Nicotine dependence(addiction) remains a major global public health challenge. Despite widespread awareness of harms of smoking, tobacco & nicotine use continues to contribute significantly to morbidity and mortality. Nicotine plays a crucial role in this by reinforcing addictive behavior and prolonged exposure to harmful substances.
In Pakistan, nicotine consumption occurs through various means which include traditional means such as cigarettes, hookah, sheesha & smokeless tobacco products like naswar, gutka and paan, and emerging alternatives like e-cigarettes, nicotine patches and pouches. The coexistence of traditional and emerging products presents unique challenges for health education, regulation and cessation efforts. this article aims to present medical overview of nicotine and its health effects.
Pharmacology of Nicotine:
Nicotine is a tertiary amine alkaloid derived from Nicotiana tabacum. It is psychoactive, highly addictive and is rapid acting central nervous system stimulant with paradoxical depressant effects at high doses
It is lipid soluble (Fat Soluble) which allows it to enter blood stream rapidly, cross into the brain within seconds by penetrating blood brain barrier, cross placenta and reach the unborn baby. Nicotine effects body in 7-10 seconds through smoking while its effects are slow and steady while using smokeless tobacco products.
1- Absorption into Body:
Nicotine can enter body through:
- Lungs (Cigarettes, Sheesha, Vaping)
- Mouth lining (Naswar, Gutka, Pouches etc.)
- Skin (Patches)
Once absorbed it quickly reaches brain, heart, Adrenal gland and nerves.
2-Metabolism:
It is primarily metabolized in liver where enzyme CYP2A6 convert it into Cotinine is used as a biomarker to measure nicotine exposure in body.
3-Elimination:
Nicotine is mainly excreted through kidneys. It stays in body for about 2 hours while cotinine stays for 16-20 hours
Effects on Autonomic Nervous System:
The autonomic nervous system controls all involuntary bodily functions i.e. heartbeat, BP, digestion etc. It has two parts: Sympathetic and Parasympathetic Nervous system. The balance between these two parts is necessary for normal body functioning.
Nicotine works by binding to special receptors on nerve cells called Nicotine Acetylcholine receptors. These receptors are present in autonomic nerves, Brain centers and adrenal gland. When nicotine binds to these receptors nerve cells become active, stress hormones like adrenaline are released while heart and blood vessels receive strong stimulation.
Although nicotine activates both sympathetic and parasympathetic nerves, but the sympathetic effects (stress) dominate, especially after repeated use. This internal imbalance in ANS leads to severe effects on body.
Effects on Body:
1-Heart and BP:
Nicotine increases the heartbeat, raise BP and cause narrowing of blood vessels which means the heart work harder than normal, increasing the risk of heart diseases and stroke.
2-Brain and Mental Effects:
It stimulates the release of dopamine and also effect other neurotransmitters such as acetylcholine, norepinephrine, serotonin and glutamate. The releases of these neurotransmitters increase short term alertness, focus, learning and temporary mood relaxation. But with time it leads to anxiety, irritability and dependence development.
3-Stomach and Digestion:
Nicotine makes the stomach lining weaker causing reduction in appetite, nausea and stomach pain.
4-Sweating and Tremors:
it causes excessive sweating, shaky hands and feeling of restlessness.
Addiction:
As nicotine increases dopamine, a chemical linked to pleasure and reward. So repeated use leads to brain dependence on nicotine. This cycle causes strong addiction.
Long Term Effects:
Chronic nicotine use causes constant stress state, high sympathetic stimulation and loss of natural nervous balance. This results in the persistent high BP, reduced heart rate, irregular heartbeats, digestive and sleep problems.
Withdrawal Effects:
When a person stops using nicotine following occurs:
- Heart rate slows down
- Hunger increases
- anxiety
- headache
- irritability
- digestion feels disturbed
These symptoms are strong in first two days while gradually disappears. It shows that nervous system is trying to return to normal balance.
Cure and Treatment of Nicotine dependence:
There is no instant cure, but nicotine addiction is fully treatable and reversible.
1-Behavioural Treatment:
to help break psychological habit counseling, Cognitive Behavioral Therapy (CBT) is used. Support from family and friends plays a crucial role in treatment of nicotine dependence.
2-Nicotine Replacement Therapy (NRT):
NRT is used to reduce withdrawal symptoms by administrating controlled doses through nicotine gums, pouches & lozenges. These are all smokeless tobacco products.
3-Medicines:
In some severe cases, medicines that reduce nicotine cravings are used. These are medicines that blocks nicotine pleasure and should only be used under medical supervision.
4-Lifestyle:
Changes in lifestyle also help to fight nicotine dependence. Doing regular exercise, eating healthy and having good sleep reduces addiction. Avoiding triggers such as tea, stress and social cues are recommended.
Prevention Strategies:
At individual level, first of all never start tobacco use, avoid peer pressure and learn how to manage stress. While parents should avoid tobacco use in front of their children and educate children about harms of nicotine products at early age. Community awareness programs and access to cessation clinics is likely to decrease the nicotine usage.
Nicotine is a powerful psychoactive chemical that directly interferes with body’s Autonomic control, it may temporarily relax or stimulate the user, but it pushes the body medically into a constant stress stage, damaging heart and nerves in the long run. The good thing is ANS can recover with proper treatment, support and prevention. Addressing nicotine usage is essential for individual health as well as national public health.