Amyl Nitrite.
Amylene Hydrate.
Aniline Sulphate.
Antipyrine.
Apomorphine: to prevent; in emetic doses.
Argentic Nitrate: sometimes useful, but objectionable from risk of discoloring the skin.
Arsenic: in epileptiform vertigo.
Asafetida.
Atropine.
Anesthetics: rarely.