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

A pharmacokinetic simulation tool for inhaled corticosteroids

The pharmacokinetic (PK) behavior of inhaled drugs is more complicated than that of other forms of administration. In particular, the effects of certain physiological (mucociliary clearance and differences in membrane properties in central and peripheral (C/P) areas of the lung), formulation (as it relates to drug deposition and particle dissolution rate), and patient-related factors (lung function; effects on C/P deposition ratio) affect the systemic PKs of inhaled drugs. The objectives of this project were (1) to describe a compartmental model that adequately describes the fate of inhaled corticosteroids (ICS) after administration while incorporating variability between and within subjects and (2) based upon the model, to provide a freely available tool for simulation of PK trials after ICS administration. This compartment model allows for mucociliary removal of undissolved particles from the lung, distinguishes between central and peripheral regions of the lung, and models drug entering the systemic circulation via the lung and the gastrointestinal tract. The PK simulation tool is provided as an extension package to the statistical software R ('ICSpkTS'). It allows simulation of PK trials for hypothetical ICS and of four commercially available ICS (budesonide, flunisolide, fluticasone propionate, and triamcinolone acetonide) in a parallel study design. Simulated PK data and parameters agreed well with literature data for all four ICS. The ICSpkTS package is especially suitable to explore the effect of changes in model parameters on PK behavior and can be easily adjusted for other inhaled drugs.

Flunisolide HFA

Flunisolide is a synthetic corticosteroid approved for the treatment of persistent asthma and delivered by means of a metered-dose inhaler (MDI). A new formulation of flunisolide, using hydrofluoroalkane (HFA) as a propellant, has been developed to comply with the mandated worldwide phase-out of ozone-depleting chlorofluorocarbon (CFC) propellants. Aerosol particle size in the new flunisolide HFA solution is smaller than the flunisolide CFC suspension (1.2 vs 3.8 microm mass median aerodynamic diameter). Aerosol particle size is a key element in determining lung deposition and the regional distribution of inhaled medication within the lung. In addition, the flunisolide HFA MDI has been redesigned to include a built-in spacer. These features have improved distal lung deposition. Flunisolide HFA, at one-third the dosage (170 and 340 microg twice daily), had similar efficacy to flunisolide CFC (500 and 1000 microg twice daily) and significantly greater efficacy than placebo in a randomized, double-blind, placebo-controlled, 12-week study in patients with mild to moderate asthma. Flunisolide HFA was well tolerated in all trials. A long-term study found no suppression of adrenal function and minimal systemic effects were observed both in adults and children.

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.

Evaluation of efficacy and safety of flunisolide hydrofluoroalkane for the treatment of asthma

BACKGROUND

Inhaled corticosteroids are currently recommended as first-line therapy for the long-term control and management of persistent asthma. Flunisolide hydrofluoroalkane (HFA) is a new formulation of the corticosteroid flunisolide that is delivered by a metered-dose inhaler containing an HFA propellant. HFA replaces the chlorofluorocarbon (CFC) propellant of the previous formulation, producing aerosols of smaller average particle size.

OBJECTIVE

This article reviews the physical and pharmacologic properties, deposition profile, and potential clinical benefits of flunisolide HFA for the treatment of asthma.

METHODS

Data included in this review were found via MEDLINE (search term, flunisolide HFA).

RESULTS

Flunisolide HFA has a mass median aerodynamic diameter (MMAD) of 1.2 microm, smaller than the 3.8 microm MMAD of the CFC formulation. Compared with flunisolide CFC, more of each flunisolide HFA dose reaches the lungs and less is deposited in the oropharynx. In addition, scintigraphic studies have found that the extra-fine particle size of flunisolide HFA gives it better access to small airways. In short- and long-term clinical studies, flunisolide HFA has been found to significantly increase pulmonary function relative to placebo. Although not statistically superior to the previous CFC formulation, flunisolide HFA exhibited small improvements in secondary efficacy measures, such as as-needed albuterol use and asthma symptoms, relative to flunisolide CFC. Furthermore, research suggests that the new HFA formulation has a low risk of systemic corticosteroid effects (eg, hypothalamic-pituitary-adrenal axis suppression, growth inhibition in children). Also, lower levels of oropharyngeal deposition, such as those seen with flunisolide HFA, are associated with lower incidence of local effects (eg, candidiasis).

CONCLUSION

Flunisolide HFA offers effective asthma control with a high level of tolerability in an extra-fine particle formulation that distributes corticosteroid to all areas of the lung, including small airways.