Symbicort Preparations: Are They the Same?

For many years only the Symbicort^® Turbuhaler device was available on the Pharmaceutical Benefits Scheme (PBS). More recently, the Rapihaler^® device has been included on the PBS and is gaining popularity. This article aims to explore the differences between the Turbuhaler^® and Rapihaler^® devices.

Symbicort^® is indicated for use in adults and adolescents (>12 years old) to treat asthma in which the combination of an inhaled corticosteroid (ICS) and a long-acting beta-agonist (LABA) is appropriate, and for use in chronic obstructive pulmonary disease (COPD). Symbicort^® is not recommended in patients younger than 12 years of age.

For many years Symbicort^®, the combination of budesonide and eformoterol, had only been available as a dry powder inhaler (DPI) formulation and delivered using a Turbuhaler^®.  In 2013, the pressurised metered-dose inhaler (pMDI) was PBS listed for the treatment of asthma and COPD.

Table 1 shows the Symbicort^® preparations that are currently available. Please note that not all Rapihaler^® strengths are registered in Australia.

Table 1: Symbicort^® preparations available

*Not currently registered in Australia.

Symbicort^® differs from other currently available combination ICS and LABA inhalers in that it can be used as both a preventer and as a reliever. This is known as the SMART (Symbicort^® maintenance and reliever therapy) regimen. Under this regimen, Symbicort^® is prescribed as a regular (usually twice daily) dose with additional doses if required. Symbicort^® can be used in this way due to the relatively fast onset of action of the eformoterol component, which can act within one to three minutes. The higher strength Symbicort^® inhalers (the Turbuhaler^® 400/12, Rapihaler^® 100/6 and Rapihaler^® 200/6) should not be used for the asthma SMART regimen. Additionally, the Symbicort^® Turbuhaler^® 400/12 should not be used in patients under the age of 18.

It is important to note that the approved doses of the Symbicort^® Rapihaler and the Symbicort^® Turbuhaler for maintenance therapy of asthma are not equivalent. To provide uniformity in dose, the Symbicort^® Rapihaler should be given as two actuations. However, the Turbuhaler^® can be used in single inhalations to provide the total dose. The Rapihaler^® is available in lower strengths than the Turbuhaler^® for this reason. Since the inhalers are not equivalent, a Rapihaler^® cannot be directly substituted for a Turbuhaler^® in patients already using the Symbicort^® Turbuhaler device, or vice versa. Table 2 shows the dose equivalence between the Turbuhaler^® and Rapihaler^® preparations. It is important that patients are also aware of the difference in dosing between the two types of device.

Table 2. Dose equivalence of Symbicort^® devices

Selection between the Turbuhaler^® and the Rapihaler^® should be guided by patient factors; particularly patient preference and the ability of the patient to use the device.

Patient factors that can influence device choice include:

• Dexterity
• Lung function
• Age
• Cognition
• Risk of adverse effects
• General health status
• Previous device experience
• Patient preference

There has not been found to be any difference in therapeutic efficacy between DPI and pMDI type inhalers.  The National Asthma Council of Australia recommends that doctors ensure each patient is capable of using the inhaler device correctly, particularly in the older population who commonly display incorrect inhaler technique.

One advantage of the Symbicort^® Rapihaler is that it can be used with a spacer, whereas the DPI containing Turbuhaler^® cannot. Spacers are recommended for patients using ICS-containing inhalers, and help to increase drug deposition into the lungs and decrease drug deposition in the mouth and pharynx. By decreasing the deposition of the ICS to locations other than the lungs, a spacer helps to reduce the incidence of oropharyngeal candidiasis and hoarseness and can decrease systemic absorption.

Health care providers must be mindful that two different Symbicort^® delivery devices are available on the PBS, and that these are not therapeutically equivalent. Prescriptions should be written clearly specifying whether a Turbuhaler^® or a Rapihaler^® should be supplied. Patients should also be made aware that the preparations are not equivalent or interchangeable, to avoid errors in dosing.