PSYC62H3 Lecture 7: Mild Stimulants

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3 May 2018
School
Department
Course
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
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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.

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