Notice type: 3rd Party Publications

Date: 31/10/2006


Product name or type:

MIMS Publication October 2006

Problem Or Issue:
Recently the Health Products Regulatory Authority (IMB) has received a number of enquiries about the interchangeability of inhaled corticosteroids (ICS) for the treatment of asthma. 

For environmental reasons, over the last six or seven years the chlorofluorocarbon (CFC) propellant in marketed metered dose inhalers has been replaced with a hydrofluoroalkane (HFA) propellant. This process has been gradual due to the time required for manufacturers’ clinical development and regulatory approval. In addition, every effort has been made to ensure that the switch did not result in a shortage of available medicines. Information regarding the transition from CFC inhalers to CFCfree products was previously highlighted in the IMB’s Drug Safety Newsletter. 

In the case of ICS, the physico-chemical properties of the steroid formulation and the change of propellant have resulted in a change in the droplet size of the emitted particle spray. HFA-driven products emit a higher proportion of small particles, five microns or less, known as the respirable fraction. Such particles are deposited in the small airways where the drug may be absorbed into the pulmonary vasculature and contribute to the systemic and other known adverse effects common to all corticosteroids. Traditionally, the respirable fraction of CFC-driven products has been in the range 5 – 25%. With the change to HFA, the respirable fraction has increased and products with respirable fractions of 40 – 60% are now available. This increase in bioavailability is also in part due to improvements in the technology and engineering of the delivery device. 

There is evidence that following a milligram for milligram switch from CFC- to HFA-driven steroids the bioavailability of the HFA product is greater, with a consequential increase in the potential for adrenal suppression. However, manufacturers have included proposals on dosage reduction when changing from CFC to HFA products to address this issue. In general, those products with high respirable fractions have a recommended reduction in dose while those with lower respirable fractions have not. All products carry advice in the prescribing and patient information that, having achieved asthma control, the dose of ICS should be reduced to the lowest that will maintain control. 

To date, the IMB has not received reports of adverse reactions suspected in association with switching between inhaled steroids, or concerns regarding confusion among healthcare professionals or patients/caregivers relating to switching of products. Nevertheless, patients and prescribers are reminded that inhaled steroids are not interchangeable; and that the prescribing and patient information for each product should be followed. 

Finally, the IMB would like to take this opportunity to remind healthcare professionals that any suspected adverse reactions should be reported to the IMB in the usual way. A downloadable version of the ADR report form is available from the HPRA’s website ( 

Downloaded forms may be completed and sent by freepost to the HPRA. Envelopes should be marked 

Pharmacovigilance Unit, 
Health Products Regulatory Authority, 
The Earlsfort Centre, 
Earlsfort Terrace, 
Dublin 2. 

Alternatively, completed forms may be submitted by fax (01- 6762517). 
Post-paid report cards are also available from the Pharmacovigilance Unit at the HPRA (01- 6764971).

Background Information Or Related Documents:

« Back