Trazodone

Uses

Trazodone is a serotonin uptake inhibitor used to treat major depressive disorder.

Trazodone is indicated for the treatment of major depressive disorder (MDD). It has been used off-label for adjunct therapy in alcohol dependence, and off-label to treat anxiety and insomnia. It may also be used off-label to treat symptoms of dementia, Alzheimer’s disease, schizophrenia, eating disorders, and fibromyalgia due to its effects on various neurotransmitter receptors.

Trazodone is also used to associated treatment for these conditions: Alcohol Dependency, Alzheimer's Disease (AD), Anxiety, Dementia, Eating Disorders Symptoms, Fibromyalgia, Insomnia, Major Depressive Disorder (MDD), Pain, Inflammatory, Schizophrenia, Moderate to severe pain

How Trazodone works

The mechanism of action of trazodone is not fully understood, however, it is known to inhibit the reuptake of serotonin and block both histamine and alpha-1-adrenergic receptors. Despite the fact that trazodone is frequently considered a selective serotonin reuptake inhibitor, several reports have shown that other mechanisms including antagonism at serotonin 5-HT1a, 5-HT1c, and 5-HT2 receptor subtypes may occur. The strongest antagonism of trazodone is reported to occur at the serotonin 5-HT21c receptors, preventing serotonin uptake. In addition to acting on serotonin receptors, trazodone has been shown to inhibit serotonin transporters. The antidepressant effects of trazodone result from the inhibition of receptor uptake, which normally decreases circulating neurotransmitters, contributing to depressive symptoms.

Toxicity

The oral LD50 of trazodone is 690 mg/kg in rats.

An overdose of trazodone may result in central nervous system, cardiac, respiratory effects. Signs and symptoms may include dyspnea, bradycardia, hypotension, mental status changes, lack of coordination, and coma, among others. In addition, an overdose may result in priapism, a persistent unrelievable penile tissue erection that may cause permanent damage if not treated promptly. No specific antidote exists for a trazodone overdose. If an overdose occurs, consider the possibility that trazodone may have been combined with other drugs. Contact a poison control center in case of overdose for the most current management guidelines. Dialysis does not accelerate trazodone clearance.

Food Interaction

• Avoid alcohol.
• Avoid St. John's Wort. The risk of serotonin syndrome may be increased.
• Take after a meal. Should be taken shortly after a light meal or snack.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Trazodone Drug Interaction

Major: duloxetine, escitalopram, fluoxetine, bupropion, sertralineModerate: aripiprazole, clonazepam, lamotrigine, pregabalin, acetaminophen / hydrocodone, quetiapine, topiramate, alprazolam, cetirizineMinor: levothyroxineUnknown: amphetamine / dextroamphetamine, omega-3 polyunsaturated fatty acids, cyanocobalamin, ascorbic acid, cholecalciferol

Trazodone Disease Interaction

Moderate: angle closure glaucoma, mania, seizures, suicidality, cardiovascular disease, hyponatremia, hypotension, renal/liver disease

Volume of Distribution

A single-dose pharmacokinetic study of 8 volunteers taking trazodone determined a volume of distribution of 0.84 +/- 0.16 L/kg. The FDA medical review of trazodone reports a volume of distribution of 0.47 to 0.84 L/kg.

Elimination Route

Trazodone is rapidly absorbed in the gastrointestinal tract after oral administration, with a bioavailability ranging from 63-91% and an AUC0−t of 18193.0 ng·h/mL. Food may impact absorption in a variable fashion, and may sometimes lead to decreases in the Cmax of trazodone. In the fed state in 8 healthy volunteers, the Cmax was measured to be 1.47 +/- 0.16 micrograms/mL, and in the fasted state, was measured at 1.88 +/- 0.42 micrograms/mL. The average Tmax after a single dose of 300 mg was 8 hours. Food may increase absorption by up to 20%.

Half Life

The plasma elimination half-life was markedly prolonged (13.6 versus 6 hours) elderly volunteers in the fasted state when compared with younger volunteers. Another study of 8 healthy individuals taking a single dose of trazodone indicated a terminal elimination half-life of 7.3 +/- 0.8 hr.

A two-phase pattern of trazodone elimination has been reported. Initially, the half-life is reported to range from 3 to 6 hours and the second phase of elimination to range from 5 to 9 hours.

Clearance

A decrease in total apparent clearance (5.1 versus 10.8 L/h) was seen elderly volunteers in the fasted state when compared with younger volunteers. Another pharmacokinetic study determined the total body clearance of trazodone to be 5.3 +/- 0.9 L/hr in 8 healthy patients taking a single dose of trazodone.

Elimination Route

Less than 1% of an oral dose is excreted unchanged in the urine. In a pharmacokinetic study, about 60-70% of radiolabeled was excreted urine within 48 hours. Approximately 9-29% was found to be excreted in feces over a range of 60 to 100 hours. According to the FDA medical review, the kidneys are responsible for 70 to 75% of trazodone excretion. About 21% of trazodone is reported to be excreted by the fecal route and 0.13% of the parent drug is eliminated in the urine as unchanged drug.

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