Algin 5 mg/2 ml Injection is an antispasmodic medication containing Tiemonium Methylsulphate, a synthetic quaternary ammonium compound. It functions by inhibiting acetylcholine and histamine at muscarinic receptors, leading to the relaxation of smooth muscles in the gastrointestinal tract, biliary system, urinary bladder, and uterus. This action helps alleviate pain and discomfort associated with spasms in these areas.