Delivery devices

Medications used to treat asthma are usually administered by inhalation. In terms of the benefit:harm ratio, inhaled drug delivery is superior to oral or parenteral delivery for SABAs, anticholinergics, LABAs and ICS.²²

• Two different methods of inhalation are used:
• Metered-dose inhaler (MDI) with or without the use of a spacer
• Dry-powder inhaler (DPI).
• Provided the devices are used correctly, there is no evidence of long-term clinical advantage of one device over another.²³
• In general, patients with adequate inspiratory force and adequate hand-lung coordination can use either a DPI or an MDI. For older patients who have inadequate inspiratory force and/or poor coordination, use of an MDI with a spacer is preferred. Alternatively, a breath-activated MDI may warrant consideration.
• A DPI or an MDI used with a spacer may reduce the oropharyngeal disposition of medication and may reduce the local effects of ICS.²² However, there is no evidence that these devices reduce the systemic adverse effects of ICS, possibly because systemic absorption occurs as much through the bronchial circulation as it does through oral or gastrointestinal absorption.²²

Deposition

• DPI: Deposition in the lung depends primarily on the inspiratory force. Both Turbuhaler and Accuhaler demonstrate acceptable drug delivery at inspiratory flow rates greater than 30 L/min.
• MDI: Deposition via MDI depends primarily on hand-lung coordination; the inspiratory force has no effect on either dosage delivery or average particle size. If adequate inhalation is not feasible, an MDI with a spacer is preferred. If inhalation is adequate, the patient's inspiratory force and coordination determine the choice between an MDI (whether or not 'breath-actuated' or with a spacer) and a DPI. A rare side effect of metered-dose aerosols is bronchoconstriction.²⁴

Prescribing devices

• When prescribing multiple medications, aim for consistency in the method of administration. MDIs with holding chambers produce outcomes at least equivalent to nebuliser delivery.²⁵ Only in exceptional cases should oral beta₂ agonist therapy or inhalation using an electric-powered jet nebuliser be considered.
• There is no evidence to dictate an order in which devices should be tested. In the absence of evidence, the most important points to consider are patient preference and local cost.
• In adults and children, patient preference and ability to use the device effectively should play a key role in the choice of delivery device (age is a major determinant in ability to use a device effectively). If the patient is unable to use a device satisfactorily an alternative should be found.
• The medication needs to be titrated against clinical response to ensure optimum efficacy.
• Inhaler technique should be reassessed as part of structured clinical review.

Inhaled drug delivery is superior to oral (or parenteral) delivery for SABAs, anticholinergics, LABAs and ICS. There is no significant difference between delivery devices when used correctly. MDI plus large-volume spacer is at least as effective as a wet nebuliser in mild to moderate acute asthmatic episodes. People with asthma should receive adequate training in their inhaler technique to ensure competence. Device technique should be reassessed and reinforced frequently at appropriate opportunities. Choice of device should be made on the basis of ease of use, patient preference/suitability and overall cost.

Device training

• It is essential that adults with asthma be competently trained in the correct technique of inhaler use. With good instruction, most adults are able to effectively use any of the commercially available devices. The device that best fits the needs and tolerability of the patient should be chosen.²²
• Before considering a higher dose of medication or the addition of another agent, reassess the inhaler technique and adherence. The technique should be reviewed regularly, especially if asthma is poorly controlled.²²

Content Created (Thursday, 16 November 2006)