Insufflation (Latin insufflatio "blowing on" or "into") is the practice of inhaling a substance. Insufflation has medical use as a route of administration for many respiratory drugs used to treat conditions in the lungs (e.g., asthma or emphysema) and paranasal sinus (e.g., allergy).
The technique is common for many recreational drugs and is also used for some entheogens. Nasal insufflation (snorting) is commonly used for many psychoactive drugs because it causes a much faster onset than orally, and bioavailability is usually, but not always, higher than orally. This bioavailability occurs due to the quick absorption of molecules into the bloodstream through the soft tissue in the mucous membrane of the sinus cavity
and portal circulation bypass. Some drugs have a higher rate of
absorption, and are thus more effective in smaller doses, through this
route. Prodrugs, drugs that are metabolized or activated by the liver
(such as codeine),
should not be insufflated, because they need to be metabolized by the
liver to break down into the compounds that are active (drugs absorbed
through the GI tract pass through the liver before entering the systemic
circulation, where drugs which are insufflated are absorbed directly
into the systemic circulation).