Tricyclic Antidepressants (TCA):
As their name implies, TCA’s are primarily used to treat depression in adults. In children they are actually not very effective as anti-depressants, but they can be quite helpful for a variety of other things including attention, tics, anxiety, migraine, enuresis, and autism. Like the stimulants, they have been around for many years, and are indeed the second oldest anti-depressant known. There are too many TCA’s to list all of them here, but the most commonly used ones include Nortriptyline (Pamelor),Desipramine (Elavil), andImipramine (Tofranil). They all function similarly and have similar risks and side-effects. TCA’s have been shown in many studies to effectively reduce the symptoms of ADD including impulsivity, distractibility, hyperactivity, and inattention. Moreover, when compared “head to head” against the stimulants, they seem to work equally well. Because the stimulants and TCA’s have different mechanisms of action, they can be combined. Many times, both together will be more effective for a particular child than either one given alone.
TCA’s have a different side-effect profile than stimulants do. Indeed, TCA’s actually help many of the side effects caused by stimulants. Stimulants suppress appetite, TCA’s tend to increase it. Stimulants can cause insomnia, while TCA’s are actually sometimes used to treat insomnia. Stimulants can worsen depression, anxiety, aggressive feelings, and anger while TCA’s tend to have a beneficial impact on all of those things. Finally, stimulants can sometimes cause headaches, while TCA’s help them. For all these reasons, TCA’s are one of the things we may add or switch to when a child has experienced unacceptable side effects with the stimulants. Sometimes also we may use TCA’s as “first line” in a child who has two diagnoses, both ADD and something else such as Anxiety Disorder, Tic Disorder, Migraine, or Enuresis. In this case by starting with a TCA we hope to “kill two birds with one stone”.
TCA’s have several other advantages over stimulants. Not the least of these is the fact that many of them come in liquid forms that can make administration to young children much easier. TCA’s, when given 2-3 times daily, also tend not to wear off and avoid the “ups and downs” of many stimulants.
If TCA’s are so good, why are they considered second or third line, rather than first line, drugs for ADD? The main reason is that TCA’s do have some significant risks associated with them. The biggest of these is an irregular heartbeat, which can (very rarely) be fatal. For the most part, this risk is dose related – the higher the level of these drugs in the bloodstream, the more prone to irregular heartbeat a person becomes. The vast majority of TCA related deaths happen with overdose, and deaths in non-overdose situations are very rare (if they happen at all). Most experts believe that TCA-related deaths are preventable and that the way to prevent them is to monitor blood levels in people being prescribed TCA’s to be sure that their dose is not too high. Many also monitor the EKG in patients treated with TCA’s, because the way this medicine produces heart symptoms is by slowing the electrical conduction of the heart, and this can be seen on an EKG in it’s early stages before it causes symptoms (moreover, certain people who have slow conduction to begin with and therefore may be more prone to problems with TCA’s can be identified by EKG prior to treatment). Whether BOTH blood tests and EKG’s are really necessary, or whether one or the other will suffice, remains controversial. In any case, the necessity for this kind of monitoring with blood tests and/or EKG’s makes managing a child on TCA’s a far more labor-intensive process for both the parents and the physician than treatment with stimulants is.
TCA’s also can have certain other side effects. The most famous one among adults treated for depression is decreased libido or even impotence, although, one would hope this is not an important consideration for the pediatric age group. Of more concern is the potential for excessive weight gain related to increased appetite. Some children on TCA’s can experience sleepiness during the day, dry mouth, or constipation. All of these minor side effects can usually be managed through changes in dosing or the particular TCA being used.
The usual dosing range for ADD of a TCA is between 1 – 5 mg per kg of total daily dose. The one exception is Nortriptyline, which has a range of 1 – 3 mg per kg per day. The main purpose of blood test monitoring is to make sure that the level is not too high. Many children experience a beneficial effect for their ADD at blood levels considerably below the usual “therapeutic range” used for treating adult depression. If a child’s level is “low” by this standard but they are still seeing good clinical effects, there is no reason to increase the dose. The full effect of a TCA is not seen until the child has been on it for several weeks.