generally well tolerated in healthy adults.

[Inhaled corticosteroids and growth: should we be worried?]

Inhaled corticosteroids (ICSs) are the cornerstone and the first stage of asthma treatment. The objective of this study was to synthesize data on the potential effects of ICSs on growth in children. Studies on the short-term impact of ICSs on growth evaluated by knemometry cannot be extrapolated to the medium or long term and therefore have no utility in real life for a given person. In the medium term, the various ICSs given at the usual doses cause a small reduction in growth after 6 months of treatment. This slowdown occurs at the beginning of treatment, especially in younger children, and the growth velocity corrects itself later but without catching up. In the long term, the prolonged use of ICSs seems to induce a small reduction in the final size in adulthood (close to 1cm) occurring in the first 2 years of treatment without worsening over time. The impact of gender, age at onset of treatment, different ICSs, modes of inhalation, and severity of asthma should also be studied further. The benefit of ICSs in asthma treatment is greater than the risk of side effects, including on growth. The majority of the therapeutic effect is obtained for small to moderate doses of ICSs. Regular adjustment of ICS dose for optimal asthma control should also reduce ICS dose and the impact on growth.

The relationship between fluticasone furoate systemic exposure and cortisol suppression

INTRODUCTION

The inhaled corticosteroid (ICS) fluticasone furoate is in development, in combination with the long-acting beta2-agonist vilanterol for the once-daily treatment of asthma and chronic obstructive pulmonary disease and as a monotherapy treatment for asthma. Corticosteroids, including ICSs, have the potential to induce dose-dependent systemic effects on the hypothalamic-pituitary-adrenal (HPA) axis. Cortisol suppression has been observed in asthma patients with normal HPA axis function at baseline on receiving high doses of ICSs, and is associated with adverse effects on a number of physiological processes. The measurement of 24-h serum cortisol and 24-h urinary cortisol excretion are sensitive methods for assessing adrenocortical activity, and can evaluate cortisol suppression in a dose-dependent manner.

OBJECTIVE

The purpose of the meta-analysis presented here was to characterize the population pharmacokinetic/pharmacodynamic relationship between fluticasone furoate systemic exposure [as measured by area under the concentration-time curve over 24 h postdose (AUC24)] and both 24-h weighted mean serum cortisol (WM24) and 24-h urine cortisol excretion in healthy subjects and subjects with asthma.

METHODS

The serum cortisol meta-analysis integrated eight studies; five Phase I studies in healthy subjects, two Phase IIa studies, and one Phase III study in subjects with asthma. Each study included serial blood sampling for estimation of WM24. The urine cortisol meta-analysis integrated three studies: one Phase I study in healthy subjects, and one Phase IIb and one Phase III study in subjects with asthma. Each study included complete 0-24 h urine collection for estimation of urine cortisol excretion. All studies included blood sampling for estimation of fluticasone furoate AUC24. A sigmoid maximum effect (E max) model was fitted to fluticasone furoate AUC24 and serum cortisol and urine cortisol data using nonlinear mixed-effect modeling with the computer program NONMEM(®).

RESULTS

Over a wide range of systemic fluticasone furoate exposure representing the therapeutic and supratherapeutic range, the relationship between fluticasone furoate AUC24 and WM24 and 24-h urine cortisol excretion was well described by an E max model. The average estimate of AUC producing 50 % of maximum effect (AUC50) was similar for the serum cortisol and urine cortisol models with values of 1,556 and 1,686 pg · h/mL, respectively. Although formulation/inhaler was shown to be a significant covariate on the estimates of both WM24 at zero concentration (C0) and AUC50 in the serum cortisol model, the differences were small and believed to be due to study variability. Age was shown to be a significant covariate on the estimates of both C 0 and AUC50 in the urine cortisol model, and was considered to be a reflection of lower urine cortisol excretion in adolescents.

CONCLUSION

A pharmacokinetic/pharmacodynamic model has been established over a wide range of systemic fluticasone furoate exposure representing the therapeutic and supratherapeutic range to both WM24 and 24-h urine cortisol excretion. The values of AUC50 of 1,556 and 1,686 pg·h/mL, respectively, are several times higher than average fluticasone furoate AUC24 values observed at clinical doses of fluticasone furoate (≤200 μg). The models predict a fluticasone furoate AUC24 of 1,000 pg·h/mL would be required to reduce 24-h serum cortisol or 24-h urine cortisol excretion by 20 and 17 %, respectively.

Hydrofluoroalkane preparations of fluticasone propionate

Fluticasone propionate is approved for the long-term maintenance therapy of persistent asthma of all severities, and its safety and efficacy has been well established in clinical trials and practice. With the need to phase out chlorofluorocarbons (CFCs) as propellants in pressurized metered-dose inhalers (pMDIs), hydrofluoroalkane (HFA) propellants have been introduced as a safer, environmentally friendly alternative. A HFA formulation of fluticasone propionate has been developed as a microgram-equivalent replacement for the traditional CFC pMDI. Clinical trials have demonstrated that the fluticasone propionate HFA pMDI is an acceptable clinical alternative for the CFC pMDI with similar safety and efficacy.

Suppression of GATA-3 nuclear import and phosphorylation: a novel mechanism of corticosteroid action in allergic disease

BACKGROUND

GATA-3 plays a critical role in regulating the expression of the cytokines interleukin (IL)-4, IL-5, and IL-13 from T helper-2 (Th2) cells and therefore is a key mediator of allergic diseases. Corticosteroids are highly effective in suppressing allergic inflammation, but their effects on GATA-3 are unknown. We investigated the effect of the corticosteroid fluticasone propionate on GATA-3 regulation in human T-lymphocytes in vitro and in vivo.

METHODS AND FINDINGS

In a T lymphocyte cell line (HuT-78) and peripheral blood mononuclear cells stimulated by anti-CD3 and anti-CD28 in vitro we demonstrated that fluticasone inhibits nuclear translocation of GATA-3 and expression of Th2 cytokines via a mechanism independent of nuclear factor-kappaB and is due, in part, to competition between GATA-3 and the ligand-activated glucocorticoid receptor for nuclear transport through the nuclear importer importin-alpha. In addition, fluticasone induces the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), the endogenous inhibitor of p38 MAPK, which is necessary for GATA-3 nuclear translocation. These inhibitory effects of fluticasone are rapid, potent, and prolonged. We also demonstrated that inhaled fluticasone inhibits GATA-3 nuclear translocation in peripheral blood lymphocytes of patients with asthma in vivo.

CONCLUSIONS

Corticosteroids have a potent inhibitory effect on GATA-3 via two interacting mechanisms that potently suppress Th2 cytokine expression. This novel mechanism of action of corticosteroids may account for the striking clinical efficacy of corticosteroids in the treatment of allergic diseases.

Salmeterol/fluticasone propionate via Diskus once daily versus fluticasone propionate twice daily in patients with mild asthma not previously receiving maintenance corticosteroids

BACKGROUND AND OBJECTIVE

The efficacy and safety of twice-daily inhaled salmeterol/fluticasone propionate combination (SFC) therapy have been well established in the treatment of adults and adolescents with asthma. Once-daily administration of SFC could also be appropriate in patients with mild persistent asthma. This study aimed to investigate whether once-daily SFC 50 microg/100 microg was at least as effective as fluticasone propionate (FP) 100 microg twice daily, and more effective than twice-daily placebo, over 52 weeks as initial maintenance therapy in patients with mild persistent asthma.

METHODS

This was a randomized, double-blind, double-dummy, placebo-controlled, multicentre, parallel-group study carried out in primary and secondary care. Patients aged between 12 and 79 years with a documented clinical history of asthma for > or =6 months who were currently receiving inhaled short-acting beta(2)-adrenoceptor agonists only were enrolled. Patients were randomized to receive either once-daily inhaled SFC 50 microg/100 microg, twice-daily inhaled FP 100 microg (i.e. twice the dose of FP compared with SFC) or placebo for 52 weeks. The primary efficacy endpoints were mean morning peak expiratory flow (PEF), as recorded by patients prior to the use of bronchodilator or study medication, and the rate of investigator-recorded asthma exacerbations.

RESULTS

Patients receiving twice-daily FP and once-daily SFC showed greater improvements in mean morning PEF compared with those receiving placebo (FP, difference in means 20.1 L/min; 95% CI 14.7, 25.5; p < 0.001; SFC, difference in means 14.8 L/min; 95% CI 9.4, 20.2; p < 0.001). The difference in adjusted mean PEF between once-daily SFC and twice-daily FP was -5.3 L/min (95% CI -9.1, -1.6). PEF results showed that once-daily SFC was non-inferior to twice-daily FP. Over 52 weeks, there was a 35% reduction in exacerbation rates with once-daily SFC, which in this respect demonstrated superiority over placebo (p < 0.001). Non-inferiority between once-daily SFC and twice-daily FP with respect to exacerbation rates was not shown. Once-daily SFC significantly improved clinic forced expiratory flow between 25% and 75% of forced vital capacity (difference in means 0.129 L/s; p < 0.001) and clinic PEF (difference in means 10.8 L/min; p < 0.001) compared with twice-daily FP. Both treatments were well tolerated and the safety profile of each was similar to that seen with placebo.

CONCLUSION

In patients with mild persistent asthma not previously receiving maintenance therapy, once-daily SFC 50 microg/100 microg is an effective treatment compared with placebo, and was non-inferior to twice-daily FP 100 microg with respect to mean morning PEF. However, in this study, once-daily SFC was not as efficacious as twice-daily FP in reducing asthma exacerbation rates. This study confirms the benefits of regular maintenance treatment in patients with mild persistent asthma.

Effects of inhaled ciclesonide and fluticasone propionate on cortisol secretion and airway responsiveness to adenosine 5'monophosphate in asthmatic patients

The efficacy and systemic effects of ciclesonide, a novel glucocorticosteroid, inhaled via pressurized metered-dose inhaler (pMDI) were compared with fluticasone propionate pMDI in 26 patients with asthma, using a randomized, double blind, placebo-controlled, double dummy, 6-period crossover study design. Treatments were placebo, ciclesonide 320 microg (ex-actuator dose) once daily (o.d.), ciclesonide 640 microg o.d., ciclesonide 640 microg twice daily (b.i.d.), fluticasone propionate 440 microg (ex-actuator dose) b.i.d., and fluticasone propionate 880 microg b.i.d. The primary variable was area under the plasma cortisol concentration-time curve over 24 h (plasma cortisol AUC(0-24), relative to placebo) derived from samples taken every 2 h, on the 9th day of treatment. Secondary variables were 24-h urinary cortisol excretion and PC20 for adenosine 5'-monophosphate (AMP) (relative to placebo and expressed in doubling concentrations). Ciclesonide did not affect 24-h cortisol secretion. Fluticasone propionate suppressed cortisol secretion as demonstrated by a decrease in plasma cortisol AUC(0-24), relative to placebo, by 29% (95% CI 15-41) and 59% (95% CI 51-66) with 440 and 880 microg b.i.d., respectively. PC20 more than doubled with each active treatment, but no statistically significant dose-response effect could be established. It was concluded that moderate to high doses of fluticasone propionate suppressed cortisol secretion, that ciclesonide did not suppress cortisol secretion, and that all active treatments decreased hyperresponsiveness to AMP.

Effects of mometasone furoate dry powder inhaler and beclomethasone dipropionate hydrofluoroalkane and chlorofluorocarbon on the hypothalamic-pituitary-adrenal axis in asthmatic subjects

STUDY OBJECTIVES

Mometasone furoate dry powder inhaler (MF-DPI) [400 mug] is an inhaled corticosteroid (ICS) that is effective in the treatment of asthma. MF-DPI has a low potential for suppression of the hypothalamic-pituitary-adrenal (HPA) axis at its clinical dose. The effect of MF-DPI, 400 microg qd, on the HPA axis was compared to that of beclomethasone dipropionate (BDP) using hydrofluoroalkane (HFA) and chlorofluorocarbon (CFC) propellants via metered-dose inhalers (MDIs) twice daily.

DESIGN AND INTERVENTIONS

This randomized, third-party blind, parallel-group study compared the effects of MF-DPI 400 mug one puff qd in the morning (n = 18), HFA-BDP 200 microg two puffs MDI bid (n = 18), and CFC-BDP 400 microg two puffs MDI bid (n = 17) for 14 days on the area under the 24-h serum cortisol concentrations curve (AUC(0-24)) and on total 24-h urinary free cortisol excretion in mild asthmatic subjects. Effects on morning/evening peak expiratory flow (PEF) and on inhaled albuterol use were also assessed. Adverse events that occurred during or > or = 30 days after the study were recorded.

RESULTS

The mean decrease from baseline in the serum cortisol concentrations AUC(0-24) in the MF-DPI group was significantly less than in either the HFA-BDP (p = 0.024) or the CFC-BDP (p = 0.011) groups. Decreases in serum cortisol concentrations AUC(0-24) in the two BDP groups did not differ from one another. The MF-DPI group trended toward higher morning and evening PEF than either BDP group. Treatment-associated adverse events were reported by seven subjects in the MF-DPI group, vs one subject in the HFA-BDP and three subjects in the CFC-BDP groups; these were mild, and no subject discontinued treatment due to an adverse event.

CONCLUSIONS

Fourteen days of treatment with MF-DPI 400 microg qd was associated with a significantly lesser decrease in the serum cortisol concentrations AUC(0-24) compared with HFA-BDP 200 microg MDI or CFC-BDP 400 microg MDI bid.

Incorporating pharmacokinetic differences between children and adults in assessing children's risks to environmental toxicants

Children's risks from environmental toxicant exposure can be affected by pharmacokinetic factors that affect the internal dose of parent chemical or active metabolite. There are numerous physiologic differences between neonates and adults that affect pharmacokinetics including size of lipid, and tissue compartments, organ blood flows, protein binding capacity, and immature function of renal and hepatic systems. These factors combine to decrease the clearance of many therapeutic drugs, which can also be expected to occur with environmental toxicants in neonates. The net effect may be greater or lesser internal dose of active toxicant depending upon how the agent is distributed, metabolized, and eliminated. Child/adult pharmacokinetic differences decrease with increasing postnatal age, but these factors should still be considered in any children's age group, birth through adolescence, for which there is toxicant exposure. Physiologically based pharmacokinetic (PBPK) models can simulate the absorption, distribution, metabolism, and excretion of xenobiotics in both children and adults, allowing for a direct comparison of internal dose and risk across age groups. This review provides special focus on the development of hepatic cytochrome P-450 enzymes (CYPs) in early life and how this information, along with many factors unique to children, can be applied to PBPK models for this receptor population. This review describes a case study involving the development of neonatal PBPK models for the CYP1A2 substrates caffeine and theophylline. These models were calibrated with pharmacokinetic data in neonates and used to help understand key metabolic differences between neonates and adults across these two drugs.

Deposition and effects of inhaled corticosteroids

Inhaled corticosteroids are now recommended as maintenance therapy for all but the mildest cases of asthma, and may be delivered by a variety of devices and formulations. Drug delivery may be assessed by both in vitro and in vivo methods. Although drug deposition in the lungs is expected to predict clinical response, this relationship is often masked by the flat nature of corticosteroid dose-response curves. The effects of inhaled corticosteroids depend not only upon the pharmacology of the drug being administered, but also upon its delivery system, with more efficient devices not only improving therapeutic effect but also potentially increasing systemic adverse effects. Modern delivery systems that enhance drug targeting to the lungs make it possible to use lower dosages of inhaled corticosteroid, such that the clinical response is maintained but systemic exposure reduced.

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.

Therapeutic ratio of hydrofluoroalkane and chlorofluorocarbon formulations of fluticasone propionate

OBJECTIVES

To compare the therapeutic ratio of chlorofluorocarbon (CFC) and hydrofluoroalkane-134a (HFA) formulations of fluticasone propionate (FP).

METHODS

We performed a randomized, placebo-controlled, crossover study comparing 6 weeks of treatment with FP using 500 micro g/d and 1,000 microg/d formulations of CFC and HFA. The primary end points were provocative dose of methacholine causing a 20% fall in FEV1 (PD20) and overnight urinary cortisol/creatinine excretion.

RESULTS

Eighteen patients with mild-to-moderate asthma and geometric mean (SEM) PD20 of 82.3 micro g (19.2 micro g) completed the study. All treatments significantly improved PD20 values and morning peak expiratory flow vs placebo, while 1,000 microg/d was significantly better than 500 microg/d for the CFC formulation of FP (CFC-FP) but not the HFA formulation of FP (HFA-FP). Only 1,000 microg/d of CFC-FP caused significant suppression of overnight urinary cortisol/creatinine compared to placebo. There were no differences between formulations at either dose.

CONCLUSIONS

The increased airway benefit with CFC-FP > 500 microg/d was offset by greater systemic effects. Although HFA-FP had fewer systemic effects than CFC-FP at 1,000 microg/d, there was no benefit to increasing HFA-FP to > 500 microg/d.

A comparison of methods for assessing hypothalamic-pituitary-adrenal (HPA) axis activity in asthma patients treated with inhaled corticosteroids

Suppression of the hypothalamic-pituitary-adrenal (HPA) axis is an accepted indicator of potential side effects from inhaled corticosteroids. Although cortisol monitoring is frequently used to detect changes in HPA axis activity, the optimal method for identifying the subset of asthma patients on inhaled steroids who experience severe cortisol suppression of potential clinical significance has not been established. The objective of this study was to compare several methods for assessing HPA axis activity in asthma patients taking inhaled corticosteroids. After screening, 153 patients with mild to moderate asthma were randomly assigned to receive inhaled fluticasone propionate (110, 220, 330, or 440 microg bid), flunisolide (500 microg or 1000 microg bid), or one of two control regimens (prednisone or placebo) for 21 days. Salivary (8 a.m.) and urinary (24-h) cortisol determinations were compared against 22-hour area under the serum cortisol concentration-time curve (AUC0-22 h) measured at baseline and on day 21. Comparisons were also made against 8 a.m. serum cortisol. A significant positive correlation was found between AUC0-22 h of serum cortisol and 8 a.m. serum cortisol level (r = 0.5140; p = 0.0001). The AUC0-22 h of serum cortisol was weakly correlated with 24-hour urinary cortisol levels, both corrected (r = 0.4388; p = 0.0001) and uncorrected (r = 0.3511; p = 0.0001) for creatinine excretion. The 8 a.m. salivary cortisol level correlated positively with the 8 a.m. serum cortisol level (r = 0.5460; p = 0.0001). Salivary cortisol was both sensitive and specific for the detection of a 50% decline in AUC0-22 h of serum cortisol. Cortisol reductions of this magnitude have been observed following repeated use of inhaled steroids. Because it is noninvasive, salivary cortisol measurement offers distinct advantages as a screening method for detecting pronounced HPA axis suppression in asthma patients receiving corticosteroid therapy.

Single-dose and steady-state pharmacokinetic and pharmacodynamic evaluation of therapeutically clinically equivalent doses of inhaled fluticasone propionate and budesonide, given as Diskus or Turbohaler dry-powder inhalers to healthy subjects

Direct comparisons of the pharmacokinetic (PK) and systemic pharmacodynamic (PD) properties of inhaled corticosteroids after single and multiple dosing in the same subjects are scarce. The objective of this study was to compare thePK/PDproperties of clinically equivalent, single, and multiple doses of dry-powder formulations of inhaled fluticasone propionate (FP 200 and 500 microg via Diskus) and budesonide (BUD, 400 and 1,000 microg via Turbohaler). Fourteen healthy subjects completed a double-blind, double-dummy, randomized, placebo-controlled, five-way crossover study consisting of a single dose administered at 8 a.m. on day 1 followed by 4 days of twice-daily dosing at 8 a.m. and 8 p.m. on days 2 to 5. Serum concentrations of FP and BUD were measured using validated liquid chromatography/ mass spectrometry assays. The 24-hour cumulative cortisol suppression (CCS) in serum was monitored as the pharmacodynamic surrogate marker. Peak serum concentrations following single and multiple dosing were observed 10 to 30 minutes after inhalation for BUD and 30 to 90 minutes afterinhalation of FP with no influence of dose ordosingregimen. After a single dose of 1000 microg BUD and 500 microg FP the median estimates of terminal half-life and mean residence time were 3.5 and 3.9 hours for BUD and 10.1 and 12.0 hours for FP, respectively. Using previously reported intravenous data, the mean absorption times (MAT) were calculated to be around 2 hours and 7 hours for BUD and FP respectively. On average, the area under the curve (A UC) at steady state (day 5) was up to 30% higher for BUD compared to that over a 12-hour period following the first dose on day 1, whereas A UC estimates were 50% to 80% higherforFP at steady state, indicating accumulation. However, the steady-state Cmax values were seven to eight times and AUC values three to four times higher for BUD than for FP. Comparison of active treatment data with placebo showed that CCS after a single dose was not pronounced for any of the doses/drugs studied. On day 5, both doses of BUD caused statistically significant suppression (CCS of 19% for the 400 microg dose and 36% for the 1,000 microg dose). For FP only the high dose had a statistically significant effect on serum cortisol (CCS of 14% for the 200 microg dose and 27% for the 500 microg dose). Compared to BUD, FP has slower pulmonary absorption and slower elimination kinetics. However, following inhalation of therapeutically equipotent, multiple twice-daily doses in healthy subjects, the systemic effects of FP delivered via Diskus on AUC24 serum cortisol were relatively low and similar to those of BUD delivered via Turbohaler.

Safety of inhaled corticosteroids in children with asthma

Inhaled corticosteroids (ICS) have become the mainstay of therapy in chronic childhood asthma. Despite the long history and the documented efficacy of these drugs in controlling asthma, concerns still abound regarding the safety of these drugs in children, most specifically related to the potential for adrenal suppression and growth retardation. Recently published studies suggest that adrenal function remains intact when low and moderate doses of these drugs are used. Long-term studies of growth in children suggest that despite an initial decrease in growth velocity, ultimate adult height is not affected significantly by the use of ICS. Other complications of glucocorticoids are not usually seen with low and moderate doses. With proper monitoring and follow-up observation, asthma control can be achieved with these drugs in a safe and effective manner.

Pharmacokinetics of fluticasone propionate inhaled via the Diskhaler and Diskus powder devices in healthy volunteers

OBJECTIVE

The aim of these studies was to determine the absolute bioavailability in healthy volunteers of inhaled fluticasone propionate (FP) administered as a single dose via the Diskhaler and Diskus powder devices, and the pharmacokinetics of inhaled FP after repeated administration via the Diskhaler device.

METHODS

In 2 of the studies, single inhaled doses of FP were administered via the Diskhaler and the Diskus powder devices, and, in the third study, repeated doses of FP were administered via the Diskhaler. In the single dose studies, 12 healthy volunteers were randomised to receive FP 1000 microg by inhalation and FP 250 microg intravenously, using a double-blind crossover design. In the repeated dose study, 24 healthy volunteers received FP 1000 microg twice daily for 7.5 days.

RESULTS

Systemic exposure to FP after administration of a single 1000 microg inhaled dose of FP via the 2 powder devices was similar; the area under the plasma FP concentration-time curve (AUC) to infinite time (AUCinfinity) was 2.08 microg/L x h [95% confidence intervals (CI): 1.63-2.64] for Diskhaler and 2.49 microg/L x h (95% CI: 2.09-2.96) for Diskus. Maximum plasma FP concentration (Cmax) was 0.34 microg/L for both devices. Mean bioavailability values via the Diskhaler and Diskus were 11.9% (95% CI: 9.0-15.7%) and 16.6% (95% CI: 13.6-20.3%), respectively. No clinically significant reductions in urinary cortisol excretion were recorded in these 2 studies. After repeated administration with the Diskhaler, steady state was achieved by dose 3 (i.e. day 2) onwards. After dose 15, the AUC up to 12 hours (AUC12h) was 2.25 microg/L x h and Cmax was 0.38 microg/L. The mean steady-state to single dose accumulation ratio after twice-daily administration was 1.49 (95% CI: 1.36-1.62).

CONCLUSION

The pharmacokinetics of FP administered by the 2 powder devices are similar in healthy volunteers, although systemic bioavailability was greater with the Diskus.

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.