Trazodone hydrochloride is a triazolopyridine derivative designated as 2-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-1,2,4-triazo-lo[4,3-a] pyridin-3(2H)-one hydrochloride. It is a novel compound, unrelated to tri or tetracyclics, or the SSRI's.
Where SWIJ is it comes 50, 100, 150 and 300mg tablets.
The mechanism of action is not fully understood, but it appears to selectively inhibit serotonin reuptake and potentiate the behavioural changes induced bt serotonin precursors such as 5HTP.
It is well absorbed orally (when taken on an empty stomach). Peak plasma levels occur approx one hour after ingestion.
It is licensed (where SWIJ is) for depression, but is often used off-license for insomnia.
In depression results are said to take at least two weeks (ie: it acts quicker than the traditional SSRI's)., although 25% of people take longer to respond.
Initial doses (for depression) are 150mg daily in divided doses. Max outpatient dosage is 400mg. Up to 600mg daily has been used in psychiatric in-patient settings.
Adverse effects include: akathisia, allergy/anaphylaxis, anemia, chest pain, urinary retention, early menstrual periods, flatulence, hallucinations/delusions, hematuria, hypersalivation, hypomania, impaired speech, impotence, increased appetite, increased (and also decreased) libido, increased urinary frequency, missed periods, muscle twitches, numb-ness, and retrograde ejaculation.
There is a potential for drug interactions when trazodone is given with CY34PA inhibitors (many antifungal and antiviral drugs fall into this category and dramatically increase plasma trazadone levels)). Carbamazepine results in reduced plasma Trazadone levels, and digoxin, warfarin and many antibiotics also interact. It is not known whether there is an MAO interaction.
The oral LD50 is 610 mg/kg in mice, 486 mg/kg in rats, and 560 mg/kg in rabbits.
In overdosage Trazadone can cause the following: Priapism, respiratory arrest, seizures, and ECG changes (including arrhythmias), also coma and vomiting.
Sources: BNF and rxlist