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Some antidepressants, notably the tricyclics, are commonly used off-label in the treatment of neuropathic pain, whether or not the patient is depressed. Smaller doses are generally used for this purpose, and they often take effect more quickly.
The therapeutic effects are believed to be related to an effect on neurotransmitters, particularly by inhibiting the monoamine transporter proteins of serotonin and norepinephrine. Selective serotonin reuptake inhibitors (SSRIs) specifically prevent the reuptake of serotonin (thereby increasing the level of serotonin in synapses of the brain), whereas earlier monoamine oxidase inhibitorMonoamine oxidase inhibitors MAOIs are a class of antidepressant drugs prescribed for the treatment of depression. Due to potentially serious dietary and drug interactions they are used less frequently than other classes of antidepressant drugs (for examps (MAOIs) blocked the destruction of neurotransmitters by enzymeAn enzyme is a protein, or protein complex, that catalyzes a chemical reaction. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it ots which normally break them down. Although these drugs are clearly effective in treating depression, the current theory still leaves unanswered questions. For example, concentrations in the bloodBlood is a circulating tissue composed of fluid plasma and cells ( red blood cells, white blood cells, platelets). Medical terms related to blood often begin in hemo or hemato ( BE: haemo and haemato from the Greek word for "blood". Blood of different spe build to therapeutic levels in only a few days and begin affecting neurotransmitter activity immediately. Changes in mood, however, often take four weeks or more to appear. One explanation holds that the "down-regulation" of neurotransmitter receptorsTransmembrane receptors are integral membrane proteins, which reside and operate typically within a cell's plasma membrane, but also in the membranes of some subcellular compartments and organelles. Binding to a signalling molecule or sometimes to a pair—an apparent consequence of excess signaling and a process that takes several weeks—is actually the mechanism responsible for the alleviation of depressive symptoms. Another theory, based on recent research published by the National Institutes of HealthThe National Institutes of Health is an institution of the United States government which focuses on medical research. The Institutes are located in Bethesda, Maryland. The predecessor of the National Institutes of Health (NIH) began in 1887 as the Labora in the United StatesThe United States of America also referred to as the United States U. America ¹ or the States is a federal republic in central North America, stretching from the Atlantic in the east to the Pacific Ocean in the west. It shares land borders with Canada in, suggests that antidepressants may derive their effects by promoting neurogenesisNeurogenesis" literally means "birth of neurons". Neurogenesis is most prevalent during pre-natal development and is the process by which neurons are created to populate the growing brain. Adult Neurogenesis Neurons are born in the adult. We know that adu in the hippocampusThe hippocampus is a part of the brain located inside the temporal lobe (humans have two hippocampi, one in each side of the brain). It forms a part of the limbic system and plays a part in memory and navigation. The name derives from its curved shape, wh.
Note that antidepressants may actually make the mania component of bipolar disorder worse, and should be used with great care in the treatment of that disorder, usually in conjunction with mood stabilisers. Their use should be monitored by a psychiatrist, but in countries such as Britain, New Zealand and the United States, primary care physicians are able to prescribe antidepressents without consulting a psychiatrist. In particular, it has been noted that the most dangerous period for suicide in a patient with depression is immediately after treatment has commenced, as antidepressants may reduce the symptoms of depression such as psychomotor retardation or lack of motivation before mood starts to improve.
Antidepressants can often cause side effects, and an inability to tolerate these is the most common cause of discontinuing the medication. Sexual dysfunction is a very common side effect. Although recent drugs have fewer side effects, patients sometimes report severe side effects associated with their discontinuation, particularly with Paroxetine. Additionally, certain patients do not respond to antidepressant drugs.
Like many psychiatric drugs, antidepressants were discovered by accident. The first antidepressants, imipramine, a tricyclic, and iproniazid , a monoamine oxidase inhibitor, were discovered in the 1950s. These drugs were found to have the side effect of improving the patients' mood. However, the newer SSRI antidepressants were early examples of rational drug design.
Many antidepressants also are used for the treatment of anxiety disorders, and tricyclic antidepressants are used in the treatment of chronic pain disorders such as Chronic Functional Abdominal Pain (CFAP), Myofacial Pain Syndrome , and post-herpetic neuralgia.
Classes of antidepressant:
Despite controversy, alternative treatments for depression such as the herbal remedy St John's wort and SAM-e have also gained popularity in recent years, although their effectiveness is open to debate. Tryptophan dietary supplements, although banned in many countries, have also been used as a natural antidepressant for some.