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Glossary

Plain explanations for medical terms used on this site.

Abnormal Involuntary Movement Scale (AIMS)(AIMS)

A standardized assessment used to score the severity of tardive dyskinesia and other involuntary movements across multiple body regions.

Also called: AIMS assessment

Agonist

A molecule that activates a receptor, producing a biological response.

Agranulocytosis

Severe neutropenia in which the absolute neutrophil count (ANC) falls to very low levels (often <500 cells/µL), markedly increasing infection risk.

Also called: severe neutropenia, low ANC

Akathisia

A feeling of inner restlessness with a need to move (a type of movement side effect).

Alcohol use disorder (AUD)(AUD)

A diagnosis describing a problematic pattern of alcohol use that leads to impairment or distress. Treatment often includes counseling/support and may include medications such as naltrexone, acamprosate, or disulfiram.

Also called: alcohol use disorder, alcohol dependence

Alpha-2 adrenergic agonist

A medication that stimulates alpha‑2 adrenergic receptors, reducing sympathetic (“fight-or-flight”) output. Used for hypertension and sometimes to ease opioid withdrawal symptoms (e.g., clonidine, lofexidine).

Also called: alpha2 adrenergic agonist, alpha2-adrenergic agonist, alpha-2 agonist, α2 agonist, α2 adrenergic agonist, α2-adrenergic agonist

ANC(Absolute Neutrophil Count)

A blood test measuring infection‑fighting white blood cells.

Antagonist

A molecule that blocks a receptor and prevents activation by other substances.

Anticholinergic side effects

A constellation of effects—dry mouth, constipation, urinary retention, blurred vision, cognitive slowing—due to blockade of muscarinic acetylcholine receptors.

Also called: antimuscarinic effects, anticholinergic, anticholinergic effects

Assertive Community Treatment(ACT)

A multidisciplinary team model that delivers intensive, wraparound services in the community for people living with serious mental illness, often 24/7.

Also called: ACT team, assertive outreach

Assisted Outpatient Treatment(AOT)

A civil court order that requires someone with serious mental illness to follow a community treatment plan while living outside the hospital; also called outpatient commitment.

Also called: outpatient commitment, court-ordered outpatient treatment

Augmentation (RLS)

A medication-related worsening pattern in restless legs syndrome where symptoms start earlier in the day, become more intense, or spread to other body parts after initial improvement (often discussed with dopamine agonists).

Also called: RLS augmentation, augmentation in RLS

Benzodiazepine

A class of sedating medicines used for anxiety, panic, and sometimes insomnia. They can cause drowsiness and falls, and long-term use can lead to dependence and withdrawal.

Also called: benzodiazepines, benzo, benzos, BZD, BZDs

Bioavailability

The proportion (up to 100%) of an administered dose that reaches systemic circulation unchanged, and the rate at which it does so.

Also called: absorption fraction

BMI(Body Mass Index)

A number that uses height and weight to estimate body fat.

Boxed warning

The FDA’s strongest safety warning found at the top of a drug’s label.

Also called: black box warning

Buprenorphine induction

The initial phase of starting buprenorphine where doses are introduced and adjusted to control withdrawal and cravings. It is usually started after opioid withdrawal begins to reduce the risk of precipitated withdrawal.

Also called: buprenorphine initiation, buprenorphine induction phase

Cataplexy

A sudden, brief loss of voluntary muscle tone triggered by strong emotion, most commonly seen in narcolepsy.

Also called: cataplectic attack

CBT(Cognitive behavioral therapy)

A structured therapy that teaches skills to change unhelpful thought patterns and behaviors. It is commonly used for anxiety and depression and can be combined with medication.

Also called: cognitive behavioral therapy, cognitive-behavioral therapy

CBT-I(Cognitive behavioral therapy for insomnia)

A structured sleep-focused therapy that improves chronic insomnia by combining sleep education, stimulus control, and other techniques. Benefits often last longer than medication-only approaches.

Also called: cognitive behavioral therapy for insomnia, cbt for insomnia

Coordinated Specialty Care(CSC)

A collaborative early psychosis treatment model that combines medication management, psychotherapy, family education, case management, and supported employment/education services.

Also called: CSC team, early psychosis coordinated care

CYP(Cytochrome P450)

A family of liver enzymes that process many medicines (for example, CYP3A4, CYP2D6).

Also called: CYP enzymes

DDI(Drug–drug interaction)

When one medicine changes how another medicine works or is processed.

Also called: drug interaction

DOI(Digital Object Identifier)

A permanent identifier for a digital article (e.g., 10.xxxx).

Dopamine agonist

A medicine that stimulates dopamine receptors. Used in Parkinson’s disease and sometimes restless legs syndrome; can cause nausea, sleepiness, hallucinations, and impulse-control problems.

Also called: dopaminergic agonist, dopamine receptor agonist

DORA(Dual orexin receptor antagonist)

A class of sleep medicines that block orexin signaling (a wake-promoting system) to help with sleep onset and/or sleep maintenance.

Also called: dual orexin receptor antagonists, orexin receptor antagonist, orexin receptor antagonists

Dystonia

Sustained or intermittent muscle contractions that cause abnormal (often painful) movements or postures. Acute dystonia can occur as a medication side effect (for example with antipsychotics) and may involve the neck, jaw, tongue, or eyes (oculogyric crisis).

Also called: acute dystonia, oculogyric crisis, torticollis

ECG(Electrocardiogram)

A test that records the heart’s electrical activity.

Also called: EKG

EPS(Extrapyramidal symptoms)

Movement side effects like stiffness, tremor, or restlessness (akathisia).

Also called: movement side effects

FGA(First‑generation antipsychotic)

Also called typical antipsychotics; older agents such as haloperidol and fluphenazine.

Also called: typical antipsychotic, first generation antipsychotic

GAD(Generalized anxiety disorder)

A pattern of persistent, hard-to-control worry that lasts for months and causes distress or impairment, often with symptoms like restlessness, muscle tension, irritability, and sleep disturbance.

Also called: generalized anxiety disorder, generalised anxiety disorder

GHB(Gamma-hydroxybutyrate)

A CNS depressant also known as gamma-hydroxybutyrate. Illicit GHB is associated with profound sedation and respiratory depression; prescription oxybate products are regulated controlled substances and typically dispensed under a REMS.

Also called: gamma-hydroxybutyrate, gamma hydroxybutyrate

Glaucoma

A group of eye conditions that can damage the optic nerve, often related to increased intraocular pressure. Some medicines (including anticholinergics) can precipitate acute angle-closure glaucoma in susceptible people, which is an emergency.

Also called: angle-closure glaucoma, acute angle-closure glaucoma

Glucagon-like peptide-1 (GLP-1)(GLP-1)

An incretin hormone that helps regulate blood sugar and appetite. GLP-1 receptor agonist medications mimic GLP-1 signaling to improve glycemic control and promote weight loss.

Also called: glucagon like peptide 1, glucagon-like peptide 1, GLP1

Glucose-dependent insulinotropic polypeptide (GIP)(GIP)

An incretin hormone that stimulates insulin secretion in a glucose-dependent manner. Some newer metabolic medications target both GIP and GLP-1 signaling.

Also called: gastric inhibitory polypeptide

GSK‑3(Glycogen synthase kinase‑3)

An intracellular enzyme involved in cell signaling and circadian rhythms. Lithium inhibits GSK‑3 as part of its mood‑stabilizing effects.

Also called: glycogen synthase kinase 3, GSK3

Half‑life

How long it takes for half of a medicine to leave the body.

Also called: t1/2

Harm reduction

Strategies that reduce the harms of substance use without requiring abstinence (for example: naloxone access, safer-use counseling, syringe services).

Also called: harm-reduction

HDAC(Histone deacetylase)

Enzymes that modify chromatin and gene expression. Valproate inhibits HDACs, which may contribute to its clinical effects.

Also called: histone deacetylase enzyme

Hemophagocytic lymphohistiocytosis(HLH)

A rare, life‑threatening immune overactivation syndrome that presents with persistent fever, enlarged liver or spleen, cytopenias, and organ failure; requires urgent evaluation and treatment.

Hepatic impairment

Reduced liver function; doses may need to be adjusted.

Also called: liver impairment

HLA-A*3101

A human leukocyte antigen allele associated with increased risk of carbamazepine-induced rash in some populations; screening can guide safer prescribing.

HLA‑B*1502

A genetic marker; if present in some people of Asian ancestry, certain medicines can raise risk of severe rash.

Also called: HLA-B1502, HLA-B*1502

Hypertensive crisis

A sudden, severe rise in blood pressure that can cause headache, chest pain, or stroke; requires emergency care, especially in patients on MAO inhibitors after consuming high-tyramine foods or interacting drugs.

Also called: hypertensive emergency

Hypomania

A milder form of mania with elevated or irritable mood, increased energy, and decreased need for sleep that does not cause marked impairment or require hospitalization.

Hyponatremia

Low blood sodium level that can cause confusion, headache, seizures, or falls; often due to medications with antidiuretic effects.

Also called: low sodium

Idiopathic hypersomnia(IH)

A central disorder of hypersomnolence marked by chronic excessive daytime sleepiness despite adequate or prolonged sleep; sleep inertia (difficulty waking) and long sleep time can be prominent.

Also called: IH

In vitro

Studies done outside a living organism (e.g., test tube or cell culture).

In vivo

Studies done in a living organism (e.g., in people or animals).

Indications

The conditions a medicine is approved to treat.

Also called: uses

Individual Placement and Support(IPS)

An evidence-based supported employment approach that helps people with serious mental illness obtain and keep competitive jobs through rapid job search and ongoing coaching.

Also called: IPS supported employment

LAI(Long‑acting injectable)

A shot given every few weeks/months that slowly releases medicine.

Also called: depot, injectable

Mania

A period of abnormally elevated or irritable mood with increased energy, decreased need for sleep, impulsivity, and impaired judgment that can disrupt daily functioning.

MAOI(Monoamine oxidase inhibitor)

A class of antidepressants that inhibit monoamine oxidase A/B. Requires dietary restrictions at some doses and careful interaction management (washouts).

Also called: monoamine oxidase inhibitor, MAOIs, MAO inhibitors

Medication for opioid use disorder (MOUD)(MOUD)

Medications proven to treat opioid use disorder—most commonly buprenorphine, methadone, or naltrexone—used as part of a broader treatment plan. Sometimes called medication-assisted treatment (MAT).

Also called: medications for opioid use disorder, medication treatment for opioid use disorder, medication-assisted treatment, MAT

Medullary thyroid carcinoma (MTC)(MTC)

A type of thyroid cancer arising from parafollicular (C) cells. Some GLP-1–based therapies carry a boxed warning about thyroid C-cell tumors in rodents and are contraindicated in people with personal or family history of MTC.

Also called: medullary thyroid cancer, thyroid C-cell carcinoma

Meta‑analysis

A study that combines results from many studies to get a clearer answer.

Also called: systematic review with meta‑analysis

Metabolic syndrome

A cluster of risk factors—central obesity, dyslipidemia, hypertension, impaired glucose tolerance—that raise cardiovascular risk. Several antipsychotics can worsen these measures.

Also called: syndrome X, insulin resistance syndrome

Metabolism

How the body breaks down a medicine (often by liver enzymes).

Metabolite

A substance formed when a medicine is broken down. Some metabolites are active (contribute to effects), others are inactive.

MOA(Mechanism of Action)

How a medicine works in the body.

Also called: mechanism

Monitoring

Tests or check‑ins to help use a medicine safely (for example, labs).

Also called: follow‑up

Monohydroxy derivative (MHD)(MHD)

The active metabolite of oxcarbazepine (also called licarbazepine) that provides most of the drug’s clinical effect; serum levels drive pharmacokinetics and can accumulate in renal impairment.

Also called: licarbazepine

Multiple endocrine neoplasia type 2 (MEN2)(MEN2)

An inherited syndrome associated with endocrine tumors (including medullary thyroid carcinoma). GLP-1–based therapies with thyroid C-cell tumor warnings are contraindicated in people with MEN2.

Also called: MEN 2, multiple endocrine neoplasia type II

Negative symptoms

Symptoms like reduced motivation, blunted affect, and social withdrawal.

NET(Norepinephrine transporter)

A protein that pumps norepinephrine back into neurons. SNRIs block NET (often at higher doses) to raise norepinephrine.

Also called: norepinephrine reuptake transporter

Neuroleptic malignant syndrome(NMS)

A rare, life-threatening reaction to dopamine-blocking drugs marked by severe rigidity, high fever, autonomic instability, and mental status changes. Requires urgent treatment.

Also called: neuroleptic malignant reaction

Neurotransmitters

Neurotransmitters are chemical messengers released by neurons to relay signals across synapses. They help regulate mood, cognition, movement, sleep, appetite, and more. Key families include the dopamine receptors (D1–D5) and serotonin receptors (5-HT1–5-HT7). Imbalances in dopamine, serotonin, glutamate, or GABA pathways have been linked to schizophrenia and other conditions. Modern antipsychotics modulate multiple receptors, and many psychiatric drugs also interact with muscarinic, histamine, and adrenergic receptors, contributing to both therapeutic effects and side effects.

Also called: brain receptors, neurochemistry

Nicotine replacement therapy (NRT)(NRT)

Nicotine delivered without tobacco smoke (patch, gum, lozenge, inhaler, nasal spray) to reduce withdrawal symptoms and cravings during smoking cessation.

Also called: nicotine replacement therapy, nicotine replacement, NRT

ODT(Orally disintegrating tablet)

A tablet that dissolves on the tongue without water, useful when swallowing solid tablets is difficult.

Also called: orally‑disintegrating tablet, orally disintegrating tablet

Open access

A research paper that is free for anyone to read online without a paywall.

Also called: OA

Opioid overdose

A life-threatening opioid poisoning where breathing slows or stops (respiratory depression). Naloxone can temporarily reverse opioid effects while emergency help is on the way.

Also called: opioid poisoning, opioid overdose

Opioid use disorder (OUD)(OUD)

A diagnosis describing a problematic pattern of opioid use that leads to impairment or distress. Evidence-based treatment often includes medications (buprenorphine, methadone, or naltrexone) plus counseling/support.

Also called: opioid use disorder, opioid dependence

Oral overlap

Taking pills for a short time after starting an injection so medicine is covered while the shot starts working.

Also called: overlap

Oral suspension

A liquid formulation of a medication that is measured with an oral syringe or cup, useful for flexible dosing when tablets are impractical.

Also called: liquid formulation

OROS(Osmotic‑controlled Release Oral System)

A tablet technology that uses osmotic pressure to deliver a controlled drug release over time (e.g., paliperidone ER).

Also called: osmotic release oral system

Orthostatic hypotension

A drop in blood pressure when moving from sitting to standing that can cause dizziness or fainting. Some antipsychotics with alpha-adrenergic blockade raise this risk.

Also called: postural hypotension

P‑glycoprotein(P‑gp)

A transport protein that pumps many drugs out of cells; can affect how medicines are absorbed and eliminated.

Also called: P-gp, P glycoprotein

Parkinsonism

A cluster of movement symptoms such as stiffness, tremor, slowed movements (bradykinesia), and shuffling gait. Parkinsonism can be due to Parkinson’s disease or can be medication-induced (notably by dopamine-blocking antipsychotics).

Also called: drug-induced parkinsonism, antipsychotic-induced parkinsonism

PDSS(Post‑Injection Delirium/Sedation Syndrome)

A rare reaction after some injections (like olanzapine LAI) that needs monitoring after the shot.

Pharmacokinetics(PK)

The study of how the body handles a drug from administration to elimination: absorption, distribution, metabolism, and excretion.

Also called: drug disposition

PMCID(PubMed Central Identifier)

An ID for free, full‑text articles in PubMed Central.

PMID(PubMed Identifier)

A unique number used to find a study in PubMed.

Positive symptoms

Symptoms like hallucinations, delusions, and disorganized thinking often seen in schizophrenia.

Precipitated withdrawal

A sudden opioid withdrawal syndrome caused when an opioid antagonist or partial agonist displaces opioids from receptors (for example: starting buprenorphine too soon after a full opioid agonist).

Also called: precipitated opioid withdrawal

Prolactin

A hormone; some medicines can raise it and cause symptoms like breast changes.

QRS

A part of the ECG tracing representing ventricular depolarization; excessive widening may signal conduction issues.

QTc

A heart rhythm measure on an ECG. Some medicines can prolong the QT interval.

Also called: QT interval

RCT(Randomized Controlled Trial)

A study where people are randomly assigned to treatments to compare results.

REMS(Risk Evaluation and Mitigation Strategy)

An FDA safety program for certain medicines.

Renal impairment

Reduced kidney function; doses may need to be adjusted.

Also called: kidney impairment

Restless legs syndrome(RLS)

A neurologic sleep-related condition with an urge to move the legs, usually worse at rest and in the evening/night, that is relieved by movement.

Also called: restless legs, RLS

Samidorphan

An opioid receptor antagonist paired with olanzapine in Lybalvi to blunt weight gain; it blocks µ-opioid receptors for about 24 hours and renders opioid analgesics ineffective.

Also called: ALKS 33

Serotonin syndrome

A potentially life-threatening reaction from too much serotonin activity causing agitation, confusion, sweating, fever, tremor, clonus, and rapid changes in heart rate or blood pressure.

Also called: serotonin toxicity

SERT(Serotonin transporter)

A protein that pumps serotonin back into neurons. SSRIs block SERT to raise serotonin in synapses.

Also called: serotonin reuptake transporter

Serum level

How much medicine is in the blood.

Also called: blood level

SGA(Second‑generation antipsychotic)

Also called atypical antipsychotics; generally lower EPS risk than FGAs and include agents like aripiprazole, quetiapine, risperidone, and olanzapine.

Also called: atypical antipsychotic, second generation antipsychotic

SIADH(Syndrome of Inappropriate Antidiuretic Hormone)

A condition where the body retains too much water due to excess antidiuretic hormone, leading to low sodium (hyponatremia). Some antidepressants increase risk in older adults.

Also called: syndrome of inappropriate antidiuretic hormone, hyponatremia (drug‑induced)

Sialorrhea

Excess saliva production that can cause drooling; commonly occurs with clozapine and some other antipsychotics.

Also called: hypersalivation

Sigma-1 receptor

An intracellular chaperone protein at the endoplasmic reticulum that modulates neurotransmitter signaling, calcium flux, and stress responses; agonism may enhance antidepressant and anxiolytic effects.

Also called: σ1 receptor, sigma1 receptor

SMI(Serious Mental Illness)

Conditions like schizophrenia, bipolar disorder, or schizoaffective disorder that substantially interfere with functioning and are the focus of this resource.

Also called: serious mental illness

SSI/SSDI Outreach, Access, and Recovery(SOAR)

A SAMHSA-supported initiative that helps people experiencing or at risk of homelessness, including those with serious mental illness, apply for SSI or SSDI disability benefits successfully.

Also called: SOAR program

Steady state

The point at which a drug’s intake and elimination balance so blood levels stay consistent between doses.

Also called: steady‑state

Stevens-Johnson syndrome / toxic epidermal necrolysis(SJS/TEN)

A severe drug-induced skin reaction that can start with flu-like symptoms and progresses to painful blistering and detachment of skin and mucosa; requires emergency medical care.

Also called: Stevens-Johnson syndrome, toxic epidermal necrolysis

Tardive dyskinesia

Involuntary movements (like face/tongue) that can appear after long‑term use of some medicines.

Also called: TD

TDM(Therapeutic Drug Monitoring)

Checking medicine levels in blood to guide safe and effective dosing.

Also called: therapeutic drug monitoring

Tetracyclic antidepressant(TeCA)

An older antidepressant class (e.g., maprotiline) that selectively increases norepinephrine while causing strong antihistamine and anticholinergic effects, leading to sedation, weight gain, and higher seizure risk.

Also called: tetracyclic, TeCA

Therapeutic drug monitoring(TDM)

Laboratory measurement of medication concentrations (usually trough blood levels) to keep a drug within a target range and avoid toxicity or lack of effect.

Also called: drug level monitoring, TDM

Therapeutic range

The blood level range where a medicine is most likely to work without undue side effects.

Also called: therapeutic drug level

Treatment-resistant schizophrenia(TRS)

Schizophrenia that has not responded to at least two adequate trials of different antipsychotics, often leading clinicians to consider clozapine.

Treatment‑resistant schizophrenia(TRS)

Schizophrenia that has not responded to at least two adequate trials of different antipsychotics, often prompting consideration of clozapine.

Trough

A blood level taken right before the next dose (lowest point).

Also called: pre‑dose level

Tyramine

An amino acid found in aged or fermented foods (cheese, cured meats, soy sauces) that can trigger dangerous blood pressure spikes in patients taking MAO inhibitors.

Vesicular monoamine transporter 2 (VMAT2)(VMAT2)

A presynaptic transporter that loads dopamine, norepinephrine, and serotonin into synaptic vesicles; inhibiting VMAT2 reduces neurotransmitter release.

Glossary — PsychMed