Nicotine and caffeine are both very popular drugs used across the world. They are drugs that are highly addictive and have many harmful short term and long term effects on the body. Nicotine is a drug that is extracted from tobacco leaves, and is found mostly in cigarettes. Caffeine is taken from plants, and is found in coffee and other drinks such as tea and energy drinks. Both drugs have connections to harmful symptoms such as anxiety, insomnia, and irritability.
        Nicotine is a popular drug due to its relaxing effects. At first, nicotine reduces stress, increases alertness and higher cognitive function. These pleasant effects, which resemble effects of anti-depressant medicines, are caused by the release of the dopamine, serotonin, and norepinephrine. These are neurotransmitters, chemicals found in the brain that account for things such as mood. Some smokers believe that smoking helps relieve depression, because of its effects on the brain.(Pharmacology, 601)
       Nicotine has powerful withdrawal symptoms. During withdrawal, the symptoms are anxiety, nervousness, restlessness, impaired cognitive function, increased appetite and weight gain(Pharmacology, 601). Previous users may also experience lack of sleep and difficulty to pay attention (Hyprocretin mechanisms, 25). Smokers often will become extremely depressed once they stop using the drug. This is because the user’s body is no longer getting those neurotransmitters at the same levels as it was before. This will cause a large drop in the mood of the user. (Pharmacology, 601)
	There are many short lasting side effects of caffeine. Caffeine is known as a central nervous system stimulant, because of how it heightens physical and psychological functioning. It is taken for how it increases energy, mood, and alertness. Through abusing the drug, caffeine can cause intoxication, anxiety, insomnia, and depression (Substance Abuse, 151). These effects will last for around 4 to 6 hours after consumption. (Caffeine Intoxication, 2)
	Nicotine is an ingredient found in tobacco leaves. It can be ingested through oral snuff, pipe tobacco, and cigarettes. From there, it reaches the blood stream. Cigarette tobacco has the highest amount of nicotine, containing 10-14 mg of the drug. When smoking, about 1-1.5 mg of nicotine is absorbed. Nicotine is also found in potatoes, tomatoes, and eggplants, though in very small levels. (Nicotine Chemistry, 1,2)
         Caffeine is one of the most widely used drugs in the world. Caffeine is made from plants such as guarana, cacao pod, and the cola nut. The average American adult consumes around 200-300 mg a day.(Substance Abuse, 151) Caffeine is found in plants and added to foods and drinks (Substance Abuse, 151). Even tea, which contains caffeine, is the second most popular drink in the world behind water.(Caffeine, 8). This drug is most often consumed through drinking.
         Nicotine is extremely addictive. Addiction to nicotine depends on how the nicotine is taken. Cigarette nicotine is the most addictive form of nicotine. This is because it gives a rapid delivery of the nicotine to the brain. Once it’s inhaled, nicotine passes through the bloodstream into the brain, where the brain is exposed to high levels of nicotine. Afterwards, the enjoyable effects of nicotine occur which makes the drug so addictive. (Pharmacology of Nicotine, 602)
         Nicotine is rapidly absorbed as tobacco enters the lung. The absorption of nicotine depends on its pH. Nicotine is a weak base and has a pH of around 8, so it does not cross membranes quickly. The nicotine is absorbed quickly as it reaches the airways of the lung. This is because of the large surface area of the lung’s alveoli and the small airways. As the user is smoking, blood concentrations of nicotine rise. The peak of the blood concentration is when the user has finished smoking.(Nicotine chemistry, 2)
        Nicotine is metabolized in the liver. About 80% of nicotine is converted to cotinine, a metabolite known as the lactam derivative. Cotinine will stay present in the user. This is a two step process using the nicotine iminium ion. Cotinine and nicotine are both bounded to melanin over time and partly end up in the user’s hair and nails (Nicotine Chemistry, 4).
      After nicotine enters the user’s body, it flows through the bloodstream and distributes to body tissues. From there, it takes about 10-19 seconds to pass through the brain. Between cigarettes, the brain’s nicotine levels will fall. This creates an opportunity for the receptors to resensitalize. After the last cigarette, the nicotine levels fall and then are eliminated from the body. Nicotine lasts in the user’s system for about 40 hours(Pharmacology, 599).
	Caffeine has been thought to be the cause of many harmful diseases and side effects. According to Caffeine (346), caffeine intake in can lead to the loss of calcium and bone loss. In the experiment, the subjects experienced negative side effects from anywhere between two cups of coffee a day to four to five cups of coffee. However, some of their subjects showed no significant effect. Also, studies have shown that caffeine has a link to aggression and violence. (Caffeine, 271)
	Once caffeine is consumed, it will stay in the body for around four and a half hours. After taken through the oral route, caffeine is metabolized in the liver. This activates the dimethylzanthine stimulants theobromine and theophylline(Caffeine Intoxication, 2). Caffeine easily crosses the biological membranes, which leads to easy absorption in the body(Caffeine, 226).  The distribution of caffeine throughout the body is 0.6 L/kg. 36% of that is bound to protein. In a healthy adult, the elimination of caffeine takes up to around 4.5 hours.(Caffeine Intoxication, 2)
        Caffeine users may experience withdrawal effects if they stop taking in the drug. Some of these symptoms are insomnia, nausea, depression, aches, and muscle stiffness. One common symptom, fatigue, along with headaches, are the first to occur. Withdrawal symptoms usually occur 12 to 24 hours after caffeine abstinence. Symptoms have been said to only occur when taking high doses of the drug (Caffeine, 277).
	Caffeine has an impact on calcium metabolism. Addiction to caffeine can lead to osteoporosis, bone loss, and a disturbance in calcium balance. Large amounts of caffeine have been said to lead to hypercalcuria, which is an extreme loss of calcium through excretion. However, to have an impact on the user’s calcium balance, they would need to take in more than four cups of coffee a day. (Caffeine, 346)
        Caffeine abuse can show itself in many ways. When caffeine is abused, it affects almost every organ system.  This can lead to hyperglycemia, seizures, and electrolyte disturbances. It was thought that caffeine affected cancers of many organs, though after many studies there appears to be no correlation. (Caffeine, 334)
	Nicotine is a amine that is made of a pyridine and pyrrolidine ring. Nicotine is also an alkaloid of tobacco. Nicotine binds to nicotine receptors in the brain. When nicotine binds to nicotine receptors, there are different functional states of the nicotine. These functional states include resting state, activated state, and desensitized state. These are different types of nicotine receptors, which explain why there are multiple effects of nicotine in humans. These receptors are found on cell bodies and nerve terminals. (Pharmacology, 598)