80-49-9

White or almost white, crystalline powder or colourless crystals

anticholinergic (opthalmic)

Homatropine methylbromide or Methylhomatropine bromide is a quaternary ammonium salt of methylhomatropine. Methylhomatropine is a peripherally acting anticholinergic medication that inhibits muscarinic acetylcholine receptors and thus the parasympathetic nervous system. Methylhomatropine does not cross the blood–brain barrier. Methylhomatropine is used, in addition to papaverine, as component of mild drugs that help "flush" the bile.

Equipin (Mission); Homapin (Mission).

Homatropinemethylbromide, 3 -hydroxy-8-methyl-1 H,5 H-tropaniumbromide mandelate (Novatropine, Mesopin), occurs as a bitter,white, odorless powder and is affected by light. The compoundis readily soluble in water and alcohol but insoluble inether. The pH of a 1% solution is 5.9 and that of a 10% solutionis 4.5. Although a solution of the compound yields a precipitatewith alkaloidal reagents, such as mercuric potassiumiodide test solution, addition of alkali hydroxides or carbonatesdoes not cause the precipitate that occurs with nonquaternarynitrogen salts (e.g., atropine, homatropine).

Homatropine methylbromide is transported poorly acrossthe blood-brain barrier because of its quaternary ammoniumgroup and, therefore, has far fewer stimulant properties thanatropine. It does have all the characteristic peripheralparasympathetic depressant properties of atropine and isused to reduce oversecretion and to relieve GI spasms.