These methods are resorted to when quick results are demanded or when there are reasons against the use of other routes. The agents should usually be in solution and non-irritating. The operation should, of course, be aseptic.

By Absorption from the Skin.

This is not often a practical route for producing the systemic effect of a drug. The principal exception is inunction of mercury for syphilis.

By Inhalation.

To produce a systemic effect by absorption from the mucous membrane of the respiratory tract a drug must be in the form of a vapor. The most common example of this form of administration is the use of chloroform, ether, amyl nitrite, etc.

Local Effect.

This may be produced by any method that brings the agent into contact with the part to be affected. Solutions, mixtures, ointments, powders, and practically all forms of medication are employed. Examples are: liniments, ointments, dusting powders, eye-washes, nasal sprays, gargles, mouth-washes, enema, injections, caustics, etc.