Trazodone Glossary
Plain-language definitions for the medical and pharmacology terms used across the Guide, Side-Effect Library, and Interaction Library.
A
- Active metabolite
- A breakdown product of a drug that is itself pharmacologically active. Trazodone is partly converted in the liver to meta-chlorophenylpiperazine (mCPP), which has its own serotoner…
- Angle-closure glaucoma risk
- A sudden increase in eye pressure that some antidepressants, including trazodone, can trigger in people with a particular anatomical eye risk factor (narrow anterior chamber angle)…
- Anticholinergic effects
- Side effects — such as dry mouth, blurred vision, or constipation — caused by blocking acetylcholine receptors. Trazodone has weaker anticholinergic activity than older tricyclic a…
- Augmentation therapy
- Adding a second medication to an existing treatment to boost its effect, rather than replacing the first medication. Low-dose trazodone is sometimes added at bedtime to another ant…
B
- Bioavailability
- The proportion of a dose that reaches the bloodstream in active form. Food can change how quickly and how completely oral trazodone is absorbed.
- Boxed warning
- The FDA's strongest safety warning, placed at the top of a drug's prescribing information. Trazodone carries the antidepressant-class boxed warning about increased suicidal thought…
C
- Controlled substance schedule
- A classification system the DEA uses to regulate drugs based on abuse potential. Trazodone is not a scheduled controlled substance.
- CYP3A4
- A liver enzyme responsible for metabolizing many medications, including trazodone. Drugs that strongly inhibit or induce CYP3A4 can significantly raise or lower trazodone levels in…
D
- Discontinuation syndrome
- A cluster of symptoms — such as nausea, insomnia, irritability, or flu-like feelings — that can occur when an antidepressant is stopped abruptly, especially after longer-term or hi…
- Drug interaction
- A change in how a medication works, or in its side-effect risk, caused by another drug, supplement, food, or substance taken at the same time.
E
- Extended-release (ER) formulation
- A tablet designed to release medication slowly over time, allowing once-daily dosing. An extended-release trazodone product (brand name Oleptro) was previously marketed in the Unit…
F
- First-pass metabolism
- The process by which a drug taken by mouth is partly broken down by the liver before reaching the rest of the body, reducing the amount that becomes active in the bloodstream.
G
- Generic drug
- A medication containing the same active ingredient, strength, and dosage form as a brand-name drug, approved by the FDA as therapeutically equivalent. Trazodone has been available…
H
- Half-life
- The time it takes for the amount of a drug in the body to fall by half. For trazodone, published estimates generally fall in the range of about 5 to 9 hours in adults, though indiv…
I
- Immediate-release (IR) tablet
- The standard, most commonly prescribed trazodone tablet form, which releases the full dose promptly after swallowing rather than over an extended period.
M
- Major depressive disorder (MDD)
- A mood disorder involving persistent sadness or loss of interest that interferes with daily functioning. MDD is the only condition for which trazodone carries formal FDA approval.
- Mechanism of action
- The biological process by which a drug produces its effects in the body — for trazodone, this centers on serotonin receptor blockade, weak serotonin reuptake inhibition, and antihi…
- Medication guide
- An FDA-required, patient-facing handout that pharmacies must provide with certain prescriptions, summarizing key risks in plain language. Trazodone is dispensed with a Medication G…
O
- Off-label use
- Prescribing an FDA-approved drug for a purpose, dose, or age group not specifically listed on its approved label. Using low-dose trazodone for insomnia is a well-known example.
- Orthostatic hypotension
- A drop in blood pressure that occurs when standing up from sitting or lying down, which can cause dizziness, lightheadedness, or fainting.
P
- Priapism
- A prolonged, and often painful, erection unrelated to sexual arousal. It is a rare but medically documented risk of trazodone use in men and is considered a medical emergency if it…
- PRN dosing
- Taking a medication only when needed for a specific symptom, rather than on a fixed daily schedule. Some prescribers allow PRN low-dose trazodone for occasional sleep trouble.
Q
- QT prolongation
- A lengthening of the QT interval on an electrocardiogram (ECG), which can, in rare cases, increase the risk of a dangerous heart rhythm called torsades de pointes.
S
- SARI (Serotonin Antagonist and Reuptake Inhibitor)
- A class of antidepressant that both blocks certain serotonin receptors (mainly 5-HT2A) and weakly inhibits the reuptake of serotonin. Trazodone is the most widely prescribed drug i…
- Sedative-hypnotic
- A general term for medications that promote calmness or sleep. Trazodone is not FDA-approved as a sedative-hypnotic, but its sedating side effect is why it is commonly prescribed o…
- Serotonin syndrome
- A potentially serious condition caused by excess serotonin activity in the nervous system, most often from combining multiple serotonergic medications. Symptoms range from mild to…
- SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion)
- A condition causing the body to retain too much water relative to sodium, leading to low blood sodium (hyponatremia). It is a recognized, uncommon risk with trazodone and other ant…
T
- Therapeutic index
- A measure of how large the gap is between an effective dose and a harmful dose. Trazodone is generally considered to have a wider — safer — margin than older tricyclic antidepressa…
- Titration
- Gradually adjusting a medication dose upward or downward over time to find the level that balances benefit and side effects for a given person.
W
- Washout period
- A waiting period between stopping one medication and starting another, used to let the first drug clear the body and reduce interaction risk. A roughly 14-day washout is typically…