Inhaled beclomethasone (BDP) with non-CFC propellant (HFA 134a) is equivalent to BDP-CFC for the treatment of asthma

Generics, chemisimilars and biosimilars: is clinical testing fit for purpose?

The effectiveness and safety of generic drugs are backed by sound physicochemical control and regulatory bioequivalence acceptance criteria. Statistical testing of bioequivalence, comparing the pharmacokinetic profiles of the test and reference products, was made possible by modern drug assays. When the pharmacokinetic profile correlates with the dose, such comparisons show assay sensitivity and readily detect differences in dose. For large biological molecules, different manufactured batches cannot be validated using pharmacokinetic data alone. For these biosimilars, there is a three-stage assessment of pharmaceutical quality, laboratory testing and clinical data. This approach has also been applied to certain chemical products, termed 'chemisimilars', which have variable or complex synthesis of the active substance, or complex formulation, or a complex delivery device. Although there may be no detectable difference between the test and reference on clinical testing, many of the outcome measures are insensitive to even large differences in dose. For testing to be fit for purpose it should distinguish important dose differences, but many clinical tests of chemisimilars and biosimilars do not. As pharmacokinetic and pharmacodynamic technology advances, the trend of replacing dose-insensitive clinical trial data with equivalence tests that show assay sensitivity can be expected to continue.

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

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

Propellant-driven metered-dose inhalers for pulmonary drug delivery

The current market for pulmonary drug delivery is at a bottleneck. The therapeutic advantages of inhalation aerosols, and the potential for the lungs as a route for systemically acting drugs, vaccines and gene therapeutic agents, have resulted in a rapid growth of the industry. Alongside this, the environment of inhaler design and formulation has changed markedly in recent years. Environmental concerns over propellants, the commercial success of dry powder inhalers, and the apparent lack of advancement of propellant-driven metered-dose inhalers (pMDIs) has led to a less clear future for these devices. This review critically assesses these pressures and also potential opportunities for the pMDI. It is proposed that the future role of pMDIs will be determined by several important forces that can be classified under 'technology development' or 'market climate' categories. Technology development forces will be strengthened by the ability of the industry to have a systematic understanding of mechanisms of spray formation, perform subsequent and continued device and formulation advances, and a focus on all patient groups: particularly paediatric and geriatric populations. The ability to succeed in these areas will be largely determined by the willingness to invest in fundamental research of pMDI technologies.

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.

The influence of inhaler selection on efficacy of asthma therapies

Many different devices are available to aid inhalational drug delivery. Although each device is claimed to have advantages over its rivals, the evidence to support greater efficacy of a particular device is scanty. Most comparative studies are underpowered or flawed in their design. They may use inappropriate end-points, or involve healthy subjects, whose response may be very different from the patient with acute severe asthma. The dosage of drug used in a trial may be at the shallow part of the dose-response curve, masking differences in devices. Only in a few cases have clinical trials detected a significant difference between devices, and trials have rarely taken patient preference into account. The most efficacious device in practice is likely to be the one that the patient will use regularly and in accordance with a health care workers' recommendations.

Inhaler devices for the treatment of asthma and chronic obstructive airways disease (COPD)

The research evidence on the effectiveness of inhaler devices for the treatment of asthma and chronic obstructive pulmonary disease published in a recent issue of Effective Health Care is reviewed.

The usefulness of a daily pain management diary for outpatients with cancer-related pain

PURPOSE/OBJECTIVES

To describe the usefulness of daily pain management diaries to outpatients with cancer who participated in a randomized clinical trial of the PRO-SELF Pain Control Program.

DESIGN

Randomized clinical trial in which a daily pain management diary was used for data collection in the control group and for data collection and nurse coaching regarding the pain management program in the intervention group.

SETTING

Seven outpatient oncology settings.

SAMPLE

155 patients with pain from bone metastases and 90 family caregivers.

METHODS

Content and statistical analysis of audiotaped answers to a semistructured questionnaire.

MAIN RESEARCH VARIABLES

Patients' and family caregivers' perceptions of the usefulness of a daily pain management diary; specific ways in which the diary was used.

FINDINGS

Patients in both the intervention (75%) and control groups (73%) found the diary useful. The diary was used to heighten awareness of pain, guide pain management behavior, enhance a sense of control, and facilitate communication. Family caregivers in both groups also reported that the diary was useful.

CONCLUSIONS

The completion of a daily pain management diary is useful to patients and family caregivers and may function as an intervention for self-care.

IMPLICATIONS FOR NURSING

Research-based evidence supports the importance of using a daily pain management diary in clinical practice.

Systematic review of clinical effectiveness of pressurised metered dose inhalers versus other hand held inhaler devices for delivering corticosteroids in asthma

OBJECTIVE

To determine the clinical effectiveness of pressurised metered dose inhalers (with or without spacer) compared with other hand held inhaler devices for the delivery of corticosteroids in stable asthma.

DESIGN

Systematic review of randomised controlled trials.

DATA SOURCES

Cochrane Airways Group trials database (Medline, Embase, Cochrane controlled clinical trials register, and hand searching of 18 relevant journals), pharmaceutical companies, and bibliographies of included trials.

TRIALS

All trials in children or adults with stable asthma that compared a pressurised metered dose inhaler with any other hand held inhaler device delivering the same inhaled corticosteroid.

RESULTS

24 randomised controlled trials were included. Significant differences were found for forced expiratory volume in one second, morning peak expiratory flow rate, and use of drugs for additional relief with dry powder inhalers. However, either these were within clinically equivalent limits or the differences were not apparent once baseline characteristics had been taken into account. No significant differences were found between pressurised metered dose inhalers and any other hand held inhaler device for the following outcomes: lung function, symptoms, bronchial hyper-reactivity, systemic bioavailability, and use of additional relief bronchodilators.

CONCLUSIONS

No evidence was found that alternative inhaler devices (dry powder inhalers, breath actuated pressurised metered dose inhalers, or hydrofluoroalkane pressurised metered dose inhalers) are more effective than the pressurised metered dose inhalers for delivery of inhaled corticosteroids. Pressurised metered dose inhalers remain the most cost effective first line delivery devices.

Rationale for the choice of an aerosol delivery system

The choice of an aerosol delivery system depends on numerous factors such as the drug itself, the characteristics of the aerosol generator, the patient and his or her disease, the physician, and the clinical setting, notably an emergency situation or not. Some rules always apply: an ultrasonic nebulizer should not be used to aerosolize a drug suspension; whenever possible, the same type of aerosol generator should be used for all inhaled medications received by a given patient; for outpatients, education is a major factor to ensure treatment efficacy. When the deposition of the aerosolized drug is aimed at the terminal respiratory units, nebulizers that generate micronic aerosols should be chosen. When the deposition of the aerosolized drug is aimed at the conducting airways, the metered dose inhaler (MDI) is the first choice. However, the MDI is often ill-used, notably in children and elderly people. Therefore, other inhalation devices have been developed: spacers, dry-powder inhalers, breath-actuated MDIs and, more recently, piezo-electric devices. They have been shown to increase lung deposition of drugs in poor coordinators but they all have limitations, which may affect their clinical efficacy. These limitations include the cumbersome dimensions of spacers, the dependency of lung deposition of dry powders on the inspiratory flow rate, the need for reformulation of breath-actuated or not MDIs with CFC-free gases. Nebulization of drugs should be considered only when no portable device is available for the considered drug, or in case of failure of other forms of aerosol administration.

Safety of inhaled and intranasal corticosteroids: lessons for the new millennium

Although inhaled and intranasal corticosteroids are first-line therapy for asthma and allergic rhinitis, there has recently been an increasing awareness of their propensity to produce systemic adverse effects. The availability of more potent and lipophilic corticosteroids and new chlorofluorocarbon (CFC)-free formulations has focused attention on these safety issues. The main determinant of systemic bioavailability of these drugs is direct absorption from the lung or nose, where there is no first-pass inactivation. Consequently, the systemic bioavailability of inhaled corticosteroids is greatly influenced by the efficiency of the inhaler device. Thus, when comparing different inhaled corticosteroids it is imperative to consider the unique drug/device interaction. The pharmacokinetic profile is important in determining the systemic bioactivity of inhaled and intranasal corticosteroids. For highly lipophilic drugs, such as fluticasone propionate or mometasone furoate, there is preferential partitioning into the systemic tissue compartment, and consequently a large volume of distribution at steady state. In contrast, drugs with lower lipophilicity, such as triamcinolone acetonide or budesonide, have a smaller volume of distribution. The systemic tissue compartment may act as a slow release reservoir, resulting in a long elimination half-life for the lipophilic drugs. For intranasal corticosteroids, a high degree of lipophilicity diminishes water solubility in mucosa and therefore increases the amount of drug swept away by mucociliary clearance before it can gain access to tissue receptor sites. This may reduce the anti-inflammatory efficacy in the nose, but might also reduce the propensity for direct systemic absorption from the nasal cavity. The hydrofluoroalkane (HFA) formulations of beclomethasone dipropionate are solutions and exhibit a much higher respirable fine particle dose than do the CFC formulations. Dose-response studies with one of the HFA formulations have shown therapeutic equivalence at half the dosage, with little evidence of adrenal suppression at dosages up to 800 microg/day. A lack of similar studies for another of the available HFA formulations has led to a discrepancy in the recommendations for equivalence. Although in vitro studies have pointed to a similar fine particle distribution for the HFA and CFC formulations of fluticasone propionate, this is not supported by in vivo data for lung bioavailability, suggesting that care will be required when switching these formulations. Prescribers of inhaled and intranasal corticosteroids should be aware of the potential for long term systemic effects. The safest way to use these drugs is to 'step-down' to achieve the lowest possible effective maintenance dosage.

Transition to CFC-free metered dose inhalers--into the new millennium

Metered dose inhalers (MDIs) are the most popular vehicle for drug delivery into the lungs and some 500 million are manufactured each year. All MDIs marketed prior to 1995 contained chlorofluorocarbons (CFC) as a propellant. These are implicated in the depletion of stratospheric ozone and, except for specific exemptions, their production has been banned since 1996 under the terms of the Montreal Protocol. Hydrofluoroalkanes have been identified as suitable alternatives for MDI propellants but their physico-chemical properties differ significantly from CFCs and an extensive redevelopment and testing programme has been required to demonstrate the safety, quality and efficacy of HFA containing MDIs. Hydrofluoroalkanes contribute to global warming but the benefit to human health through continued MDI availability currently outweighs the environmental concern. Several HFA-MDIs have reached the market and the transition to replace existing CFC-MDIs is now underway.

Aerosol therapy for asthma

Inhaled drugs play an important role in asthma management. The correct use of an appropriate delivery device is necessary to achieve the desired therapeutic effects of the drug. Currently, chlorofluorocarbon-propelled metered-dose inhalers, with or without spacers, are the most popular aerosol delivery devices. With the planned phase out of the chlorofluorocarbon metered-dose inhalers, the use of other delivery devices is being emphasized. To achieve optimal therapeutic effects, the drug and the delivery device should be considered a "couple". Aerosol delivery devices should provide an adequate "drug dose to the lung", be cost effective, simple to operate, minimize oropharyngeal deposition and systemic side effects, and match the patient's requirements. A new generation of aerosol delivery devices, incorporating the latest advances in aerosol technology, is likely to fulfill many of the goals mentioned above.

Therapeutic equivalence of inhaled beclomethasone dipropionate with CFC and non-CFC (HFA 134a) propellants both delivered via the Easibreathe inhaler for the treatment of paediatric asthma

Chlorofluorocarbon (CFC)-containing inhalers for use in the treatment of asthma are to be phased out under the terms of the Montreal Protocol (1). In this multi-centre, randomized, double-blind study, the therapeutic equivalence of two formulations of beclomethasone dipropionate (BDP) containing CFC or non-CFC (HFA134a) propellant, both delivered via the Easibreathe (Norton Healthcare Ltd, London, U.K.) inhaler, was determined in 229 asthmatic children. Each child received 100 microg doses of BDP (containing either CFC or HFA propellant) twice daily for 12 weeks. Both CFC and HFA formulations produced statistically and clinically significant improvements in patient's lung function and symptom scores when administered via the Easibreathe inhaler. The improvements in mean morning peak expiratory flow (PEF) were 41 l min(-1) and 34 l min(-1) for the BDP-HFA and BDP-CFC products respectively (P<0.001) and for mean evening PEF the improvements were 38 l min(-1) and 38 l min(-1), respectively (P<0.001). Similar findings were demonstrated for the other efficacy parameters. The two formulations were statistically equivalent with respect to efficacy. For mean morning PEF the estimated treatment difference (BDP-CFC/BDP-HFA ratio) was 102.6% (95% CI 99.1, 106.2). Similar equivalence was shown for the other efficacy parameters. Both products were well tolerated, with no difference in the adverse event profiles, effects on 24 h urinary cortisol or Candida colonisation. This study demonstrates that the new formulation of BDP with HFA-134a propellant is equivalent to and directly substitutable for BDP with the older CFC propellant in a dose for dose manner. This should enable a seamless transition from one product to the other when CFC containing products are eventually phased out. In addition this study has also shown that the Easibreathe inhaler is an effective delivery system for use with inhaled products for the treatment of asthma in children.

Pharmacokinetics of chlorofluorocarbon and hydrofluoroalkane metered-dose inhaler formulations of beclomethasone dipropionate

AIMS

To compare the pharmacokinetic profile of Beclazone (beclomethasone dipropionate) in its chlorofluorocarbon (CFC)-based and CFC-free formulations.

METHODS

Ten healthy adults received a single 1,000 microg nominal dose (ex-valve) of beclomethasone dipropionate from a CFC inhaler (BEC-CFC) or from a CFC-free inhaler containing hydrofluoroalkane (HFA)-134a (BEC-HFA) in an open-label, randomized, two-way, crossover study. Blood samples were collected predose and over 12 h after inhalation. Comparisons were made of maximum plasma concentration of beclomethasone 17-monopropionate (17-BMP) (Cmax), and area under the plasma concentration vs time curve (AUC).

RESULTS

The tmax was significantly (P<0.05) earlier with BEC-HFA and plasma levels were significantly higher following administration of BEC-HFA than BEC-CFC. Geometric mean values for AUC were 1.5 fold greater (90% CI 1.3-1.9) and for Cmax were 1.9 fold greater (90% CI 1.6-2.6) following BEC-HFA than BEC-CFC.

CONCLUSIONS

Our data in healthy volunteers would not be consistent with the manufacturers' recommendation for a microgram equivalent (1:1) nominal dose switch between these HFA and CFC formulations. Further well designed trials are required in asthmatic patients to properly define their respective dose-response relationships for antiasthmatic and systemic adverse effects.