Substance Use Disorders

Vocabulary flashcards covering concepts, definitions, mechanisms of action, and receptor pharmacology from the lecture on substance use disorders.

Psychoactive Drugs

Chemicals that affect the nervous system and alter cognition, mood, perception, consciousness, or behavior.

Psychopharmacology

The study of psychoactive drugs and how they affect the nervous system, influencing behaviors, moods, perception, and consciousness.

Pharmacokinetics

The study of how the body affects a drug, including its metabolism, distribution through the blood, and elimination.

Pharmacodynamics

The study of how drugs affect the body, encompassing receptor affinity and drug efficacy.

Affinity

A measure of how well a drug binds to specific biological receptors and transporters.

Efficacy

The functional response or action a drug produces in the body after binding to its receptor.

Addiction

A condition characterized by a compulsive need to repeatedly readminister a drug despite harm to the user.

Nucleus Accumbens

A key brain region in the dopamine reward circuit that is heavily implicated in addiction.

Bioavailability

The extent and rate at which an active drug ingredient is absorbed and becomes available at the site of action.

Oral Administration

The swallowing of pills or liquids, which is the most common form for prescription drugs but yields low bioavailability due to digestive breakdown.

Injection

The administration of drugs via needle into a vein (intravenous), muscle (intramuscular), or under the skin (subcutaneous), providing high bioavailability.

Inhalation

A rapid-action route of administration involving smoking, vapor, gas, or mist through the respiratory system.

Insufflation

The rapid-action administration of gas, powder, or vapor by snorting through the nasal passages.

Direct Agonist

A drug that directly attaches to neurotransmitter receptors and mimics the action of endogenous neurotransmitters.

Indirect Agonist

A drug that increases neurotransmitter activity without binding directly to the receptor, such as by serving as a precursor, blocking reuptake, or inhibiting degrading enzymes.

Antagonist

A substance that blocks or hinders the normal action of a neurotransmitter.

Tolerance

A state of lessened behavioral or physiological responsiveness resulting from repeated drug administration, requiring increased doses to achieve the same effect.

Withdrawal

A set of symptoms occurring when a drug is discontinued, typically producing behavioral and physiological effects opposite to those caused by the drug.

$GABA_A$ Receptor Complex

A ligand-gated chloride channel containing distinct binding sites for $GABA$, benzodiazepines, ethanol, propofol, neurosteroids, and volatile anesthetics.

Barbiturates

A class of sedative drugs introduced in 1904 that bind to $GABA_A$ receptors and increase the duration of $Cl^-$ channel opening.

Benzodiazepines

A class of anxiolytic drugs introduced in 1960 that bind to $GABA_A$ receptors and increase the frequency of $Cl^-$ channel opening.

Alcohol Mechanism of Action

Acts as an agonist at $GABA_A$ and glycine receptors and an antagonist at glutamate receptors, while indirectly increasing dopamine release.

Crack Cocaine

A highly addictive, smoked form of cocaine produced by mixing cocaine hydrochloride with a base such as ammonia or baking soda to form crystals.

Methamphetamine

A potent, highly addictive smoked psychostimulant crystal that causes vesicle dopamine leakage, reduces dopamine transporters, and causes severe physical and cardiovascular side effects.

Teratogens

Chemicals or drugs that can cause developmental malformations or birth defects in a fetus.

MDMA Neurotoxicity

The degenerative and toxic damage caused to serotonergic axon terminals following administration of MDMA (Ecstasy).

Opioids

A broad category of analgesic drugs that interact with endogenous opioid receptors, encompassing natural opiates like morphine and heroin as well as synthetics like oxycodone and fentanyl.

Oxycodone (OxyContin)

A time-released synthetic opioid introduced in the 1990s to treat chronic pain, which led to high rates of addiction when crushed and misused.

Fentanyl

An extremely potent synthetic opioid with high receptor affinity that can be lethal at microgram-level doses.

Mu ($\mu$) Opioid Receptor

The primary receptor sub-type targeted by opioids to produce analgesia in the periaqueductal gray and ventromedial medulla, which can also trigger respiratory suppression.

Naloxone (Narcan)

A competitive opioid antagonist with high affinity for opioid receptors that rapidly reverses opioid-induced respiratory depression and prevents overdose deaths.

Psychedelics

A sub-class of hallucinogens, including LSD, psilocybin, mescaline, and DMT, that act primarily as agonists at $5\text{-HT}_{2A}$ serotonin receptors.

Dissociative Hallucinogens

A class of hallucinogenic substances including PCP, ketamine, and DXM that alter perception and produce feelings of detachment from the environment or self.

Cannabinoid Receptor Brain Distribution

High densities of cannabinoid receptors localized in subcortical and cortical structures, including the globus pallidus, substantia nigra, hippocampus, and cerebellum.

Endocannabinoid Retrograde Signaling

The mechanism where endocannabinoids released from postsynaptic pyramidal neurons travel backward across the synapse to activate presynaptic $CB_1$ receptors, inhibiting $Ca^{2+}$ channels and reducing GABA release.

THC (Tetrahydrocannabinol)

The primary psychoactive component of marijuana that acts as an agonist at $CB_1$ receptors and elevates dopamine levels.

CBD (Cannabidiol)

A non-psychoactive constituent of cannabis that acts on $CB_2$ receptors and exhibits anti-inflammatory potential.