Final answer:
A spacer is the add-on device or extension used with a Metered Dose Inhaler (MDI) to administer drugs. It improves medication delivery to the lungs and helps reduce the risk of side effects.
Step-by-step explanation:
The add-on device or extension used with a Metered Dose Inhaler (MDI) to administer drugs is called a spacer. A spacer is a holding chamber that attaches to the MDI and helps improve the delivery of medication to the lungs. It acts as a reservoir, allowing the medication to mix with the air, making it easier to inhale.
When an MDI is used alone, coordination is required to press down on the canister while inhaling the medication. However, with the spacer, the medication is first released into the chamber, and then the user can inhale at their own pace, making it more effective and reducing the risk of side effects.
For example, an asthma patient using a spacer with their MDI can receive the full dose of their medication, as opposed to relying solely on their inhaler technique, which may be less precise.