Nicotine is the drug in tobacco leaves. But when in cigarettes composition is added ammonia then the nicotine is up to 100 times, according to a recent study.
Ammonia is a compound with the formula NH3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous.
Many Tobacco Industries denied the claim that ammonia enhances the effect of nicotine.
The process of increasing the impact of nicotine by adding ammonia is called "free-basing," which is similar to the chemical process used to heighten the effects of cocaine.
Like cocaine, nicotine exists in two forms - acid and base. When ammonia is added, the nicotine converts from acid to base form. The base form can vaporize more easily from the smoke particles into the gas phase, enabling it to deposit directly on the lung tissue and immediately extend throughout the body.
Although the research has shown that ammonia makes nicotine more available from cigarette smoke, scientists continue to warn that more research needs to be done to determine whether "the increased chemical availability translates into a more rapid uptake of nicotine by the smoker."
In fact, the documents show that R. J. Reynolds officials seized on a decision by Philip Morris, which in the mid-1960 began to use ammonia in its production process. By 1973, Marlboro sales were steadily rising, and officials of R. J. Reynolds, which was then losing its grip as the nation's leading cigarette maker, believed that the addition of ammonia was a key to the success of Marlboro, as well as a Brown & Williamson product, Kool.

They suspected that the use of ammonia yielded more free nicotine and increased the cigarette's punch, internal company documents show.