Several classes of drugs are used as medicine for depression. These drugs are often referred to as antidepressants. Depression is the most common mood disorder that is treated with antidepressants, although they may also be used to treat anxiety, bipolar disorders and obsessive-compulsive disorder. The most common classes of antidepressants are SSRIs, SNRIs, MAOIs and tricyclic antidepressants.
SSRIs
Selective serotonin reuptake inhibitors (SSRIs) are the class of drugs mostly widely used to treat depression. Serotonin is a chemical in the brain used to transmit signals between neurons in the brain that help regulate mood. SSRIs work by inhibiting serotonin reuptake in presynaptic neurons in the brain. Types of SSRIs include fluoxetine, fluvoxamine, sertraline, paroxetine, escitalopram and citalopram.
SNRIs
Serotonin-norepinephrine reuptake inhibitors (SNRIs) are a newer class of drugs that inhibit the reuptake of both neurotransmitters serotonin and norepinephrine. Norepinephrine neurotransmitters are involved in attention, arousal and the neurological reward structures. Norepinephrine activates areas in the brain, called reward structures, that increase and regulate behavior by inciting physical pleasure. This class of drugs includes desvenlafaxine, duloxetine, milnacipram and venlafaxine.
MAOIs
Monoamine oxidase inhibitors (MAOIs) are one of the oldest classes of antidepressants. MAOIs work by preventing the neurotransmitters associated with mood--serotonin, norepinephrine and dopamine--from being metabolized by the enzyme monoamine oxidase. Because of their harmful interaction with certain foods and drugs, MAOIs are generally not prescribed unless other antidepressants do not relieve symptoms. Types of MAOIs include phenelzine and tranylcypromine.
Tricyclic Antidepressants
Tricyclics, also called TCAs, were the most commonly used antidepressants until the advent of SSRIs in the 1990s. Tricyclics inhibit the absorption of both serotonin and norepinephrine and to a lesser extent, dopamine. Tricyclics generally have more side effects than other antidepressants. Types of TCAs include amitriptyline, amoxapine, desipramine, doxepin, imipramine, nortriptyline, protriptyline and trimipramine.
Additional Medicine
Additional drugs and classes of drugs are used as antidepressants. These include noradrenergic and specific serotonergic antidepressants (NaSSAs), melatonergic agonists and norepinephrine (noradrenaline) reuptake inhibitors (NRIs). Trazodone is a particular drug that may also be used as an antidepressant or taken with other antidepressants for those experiencing insomnia. In addition, buspirone is often used in the treatment of anxiety but has been used in treating depression and other mood and anxiety disorders.
