NETA - Lower doses of trazodone have little antidepressant activity anyway. Taking half a tablet is perfectly okay.

Antidepressant doses of trazodone run around 300mg to 400mg daily, in divided doses (eg. 200mg twice daily or 100mg three times daily). I have seen doses up to 600mg/day. Shortly after Desyrel™ (trazodone; in U.S. also Trialodine™ and Trazon™) was released in the early 1980s, it was found to be far too sedating to be regularily used as an antidepressant. It was effective in depressions with an anxiety component, but even these people were oversedated. The sedation was worse at the beginning of therapy (ie. drowsiness is a particularily bothersome start-up side effect), but the sedation continued beyond the start-up period. This led to many reports of associated fatigue, lethargy, concentration difficulty, and impaired memory.

Another troubling side effect was increases in prolactin, leading, in some cases, to gynecomastia (enlargement of breast) and galactorrhea (leaking breasts).

Desyrel at higher doses also caused heart problems in some "at risk" people (eg. orthostatic hypotension - dizziness & fainting upon rising from a sitting or prone position; shortness of breath; heart palpitations; etc.). Desyrel was developed to be a safer antidepressant than the tricyclic antidepressants (TCAs) and the monoamine oxidase inhibitors (MAOIs), but clinically it was seen that it caused similar problems as the older drugs at therapeutic doses.

One interesting side effect of Desyrel is increased libido. When I had first graduated from pharmacy school in 1984 I was following the drug file of an older lady (approx. 80 years old) who was taking Desyrel. Her husband pulled me aside one day (he was in his mid-80s) and said that his wife had become insatiable, and he could not keep up with her demands. I really felt sorry for him; he did look very tired. That was my introduction to Desyrel.

A particularily nasty side effect of trazodone at high doses is priapism (sustained, painful erection). This can be a medical emergency, requiring a discontinuation of the drug, and a trip to the ER. Permanent damage can occur if priapism lasts longer than 24 hours, because of the stagnant, unoxygenated blood remaining in one place too long, possibly leading to permanent erectile damage and impotence in the worst cases. In about a third of cases of priapism, surgical intervention is required. Again, this was only seen at higher, antidepressant doses (400mg to 600mg/day) of trazodone.

Because of these problems, trazodone was not widely used as an antidepressant after the initial surge in use shortly after it's release. For many years trazodone was a drug looking for an indication (disorder). It was tried as an impotence cure, but was overall ineffective in most cases. Then in 1990 Prozac™ (fluoxetine) was released, and it seemed that trazodone was headed for "obsolete drug heaven".

Prozac, for many people, was found to be activating and these people had trouble sleeping. Some doctors started using trazodone as an alternative to the more dangerous barbiturate sleeping pills and benzodiazepines (like Valium™ and Dalmane™). At the time, benzos were being bashed by the media, due to horror stories of addiction and severe withdrawl symptoms. The anti-benzo media hype was blown out of proportion to the actual problems with this class of drugs.

Psychiatrists needed a hypnotic (sleeping pill) that was safer in instances where there was a risk of suicide (barbiturates can be lethal in overdose) &/or in instances where the drug abuse was a concern (benzodiazepines were - and are - being used recreationally &/or as an "escape").

Although there are few placebo-controlled clinical trials testing trazodone as a hypnotic, many psychiatrists began using low doses of trazodone to induce sleep. Trazodone was found to be safe and effective as a hypnotic in doses of 25mg to 100mg at bedtimes. Clinical experience with this drug resulted in many case reports being written to psychiatry journals in the form of "letters to the editor" and trazodone use increased. Word of trazodone effectiveness spread.

It was found that at lower doses, trazodone use was not associated with the frightening, sometimes debilitating, side effects seen at the higher antidepressant doses. Being a serotonergic antidepressant, there was some initial concern of using trazodone as a hypnotic in combination with other serotonergic antidepressants (eg. Prozac and other SSRIs). There is a theoretical risk of "serotonin syndrome", characterized by arrythmias (rapid heartbeat), hyperpyrexia (high fever), malaise, profuse sweating, nausea, and vomiting. This can, if not treated promptly lead to hypertensive crisis.

There "does not" seem to be a problem with serotonin syndrome when combining SSRIs [like Prozac, Paxil™ (paroxetine), Zoloft™ (sertraline), Luvox™ (fluvoxamine), or Celexa™ (citalopram)] with low doses (less than 150mg) of trazodone. Some psychiatrists I know also give trazodone to their patients with insomnia who are taking activating TCAs [like Norpramin™ (desipramine) or Aventyl™ (nortriptyline - Pamelor™ - U.S.)] or even some serotonergic TCAs [like Anafranil™ (clomipramine)]. Most psychiatrists do avoid giving trazodone with the MAOIs [Nardil™ (phenelzine); Parnate™ (tranylcypromine); or Marplan™ (isocarboxazid)] because of the potential for MAOIs to induce serotonin syndrome, even when combined with low doses of serotonergic antidepressants.

Just another note on drug interactions (other than MAOIs). Trazodone may potentiate the effects of other CNS depressants (eg. alcohol, benzodiazepines, barbiturates, other sedatives) causing increased sedation. Also, trazodone may increase blood levels of digoxin (Lanoxin™) and phenytoin (Dilantin™), but this does not mean that these two drugs cannot be used with trazodone. Their dosage may (or may not) need to be lowered slightly if trazodone is added.

So, in conclusion, Desyrel™ (trazodone) in low doses (25mg to 100mg) at bedtimes is an inexpensive, safe and effective hypnotic, with no abuse potential. It can be added to most psychiatric medication regimens and one only needs to take as much as is needed to induce sleep, when used for insomnia.

Still NETA, I would tell your doc that you are only taking half the dose of your trazodone; it keeps everyone on the same page, with regard to your medication regimen.

I apologize for the lengthy post, but I was bored this morning, and I wanted to see if I could remember all that I am supposed to know about trazodone used as a sleeping pill.

Is there anything that I wrote that you would like me to explain further or more clearly? - Cam