Not approved as NRTs
Some smokeless consumer products available can function as alternative nicotine delivery systems (ANDS) but they have not received FDA approval as smoking-cessation therapy aids that are safe and effective. Snus and nasal snuff also allow for nicotine administration outside of tobacco smoking. Nicotine pouches are described as similar to or a tobacco-free variant of snus. They are pre-portioned and are held in the users lip or cheek allowing for sublingual or buccal delivery of flavors and high doses of nicotine. The small pouches are not like chewing tobacco, as the user does not need to spit since the contents of the pouches stay inside during use. Swedish pouches have been available on the American consumer market since at least 2016 but their popularity and controversy surged in 2019 & 2020. In the US and UK concerns have been raised that nicotine pouches are seemingly too similar to banned snus products, is aimed at teenagers, further complicating the youth vaping trend, falling into the hands of adolescents easily, and are discrete enough to easily pass for regular gums or lozenges.Nicotine infused toothpicks are another product that has been available in the United States since at least 2013. They can have a total nicotine delivery that is comparable to that of nicotine gum. Nicotine toothpicks generally are infused with food-grade flavorings and 1–3 mg of nicotine, which is similar to that of other oral-delivery nicotine products and some cigarettes. In spite of these similarities, as of 2018 they have been a subject of controversy.
Other conditions
Nicotine replacement therapies should be used cautiously in individuals with the following conditions: severe reactive airway diseases (for nasal spray), chronic nasal disorders such as sinusitis, polyps, rhinitis, or allergy (for nasal spray), diabetes (insulin-dependent), gastrointestinal diseases such as esophagitis, active gastric or peptic ulcer disease, liver problems, hyperthyroidism,pheochromocytoma, phenylketonuria (for lozenges), renal problems, and skin conditions such as psoriasis or dermatitis (for the transdermal patch). Mechanism of action
Nicotine replacement therapy works by reducing cravings due to nicotine addiction. Smoking cigarettes releases high doses of nicotine to the brain in a matter of seconds as opposed to low doses released over a period of minutes to hours by the various forms of nicotine replacement therapy. Nicotine from NRT does not reach as high a concentration in the blood as does nicotine from smoke inhalation due to different absorption methods. NRT relies on systemic venous absorption, whereas nicotine from cigarettes reaches the arterial system. Nicotine replacement products vary in the time it takes for the nicotine to enter the body and the total time nicotine stays in the body. The more quickly a dose of nicotine is delivered and absorbed, the higher the addiction risk. It is possible to become dependent on some NRTs.Nicotine patches are applied to the skin and continuously administer a stable dose of nicotine slowly over 16–24 hours. Nicotine gum, nicotine sprays, nicotine toothpicks, nicotine sublingual tablets, and nicotine lozenges administer nicotine orally with quicker nicotine uptake into the body but lasting a shorter amount of time.