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Lecture 26
Biology of Substance Abuse
Drug Administration and Absorption
• Ingestion
• Injection
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– Subcutaneously (SC)
– Intramuscularly (IM)
– Intravenously (IV)
Inhalation
Absorption through mucous membranes
Drug Tolerance
• Definition
• Metabolic tolerance
• Functional tolerance
• Cross tolerance
• No unitary mechanism
Addicts
• Habitual drug users
– Adverse effects on their health, social life
– May be linked to psychological
dependence
Tobacco
• Nicotine
• Acts on the nicotinic receptor (a type of
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acetylcholine receptor)
Increases blood pressure, heart rate, and
release of epinephrine (adrenaline)
Addiction may have a genetic basis….?
Many side effects and withdrawal symptoms
Alcohol
• Most used and abused
• Affects general nervous system
• Activates a specific type of GABA and
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glutamate receptor
Addiction has a major genetic component
Long term use can cause irreversible damage
to the brain, liver, heart, and stomach
Marijuana
• Active ingredient is THC
• Intensifies sensory experiences, increases
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appetite
Lack of energy and ambition
Many medical uses
Binds to cannabinoid receptors in the brain,
but the exact mechanisms of action are not
clear
Cocaine and Amphetamines
• Crack cocaine
• Extremely addictive, mild withdrawals
• Blocks reuptake of NE and DA
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(catecholamines)
Effects are brief
Opiates
• Include morphine, heroin, codeine
• Produces a pleasant state and decreases
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sensitivity to pain
Bad side effects
Attaches to endogenous receptors
Biopsychological Theories of drug
addiction
• Moral model
• Disease model
• Physical-dependence theory
• Positive-incentive theory
Vulnerability to Drugs
• Biological factors
• Personal characteristics
• Family situation
• Social and community factors
Treatment for Drug Abusers
• Drugs for detoxification
• Agonists of drugs that produce addiction
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states
Antagonists to the addictive drug
Anti-craving medications
Medication that blocks drug metabolism