Drugs and behavior test 1
Pharmacokinetics
Pharmacokinetics = the movement of drugs through the body
The Four Processes of Pharmacokinetics
Absorption – how a drug enters the bloodstream
Distribution – how the drug moves throughout the body via the bloodstream
Metabolism – how the drug is broken down in the body
Elimination – how the drug is removed from the body
Absorption
Definition
Absorption is the process by which a drug enters the bloodstream
Routes of Drug Absorption
Oral (By Mouth)
Examples:
Pills
Cough syrup
Alcohol
Edibles/gummies
Requirements:
Drug must be stable in stomach acid or it will be destroyed
Absorption site:
Majority occurs in the small intestine
Rectal
Example:
Suppositories
Works well due to:
High concentration of blood vessels
Parenteral Routes
(Administration methods that do not involve the digestive tract)
Inhalation (NOT snorting)
Inhaling drugs into the lungs
Examples:
Smoke
Paint fumes
Whippets
Poppers
Vapes
Hookah
Characteristics:
One of the fastest ways to feel drug effects
Rapid absorption through lung tissue into the bloodstream
Transdermal (Through the Skin)
Examples:
Nicotine patches
Hormonal patches
Fentanyl patches
Lidocaine patches
Gels
Characteristics:
Slow route of administration
Drug must be fat-soluble to pass through the skin
Water-soluble drugs will not absorb well
Absorption Through Mucous Membranes
Examples:
Snorting cocaine
Snorting heroin
Nitroglycerin
Zyns
Afrin
Occurs in:
Nose
Mouth
Other mucous membranes
Drugs enter bloodstream through highly vascular tissue
Injection Routes
Administered using a syringe or hypodermic needle
Intravenous (IV)
Injection directly into a vein
Characteristics:
Fastest way to get a drug into the bloodstream
Immediate effects
Intramuscular (IM)
Injection directly into a muscle
Important rule:
IM drugs should NEVER be injected intravenously
Subcutaneous (SubQ)
Injection below the skin, into the fat layer
Intradermal
Injection within the dermis layer of the skin
Speed of Absorption (Key Comparisons)
Fastest entry into the bloodstream:
→ Intravenous (IV)Fastest delivery to the brain (psychological effects):
→ Inhalation
Distribution
Definition
Distribution is the movement of a drug throughout the body via the bloodstream
Role of the Bloodstream
Carries drugs:
To organs
To tissues
To the brain
Heart Anatomy (Blood Flow Basics)
Heart Chambers
Right atrium
Right ventricle
Left atrium
Left ventricle
Blood Vessels
Arteries – carry blood away from the heart
Veins – carry blood toward the heart
Blood Circulation Pathway
Blood from the body enters the right side of the heart
Right atrium → right ventricle
Deoxygenated blood is sent to the lungs
Blood becomes oxygenated in the lungs
Oxygenated blood returns to the left side of the heart
Left atrium → left ventricle
Oxygenated blood is pumped out to the body
Blood Supply to the Brain
Blood enters the brain via the carotid arteries
Blood exits the brain via the jugular vein
Metabolism
Primary Organ
The liver plays the primary role in drug metabolism
Key Terms
Hepatic Biodegradation
The liver breaking down a drug or chemical
Hepatocytes
Liver cells that release enzymes to break down drugs
Biotransformation
The process of transforming a drug into another substance
Metabolites
The products of drug metabolism
Important note:
Not all metabolites are equal
Some are:
Inactive
Active
Toxic
Brain Structures & Their Functions
Limbic System & Related Structures
Amygdala
Plays a major role in fear, threat detection, and emotional processing
Involved in emotional memory (especially fear-related memories)
Hippocampus
Responsible for learning and forming new memories
Works closely with the temporal lobe
Damage can impair the ability to form new memories
Temporal Lobe
Involved in memory, auditory processing, and language comprehension
Motor Control Structures
Basal Ganglia
Controls voluntary motor movement
Important for movement accuracy and coordination
Dysfunction is linked to movement disorders (e.g., Parkinson’s disease)
Sensory Relay & Homeostasis
Thalamus
Acts as a sensory and motor relay station
Sensory information from the body goes to the thalamus before being sent to the cortex
Hypothalamus
Located below the thalamus
Regulates:
Body temperature
Eating
Drinking
Drug effects:
MDMA/Ecstasy → increases body temperature
Stimulants → decrease appetite by affecting the hypothalamus
Pituitary Gland
Known as the “master gland”
Releases hormones into the body
Works closely with the hypothalamus
Midbrain & Pain Regulation
Midbrain
Involved in arousal, movement, and sensory processing
Reticular Formation / Reticular Activating System (RAS)
Regulates alertness and arousal
Affects adrenaline levels
Substantia Nigra
Produces dopamine
Degeneration is associated with Parkinson’s disease
Periaqueductal Gray (PAG)
Plays a major role in pain management
Brain releases:
Endorphins
Enkephalins
These chemicals reduce pain perception
Opiates (e.g., heroin) mimic endorphins to relieve pain
Hindbrain Structures
Locus Coeruleus
Group of cells in the reticular formation
Releases norepinephrine
Involved in arousal, attention, and stress
Raphe Nucleus
Releases serotonin
Drugs affecting serotonin:
LSD
Psilocybin
Cerebellum
Controls balance, coordination, and fine motor movement
Alcohol significantly affects cerebellar function
Pons
Plays a role in respiratory control
Works in conjunction with the medulla
Medulla
Controls vital functions:
Heart rate
Respiration
Drug effects:
Stimulants increase heart rate
Alcohol, especially when combined with benzodiazepines or barbiturates, can dangerously suppress respiration
Narcan (naloxone) blocks the effects of opiates
Nervous System & Brain Protection
Sympathetic Nervous System
Responsible for fight-or-flight response
Ventricles
Filled with cerebrospinal fluid (CSF)
Cushion and protect the brain
Meninges
Protective layers that surround the brain and spinal cord
Blood Supply
Blood enters the brain through the carotid arteries
Effects of Drugs on the Brain
Neurons
The brain contains approximately 100 billion neurons
Each neuron has four main parts:
1. Dendrites
Branch-like structures at the end of the neuron
Receive information from other neurons
Many drugs bind to receptors on dendrites
Ions enter dendrites (not neurotransmitters)
2. Cell Body (Soma)
Integrates information from dendrites
Produces proteins and receptors
3. Axon
Long tube-like structure
Carries electrical signals from one neuron to another
4. Terminal Buttons
Located at the end of the axon
Release neurotransmitters
Neurotransmission
Neurotransmitters:
Do not enter dendrites
Bind to receptors on the surface of dendrites
Binding causes ion channels to open, allowing ions to enter the neuron
General Definitions
Drug: A chemical substance that, when taken into the body, alters the structure or functioning of the body in some way, excluding nutrients considered related to normal functioning.
Psychoactive Drug: A drug that influences the functioning of the brain and consequently affects human behavior and experience.
Neurotransmitter Activity and Regulation
The "Lock and Key" Analogy
Receptors and neurotransmitters operate like a lock and key; specific neurotransmitters are designed to fit into specific receptor sites to trigger a response.
Mechanisms of Deactivation
Degrading Enzymes
Chemicals that break down neurotransmitters post-release, disabling their binding to receptors (e.g., breaking dopamine into inactive components).
Reuptake
The process of recycling where neurotransmitters are pulled back from the synaptic cleft into the terminal buttons of the presynaptic neuron.
Binding Sites and Drug Effects
Agonists vs Antagonists
Agonists: Drugs that enhance the function of a neurotransmitter.
Promote synthesis (creating more neurotransmitters in the neuron).
Promote release from the terminal buttons.
Block degrading enzymes or reuptake to keep neurotransmitters in the synapse longer.
Stimulate receptors by mimicking the neurotransmitter.
Antagonists: Drugs that decrease the function of a neurotransmitter.
Inhibit synthesis.
Block release.
Stimulate degrading enzymes or reuptake.
Block receptors, preventing the actual neurotransmitter from binding.
Binding Sites: Some drugs have their own unique binding sites rather than competing for the primary neurotransmitter site.
Major Neurotransmitter Systems
1. Acetylcholine (ACh)
Synthesis and Distribution: Produced in 3 brain areas and released throughout the brain. synthesized from Choline and Acetyl coenzyme A (Acetyl−CoA)
Choline Acetyltransferase (ChAT): The enzyme that synthesizes ACh by transferring an acetate ion.
Acetylcholinesterase (AChE): The enzyme that breaks down ACh.
Receptors: Can be excitatory or inhibitory depending on receptor type (Nicotinic and Muscarinic receptors).
Drug Interactions:
Curare: A competitive antagonist that blocks ACh at the neuromuscular junction, causing paralysis.
Botulinum Toxin: Inhibits ACh release, leading to paralysis.
Other Toxins: Black widow venom, Tetanus, and Nerve gas also target the ACh system.
2. Glutamate (Glu)
Characteristics: An amino acid and the primary excitatory neurotransmitter; found and made throughout the brain.
Receptors: AMPA and NMDA receptors.
Drugs/Toxins: MSG, Phencyclidine (PCP), and Carbon Monoxide (CO).
CO Toxicity: Disrupted ventilation leads to oxygen replacement and toxicity affecting glutamate signaling.
3. GABA (Gamma−AminobutyricAcid)
Characteristics: Synthesized from glutamate; the primary inhibitory neurotransmitter found throughout the brain.
Receptors: GABA−A and GABA−B.
Drug Interactions:
Agonists: Antiepileptics ( Tegretol, Phenobarbital) and Antianxiety meds (Benzodiazepines, Valium, Xanax, Klonopin).
Antagonists: Strychnine is a neurotoxin that blocks GABA, resulting in seizures.
Lithium also affects this system.
4. Dopamine (DA)
Synthesis: Converted from Tyrosine. Produced in 2 specific parts of the brain.
Functions: Can be excitatory or inhibitory; utilizes metabotropic receptors. Degraded by MAO and COMT.
Drug Interactions:
Agonists: Amphetamines (stimulants that promote release), Cocaine (blocks reuptake), and Methylphenidate (Ritalin).
Antagonists: Antipsychotics (Thorazine, Haldol, Clozapine) which block DA receptors.
5. Norepinephrine (NE)
Synthesis: Made in the Locus Coeruleus and released everywhere. Epinephrine is synonymous with Adrenaline.
Functions: Excitatory (alpha - ionotropic) or inhibitory (beta - metabotropic). Degraded by MAO and COMT.
Drug Interactions: Same as DA, plus Beta Blockers (Propranolol, Inderal) which reduce physical anxiety symptoms by inhibiting NE receptors.
6. Serotonin (5−HT)
Synthesis: Made from Tryptophan in the Raphe Nuclei.
Characteristics: Primarily excitatory with 14 different metabotropic receptors. Degraded by MAO and COMT.
Drug Interactions: MAOIs, SSRIs (Paxil, Prozac, Zoloft), and LSD(a serotonin agonist).
Psychoactive Impact and Toxicity
MDMA (Ecstasy): Induces excitement but is noted for neurotoxicity; protective measures are important post-use.
Tryptophan Myth: The idea that turkey causes sleepiness via serotonin production remains inconclusive and debated.
Controlled substances= a drug on a federal level that is illegal to use or poses or controlled by government (perscription)
Schedule I — high potential for abuse, no accepted medical use
Examples: heroin, LSD, mescaline, marijuana, PCP
Schedule II — high potential for abuse, some accepted medical use
Examples: codeine, morphine, cocaine, methadone, amphetamines, short-acting barbiturates
Schedule III — some potential for abuse, accepted medical use ((with potential dependence)
Examples: long-acting barbiturates, narcotic solutions or mixtures
Schedule IV — llow potential for abuse, accepted medical use
Examples: antianxiety drugs and sedative-hypnotics
Schedule V — minimal potential for abuse, widespread medical use
Examples: prescription cough medicines not containing codeine, llaxatives
Drug Names:
Chemical name
4, 5α-epoxy-14-hydroxy-3-methoxy-17-methylmorphinan-6-one hydrochloride
Generic name
Oxycodone hydrochloride
Brand name(s)
OxyContin®
Street names
“OCs”,“Oxy”
Two Types of Drug Use:
INSTRUMENTAL USE: A person iis taking a drug with a specific socially-approved goal in mind. (taking meds for headache)
RECREATIONAL USE: A person is taking a drug for the sole purpose of experiencing its psychoactive properties (e.g., to get “hiigh”).
Licit- Legal
Illicit- Illegal
DRUG ABUSE/DRUG MISUSE
Drug abuse is a form of drug-taking behavior that results in some form of physical, mental, or social impairment.
Drug misuse is a form of drug-taking behavior in which a prescription or nonprescription (over-thecounter) drug is used inappropriately.
Drug Effects:
Therapeutic effects of a drug
Desired physical or psychological effect of a drug
Side effects of a drug
Undesired physical or psychological effect of a drug
Motivations for Drug Use
Experimentation
Pleasure /Escape Boredom
Peer Influence
Spiritual Purpose
Self Discovery
Social Interaction
Rebellion
Drug Dependence and Addiction
Physical Dependence
The use of a drug to avoid withdrawal symptoms if the drug is not taken
Withdrawal
Abstinence syndrome (dated term)
Physical dependance only occurs with withdrawl
Psychological Dependence
Motivation to use a drug based on craving for the pleasurable effects
Positive reinforcement
Negative reinforcement
DRUG TOLERANCE
Definition: a gradually diminished physical or psychological effect of a drug upon repeated administrations
Need a larger amount of drug to achieve effect originally obtained by smaller amount
MECHANISMS FOR DRUG TOLERANCE
Metabolic tolerance
The liver breaks down the drug faster after repeated administrations than it did initially
Pharmacodynamic tolerance
Receptors that have been stimulated by the drug over time decrease in number or become less sensitive to it
Behavioral Tolerance
Conditioning to a context