Pharmacological factors that influence the choice of inhaled corticosteroids

Influence of dentures on residual inhaled corticosteroids in the mouths of elderly asthma patients

BACKGROUND

The influence of dentures on residual inhaled corticosteroids (ICSs) in the mouths of elderly asthmatic patients and the appropriate time for gargling after inhaling ICSs are unclear.

METHODS

Twenty elderly patients in whom moderate persistent asthma was stably controlled using fluticasone propionate Diskus (FP, n = 10) or hydrofluoroalkane-beclomethasone dipropionate (HFA-BDP, n = 10) for more than 3 months and who wore dentures daily were switched to the other type of ICS for 4 weeks in a crossover manner. The residual amount of each ICS in their mouths after inhalation was measured along with determination of peak inspiratory flow (PIF) and pharyngeal culture for detecting Candida albicans.

RESULTS

The total amounts of residual ICSs in gargling fluids (μg) with HFA-BDP were significantly greater than those with FP (15.6 ± 14.6 vs. 11.5 ± 13.8, p = 0.028). The residual amounts of HFA-BDP were significantly greater in the patients with complete dentures than in those with partial dentures. The residual amounts of FP were significantly correlated with the PIF values in the FP treatment (p = 0.013) but not in the HFA-BDP treatment (p = 0.202). No residual ICSs remained after the third gargling in either treatment. The occurrence of candidiasis during the HFA-BDP period was significantly higher than that during the FP treatment (p = 0.046).

CONCLUSION

The dentures of elderly asthmatics affect the oral residues of ICSs and occurrence of candidiasis in HFA-BDP treatment; meanwhile, the PIF values affected these factors in FP treatment. Three times gargling after inhaling ICSs is required.

Evidence of the in vivo esterification of budesonide in human airways

AIMS

Budesonide, unlike fluticasone propionate, undergoes fatty acid esterification in the lungs, and there is a need to characterize fully the distribution and fate of the two drugs after inhalation in humans.

METHODS

This open-label, randomized study was performed in adults undergoing whole lung or lobar resection resulting from lung cancer. Patients were given single 1000-mug doses of both budesonide and fluticasone propionate via dry powder inhalers before surgery. Tissue samples from peripheral and central lung, an ex vivo bronchial brush sample and intercostal muscle, together with plasma samples, were taken during surgery and analysed by liquid chromatography plus tandem mass spectrometry.

RESULTS

Lung tissue samples were obtained from 22 patients at surgery, 1-43 h after drug dosing. Budesonide was detectable from earliest sampling in central and peripheral lung tissue up to 10 h (in six of 22 samples), fluticasone propionate up to 22 h after inhalation (in 16 of 22 samples), and budesonide oleate up to 43 h after inhalation (in 21 of 22 samples). Budesonide, but not fluticasone propionate, was detected in intercostal muscle for up to 10 h after inhalation. Bronchial brush samples showed the presence of fluticasone propionate for up to 18 h, suggesting the presence of undissolved drug powder particles in the airway lumen.

CONCLUSION

Sustained retention of esterified budesonide in the lungs supports the prolonged duration of action of budesonide and suitability for once-daily administration.

Evaluation of tests of hypothalamic-pituitary-adrenal axis function used to measure effects of inhaled corticosteroids

OBJECTIVES

To review the evidence supporting the evaluation of hypothalamic-pituitary-adrenal (HPA) axis function as a measure of systemic exposure and clinical adverse events, discuss factors that affect systemic exposure to inhaled corticosteroids (ICSs), and review the effects of various ICSs that are currently available or under development on HPA axis function from a therapeutic perspective.

DATA SOURCES

Randomized published clinical trials and review articles on the topic of HPA axis suppression were retrieved in MEDLINE. Searches dating back to 1988 were restricted to human studies published in English.

STUDY SELECTION

Studies that evaluated HPA axis function and the methods used to measure its activities and the effects of ICSs (fluticasone propionate, budesonide, beclomethasone dipropionate, mometasone furoate, and ciclesonide) were selected.

RESULTS

Factors that influence adverse events caused by ICSs include pharmacokinetic and pharmacodynamic properties, delivery devices, and therapeutic dose and duration. Basal measurements of blood and urinary cortisol levels, reflecting basal HPA axis function, are the most sensitive markers for assessing systemic ICS bioavailability but, compared with dynamic stimulation tests, are poor clinical predictors of adrenal dysfunction.

CONCLUSIONS

Basal serologic and urinary cortisol tests provide the best measures of assessing and comparing systemic ICS exposure. Long-term clinical studies are needed to determine whether such tests are predictive of ICS toxicity.

Airway selectivity: an update of pharmacokinetic factors affecting local and systemic disposition of inhaled steroids

Topical corticosteroids remain the most efficacious single treatment for asthma and rhinitis, despite the emergence of newer drugs in recent years. The antiinflammatory properties of these products, combined with the targeting of formulations and optimization of the intrinsic pharmacokinetic features of the newer corticosteroid molecules has resulted in substantially improved airway selectivity. This review sets out to summarize the pharmacokinetic properties of inhaled corticosteroids that are important for the achievement of high levels of airway selectivity, with additional focus on the use of prodrugs/softdrugs relative to those of conventional corticosteroid molecules, mechanisms (such as esterification) by which retention at the target site is achieved while minimizing systemic exposure, and the role of plasma protein binding.

Pharmacologic characteristics and adrenal suppression with newer inhaled corticosteroids: A comparison of ciclesonide and fluticasone propionate

BACKGROUND

Inhaled corticosteroids (ICSs) are the most potent anti-inflammatory choice for patients with asthma. Selecting the most appropriate ICS for a patient requires a thorough understanding of the pharmacologic properties of each drug.

OBJECTIVE

This review details the pharmacologic properties of ciclesonide (CIC) and fluticasone propionate (FP) and reviews the available data on suppression of the hypothalamic-pituitary-adrenal axis as a measure of systemic exposure and safety profile.

METHODS

Clinical studies and case reports were identified through a MEDLINE and EMBASE search of English-language articles. The databases were searched for the years 1990 to April 2005 using the terms ciclesonide, fluticasone, ICS, and adrenal suppression. All studies were clinical trials of pharmacologic properties of the ICSs in humans.

RESULTS

A total of 1082 articles were identified. CIC and FP are 2 of the most potent ICSs. Both have high receptor-binding affinities (12 times and 18 times that of dexamethasone, respectively), and both may provide enhanced respiratory effects through a prolonged pulmonary residence time. The CIC metered dose inhaler dispenses smaller and more highly respirable particles than FP (1.1-2.1 pm vs 2.8-3.2 microm, respectively). Therefore, a greater percentage of administered CIC is topically deposited in the lungs (52% vs 12% to 13% for FP). CIC is delivered as an inactive parent compound, which is converted to its active metabolite, desisobutyryl-CIC (des-CIC), by esterases in the airways. More than 50% of a dose of CIC is deposited and distributed evenly throughout the lungs of healthy adults; lipid conjugation in the lung also may increase lung residence time. On entering the systemic circulation, both corticosteroids are rapidly cleared by the liver (elimination half-life of 3.5 hours for CIC vs 7.8 hours for FP). However, plasma protein binding is greater with CIC/des-CIC (99%/ approximately 99%) than FP (90%), resulting in reduced amounts of des-CIC (<I%) versus FP (10%) circulating free in the plasma. Although studies of low or medium doses of FP have produced conflicting results, high doses of FP (>660 pg/d) may result in adrenal suppression. CIC has not been reported to produce any significant adrenal suppression throughout its studied dose range (up to 1280 micro/d).

CONCLUSIONS

A review of the literature suggests that CIC, as compared with FP, achieves greater pulmonary deposition, causes fewer adverse oropharyngeal effects, deposits less biologically active drug in the systemic circulation, and has less potential for adrenal suppression.

Budesonide-formoterol (inhalation powder) in the treatment of COPD

The budesonide-formoterol dry powder inhaler (Symbicort Turbuhaler 160/ 4.5-640/18 microg/day) contains the long-acting beta2-adrenoreceptor agonist formoterol and the inhaled corticosteroid budesonide. Two large, 12-month trials examined the effect of budesonide-formoterol 160/4.5 microg twice daily in COPD patients who met these criteria. The studies were identical, except one in which the patients had received oral prednisolone 30 mg/ day and had inhaled formoterol 4.5 microg twice daily for 2 weeks before randomization. In terms of the FEV1, budesonide-formoterol produced an effect greater than that of both budesonide alone and formoterol alone reported in previous studies. The combination was generally more effective than either of the components in terms of peak expiratory flow, symptoms, and exacerbations. These advantages of the combination over those of either budesonide alone or formoterol alone were quite consistent. Improving lung function and decreasing symptoms significantly, budesonide-formoterol combination therapy provides significant clinical improvements in COPD, despite the limited reversibility of impaired lung function in the disease.

Safety of inhaled corticosteroids: room for improvement

Inhaled corticosteroids (ICS) are the standard of care in asthma and are widely used in the treatment of patients with chronic obstructive pulmonary disease. High-dose regimens and long-term use of ICS in predisposed individuals may be associated with a variety of side effects, similar to those observed with systemic corticosteroid therapy. Side effects associated with long-term ICS use include reduction in growth velocity, cataracts, glaucoma, osteoporosis, and fractures. Fear of unwanted complications may be of concern in all patients using ICS, particularly in age- and gender-specific populations that are more prone to develop side effects or to reduce treatment adherence because of physical, behavioral, or psychological problems. In addition to concerns about ICS safety, dosing regimens that are difficult to follow may further reduce a patient's ability to comply with treatment. Ciclesonide, a new-generation ICS with unique pharmacokinetic properties, was developed to provide effective anti-inflammatory control for asthma with once-daily administration to improve patient adherence and a high safety profile to reduce the occurrence of local and systemic side effects.

Pharmacological Approach to Evaluate Aerosol Pulmonary Deposition

Drug delivery to the lung in vivo may be assessed using pharmacokinetic or pharmacodynamic techniques. The choice of method depends on drug class specificities. Pharmacokinetic determination of deposition to the lung for drugs without hepatic first-pass effect, such as short acting beta2-agonists, has to be done shortly after inhalation to minimize the effect of gastrointestinal absorption. For medication undergoing important hepatic first-pass metabolisation, such as inhaled corticosteroid, plasma concentration indirectly reflects bronchial deposition. The pharmacodynamic profile should be assessed through clinical effects and adverse events induced by inhaled drugs. Dose ranking of lung deposition for bronchodilators requires patient selection with sufficient bronchial obstruction to maintain room for improvement after the first dose. To assess dose effect relationship between inhaled corticosteroid, the Finney parallel line bioassay is the reference method with a study period of at least 6 weeks. Analysis of side effects with high doses of beta2-agonists or inhaled corticosteroids may also be used to compare lung deposition. Finally, pharmacological evaluation of lung deposition provides complementary information to scintigraphic studies, based on their clinical relevance.

Protection by budesonide and fluticasone on allergen-induced airway responses after discontinuation of therapy

BACKGROUND

Treatment with inhaled steroids is an effective method of reducing bronchoconstriction and airway inflammation after allergen challenge. However, the duration of the protective effects of inhaled steroids after discontinuation of therapy has not been established.

OBJECTIVE

We sought to evaluate the protective effect of 1 week of inhaled steroid therapy against inhaled allergen challenge 12 hours after discontinuation of therapy.

METHODS

In this randomized, double-blind, placebo-controlled crossover trial, 26 asthmatic subjects (>18 years old) not using inhaled steroids were administered 200 microg of budesonide twice daily, 200 microg of fluticasone twice daily, or placebo twice daily for 1 week. Twelve hours after discontinuation of therapy, subjects were administered an inhaled allergen challenge. Each treatment period was separated by a 3-week washout period.

RESULTS

When compared with placebo (26% +/- 14%), there was a slight but significant protection against the allergen-induced early response after fluticasone treatment (19% +/- 10%, P = .001) but not after budesonide treatment (23% +/- 13%, P = .08). However, when the area under the curve for the early airway response was examined, there was no difference between the 2 drugs in the amount of protection ( P = .62). Partial protection was demonstrated against the late-response allergen-induced sputum eosinophilia with both treatments ( P = .001). By contrast, no protection was observed against allergen-induced airway hyperresponsiveness for either treatment.

CONCLUSIONS

The protective effects of inhaled steroids against allergen-induced early responses, airway eosinophilia, and allergen-induced airway hyperresponsiveness are partially or completely lost as early as 12 hours after discontinuation of therapy.

Budesonide/formoterol: a review of its use in asthma

Budesonide and formoterol have been combined in a single dry powder device, Symbicort Turbuhaler (budesonide/formoterol 160/9-640/18 microg/day), in an effort to simplify asthma management. The efficacy of budesonide/formoterol as maintenance therapy in patients with asthma has been examined in several randomised studies.Twice-daily budesonide/formoterol was significantly more effective than an equivalent or higher daily dose of budesonide alone or high-dose fluticasone propionate alone at improving peak expiratory flow (PEF) in adults with predominantly moderate persistent asthma. Symptom control and the risk of mild exacerbations were significantly improved versus budesonide alone. Moreover, budesonide/formoterol appeared to be as effective as concurrent therapy with equivalent dosages of budesonide and formoterol administered via separate inhalers in adults with moderate persistent asthma. Budesonide/formoterol administered once daily was as effective as twice-daily administration (equivalent daily doses) and more effective than once-daily budesonide in adults with moderate persistent asthma. Twice-daily budesonide/formoterol significantly improved PEF compared with budesonide in paediatric patients with asthma. Adjustable maintenance dosing with budesonide/formoterol was associated with significantly less study drug use than fixed dosing with budesonide/formoterol in adults with predominantly mild or moderate persistent asthma. In two of three studies (all longer than 4 months' duration), the risk of exacerbations was significantly lower with adjustable than with fixed dosing, but no difference was detected in four short-term studies. Symptom severity was maintained or improved in most patients receiving either treatment regimen. In adults with moderate-to-severe persistent asthma, adjustable maintenance dosing with budesonide/formoterol reduced the rate of exacerbations and reliever medication use compared with fixed dosing with salmeterol/fluticasone propionate. Budesonide/formoterol was well tolerated in both fixed and adjustable dosing regimens. In conclusion, in patients with persistent asthma symptoms despite treatment with inhaled corticosteroids, budesonide/formoterol administered via a single dry powder Turbuhaler device is an effective, well tolerated, convenient treatment option, which may have the potential for improved compliance. It appears to be as effective as treatment with budesonide and formoterol administered via separate inhalers and is more effective than budesonide monotherapy in improving PEF, controlling symptoms and preventing mild exacerbations. Adjustable maintenance dosing with budesonide/formoterol is associated with a lower overall dosage and appears to maintain control as effectively as fixed dosing.

Budesonide/formoterol: in chronic obstructive pulmonary disease

Budesonide/formoterol is a fixed-dose combination of the corticosteroid budesonide and the long-acting beta2-agonist formoterol, and is inhaled via the Turbuhaler device. In two large, randomised, double-blind, 12-month studies, patients with severe chronic obstructive pulmonary disease (COPD) receiving budesonide/formoterol 320/9 microg twice daily had a significantly higher forced expiratory volume in 1 second (FEV1) and significantly higher morning and evening peak expiratory flow at trial endpoint than recipients of budesonide or placebo; FEV1 was significantly higher than with formoterol in the larger study. In both studies, the rate of COPD exacerbations and exacerbations requiring oral corticosteroids was significantly reduced with budesonide/formoterol versus formoterol and placebo. Moreover, the time to first exacerbation was significantly prolonged with budesonide/formoterol versus all other treatment arms in the larger study. At 12 months, significant improvements in health-related quality-of-life scores were seen with budesonide/formoterol versus placebo in both studies. The reduction in total and individual symptom scores was significantly greater with budesonide/formoterol than with budesonide or placebo in the smaller study. Budesonide/formoterol was generally well tolerated by patients with severe COPD. The tolerability profile of the combination was similar to that of the individual components with no increase in the incidence of adverse events.

Review of the unique properties of budesonide

BACKGROUND

The aim of inhaled corticosteroid (ICS) therapy for asthma is to attain high therapeutic activity in the airways while keeping the risk of systemic adverse effects relatively low. However, the physicochemical and pharmacokinetic properties of various ICSs affect this ratio, thereby influencing their ability to fulfill the requirements of an ideal agent.

OBJECTIVE

This article reviews the physical and pharmacokinetic properties of budesonide, outlining how they, safety data, and use of different inhalation devices enable budesonide to meet many of the clinical requirements of an ideal ICS for the treatment of asthma.

RESULTS

ICS efficacy is influenced by lipophilicity, lung deposition, and retention in airway tissue, whereas the rate of elimination determines systemic activity. Budesonide is retained in the airways to a greater extent than other ICSs because of an esterification process that increases its lipophilicity. The prolonged retention of budesonide in the airways may contribute to its efficacy when administered QD. In addition to a pressurized metered-dose inhaler, budesonide is available as a dry-powder inhaler and in nebulized form, which can be used by asthma patients aged > or =6 months.

CONCLUSIONS

When combined with delivery devices suitable for a spectrum of patient groups, the physical and pharmacokinetic properties of budesonide lend it many of the characteristics of an ideal ICS, including favorable efficacy and tolerability profiles.

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

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

Flunisolide HFA vs flunisolide CFC: pharmacokinetic comparison in healthy volunteers

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

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.

Suppression of hypothalamic-pituitary-adrenal axis activity with inhaled flunisolide and fluticasone propionate in adult asthma patients

BACKGROUND

Suppression of the hypothalamic-pituitary-adrenal (HPA) axis, a potential systemic effect of inhaled corticosteroid therapy, can be quantified by monitoring serum, urinary, and salivary cortisol levels.

OBJECTIVES

1) Compare the effects on HPA axis of the inhaled corticosteroids flunisolide and fluticasone propionate versus placebo and oral prednisone. 2) Estimate dose-potency ratio for HPA-axis suppression.

METHODS

Multicenter, randomized, placebo-controlled, open-label, 21-day trial. Active regimens were flunisolide 500 and 1,000 microg, twice daily; fluticasone propionate 110, 220, 330, and 440 microg, twice daily; and prednisone, 7.5 mg daily. Enrolled patients were nonsmokers, 18 to 50 years of age, with persistent mild-to-moderate asthma and had not used oral, nasal, or inhaled corticosteroids for 6 months before study. Main outcome measures were area under serum cortisol concentration curve for 22 hours (AUC(0-22h)); 24-hour urinary cortisol level; and 8 AM salivary cortisol level.

RESULTS

One hundred fifty-three patients were randomly assigned to active treatment or placebo; 125 patients completed the study and were at least 80% compliant with their regimens. Both fluticasone propionate and flunisolide caused dose-dependent suppression of HPA axis, which was statistically greater for fluticasone propionate (P = 0.0003). Dose-potency ratio showed 4.4 times more serum-cortisol suppression/microgram increase in dose with fluticasone propionate than with flunisolide. Diurnal pattern of serum cortisol suppression was persistent with fluticasone propionate and "remitting" with flunisolide. Salivary and urinary cortisol data were qualitatively similar to serum cortisol results.

CONCLUSIONS

Fluticasone caused significantly more suppression of HPA axis than flunisolide. Flunisolide may provide a safe option for patients with asthma requiring long-term inhaled corticosteroid therapy.

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.

Inhaled budesonide/formoterol combination

Current evidence suggests that the addition of the long acting inhaled beta2-agonist formoterol to low or moderate doses of the inhaled corticosteroid budesonide is effective in improving lung function and reducing the incidence of asthma exacerbations. Concurrent use of budesonide with formoterol does not result in any untoward interaction that affects the pharmacodynamic or pharmacokinetic profiles of the individual drugs, or their adverse effect profiles. The administration of combined budesonide/formoterol is effective in improving morning and evening peak expiratory flow rates in adults with persistent asthma. Control of asthma symptoms is also significantly improved. In children aged 4 to 17 years, combined budesonide/formoterol is effective in increasing both morning and evening peak expiratory flow rates and significantly improving forced expiratory volume in 1 second (FEV1). The most commonly encountered adverse effects in clinical trials with combination budesonide/formoterol therapy have been respiratory infection, pharyngitis and coughing. No adverse effects on pulse rate, blood pressure or serum potassium have been reported with combination therapy.

Clinical considerations in the use of inhaled corticosteroids for asthma

Inhaled corticosteroids are the most potent and effective therapy for treating asthma. They exert their pharmacologic action through activation of the glucocorticoid receptor, which helps regulate gene transcription. Corticosteroids also directly inhibit several inflammatory mediators involved in the pathophysiology of asthma. In randomized, controlled clinical trials, inhaled corticosteroids, as monotherapy, are superior to other therapies in improving lung function and clinical outcomes in patients with asthma. However, the use of inhaled corticosteroids is limited by concerns of dose-related adverse effects, including growth suppression and decreased bone density. Combination regimens with these agents and other long-term therapies are beneficial in maintaining asthma control while minimizing dose-related toxicities. Several inhaled corticosteroid products are available in the United States. They differ in potency; however, clinical efficacy is similar when equipotent doses are administered. A variety of factors influence product selection and patient response, including the therapeutic ratio, pharmacokinetic properties, and the inhalation delivery device. In addition, adherence to therapy and the patient's skill in administering the inhaled drug contribute to the therapeutic outcome.

Nasal retention of budesonide and fluticasone in man: formation of airway mucosal budesonide-esters in vivo

AIMS

The efficacy of topical glucocorticosteroids in rhinitis and asthma is likely to depend on drug retention in the airway mucosa. With fluticasone propionate, retention may be achieved exclusively by lipophilicity, whereas for budesonide an additional possibility may be provided by its ability to form fatty acid esters in the airway mucosa that release the active drug. The aim of the present study was to determine the nasal mucosal retention of budesonide and fluticasone propionate, and the occurrence of budesonide-esters (budesonide-oleate, budesonide-palmitate) in the nasal mucosa.

METHODS

In the present study, involving 24 healthy subjects, we have examined nasal mucosal drug retention of single doses of topical budesonide (256 microg) and fluticasone propionate (200 microg). Treatments were given consecutively and the administration sequence was randomised. Subjects were randomised into four parallel groups and two nasal biopsies were taken from each subject, i.e. before and at 2 h, at 2 and 6 h, at 6 and 24 h, or before and at 24 h after drug administration, resulting in 12 biopsies/time point. The measurement of unesterified budesonide, budesonide-oleate, budesonide-palmitate, and fluticasone propionate was based on microwave extraction procedures combined with liquid-chromatography/tandem mass-spectrometry.

RESULTS

Neither of the analytes was detected in samples taken before glucocorticosteroid administration. After administration, unesterified budesonide, budesonide-esters, and fluticasone propionate were detected in the tissue from 23, 20, and 19 subjects, respectively. The mean tissue levels of budesonide at 2 and 6 h were 1051 and 176 pmol g(-1); the mean levels of fluticasone propionate at these time points were 237 and 10 pmol g(-1). The dose-corrected budesonide/fluticasone propionate tissue concentration ratios were 3.5 (P = 0.07) and 13.7 (P < 0.0002), respectively. At 24 h, budesonide and fluticasone propionate were detected in 8/12 and 3/12 of the biopsies, respectively.

CONCLUSIONS

The present study demonstrates the formation of budesonide-esters in the human nasal mucosa in vivo, and that budesonide is retained in the nasal mucosa to a greater extent than fluticasone propionate. It is suggested that the formation of budesonide-esters and their subsequent release of budesonide contributes to an extended retention of budesonide in the airway mucosa.

Budesonide inhalation suspension: a review of its use in infants, children and adults with inflammatory respiratory disorders

Budesonide, a topically active corticosteroid, has a broad spectrum of clinically significant local anti-inflammatory effects in patients with inflammatory lung diseases including persistent asthma. In infants and young children with persistent asthma, day- and night-time symptom scores, and the number of days in which beta2-agonist bronchodilators were required, were significantly lower during randomised, double-blind treatment with budesonide inhalation suspension 0.5 to 2 mg/day than placebo in 3 multicentre trials. Significantly fewer children discontinued therapy with budesonide inhalation suspension than with placebo because of worsening asthma symptoms in a study that included children who were receiving inhaled corticosteroids at baseline. Recent evidence indicates that budesonide inhalation suspension is significantly more effective than nebulised sodium cromoglycate in improving control of asthma in young children with persistent asthma. At a dosage of 2 mg/day, budesonide inhalation suspension significantly reduced the number of asthma exacerbations and requirements for systemic corticosteroids in preschool children with severe persistent asthma. In children with acute asthma or wheezing, the preparation was as effective as, or more effective than oral prednisolone in improving symptoms. In children with croup, single 2 or 4mg dosages of budesonide inhalation suspension were significantly more effective than placebo and as effective as oral dexamethasone 0.6 mg/kg or nebulised L-epinephrine (adrenaline) 4mg in alleviating croup symptoms and preventing or reducing the duration of hospitalisation. Early initiation of therapy with budesonide inhalation suspension 1 mg/day appears to reduce the need for mechanical ventilation and decrease overall corticosteroid usage in preterm very low birthweight infants at risk for chronic lung disease. In adults with persistent asthma, budesonide inhalation suspension < or =8 mg/day has been compared with inhaled budesonide 1.6 mg/day and fluticasone propionate 2 mg/day administered by metered dose inhaler. Greater improvements in asthma control occurred in patients during treatment with budesonide inhalation suspension than with budesonide via metered dose inhaler, whereas fluticasone propionate produced greater increases in morning peak expiratory flow rates than nebulised budesonide. Several small studies suggest that the preparation has an oral corticosteroid-sparing effect in adults with persistent asthma and that it may be as effective as oral corticosteroids during acute exacerbations of asthma or chronic obstructive pulmonary disease. The frequency of adverse events was similar in children receiving budesonide inhalation suspension 0.25 to 2 mg/day or placebo in 12-week studies. During treatment with budesonide inhalation suspension 0.5 to 1 mg/day in 3 nonblind 52-week studies, growth velocity in children was generally unaffected; however, a small but statistically significant decrease in growth velocity was detected in children who were not using inhaled corticosteroids prior to the introduction of budesonide inhalation suspension. Hypothalamic-pituitary-adrenal axis function was not affected by short (12 weeks) or long (52 weeks) term treatment with nebulised budesonide. In conclusion, budesonide inhalation suspension is the most widely available nebulised corticosteroid, and in the US is the only inhaled corticosteroid indicated in children aged > or =1 year with persistent asthma. The preparation is suitable for use in infants, children and adults with persistent asthma and in infants and children with croup.

Rationale for once-daily therapy in asthma: compliance issues

Compliance in asthma is known to be poor. Once-daily treatment provides an additional therapeutic option for the clinician whose treatment aims include maximising treatment satisfaction and compliance. Once-daily treatment is preferred by some but not all patients and may lead to greater compliance in patients who are concerned about the effect of corticosteroids on their health. When switching to once-daily treatment, patients should be given a choice as to the time of treatment to minimise the impact of forgetting a dose.