Homatropine methylbromide or Methylhomatropine bromide is a quaternary ammonium salt of methylhomatropine. It is a peripherally acting anticholinergic medication that inhibits muscarinic acetylcholine receptors and thus the parasympathetic nervous system. Certain preparations of drugs such as hydrocodone are mixed with a small, sub-therapeutic amount of homatropine methylbromide to discourage intentional overdose.

Homatropine (used in a form of bromide or methylbromide salts) is an analogue of atropine, which acts as an antagonist of muscarinic receptors. Homatropine was approved for the treatment of cough in combination with hydrocodone bitartrate.

Methylatropine (methylatroponium) is a belladonna derivative. In 1902 the Bayer Company introduced atropine methonitrate, a quaternary ammonium salt of atropine (Eumydrin), as a mydriatic for dilation of the pupil during ophthalmic examination. Due to its highly polar nature it penetrates less readily into the central nervous system than atropine and was therefore introduced for relieving pyloric spasms in infants. Atropine methyl nitrate is a muscarinic acetylcholine receptor antagonist that does not cross the blood-brain barrier. Atropine methyl nitrate has been used for its peripheral muscarinic effects (targeting the bladder, respiratory tract, and to block parasympathetic signaling to the heart, among others) and to separate central from peripheral nervous system effects, or to protect against peripheral side effects when using muscarinics that do cross the blood brain barrier.

Mandelic acid is an aromatic alpha hydroxy acid that is used for the treatment of urinary tract infections. The drug is marketed in Canada under the name Mandelamine (as a complex with methenamine). Mandelic acid exerts its antibacterial effect mainly by increasing urine acidity. Moreover, mandelic acid is used as a serum for the treatment of wrinkles.