A novel, rapid, sensitive, and validated high-performance liquid chromatographic 
(HPLC) technique, with high selectivity for stability indication, has been employed 
to determine pyridostigmine bromide and its degradation products (3-hydroxy-1-
methylpyidin-1-ium bromide and 3,4-dioxo-3,4-dihydropyeidin-1-ium) in a 
pharmaceutical formulation. Pyridostigmine bromide and its degradation products 
were identified using combinations of acetonitrile and 0.01M acetate buffer (pH=6)
in a ratio of 5:95 (v/v), through flow rates of about 1 ml/min at room temperature, 
employing a diode array detector. The linear range was determined to be 27-135
µg/ml. Our findings indicate that pyridostigmine bromide is unstable in alkaline
conditions but more stable in acidic environments and susceptible to oxidation.