Types of Antidepressants

Antidepressants work to normalize certain chemical in the brain called neurotransmitters:  serotonin, norepinephrine, and dopamine. Scientists have found that these three neurotransmitters are primarily responsible in regulating a one’s mood.  Antidepressants can be classified into several different groups:

  1. Selective Serotonin Reuptake Inhibitors (SSRIs):  Prozac (fluoxetine), Celexa (citalopram), and Paxil (paroxetine) are examples of serotonin reuptake inhibitors.
  2. Serotonin and Norepinephrine Reuptake Inhibitors (SSNIs): Effexor (venlafaxine) and Cymbalta (duloxetine) are examples of serotonin and norepinephrine reuptake inhibitors.
  3. Tricyclic antidepressants (TCAs): Elavil (amitriptyline), Tofranil (imipramine), and Pamelor (nortriptyline) are commonly prescribed tricyclic antidepressants.
  4. Monoamine Oxidase Inhibitors (MAOIs): Nardil (phenelzine) and Parnate (tranylcypromine) are examples of MAOIs.

There are, however, a few other antidepressants that do not fall into any of the above classifications and are therefore considered unique, such as:

  1. Remeron (mirtazapine)
  2. Wellbutrin (bupropion)

Each classification of antidepressant medications affect different neurotransmitters in certain, unique ways. For example, SSRIs increase the production of the neurotransmitter “serotonin” in the brain. However, MAOIs block monoamine oxidase, which is an enzyme that breaks down the particles of the neurotransmitters. Blocking their breakdown enables the neurotransmitters to remain active in the brain. Ongoing research is continually being conducted in order to fully understand antidepressants’ exact effect on a person’s brain.

Effectiveness of Antidepressants

It is generally agreed that approximately 65 percent of patients respond to the first antidepressant that is prescribed to him/her, or they respond to an increased dosage of that particular drug.  However, it can often take three to four weeks of regular, daily dosages in order for patients to feel the full therapeutic effect of antidepressants.  Often times, patients start feeling better after taking antidepressants for a while and therefore discontinue.  Unfortunately, this often results in the depression recurring.

If you get used to an antidepressant and just quit it, you may experience some withdrawal symptoms such as anxiety and irritability. Worst of all, depression may recur.

The National Institute of Mental Health (NIHM) recommends that patients continue taking an antidepressant for 6 to 12 months, or in some cases longer.  They believe that this  gives the medication enough time to be effective and can help prevent a relapse of the depression.

Risks of antidepressants

As with any type of medication, taking antidepressants has its risks.  Below is a list of some of the risks associated with antidepressants:

Suicidal Thoughts

There is an increased risk of suicidal thinking or suicide attempts by children and adolescents who take antidepressants.  In late 2004, the FDA required antidepressant manufacturers to add a boxed warning to labeling in order to alert the public about these increased risks.  The FDA later extended that warning to include young adults.

Manic Episodes

When individuals are in a manic state, they experience a sort of “high” that can make them be overly active, overly talkative, have a great deal of energy, and require less sleep than most.  If an antidepressant is prescribed to a person with bipolar disorder, it can sometimes cause mania.  This is one of the ways a doctor determines that an individual has bipolar disorder, as opposed to unipolar depression. A bipolar individual suffering from a manic episode can even become psychotic if the mania is severe.

Birth Defects

Some antidepressants have shown to increase a pregnant woman’s chance of having a child with a birth defect.  For example, in late 2005, the FDA upgraded Paxil (paroxetine) from a pregnancy risk Category C to pregnancy risk Category D. A Category D drug means that there is positive evidence that fetal risk exists.

High Blood Pressure

MAOIs tend to have the greatest risk of increasing an users blood pressure.  There are many dietary and medicinal restrictions that must be closely followed when taking an MAOI.  For example, a person taking MAOIs must avoid certain foods that contain high levels of the chemical tyramine (found in many cheeses, wines and pickles, and some medications including decongestants). MAOIs interact with tyramine in such a way that may cause a sharp increase in blood pressure, which could lead to a stroke or other complications.