Zoloft, Prozac and Paxil are all SSRIs and probably more similar than drug literature would have us believe. Paxil is the only one currently approved for treatment of social anxiety and is useful for depression with an element of anxiety. It also tends to make patients drowsy and can be useful if sleep is impaired. It causes lots of side effects, though, especially for the first couple weeks; mainly gastrointestinal and a drugged-drowsy sensation. Zoloft has fewer side effects and I tend to use it in more elderly patients. In this population, depression is often subtle and it is important to ask specifically about hobbies and activities. Prozac is cheap (generic), dependable and a good choice too. Celexa is newer and supposedly more specific for serotonin (versus dopamine or norepinephrine).
All of the SSRIs can have side effects including change in weight, anxiety, anorgasmia or ejaculation difficulties, insomnia and gastrointestinal stuff.
There are other classes. SNRIs inhibit both uptake of serotonin and norepinephrine. Hence, Effexor is now being used more commonly. Serzone is similar to the SSRIs but as a 5-HT2 inhibitor it is said to have a low rate of sexual dysfunction. Wllbutrin is an aminoketone unrelated to other classes chemically - it helps smokers and can cause seizures but no one knows how it works. Tricyclic antidepressants such as Elavil (amitryptiline) are excellent for neuropathic pain and as effective as SSRIs, but they have more side effects and overdoses can be very serious. Modified cyclics like Remeron and Trazadone are being used more commonly. I think few doctors would choose Nardil, these days, since the old MAO Inhibitors have a lot of side effects especially if taken with certain foods, cold remedies or Demerol. Moclobemide (Manerix) seems to lack these side effects and is a “selective” MAO-A inhibitor.
Theoretically, one could classify symptoms in a Venn diagram on the dopamine, norepinephrine and serotonin “symptoms” and pick the best one. In practice, this doesn’t work out wonderfully and trial and error is involved, but most doctors would ask:
Am I treating depression? Do I have a good diagnosis? Does this require medication or would lifestyle adjustments and/or counselling suffice?
Is there coexisting mania, hypomania, anxiety, neuropathic pain or personality disorder? Is there reasonable risk of overdose? Is there an “addictive personality” on a substance use history?
Would there be benefit from sedation? Which side effects does th epatient consider unacceptable?
Would this patient prefer to try a less expensive antidepressant given several might be equally effective?
How old is the patient? Do they have other health problems which would preclude the use of certain drugs? Do they have livers and kidneys which work well? Are they taking other medicines which might interfere with a possible choice?