How do inhalers deliver a consistent dose through almost 200 uses?

Question

How do they keep somewhat consistent pressure throughout with such a small vessel for the compressed air?

In: 6

Answer 1

As an asthmatic whose friend is an pulmonologist: they put more propellant in than what’s needed, so for the 120 doses, the pressure is consistent. The people that keep using the inhaler after the dose meter is at 0? They’re just getting propellant and no significant medicinal past the 0.

Think of a fully inflated tire, and you press the valve stem open, and hear the hiss of the air escaping. It stays the same pitch (consistent air flow), but then the pitch drops (slower air flow). The inhaler has enough pressure to consistently deliver the med, and then the rest of the air pressure is “wasted.”