Medications:

Selective Serotonin-Reuptake Inhibitors (SSRIs)

Selective serotonin-reuptake inhibitors (SSRIs) are now the first-line treatment of major depression. They work by increasing levels of serotonin in the brain. SSRIs include fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), fluvoxamine (Luvox), citalopram (Celexa), and escitalopram (Lexapro). There are no significant differences among SSRI brands in effectiveness for treating major depressive disorder, although individual drugs may have different side effects or benefits for specific patients. At this time, fluoxetine is the only one of these drugs to be approved for children over age 7 and adolescents.

Because they act specifically on serotonin, SSRIs have fewer side effects than older antidepressants, which have more widespread effects in the body.

Candidates for SSRIs. SSRIs appear to help people with the following conditions:

• Mild to moderately severe major depression
• Seasonal affective disorder
• Dysthymia
• Severe premenstrual syndrome and premenstrual dysphoric disorder (PMDD) -- a repackaged form of fluoxetine (Sarafem) is the first SSRI specifically FDA-approved for PMDD. Other SSRIs and newer antidepressants are also proving to be effective
• Anxiety disorders
• Bulimia
• Impulsive and aggressive behaviors in psychiatric patients and in people with no mental health problems

Duration of Effectiveness and Use. SSRIs take, on average, 2 - 4 weeks to be effective in most adults. They may take even longer, up to 12 weeks, in the elderly and in those with dysthymia. By 14 weeks, depression should be in remission in everyone who responds to the drugs. Unfortunately, recurrence is common once the drugs are stopped. Studies indicate that the standard SSRIs are generally safe, although it is still unclear which patients would most benefit from on-going medication. Some doctors recommend withdrawing from medication after a year. If depression recurs, then the patient should go back on the antidepressant.

Side Effects of SSRIs. Side effects may include:

• Nausea and gastrointestinal (GI) symptoms usually wear off over time.
• Agitation, insomnia, mild tremor, and impulsivity occur in 10 - 20% of people who take SSRIs. These symptoms may be particularly problematic in patients who also suffer from anxiety, sleeplessness, or both.
• Drowsiness affects about 20% of SSRI-treated patients. Newer SSRIs, such as escitalopram (Lexapro), may have fewer of these adverse effects.
• Dry mouth is a common side effect.
• Patients may lack motivation, feel tired, be confused, and experience mental dullness, but this side effect is fairly rare.
• Headache and flu-like symptoms may occur.
• Heart palpitations and chest pain may occur.
• Weight gain varies depending on the SSRI. Patients should be encouraged to maintain a low-calorie diet and to exercise. They should be aware that some of the weight-loss medications, notably sibutramine (Meridia), can have serious interactions with SSRIs.
• Sexual side effects include delayed or loss of orgasm and low sexual drive. They are a well-known side effect of SSRIs. Taking a supervised drug "holiday" on the weekend may improve sexual function during that time. Some of the newer SSRIs or other antidepressants may cause less severe impairment of sexual function.
• Paroxetine (Paxil) may cause birth defects if taken during the first 3 months of pregnancy. Most reported defects have been heart-related. The most common heart abnormalities are ventricular septal defects, which are holes in the muscular wall that separate the main pumping chambers of the heart. Venlafaxine (Effexor) may also be associated with birth defects. Still, recent research suggests that most types of SSRI-associated birth defects are rare and the overall risks are low. Pregnant women who are being treated for major depression should not stop taking antidepressants without first talking to their doctors. [For more information on antidepressant treatment guidelines during pregnancy, see "Treating Depression During and After Pregnancy" in Treatment section.]

Drug Interactions. SSRIs can interact with other antidepressants such as tricyclics and, in particular, monoamine oxidase inhibitors (MAOIs). SSRIs should never be taken in combination with an MAOI or within 2 weeks after discontinuing MAOI treatment. Other serious interactions have occurred with meperidine (Demerol) and illegal substances (such as LSD, cocaine, or ecstasy). SSRIs also interact with the antibiotic linezolid (Zyvox). People who take SSRIs may drink alcohol in moderation, although the combination may compound any drowsiness experienced with SSRIs, and some SSRIs increase the effects of alcohol.

Withdrawal Symptoms. Cognitive problems, sleep disturbances, increase in depressive symptoms, and electric shock-like symptoms have been known to occur with sudden discontinuation of SSRIs. The symptoms are more likely to occur with antidepressants with shorter half-lives as compared with fluoxetine, which has a long half-life. The dose of the antidepressant should be slowly reduced before stopping.

Other Neurotransmitter Inhibitors

These newer antidepressants target other neurotransmitters, such as norepinephrine or dopamine, alone or in addition to serotonin. In general, the advantages of the new designer antidepressants are:

• They may be better tolerated than the older tricyclic compounds and even some SSRIs, although long-term side effects are not fully known in this group.
• Most of these drugs have fewer adverse effects than SSRIs on sexual function.
• They may be more effective than SSRIs for severely depressed patients.
• Some of these drugs are helpful for additional problems -- such as insomnia, fibromyalgia and similar chronic pain syndromes, or smoking -- that may affect people with depression.

They do share some side effects with other antidepressants, including dizziness and dry mouth.

Dual Inhibitors. Dual inhibitors act directly on two neurotransmitters -- norepinephrine and serotonin. These drugs are also known as serotonin norepinephrine reuptake inhibitors (SNRIs). The following SNRIs are approved for treatment of major depression in adults:

• Venlafaxine (Effexor) is similar to Prozac in effectiveness and tolerability for most patients. As with SSRIs, venlafaxine may impair sexual function. The drug can increase blood pressure and heart rate and should be used with caution in patients with high blood pressure or heart disease. It can also cause uterine and vaginal bleeding unrelated to menstruation. Venlafaxine should not be taken during the last trimester of pregnancy as it can cause complications in newborn infants. Some patients report severe withdrawal symptoms, including dizziness and nausea. In 2006, the drug� ' s manufacturer warned of an increased overdose risk and advised doctors to prescribe their patients only small amounts of venlafaxine pills. In 2008, the FDA approved desvenlafaxine (Pristiq), which is chemically related to venlafaxine.
• Duloxetine (Cymbalta) also acts on both serotonin and norepinephrine. Side effects are generally mild and include dry mouth, nausea, and sleepiness. Patients with narrow-angle glaucoma or patients with liver or kidney diseases should not take duloxetine. Because duloxetine can cause liver damage, patients who drink large quantities of alcoholic beverages should not take it. Signs of liver damage include itching, dark urine, yellowing of skin and eyes (jaundice), and fatigue. Patients should immediately contact their doctor if they experience these symptoms.
• Mirtazapine (Remeron) can cause sleepiness, increased appetite, weight gain, and dizziness.

Other Antidepressants with Effects on Multiple Neurotransmitters. Bupropion (Wellbutrin, Zyban) affects the reuptake of serotonin, norepinephrine, and dopamine -- a third important neurotransmitter. In addition to depression, bupropion is also approved for smoking cessation and for treating seasonal affective disorder (SAD). Bupropion causes less sexual dysfunction than SSRIs. About 25% of patients experience initial weight loss. Side effects include restlessness, agitation, sleeplessness, headache, and stomach problems. Bupropion has a risk for seizures, which increases with higher doses. High doses may also cause dangerous heart arrhythmias.

Tricyclic Antidepressants

Before the introduction of SSRIs, tricyclics were the standard treatment for depression.

Tricyclics are sometimes grouped into two categories:

• Tertiary amines include amitriptyline (Elavil, Endep) and imipramine (Tofranil).
• Secondary amines include desipramine (Norpramin) and nortriptyline (Pamelor, Aventyl). Secondary amines may have fewer side effects, including drowsiness, than tertiary amines, but they are as toxic in high amounts.

Less commonly used tricyclics include doxepin (Sinequan), amoxapine (Asendin), maprotiline (Ludiomill), protriptyline (Vivactil), trimipramine (Surmontil), mianserin (Bolvidon), and dothiepin (Prothiaden).

Tricyclics are as effective for treating depression but they have many side effects. They may offer benefits for many people with dysthymia, who generally do not respond to SSRIs. They may also be prescribed in lower dosages to be taken at night to help with insomnia.

Side Effects of Tricyclics. Side effects are common with these medications. In fact, in an analysis of studies, more tricyclic users discontinued their drugs due to side effects than did SSRI or MAOI users. Those most often reported include:

• Dry mouth
• Constipation
• Blurred vision
• Sexual dysfunction
• Weight gain
• Difficulty urinating
• Drowsiness
• Dizziness -- blood pressure may drop suddenly when sitting up or standing.

Tricyclics can have serious, although rare, side effects:

• They tend to cause disturbances in heart rhythm, which can pose a danger for some patients with certain heart diseases. Care should be taken when these medications are prescribed to the elderly and to those at risk of overdose.
• Also of concern are reports that tricyclics, particularly imipramine as well as mianserin and dothiepin, may increase the risk for a lung disease called idiopathic pulmonary fibrosis (IPF), which can cause lung inflammation and scarring. Initial symptoms are breathlessness and dry cough.
• Tricyclics can be fatal with an overdose.
• Protriptyline can cause sun sensitivity. People who take this drug should take precautions against sunlight when they go outdoors.

Monoamine Oxidase Inhibitors (MAOIs)

Monoamine oxidase inhibitors (MAOIs) block monoamine oxidase, an enzyme which has negative effects on many of the neurotransmitters that are important for well-being. MAOIs include phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine (Parnate). Because these drugs can have very severe side effects, they are usually prescribed only when other types of antidepressants do not help. Research indicates that MAOIs are an effective option for atypical and treatment-resistant depression.

Newer MAOIs, such as selegiline (Eldepryl, Movergan), target only one form of the MAOI enzyme. They may cause fewer side effects than older MAOIs. A skin patch form of selegiline (Emsam) is also available for treatment of major depressive disorder in adults.

Candidates for MAOIs. MAOIs may also be effective for the following conditions:

• Atypical depression
• Eating disorders
• Post-traumatic stress disorder
• Borderline personality

Side Effects. MAOIs commonly cause the following side effects:

• Orthostatic hypotension (a sudden drop in blood pressure upon standing)
• Drowsiness or insomnia
• Dizziness
• Sexual dysfunction
• The most serious side effect is severe hypertension (high blood pressure), which can be brought on by eating certain foods having high tyramine content. Such foods include aged cheeses, most red wines, sauerkraut, vermouth, chicken livers, dried meats and fish, canned figs, fava beans, and concentrated yeast products.
• MAOIs can cause birth defects and should not be taken by pregnant women.

Very dangerous side effects, such as serotonin syndrome, can occur from interactions with other antidepressants, including SSRIs. Serotonin syndrome is a potentially fatal condition that is caused by the interaction of serotonergic drugs. Symptoms include confusion, agitation, sweating and shivering, and muscle spasms. There should be at least a 2-week break between taking MAOIs and other antidepressants. MAOIs can have serious interactions with other drugs as well, including some common over-the-counter cough medications. In such cases, severe high blood pressure or dangerous reactions can occur. It is important that patients discuss with their doctors any other medications they are taking.

Atypical Antipsychotics

If patients fail to respond to antidepressants, doctors may try adding on a different type of drug. (This combination strategy is called “augmentation” or “adjunctive treatment”.) Atypical antipsychotics are drugs that are usually prescribed for schizophrenia or bipolar disorder, but they can also play a role in the treatment of severe depression. In 2007, aripiprazole (Abilify) was approved in combination with antidepressant therapy for treatment of adults with major depressive disorder. Investigators are also studying whether combination treatment with the atypical antipsychotic risperidone (Risperdal) can help patients with major depression achieve remission.

Investigational Drugs

Ketamine. Ketamine, an anesthetic drug, may be helpful for patients with severe treatment-resistant depression. In a small preliminary study, a single intravenous dose of ketamine helped patients quickly recover from depression within 2 hours, and some patients sustained benefits for up to a week. (Standard antidepressant drugs usually take about 8 weeks to have an effect.) Ketamine blocks the NMDA brain protein receptor, which is involved in glutamate regulation. Glutamate is a brain chemical that is thought to be involved in depression.