In an embodiment, the present disclosure pertains to a stable formulation of a primary, secondary, and/or tertiary amino group containing composition that prevents or reduces formation of a nitroso impurity until the end of stated expiration or longer. In some embodiments, the composition includes metformin and at least one pharmaceutical excipient. In some embodiments, the at least one pharmaceutical excipient includes a magnesium salt and at least one of a calcium salt, dicalcium phosphate, polyethylene glycol, or polyethylene oxide. In some embodiments, the magnesium salt can include, without limitation, magnesium aluminum silicate, magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium silicate, magnesium stearate, magnesium sulfate, magnesium trisilicate, and combinations thereof. In some embodiments, a weight ratio of the drug to the at least one pharmaceutical excipient ranges from 1 to 99 to 99 to 1% w/w. In some embodiments, the at least one pharmaceutical excipient is a protective pharmaceutical ingredient.