PSYC62H3 Lecture 7: Mild Stimulants
PSYC62
LECTURE 7
Nicotine and caffeine
Nicotine
• Nicotine: central psychoactive ingredient in tobacco
• Tobacco: from plant leaves of Nicotiana
• Forms: cigarettes, cigars, hookah, chew, snuff, dipping tobacco, dissolvable tobacco
o Delivery mechanisms for nicotine
Pharmacokinetics
• Nicotine tar adheres to tissues in the mouth, nose, throat, lungs and skin
• Freebase form of nicotine best absorbed through mucous membranes in the mouth
• Peak absorption is 7 min. (cigarettes) to 25 min. (smokeless tobacco products)
• In liver, CYP-2A6 enzymes metabolize 80 to 90% of nicotine, producing the active metabolite
cotinine
• Half-life for nicotine is approximately two hours
o Chronic smokers have a 30% faster elimination rate of nicotine than nonsmokers
→ Scenario
• If you have Drug A in your body and now you’re taking Drug B what would be the effect of drug
if Drug A wasn’t there to begin with
o You take Drug A and in order for it to be eliminated, a lot of it must be broken down by
an enzyme
o If drug B is metabolized by the same enzyme that breaks down Drug A, it won’t be
metabolized as much and there will be a greater concentration
▪ Indv goes beyond therapeutic dose range → experience unwanted side effects
▪ Assumption that you will be metabolizing it
o Important for doctors to keep in mind that ppl may take multiple medications at once
Effect on the nervous system
• Nicotine is an agonist for cholinergic nicotinic receptors
• Receptors quickly desensitize:
o Channels close and cannot be opened even when agonist is bound
• Nicotine is also a functional antagonist:
o Receptors remain in an inactivated state longer than an activated state
o Leads to adaptive upregulation of receptors
▪ End up having more sensitive postsynaptic membrane for nicotine and
amphetamine
• PNS
o Increases sympathetic nervous system activity
• CNS
o Increases dopamine release in nucleus accumbens
o Also influences acetylcholine, glutamate, GABA, norepinephrine, serotonin, and
vasopressin
Other effects
• Cardiovascular effects: increases in HR and BP
• Nicotine also reduces appetite in both non-tobacco users and long-term smokers
Document Summary
Nicotine: nicotine: central psychoactive ingredient in tobacco, tobacco: from plant leaves of nicotiana. Forms: cigarettes, cigars, hookah, chew, snuff, dipping tobacco, dissolvable tobacco: delivery mechanisms for nicotine. Freebase form of nicotine best absorbed through mucous membranes in the mouth: nicotine tar adheres to tissues in the mouth, nose, throat, lungs and skin, peak absorption is 7 min. (cigarettes) to 25 min. (smokeless tobacco products) In liver, cyp-2a6 enzymes metabolize 80 to 90% of nicotine, producing the active metabolite cotinine: half-life for nicotine is approximately two hours, chronic smokers have a 30% faster elimination rate of nicotine than nonsmokers. If drug b is metabolized by the same enzyme that breaks down drug a, it won"t be metabolized as much and there will be a greater concentration. Indv goes beyond therapeutic dose range experience unwanted side effects: assumption that you will be metabolizing it. Important for doctors to keep in mind that ppl may take multiple medications at once.