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.

Application of the Food and Drug Administration (FDA) bioequivalent guidance of topical dermatological corticosteroid in yellow-skinned Japanese population: validation study using a chromameter

The American Food and Drug Administration (FDA) bioequivalent guidance of topical dermatological corticosteroids in 1995 (the Guidance) requires measurement of the skin blanching response with a chromameter for evaluation of cutaneously applied corticosteroid formulations. The Japanese government decided to apply the same guidelines in 2003, despite there having been no reported trial for the yellow-skinned races. The purpose of this study was to obtain basic data of corticosteroid-induced skin blanching response measured with a chromameter on yellow-skinned races. Four studies were performed according to the Japanese version of the Guidance for Industry using a chromameter on the forearms of healthy Japanese volunteers. This involved: (i) a validation study of proper duration of treatment exposure (dose duration); (ii) a comparison study of two dermatological corticosteroid products that represented different potency classes; (iii) inspection of reproducibility using right and left forearms; and (iv) study of seasonal difference. We showed that: (i) the same medication can give different values of ED(50) (the dose duration required to achieve 50% of the fitted areas under the effect curves [AUEC](max) value) under different dose durations; (ii) ED(50) do not always represent the potency of the corticosteroid; (iii) the results of AUEC at maximum duration were similar, but AUEC at an approximate ED(50) duration time varied widely; and (iv) the results of AUEC were different according to season. In conclusion the dose duration relationships, determination of the AUEC(max), and the ED(50) could be obtained on yellow-skinned races using the FDA method. However, negligible differences were found in our study regarding dose duration, reproducibility and seasonal change.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

The systemic safety of inhaled corticosteroid therapy: a focus on ciclesonide

OBJECTIVE

To review the potential systemic activity of ciclesonide and its active metabolite, desisobutyryl-ciclesonide, by evaluation of the effects on hypothalamic-pituitary-adrenal (HPA) axis function.

DATA SOURCES

EMBASE and MEDLINE searches using the keyword ciclesonide, without date restrictions, were conducted to identify published articles that related to clinical trials that included ciclesonide.

STUDY SELECTION

The primary articles that reported systemic safety data for ciclesonide were reviewed.

RESULTS

Ciclesonide (320-1,280 microg/d) demonstrated no detectable, clinically relevant effect on HPA axis function as evaluated by basal cortisol excretion measurements and dynamic stimulation tests. Furthermore, ciclesonide had no effect on the normal diurnal rhythm of endogenous cortisol secretion while simultaneously improving pulmonary function and reducing bronchial hyperresponsiveness. These results suggest that ciclesonide has a low systemic activity that may be attributable to unique pharmacologic properties, including a high degree of serum protein binding, a low oral bioavailability, and rapid systemic elimination, that reduce the level of systemically available pharmacologically active drug.

CONCLUSIONS

Even at the higher doses used to treat more severe cases of asthma, ciclesonide was observed to have no effect on HPA axis function. These data, in conjunction with the observed clinical efficacy, suggest that ciclesonide may have an improved therapeutic margin compared with some other currently available inhaled corticosteroid treatments and, therefore, the potential to improve therapeutic outcomes.

New developments in inhaled corticosteroids

Inhaled corticosteroids (ICSs) are the foundation of pharmacotherapy in persistent asthma because they control airway inflammation. The anti-inflammatory effect of ICSs is primarily topical, at their site of deposition in the airways. Consequently, deposition characteristics of the ICS and its formulation and inhalation device, in addition to intrinsic properties of the corticosteroid, influence clinical efficacy. Small-particle formulations, especially those developed in a metered-dose inhaler with the new hydrofluoroalkane propellant, may have improved lung deposition characteristics along with possibly improved clinical efficacy. Lipid conjugation of ICSs within the lungs may allow prolonged duration of effect, enabling once-daily dosing. Safety concerns of ICSs are related to systemic absorption and oropharyngeal deposition. An ICS with a longer serum half-life, especially one with a higher affinity for the corticosteroid receptor, may be associated with greater systemic effects. Increased protein binding of an ICS within the systemic circulation and high systemic clearance of an ICS may reduce the risk for systemic effects. Reduced oropharyngeal deposition and administration of a prodrug may result in fewer oropharyngeal side effects. The ideal ICS will have increased lung deposition and reduced deposition in the upper airway, resulting in better clinical efficacy and less risk for upper airway adverse effects. An ICS with high plasma protein binding and rapid clearance might pose much less risk for systemic adverse effects than currently available drugs in this class.

Ciclesonide: a novel inhaled corticosteroid

Inhaled corticosteroids (ICS) are a mainstay in the treatment of persistent asthma, a disease with increasing prevalence and cost implications worldwide. However, long-term use of currently available ICS is associated with local adverse effects that include hoarseness and oral candidiasis. In addition, systemic adverse effects including adrenal cortical suppression, osteoporosis, growth retardation, cataracts and glaucoma are also present. Ciclesonide is a novel ICS, which promises to provide airway anti-inflammatory efficacy that is comparable with that of the available ICS in addition to reducing the risk for local and systemic adverse events. Ciclesonide is an agent that is inactive until it reaches its target site, the lung, where it is converted to its active metabolite desisobutyryl-ciclesonide. In addition, other favourable pharmacokinetic and pharmacodynamic characteristics such as high protein binding, low oral bioavailability and rapid clearance contribute to the efficacy and improved systemic safety profile of ciclesonide.

Emitted dose estimates from Seretide Diskus and Symbicort Turbuhaler following inhalation by severe asthmatics

The dose emitted from dry powder inhalers may be inhalation flow-dependent. Using an ex vivo method, the Electronic Lung, we have measured the aerodynamic characteristics of the emitted dose for both active constituents from Seretide Diskus (salmeterol xinafoate 50 mcg; fluticasone propionate 500 mcg) and Symbicort Turbuhaler (formoterol 6 mcg; budesonide 200 mcg). Electronic inhalation profiles were collected from 20 severe asthmatics (mean PEFR 53% predicted) when they inhaled using a placebo Seretide Diskus and a placebo Symbicort Turbuhaler. These were replayed in the Electronic Lung with the respective active inhaler in situ. Mean(S.D.) peak inhalation flow rates (PIFR) through the Diskus and Turbuhaler were 94.7(32.9) and 76.8(26.2) l min(-1), respectively. From the Electronic Lung the Diskus inhalation profiles provided a mean(S.D.) fine particle dose (FPD) for fluticasone propionate and salmeterol of 20.4(4.8) and 18.4(4.4)% labelled dose. For Turbuhaler inhalation profiles the FPD was 23.1(12.9) and 20.7(11.1)% labelled dose for budesonide and formoterol, respectively. The linear (p < 0.001) relationships between FPD against PIFR for budesonide and formoterol were 3 (p = 0.002) and 2.8 (p = 0.007) times steeper than fluticasone propionate and salmeterol, respectively. The results highlight a more significant effect of inspiratory flow on variable dosage emission when using the Symbicort Turbuhaler compared with the Seretide Diskus.

Review in Pharmacokinetic Models on Corticosteroids

The pharmacokinetics of corticosteroids provides a large set of mathematical models which led to analyse many kinetic profiles corresponding to many clinical and/or physiological situations. In this paper, we present a review on the usefulness, advantages and limits of such models which could find a large application in medicinal chemistry.

Is the pharmacology of corticosteroids in the lung modified by age?

WHAT WE NEED TO KNOW: Is the lung in older patients with asthma less responsive to inhaled and systemic corticosteroids? (While anecdotal observations suggest this may be the case, no well conducted studies document the phenomenon.) WHAT WE NEED TO DO: Carefully plan a clinical study to compare corticosteroid responsiveness between older people with asthma and their younger counterparts. Select sensitive and clinically relevant outcome variables for this study.

Identification of enzymes involved in phase I metabolism of ciclesonide by human liver microsomes

Ciclesonide, a novel inhaled corticosteroid, is currently being developed for the treatment of asthma. Here, the enzymes catalysing the human hepatic metabolism of ciclesonide were investigated. When incubated with human liver microsomes (HLM), [14C]ciclesonide was first metabolised to the active metabolite M1 (des-isobutyryl-ciclesonide, des-CIC) and to at least two additional metabolites, M2 and M3. M3 comprises a 'family' of structurally similar metabolites that are inactive. 16-Hydroxyprednisolone was also formed in microsomal incubations of [14C]des-CIC, but at approximately one-tenth the amount of both M2 and M3. bis-p-Nitrophenylphosphate and SKF 525-A respectively inhibited des-CIC formation from [14C]ciclesonide by 82% and 49% and M2/M3 formation by 82-84% and 87-89%. Regression analysis showed significant negative correlations (r = -0.96, -0.79 and -0.71, respectively) of M2 formation with CYP3A4/5, CYP2B6 and CYP2C8 activities; M3 formation significantly correlated with CYP4A9/11 (r = 0.47). Troleandomycin and diethyldithiocarbamate inhibited M2 and M3 formation by 85% and 45%, respectively. Sulphaphenazole and quinidine had no inhibitory effects. CYP3A4 Supersomes catalysed notable formation of both M2 and M3 from [14C]des-CIC; CYP2C8 and CYP2D6, but not CYP4A11 formed smaller amounts. It is concluded that the human hepatic metabolism of ciclesonide is primarily catalysed by one or more esterases and, subsequently, by CYP3A4.

[The optimal dosing times of corticoids]

The therapeutic use of cortisol and its derivatives, anti-inflammatory corticoids, sets delicate problems to resolve because of cortisol's physiological roles and its circadian rhythms. Cortisol and the majority of its derivatives have desirable and undesirable effects that are time-related administration. The chronotherapeutic optimisation to increase desirable effects and safety of corticoids is shown in the treatment of adrenocortical failure, congenital adrenal hyperplasia and asthma. The knowledge of physiological and physiopathological rhythms of asthma permitted to realize oral treatment optimisation by using a number of corticoids. This knowledge puts in a prominent position the advantages of ciclesonide: a new inhaled corticoid. A chronobiologic approach could be used in a classic optimisation which involves a molecule modification and inhalation like routes of administration.

CONTRARY TO ADULT, NEONATAL RATS SHOW PRONOUNCED BRAIN UPTAKE OF CORTICOSTEROIDS

Neurotoxic adverse effects after systemic corticosteroid administration are elevated in preterm infants. To test whether this might be related to an immature blood-brain barrier (BBB) that permits corticosteroids to enter the brain and induce neurotoxic effects, this study assessed the differences in brain permeability of triamcinolone acetonide after intratracheal administration to neonatal (10- to 11-day-old) and adult rats. Triamcinolone acetonide (or the phosphate prodrug in the case of neonatal rats) was administered intratracheally to neonatal rats at doses of 2.5, 25, or 50 microg/kg and to adult rats at 100 microg/kg. An ex vivo receptor binding assay was used to monitor the cumulative brain and liver glucocorticoid receptor occupancies over 6 h. Brain and liver receptor occupancies in neonates were similar for the 25 and 50 microg/kg triamcinolone acetonide phosphate (brain/liver receptor occupancy ratio, 1.10 +/- 0.14 and 0.87 +/- 0.13, respectively), whereas some reduction in the brain permeability was seen at the lower dose. After intratracheal administration of 100 microg/kg triamcinolone acetonide to adult rats, receptor occupancies in the brain were significantly lower (brain/liver ratio, 0.21 +/- 0.14; p < 0.001). The study demonstrated that glucocorticoids enter the brain of neonatal rats because of an immature BBB. The results of this study support the hypothesis that neurotoxic adverse effects in preterm infants after systemic corticosteroid administration might be related to an immature BBB.

[Ciclesonide -- a new inhaled corticosteroid]

Ciclesonide is a novel inhaled corticosteroid delivered as inactive prodrug via a hydrofluoroalkane metered-dose inhaler with a deposition rate of 50 - 60 %. At its target sites, the lungs, ciclesonide is converted to an active metabolite, desisobutyryl-ciclesonide (des-CIC) [so-called on-site activation]. High lipophilicity and formation of local depot prolong pulmonary duration of action, explaining once-daily administration of ciclesonide. High protein binding and rapid clearance reduce systemic interactions. In long-term studies, ciclesonide at doses as high as 1280-1600 microg/d did not suppress biochemical markers of adrenal function. Since ciclesonide is not being activated in the oropharynx, the incidence of local adverse effects is comparable to that of placebo. Compared to other ICS, ciclesonide shows a improved therapeutic index and can, therefore, be regarded as prototype of a new, third generation of inhaled corticosteroids.

Inolimomab in steroid-refractory acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation: retrospective analysis and comparison with other interleukin-2 receptor antibodies

BACKGROUND

The use of monoclonal antibodies against interleukin-2 receptor (IL-2R)-alpha chains could be an effective treatment of acute graft-versus-host disease (GvHD). Experimental model and clinical studies have reported various results.

METHODS

Inolimomab is a murine anti-IL-2R. Eighty-five patients were evaluated retrospectively for the safety and efficacy of inolimomab given for the treatment of steroid-resistant acute GvHD (aGvHD) following allogeneic hematopoietic stem cell transplantation (HSCT). Diseases were immune deficiency, hematological malignancies, or solid tumors. Seventy-six percent of the patients received a myeloablative regimen. The source of HSCT was bone marrow for 45 patients, peripheral blood for 36 patients, and cord blood for 4 patients. Donors were 49 siblings and 36 unrelated. Acute GvHD was diagnosed within a median of 28 days after transplantation (grade II, 26 patients; grade III, 26 patients; grade IV, 33 patients). Inolimomab was administered in the event of steroid-resistant aGvHD with a median dose of 0.468 mg per kg (median period of treatment: 18 days).

RESULTS

Twenty-five complete responses and 29 partial responses (total response rate: 63%) were observed with no side effects. There was no correlation between aGvHD grading and quality of response. Better responses were observed in cutaneous aGvHD. The overall survival probability was 26% (median follow-up: 20 months). Fifty-seven percent of patients died of toxicity related mortality, mostly aGvHD. Response to inolimomab seemed sustained (11% relapse in responders).

CONCLUSION

Inolimomab is well-tolerated and effective for severe steroid-resistant aGvHD. The optimum regimen remains to be defined.

An in vivo and in vitro comparison of two powder inhalers following storage at hot/humid conditions

Dry powder inhalers (DPIs) are increasingly being used for the treatment of asthma and COPD. A potential drawback is that DPIs can be sensitive to humidity. Two DPIs, Symbicort Turbuhaler and Seretide Diskus, were stored 3 months at either 25 degrees C/30% RH or 40 degrees C/75% RH. After storage, delivered, as well as fine particle dose, FPD, were tested in vitro and lung deposition, of the steroid components, was assessed in vivo. After storage at 40 degrees C/75% RH, delivered dose as well as FPD from Symbicort Turbuhaler was virtually unchanged while FPD for Seretide Diskus decreased by about 50% despite no decrease in delivered dose. For both products, no difference in FPD was seen after storage at 25 degrees C/30% RH. These in vitro findings were confirmed in the in vivo part of the study. Lung deposition for Symbicort Turbuhaler was unaffected by 40 degrees C/75% RH storage, while for Seretide Diskus it was reduced with about 50%. The study extends previous in vitro observations of impaired performance of Seretide Diskus and demonstrates that this translates into decreased drug delivery to the site of action. The clinical importance of this finding has not been studied but could result in undertreatment.

Intranasal steroids: managing allergic rhinitis and tailoring treatment to patient preference

Allergic rhinitis (AR) can have a significant impact on patient quality of life (QoL), affecting learning ability and work productivity. Both the consequences of the impairment and the costs of treatment are associated with a large economic burden. The management of AR includes allergen avoidance, pharmacotherapy, and immunotherapy. Current pharmacotherapy options are oral and intranasal antihistamines, intranasal corticosteroids (INS), intranasal chromones, oral and intranasal decongestants, oral and intranasal anticholinergic agents, and antileukotrienes. A number of guidelines recommend INS as first-line treatment for persistent and moderate-to-severe AR. Although both patient and physician concern over the long-term safety of oral systemic steroids has previously prevented widespread use of INS, it is important to note that they have a superior risk/benefit ratio compared with other monotherapies. Indeed, the limited systemic bioavailability of INS agents, when used at recommended doses, has resulted in very low rates of systemic adverse effects, as shown by a lack of either hypothalamic-pituitary-adrenal axis or growth suppression. Large, controlled clinical studies have shown comparable efficacy and safety among the newer INS; therefore, clinicians may need to consider other factors, such as good patient compliance, when selecting an appropriate INS agent for a patient. In addition, patients often prefer one agent over another, and compliance may be improved by selecting the preferred agent. The development of two new questionnaires, the Clinical Practice Patient Preference Questionnaire and the Clinical Trial Patient Preference Questionnaire, may prove useful in selecting the optimal treatment regimen for patients.

New developments in corticosteroids

The goal of inhaled corticosteroid therapy is the targeted delivery of drug into the lung to achieve distinct pulmonary effects with reduced systemic side effects. Pharmacokinetic/pharmacodynamic assessment of pulmonary delivery suggests that an ideal inhaled corticosteroid and/or its delivery system should have the following characteristics: high pulmonary deposition efficiency, low oral bioavailability, high systemic clearance, optimized pulmonary residence time, and selective binding to the glucocorticoid receptor. Therefore, future developments will focus on improved delivery devices with higher pulmonary deposition; drugs or drug formulations providing prolonged pulmonary residence time (e.g., use of liposomes, microspheres, and nanothin coatings, or use of biological systems that achieve prolonged pulmonary residence time by ester formation and reactivation); drugs with efficient systemic clearance (e.g., soft drugs/hydrolyzable drugs); and/or improved pharmacodynamic selectivity.

How the lung handles drugs: pharmacokinetics and pharmacodynamics of inhaled corticosteroids

Bronchial asthma and allergic rhinitis are among the most common diseases of modern society and to an increasing degree a major cause of illness, hospitalization, loss of productivity, and death. Despite improvements in drug therapy over the years, the incidence is still increasing. Inhaled and intranasal corticosteroids are the drugs of choice in the therapy of asthma and allergic rhinitis. Inhalation and intranasal use result in better, target-specific delivery of corticosteroids. Higher concentrations at the site of action and minimized systemic exposure provide improved therapeutic ratios. However, there is still considerable concern over the risk of systemic side effects. It is the goal of inhaled and intranasal corticosteroid therapy to produce long-lasting therapeutic effects at the site of action and minimize systemic side effects with high clearance, low oral bioavailability and high plasma protein binding. This article reviews the pharmacokinetic and pharmacodynamic properties of corticosteroids used in asthma and allergic rhinitis.

Betamethasone pharmacokinetics after two prodrug formulations in sheep: implications for antenatal corticosteroid use

Maternal administration of betamethasone to enhance fetal lung maturation for women who threaten preterm labor is common clinical practice. However, recommendations regarding the choice of betamethasone formulations for perinatal use are vague. The disposition of betamethasone from two commonly used antenatal formulations is poorly understood. We therefore designed a study to capture the true pharmacokinetic profiles of betamethasone from these fast acting and dual-release formulations. Betamethasone in sheep plasma was measured by a newly designed, highly sensitive liquid chromatography/tandem mass spectrometry assay after intramuscular injection (n = 4) of 0.25 mg/kg betamethasone phosphate and 0.5 mg/kg betamethasone phosphate/acetate formulations. Compartmental modeling was performed using the ADAPT II program. Betamethasone pharmacokinetics could be captured for 24 h for the phosphate and for 5 days for the phosphate/acetate formulations. The phosphate formulation profile had the appearance of a traditional Bateman function with a terminal half-life of 4 h, whereas the phosphate/acetate formulation produced a biexponential decline with a terminal half-life of 14 h. The latter is much longer than is commonly reported and has been missed in the literature due to assay limitations. Extrapolations to humans indicate that although both formulations might have similar therapeutic indices, the dual formulation might be associated with a lower safety profile. In light of this newly identified long terminal half-life for the betamethasone dual formulation, dosing practices for betamethasone in pregnancy need to be reassessed.

Comparison of dexamethasone pharmacokinetics in female rats after intravenous and intramuscular administration

This study seeks a route of drug administration that would produce a pharmacokinetic profile for dexamethasone not significantly different from the intravenous route in female rats and would offer reproducible drug input with minimal stress to the animals. The intramuscular (i.m.) route of drug administration vs intravenous (i.v.) injection were compared in three female Wistar rats administered 1 mg/kg dexamethasone phosphate. Dexamethasone plasma concentrations were measured by a normal phase HPLC assay for 12 h after drug administration. Dexamethasone exhibited monoexponential behavior after intravenous dosing and was absorbed rapidly after intramuscular dosing (absorption half-life of 14 min) with 86% bioavailability. Dexamethasone had a terminal half-life of 2.3 h after drug administration by either route. The volume of distribution of 0.78 l/kg and the clearance of 0.23 l/h/kg are in good agreement with reported pharmacokinetic parameters in male rats. Intravenous dosing can be replaced by intramuscular dosing without causing any marked difference in dexamethasone pharmacokinetics.

[Strategies for the immunosuppressive therapy of intraocular inflammation]

Over the past two decades, therapeutic options for the treatment of intraocular inflammation (uveitis) have developed into a highly differentiated approach with an increasing number of drug options. In contrast to some other common sight-threatening ocular diseases, the majority of patients with uveitis can expect to receive treatment which will positively alter the course of their eye disease. Besides corticosteroids (CS) as primary systemic treatment, the most popular CS-sparing drug appears to be MTX in the treatment of uveitis. This paper suggests a strategy for the therapeutic approach to treating patients with intraocular inflammation. A table summarizes detailed information about mechanisms of action, dosage, and side effects, etc.

A novel foam vehicle for delivery of topical corticosteroids

Skin, particularly the uppermost layer--the stratum corneum--presents a formidable, largely impassable barrier to the entry of most compounds. Recently, a novel thermolabile, low-residue foam vehicle, VersaFoam (Connetics Corp, Palo Alto, Calif), has emerged that offers a number of clinical and cosmetic advantages for the delivery of therapeutic agents through the skin. Two corticosteroids--mid-potency betamethasone valerate and ultra-high-potency clobetasol propionate--are now available in this formulation, and other products are in development to deliver clindamycin and ketoconazole in the foam vehicle. A series of in vitro studies have demonstrated that the new foam has the ability to deliver the active drug at an increased rate compared with other vehicles. These findings suggest that the new foam utilizes a nontraditional "rapid-permeation" pathway for the delivery of drugs. It is likely that components within the foam (probably the alcohols) act as penetration enhancers, and reversibly alter the barrier properties of the outer stratum corneum, thus driving the delivered drug across the skin membrane via the intracellular route. This is in contrast to traditional topical delivery vehicles, which must first rely on hydration of the intercellular spaces in the stratum corneum to achieve drug delivery. The latter mechanism reflects a hydration-dependent process, which may result in comparatively slower drug permeation.

The pharmacogenetics of asthma: an update

Responses to the three major classes of asthma therapy, beta-agonists, leukotriene antagonists and inhaled corticosteroids, demonstrate wide inter-individual variability. Moreover, both asthma and the traits measured in response to asthma therapy, including forced expiratory volume at 1 s, are highly heritable. This indicates that genetics may play a prominent role in the determination of the therapeutic response to asthma. The human genetic association trials that investigate responses to each of the three major classes of asthma therapy will be summarized, and recent findings in the literature highlighted. Altogether, the available data indicate that genetics influences the likelihood of an individual responding to a given therapy, indicating that, in the future, optimal care for individuals with asthma may include genetic testing.

Corticosteroids: the mainstay in asthma therapy

Inflammation is now marked as a central feature of asthma pathophysiology and aims of current asthma management are not only to treat acute symptoms of wheezing, breathlessness, chest tightness, cough but also to suppress the underlying inflammatory component. Despite the availability of a number of drugs, corticosteroids remain the mainstay in the management of all types of asthma as these are the most potent and effective antiinflammatory agents available so far. Corticosteroids suppress virtually every step in inflammation. However therapeutic doses of oral glucocorticoids are associated with a range of adverse reactions. To overcome these side effects, inhalations have been developed to deliver glucocorticoids directly to the lungs and in the process a number of aerosol preparations have become available, which have advantage of significantly lower toxicity due to low systemic absorption from the respiratory tract and rapid inactivation. Despite considerable efforts by pharmaceutical industry, it has been difficult to develop novel therapeutic agents for asthma management, which could surpass inhaled corticosteroids. Currently the data favours using inhaled corticosteroids as monotherapy in the majority of patients in all kinds of asthma. If combination therapy is recommended to achieve additional control in severe asthma cases, other drugs such as beta-agonists, antileukotrienes, theophylline, etc. are considered as adjunct therapies to corticosteroids. This review discusses the importance of corticosteroids as first line therapy for asthma treatment with the availability of inhaled corticosteroids for chronic treatment and oral formulations for treating acute exacerbations of moderate to severe asthma.

Assessment of use of spacer devices for inhaled drug delivery to asthmatic children

In the treatment of bronchial asthma, inhaled therapy with both bronchodilators and corticosteroids represents the basis for acute and long-term management. Drug therapy in asthma is predominantly by pressurized metered dose inhalers. The impact of treatment on the disease morbidity and mortality depends to a large extent on appropriate delivery of drug to the lungs by means of a spacer device. We performed an audit on spacer use in 200 children and showed that 99% owned a spacer, 2% owned but did not use their spacer, 11% were using a spacer which was not ideal for their age, 17% had a poor technique, and 24% were not following the recommendations given on previous visits to wash the spacer only with a soapy solution. Although physicians frequently associate poor control of asthma with inadequate doses of drugs, many factors must be considered before increasing the dose of inhaled medications to children. We should all ensure that the drugs we prescribe are delivered in the best possible manner, thus improving control of asthma, reducing side effects and offering a more cost-effective therapy.

Relationship between systemic corticosteroid exposure and growth velocity: development and validation of a pharmacokinetic/pharmacodynamic model

BACKGROUND

Use of high-dose oral corticosteroids (CSs) can reduce growth velocity (GV) in children, whereas use of low-dose topical CSs has either no effect or transient effects on short-term growth and no effect on final adult height Despite the large body of literature on this topic, some fundamental questions remain concerning the relationship between CS exposure and growth effects.

OBJECTIVES

The aims of this study were to determine the relationship between CS exposure and GV in children receiving CS therapy for asthma or rhinitis, and to examine whether there is likely to be a link between GV and cortisol suppression.

METHODS

Data from 32 published studies of the effect on growth of inhaled, intranasal, and oral CSs, including delivery by dry powder inhaler, metered-dose inhaler, and aqueous nasal spray, were consolidated by expressing CS exposure in cortisol equivalents using a physiologically based pharmacokinetic/pharmacodynamic approach. The relationship between change in GV and CS exposure in cortisol equivalents was described using a nonlinear sigmoid maximum-effect (E(max)) model with the following parameters: E(max) = -5.9 cm/y; steady-state unbound AUC for 50% reduction in GV, in cortisol equivalents = 20,000 ng.h/L; Hill constant = 1.2; and change in GV at zero systemic exposure = 0.06 cm/y. Validation was achieved by comparing the model's predictions with data from 5 studies that were not included in the model development The model was also used to predict the potential of various CS regimens to reduce GV.

RESULTS

Exploratory data analysis established that change in GV was highly correlated with exposure in cortisol equivalents (P < 0.001). CSs with high systemic bioavailability by the intranasal route were predicted to have short-term growth effects exceeding the clinical equivalence limit for change in GV (+/-0.8 cm/y), whereas those with lower bioavailability were predicted to produce systemic exposures below the threshold for significant effects on GV The findings were similar for inhaled CSs and for regimens combining delivery by the intranasal and inhaled routes. In descending order, the model predicted the following ranking of the potential of the various intranasal, inhaled, and oral regimens to reduce GV, expressed as fractions or multiples of the pediatric dose (in microg/d): oral prednisolone 5000 microg/d, 0.14; inhaled beclomethasone dipropionate metered-dose inhaler 400 microg/d, 0.54; inhaled budesonide dry powder inhaler 400 microg/d, 0.66; intranasal triamcinolone acetonide aqueous nasal spray 220 microg/d, 0.74; inhaled triamcinolone acetonide metered-dose inhaler 400 microg/d, 0.75; intranasal beclomethasone dipropionate aqueous nasal spray 336 pg/d, 0.89; inhaled mometasone furoate dry powder inhaler 200 microg/d, 2.4; intranasal budesonide aqueous nasal spray 128 microg/d, 2.5; inhaled fluticasone propionate dry powder inhaler 200 microg/d, 2.6; intranasal mometasone furoate aqueous nasal spray 100 microg/d, 120; and intranasal fluticasone propionate aqueous nasal spray 100 pg/d, 150. Values >1 are predictive of no significant effect on GV. The model predicted that a 10% to 15% reduction in plasma cortisol concentration should be detectable at the lower equivalence limit for growth reduction (-0.8 cm/y). The validation procedure showed that the model was capable of predicting the results of the 5 comparative growth studies not included in model development with a correlation coefficient of 0.98.

CONCLUSIONS

Growth effects appear to be nonlinearly related to CS exposure; therefore, no-effect exposure should be possible for CSs with low systemic exposure. Growth inhibition appears unlikely to occur in the absence of detectable reductions in cortisol concentrations.

Corticosteroids, pregnancy, and HELLP syndrome: a review

Corticosteroids are potent antiinflammatory and immunosuppressive drugs, which are used in the treatment of a wide range of medical disorders. During pregnancy, several corticosteroids are administered for maternal as well as fetal reasons. Prednisone and prednisolone show limited transplacental passage and are thus used for treatment of maternal disease. Dexamethasone and betamethasone, drugs that can easily cross the placenta, are more suitable for fetal indications. During the last decade, administration of corticosteroids was introduced in the treatment of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome), a severe form of preeclampsia unique to human pregnancy. Several randomized, controlled trials as well as other prospective and retrospective studies have been performed to investigate this beneficial effect of corticosteroids on biochemical measures and clinical signs. This review discusses the characteristics of corticosteroids in humans and details the use of corticosteroids during pregnancy. A review of literature on the effect of corticosteroids on HELLP syndrome is given and possible mechanisms of action are discussed.

Treatment options for osteoarthritis

Osteoarthritis is the most common form of arthritis and can be a major source of disability. Many older patients continue to be active in sports-related activities. Therefore, treating an active patient with osteoarthritis is becoming more common. Physical therapy and weight loss continue to play a central role in the treatment of patients with osteoarthritis. Nonsteroidal anti-inflammatory drugs decrease inflammation and swelling, which makes physical therapy more effective. Intra-articular corticosteroids have been used for the treatment of osteoarthritis. However, no guidelines exist for the administration of corticosteroids and they can be associated with increased risk of tendon rupture and infection. Viscosupplementation has gained popularity in the treatment of osteoarthritis of the knee. Intra-articular injections of hyaluronic acid have been shown to decrease pain and improve functional outcomes.

Determination of the formation of the stratum corneum reservoir for two different corticosteroid formulations using tape stripping combined with UV/VIS spectroscopy. Bestimmung der Ausbildung des Reservoirs innerhalb des Stratum corneum fur zwei unterschiedliche Cortison-Formulierungen mit Hilfe der Abrissmethode und UV/VIS-Spektroskopie

BACKGROUND

The stratum corneum, the outermost layer of the skin, not only represents a barrier, but also a reservoir for topically applied substances. Both properties influence the penetration process, as does the vehicle. It determines the penetration pathway and the retention time of the topically applied substances.

METHODS

Two commercial products (Temovate Cream and Temovate Emollient), both containing 0.05% clobetasol propionate, were applied on the inner forearms of healthy volunteers. 20 tape strips were removed from each treated skin area. The horny layer profile was determined measuring the absorption of the corneocytes at 430 nm. The concentration of clobetasol propionate on the individual tapes was then analyzed.

RESULTS

We found differences in the reservoir formation depending on the formulation applied, which correlated to the biological response in the form of a blanching effect.

CONCLUSIONS

The method applied is well-suited to determine the reservoir formation in the stratum corneum for topically applied substances.

Corticosteroid injections for trochanteric bursitis: is fluoroscopy necessary? A pilot study

BACKGROUND

Numerous studies have demonstrated that therapeutic injections carried out to treat a variety of different pain conditions should ideally be performed under radiological guidance because of the propensity for blinded injections to be inaccurate. Although trochanteric bursa injections are commonly performed to treat hip pain, they have never been described using fluoroscopy.

METHODS

The authors reviewed recorded data on 40 patients who underwent trochanteric bursa injections for hip pain with or without low back pain. The initial needle placement was done blindly, with all subsequent attempts done using fluoroscopic guidance. After bone contact, imaging was used to determine if the needle was positioned on the lateral edge of the greater trochanter (GT). Once this occurred, 1 ml of radiopaque contrast was injected to assess bursa spread.

RESULTS

The GT was contacted in 78% of cases and a bursagram obtained in 45% of patients on the first needle placement. In 23% of patients a bursagram was obtained on the second attempt and in another 23% on the third attempt. Four patients (10%) required four or more needle placements before a bursagram was appreciated. Attending physicians obtained a bursagram on the first attempt 53% of the time vs 46% for fellows and 36% for residents (P=0.64). Older patients were more likely to require multiple injections than younger patients.

CONCLUSIONS

Radiological confirmation of bursal spread is necessary to ensure that the injectate reaches the area of pathology during trochanteric bursa injections.

Factors affecting the formation of a skin reservoir for topically applied solutes

The reservoir function of the skin is an important determinant of the duration of action of a topical solute. The reservoir can exist in the stratum corneum, in the viable avascular tissue (viable epidermis and supracapillary dermis) and in the dermis. A steroid reservoir in the stratum corneum has been demonstrated by the reactivation of a vasoconstrictor effect by occlusion or application of a placebo cream to the skin some time after the original topical application of steroid. Other solutes have also been reported to show a reservoir effect in the skin after topical application. A simple compartmental model is used to understand why reactivation of vasoconstriction some time after a topical steroid application shows dependency on time, topical solute concentration and the product used to cause reactivation. The model is also used to show which solutes are likely to show a reservoir effect and could be potentially affected by desquamation, especially when the turnover of the skin is abnormally rapid. A similar form of the model can be used to understand the promotion of reservoir function in the viable tissue and in the dermis in terms of effective removal by blood perfusing the tissues.

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.

Tacrolimus ointment: new preparation. Too many unknowns

(1) Drug therapy for exacerbations of atopic dermatitis (atopic eczema) should only be considered when simple measures and emollients are inadequate. The first-line option is a topical corticosteroid with a level of potency appropriate for the affected site and the patient's age. (2) Tacrolimus, an immunosuppressant used orally or parenterally to prevent graft rejection, is now marketed in France as an ointment, in two dose strengths, for the treatment of atopic dermatitis. It is approved for use when topical corticosteroids fail, in patients aged at least two years. (3) According to a comparative trial in adults, tacrolimus, when used as a first-line treatment, is no more effective than a class II (strong) topical corticosteroid. Several clinical trials show that it is better than the excipient in both adults and children. The 0.1% strength seems to be slightly more active than the 0.03% strength in adults. (4) It is not known whether tacrolimus is effective after topical corticosteroid failure. (5) In comparative trials the main systemic adverse events in patients using tacrolimus ointment were flu-like syndromes and headache. Local adverse events included burning or pruritus at the site of application in about 50% of patients. These local effects are due to both the excipient and tacrolimus. (6) Severe skin infections and skin cancer cannot be ruled out as serious side effects. (7) Tacrolimus uptake through the skin exposes patients to systemic adverse effects and drug interactions. (8) In practice, patients with atopic dermatitis, however severe, have no reason to use tacrolimus, at least pending studies showing it is effective after topical corticosteroid failure.

Anti-inflammatory effect and soft properties of etiprednol dicloacetate (BNP-166), a new, anti-asthmatic steroid

In vitro and in vivo anti-inflammatory properties and soft characteristics of etiprednol dicloacetate (BNP-166) a new steroid, which has been developed for the treatment of asthma, were investigated in this study. The compound effectively decreased cytokine production in lipopolysaccharide stimulated lymphocytes and attenuated lectin-induced proliferation of blood mononuclear cells in tissue culture. In an animal model of allergen sensitized and challenged Brown Norway rats, using topical treatment, etiprednol dicloacetate substantially attenuated the extent of allergen induced bronchoalveolar fluid eosinophilia. At every examined parameter its pharmacological effects were comparable to those of budesonide. By means of in vitro biological and analytical methods the soft character of BNP-166 was also investigated. The anti-inflammatory effect of etiprednol dicloacetate in vitro was shown to be the function of the quantity of serum components, present in the assay. This loss of activity was most likely the result of the fast metabolism of etiprednol dicloacetate, which in the presence of sera could have been demonstrated by LC/MS/MS. Our data indicate that the significant local effect of the compound will very likely be accompanied with a drastically reduced systemic activity indicating an encouraging selectivity of the pharmacological action of etiprednol dicloacetate.

Bioavailability of fluticasone propionate and mometasone furoate aqueous nasal sprays

OBJECTIVES

To compare the systemic exposure for intranasal mometasone furoate (MF) and fluticasone propionate (FP) aqueous nasal sprays (ANS) in terms of serum and urinary cortisol parameters and plasma pharmacokinetics.

METHODS

Twelve healthy subjects completed this three-way, cross-over study. They received FPANS (50 microg/spray), MFANS (50 microg/spray) or placebo ANS, eight sprays per nostril every 8 h for 4 days. Cortisol measurements were made at baseline and day 4. FP and MF plasma concentrations were also measured on day 4.

RESULTS

MFANS produced similar mean plasma AUC (123 pmol/l h) to FPANS (112 pmol/l h). Despite the use of high doses, necessary to generate adequate pharmacokinetic data, only minor reductions in cortisol parameters were found, with no difference between FPANS and MFANS.

CONCLUSIONS

FP and MF have similar and very low systemic bioavailability when administered intranasally using a high-dose regimen. It is therefore unlikely that therapeutic doses of intranasal FP or MF will produce dissimilar or significant degrees of systemic exposure or systemic effects.

Appraisal of four novel approaches to the prevention and treatment of sepsis

PURPOSE

Four novel approaches to the management of sepsis are discussed.

SUMMARY

Drotrecogin alfa (activated) has FDA-approved labeling for use in the treatment of severe sepsis. Risk of bleeding and identification of the most suitable patients have been the major issues related to use of this drug. Tight glycemic control and early goal-directed therapy (EGDT) are promising supportive strategies. Both have challenged existing views regarding safe glucose levels and the usefulness of increased oxygen delivery in sepsis. The routine maintenance of euglycemia is resource intensive, however, and benefits during treatment of sepsis are unclear. Very early initiation of measures to optimize hemodynamic variables and the ability to identify patients with cryptic shock appear to be key reasons for successful EGDT. The use of corticosteroids for septic shock has been extensively researched and has provoked controversy. Selection of patients likely to benefit on the basis of relative adrenal insufficiency and prolonged treatment may account for recently observed positive results. A model for combining the four strategies is proposed.

CONCLUSION

Novel strategies for treating sepsis include drotrecogin alfa (activated), tight glycemic control, EGDT, and low-dose corticosteroids.

Treatment options for initial maintenance therapy of persistent asthma: a review of inhaled corticosteroids and leukotriene receptor antagonists

Inhaled corticosteroids (ICSs) are recognized as the cornerstone of asthma therapy. They are considered to be the most effective anti-inflammatory medication currently available for the treatment of persistent asthma, regardless of its severity. Leukotriene receptor antagonists (LTRAs) are also used as initial maintenance therapy in patients whose asthma is uncontrolled by bronchodilators alone. There are now sufficient data available to allow a comparison of the relative effectiveness and cost-effectiveness of LTRAs and ICSs as initial maintenance therapy. The consensus from the studies reviewed in this article demonstrates that ICSs are more effective than LTRAs as initial maintenance therapy. In particular, studies on fluticasone propionate have shown that it was more effective than LTRAs in clinical outcomes: producing greater improvements in lung function and asthma control; as measured by either forced expiratory volume in 1 second (FEV1) or peak expiratory flow (PEF); by a greater reduction in daytime and night-time asthma symptoms; and short-acting beta2-agonist use. This superiority was also seen when patients were switched from an LTRA to fluticasone propionate. Similar findings have been demonstrated with beclomethasone dipropionate (BDP), showing that, in adults, this inhaled steroid also had a greater effect on pulmonary function and symptom scores than did LTRAs. Quality of life assessments showed that fluticasone propionate achieved improvements that were deemed to be clinically meaningful; these changes were significantly greater than those achieved with LTRAs. However, questionnaire-based patient preference studies comparing BDP with LTRAs showed that children and adolescents generally preferred an LTRA to BDP. A number of comparative analyses showed that inhaled fluticasone propionate is more cost-effective than either montelukast or zafirlukast; these analyses used cost per symptom-free day and cost per successfully treated patient as outcome measures, from the perspective of a third-party payer. In general, these results were supported by resource utilisation studies in real-world settings. Asthma treatment guidelines (e.g. GINA, 2002) recommend combination therapy with ICSs and a long-acting beta2-agonist as initial maintenance therapy if the disease is of sufficient severity. Studies that assessed the effectiveness, cost-effectiveness, and quality of life achieved with a salmeterol fluticasone propionate combination as initial maintenance therapy also showed it to be superior to LTRAs. In conclusion, in terms of efficacy and quality of life, fluticasone propionate is more effective than LTRAs as initial maintenance therapy and is associated with significantly lower healthcare costs and less frequent use of healthcare resources than LTRAs. There is also evidence to suggest that initial maintenance therapy with the combination of an inhaled steroid plus a long-acting beta-agonist bronchodilator may be a more effective option for the management of persistent asthma than treatment with a single-controller agent alone (ICS or LTRA).

Cushing's syndrome due to interaction between inhaled corticosteroids and itraconazole

OBJECTIVE

To report a case of an interaction between inhaled corticosteroids and itraconazole causing iatrogenic Cushing's syndrome and provide a review of the relevant literature.

CASE SUMMARY

A 70-year-old white woman on long-term treatment with high-dose inhaled corticosteroids for asthma was diagnosed as having Scedosporium apiospermum infection of the skin and subcutaneous tissues. As a result, she was treated with itraconazole for 2 months. She subsequently developed Cushing's syndrome due to a probable cytochrome P450-mediated interaction between itraconazole and budesonide. She also had secondary adrenal insufficiency requiring prolonged treatment with replacement hydrocortisone.

DISCUSSION

Budesonide is a potent glucocorticoid that is metabolized in the liver by the CYP3A4 isoenzyme to inactive metabolites. Itraconazole is a potent cytochrome P450 inhibitor. It can inhibit the metabolism of oral or inhaled corticosteroids, producing cortisol excess leading to Cushing's syndrome and adrenal insufficiency. An assessment of causality indicated a possible adverse interaction between itraconazole and budesonide.

CONCLUSIONS

The combination of itraconazole and inhaled corticosteroids is increasingly being used to treat conditions such as allergic bronchopulmonary aspergillosis. Clinicians need to be aware of the potential for an interaction between such a combination.

Idiopathic thrombocytopenic purpura: a retrospective analysis in 139 patients of the influence of age on the response to corticosteroids, splenectomy and danazol

OBJECTIVE

To review the influence of age on the response of patients with idiopathic thrombocytopenic purpura (ITP) to corticosteroids, splenectomy and danazol.

METHODS

We retrospectively reviewed a cohort of 139 consecutively treated patients with ITP diagnosed between 1985 and 1994. In particular, we analysed the therapies used, their response rates, prognostic indicators of response and adverse effects. Furthermore, we compared the efficacy and tolerability of the various therapies between younger and older patients (<60 and > or =60 years old).

RESULTS

Corticosteroids were used as first-line treatment in 118 patients with an initial response rate of 83%. Age did not affect the outcome of corticosteroid therapy, but all the patients aged > or =60 years reported adverse effects. A splenectomy was performed in 55 patients with an initial response rate of 87%. Older patients had significantly poorer outcomes from splenectomy with higher postoperative morbidity. Finally, danazol was given in 33 patients with a favourable response in 72% of cases. Compared with younger patients, older patients had a significantly better outcome with danazol.

CONCLUSIONS

Age may have significant effects on the response to and adverse effects of therapy in ITP, and this should be considered when choosing the treatment modality for the elderly.

The effect of inhaled corticosteroids on the urinary calcium to creatinine ratio in childhood asthma

BACKGROUND

The use of inhaled corticosteroids (ICS) via spacers in childhood asthma is increasing. However, concern has been raised about its long-term impact. Hypercalciuria is a known adverse effect of treatment with systemic corticosteroids. The urinary calcium to creatinine ratio (UCa:Cr) is a simple, reliable and non-invasive tool for evaluation of hypercalciuria.

AIM

To determine whether ICS can induce hypercalciuria in children with asthma.

SETTING

Outpatient clinic in a referral hospital.

METHODS

The UCa:Cr was determined in 25 children aged 3-6 years with mild-to-moderate persistent asthma before and after a 2-month course of inhaled budesonide 400 micrograms/day via an aerochamber. Children who had received oral corticosteroids, diuretics, antibiotics or theophylline were excluded.

STATISTICS

Paired Student's t-test and Fisher's exact test.

RESULTS

The mean UCa:Cr was similar in the children with asthma before and after 2 months' administration of budesonide (0.10 +/- 0.10 and 0.11 +/- 0.08, respectively; p = 0.601). The numbers of hypercalciuric children were two and five, respectively (p = 0.417). In 68% of patients, the UCa:Cr increased and in 16% the increase indicated hypercalciuria (UCa:Cr > 0.2).

CONCLUSIONS

Although the treatment of childhood asthma with budesonide 400 micrograms/day via an aerochamber does not appear to be associated with hypercalciuria, the existence of a subgroup of patients in whom ICS may induce hypercalciuria is plausible. This needs to be further evaluated in a larger study.

Pharmaceutical characteristics that influence the clinical efficacy of inhaled corticosteroids

BACKGROUND

Inhaled corticosteroids (ICSs) are the most effective therapy for the management of persistent asthma. The aim of ICS therapy is to achieve a high anti-inflammatory effect in the airways with a concomitant low risk of unwanted local and systemic effects. Direct estimates of clinical efficacy and potency based on studies in humans are difficult to interpret.

OBJECTIVE

To examine the challenges of using alternative estimates of ICS efficacy and potency, including pharmaceutical characteristics.

DATA SOURCES AND STUDY SELECTION

Articles published from 1990 to 2002 on the potency, efficacy, and tolerability of ICSs were identified using MEDLINE and in-house databases and were then reviewed. Search terms included inhaled corticosteroid, budesonide, fluticasone, beclomethasone, mometasone, and potency.

RESULTS

Differences among ICSs can be readily shown using preclinical measures, such as glucocorticoid receptor binding or skin blanching tests. However, pharmaceutical (delivery and pharmacokinetic) differences of ICSs can have a greater impact on clinical efficacy than in vitro potency differences. For example, the unique esterification of budesonide in the airways prolongs its local activity and may contribute positively to its efficacy and therapeutic index. Although comparative clinical trials suggest 6-fold differences in potencies among ICSs, there is currently no evidence to support differences in efficacy when they are administered at equipotent dosages.

CONCLUSIONS

Greater preclinical potency of an ICS does not imply greater clinical efficacy. Pharmacokinetic factors can have a significant impact on relative clinical efficacy.

In vivo multi-tissue corticosteroid microarray time series available online at Public Expression Profile Resource (PEPR)

Gene microarrays are becoming a key tool for the analysis of changes in gene expression in a variety of conditions. Use of microarrays to analyze drug responses has mainly been restricted to comparing treated versus untreated samples at a few time points. Such data do not permit the use of another important tool, pharmacokinetic/pharmacodynamic (PK/PD) modeling. Such modeling requires the simultaneous analysis of pharmacokinetic data along with time series data on dynamic responses. This report describes data obtained from two extended microarray time series (rat liver and skeletal muscle) for the in vivo responses to a single bolus dose of methylprednisolone that are uniquely available online in a single gene query format. Use of these data does not require any a priori knowledge or software normally necessary for the analysis of microarray data. Since the pharmacokinetic data and receptor model have been published, the results are amenable to PK/PD and pharmacogenomic evaluation.

Inhaled corticosteroids in childhood asthma: long-term effects on growth and adrenocortical function

Inhaled corticosteroids (ICS) are the most potent of all the available inhaled treatments, and are effective medications for long-term control of asthma. However, their use in children is limited by the risk of systemic adverse effects. Although results reported in the literature on the adverse effects of ICS are conflicting and often restricted to a small number of cases with a limited follow-up, most of them show an early decrease in growth velocity without significant influence on final adult height. Partial adrenal suppression has also been demonstrated in children treated with ICS for more than 2 months. Only children with mild persistent, moderate, or severe asthma not controlled by non-corticosteroid drugs should be treated with ICS for long periods. The dose of ICS must be individually adjusted to minimize the possible adverse effects on growth, and all children with asthma receiving long-term treatment with ICS must be regularly evaluated for growth impairment, which may necessitate dose reduction or drug replacement.

Tacrolimus dose requirement in renal transplant recipients is significantly higher when used in combination with corticosteroids

AIMS

To evaluate the effect of corticosteroids on tacrolimus pharmacokinetics.

METHODS

In a randomized trial, kidney transplant recipients were treated with tacrolimus and mycophenolate mofetil with either daclizumab (n = 31) or 3 months of prednisone (n = 34). Tacrolimus dose-adjusted predose concentrations (C0) at month 1-6 were compared between both groups and within the corticosteroid group before and after prednisone withdrawal.

RESULTS

At month 1 the tacrolimus dose-adjusted C0 in the corticosteroid group was 83 +/- 8 vs 119 +/- 17 ng ml-1 mg-1 kg-1 in the daclizumab group. The tacrolimus dose-adjusted C0 within the corticosteroid group at month 1 and 2 was 42% and 29% lower compared with month 4 (P < 0.001).

CONCLUSIONS

A higher tacrolimus dose is required to reach target concentrations when used in combination with corticosteroids.

Potential adverse effects of the inhaled corticosteroids

The purpose of this review is to provide the clinician with an update on the potential adverse effects caused by the inhaled corticosteroids (ICSs). The systemic effects of ICSs are a result of that portion swallowed and absorbed through the gastrointestinal tract and not eliminated by first-pass metabolism and that portion delivered to the lung and absorbed. If administered in high enough doses, any of the ICSs will produce clinically significant systemic activity. This review will explore the risks for clinically significant adverse effects from sustained use of ICSs, as recommended by the current guidelines. The standard method for assessing systemic activity in short-term studies is measurement of hypothalamic-pituitary-adrenal axis function. The ICSs provided in the medium dose range can produce measurable effects on the hypothalamic-pituitary-adrenal axis. However, clinically significant suppression is unlikely to occur except at high doses. The effect on growth in children over 1 to 4 years occurs at low to medium doses, might be dependent on the specific ICS, and is small (1-2 cm). The data are insufficient to determine whether there is an effect on attainment of predicted adult height. The ICSs affect bone mineral density and risk of fractures in a dose-dependent fashion that appears significant at high doses.

Quantitative interpretation of corticosteroid pharmacokinetics in inner fluids using computer simulations

The delivery of drugs to the inner ear by applying them directly onto the round window membrane is a promising way to treat human inner ear disorders. To further develop this strategy, and to design controlled clinical trials, additional preclinical studies are necessary. It is especially important to derive the time course and total dose for the various target regions within the inner ear. Since direct pharmacokinetic measurements in the human cochlea are not possible, simulations provide a valuable tool for the interpretation and planning of animal studies, for evaluating changes of application protocols and drug delivery systems, and for extrapolating the results from animal studies to the human. The present study has analyzed two previously published data sets in which concentration time courses of corticosteroids in the cochlear fluids were reported. Drug movements were simulated with a finite element computer model of the inner ear fluids. The time course of corticosteroid pharmacokinetics could be approximated for each study by consideration of the specific experimental paradigm. Although the experimental studies reported considerably different drug levels in the fluid samples taken from the cochlea, these differences were largely explained by considering the experimental design of the respective studies. After correction for experimental differences, the calculated perilymph levels of drug were within a factor of two of each other. The simulations demonstrated that an important factor controlling the drug level achieved is the time the drug solution remains in the middle ear. It can be concluded that small differences in delivery protocols may cause large variations in the drug levels achieved in the inner ear fluids.