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Antidepressants, Anti-AnxietyHistorically, the first clinically useful class of antidepressants become tricyclics, introduced in 1950s. Named for their three-ring chemical structure, they work by inhibiting norepinephrine, serotonin, and dopamine reuptake. Given the pronounced adverse effects of the tricyclics (TCAs), substantial research work was launch in the early 1970s to design more selective antidepressant focussing on influencing brain serotonin levels. Currently Selective Serotonin Reuptake Inhibitors (SSRIs) are the first choice for depression. SSRIs act only on the neurotransmitter serotonin. They are preferred over the tricyclics and the MAOIs because they can be less damaging to the heart and less dangerous when overdosed. Selection of one SSRI over another is based on individual patient response and mental health professional preference. Most antidepressants are effective, but certain types may work better for certain kinds of depression. All antidepressants, regardless of their structure, have slow onset of action, typically three to five weeks. Although adverse reaction may occur as early as the first dose, significant therapeutic improvement is always delayed. Each type of antidepressants cause unwanted effects. The most common problems are nausea, sexual problems, weight gain, sleepiness, trouble sleeping, dry mouth, constipation. Moreover, these medications can be dangerous under the certain conditions. You may experience some or none of the side effects. Unfortunately, there is no way to know beforehand if you will have troubles with a medication that you have never tried. Different antidepressants have different risks. Here we have summarised the most frequent side effects that people experience during treatment with various antidepressants. Weight Gain Nearly all antidepressants have the potential to cause weight gain with both long-term and short-term use. Unexpected weight gain ranks among the main reasons why people stop taking medications. Unwanted extra pounds can seriously impact self-esteem. There are several ways how antidepressants can lead to weight gain. They may increase the appetite, causing you to eat more, or slow down the metabolism. Antidepressants can also make you more sedentary through fatigue and tiredness. Some antidepressants (e.g. sertraline and amitriptyline) may cause strange food cravings. SSRIs-induced weight change is related to alteration in serotonin 2C receptor activity, appetite increase, carbohydrate craving, or recovery from depression1,3. It is less likely to occur when SSRIs are used for less than 6 months. Paroxetine causes the greatest incidence of weight gain than the other SSRIs. Tricyclic antidepressants (TCAs) are more likely to cause weight gain than Selective Serotonin Reuptake Inhibitors. Tricyclics appear to slow metabolism and promote carbohydrate cravings4. Because tertiary tricyclic antidepressants (e.g. amitriptyline, imipramine, and doxepin) are stronger histamine blockers than are tricyclics (e.g. desipramine and nortriptyline), the tertiary tricyclics are more likely to cause weight gain. Mirtazapine has been associated with significant weight gain and may be placed between the SSRIs and the TCAs in terms of relative risk for gaining extra pounds. Mirtazapine contributes to weight gain through blockade of histamine H1 and serotonin 2C receptors. The problem may occur even during the first 4 weeks of treatment with mirtazapine5. Most likely to cause weight gain: tricyclic antidepressants, monoamine oxidase inhibitors and mirtazapine. Among the SSRIs, paroxetine is the worst offender. Less likely to cause weight gain (weight-neutral antidepressants): Bupropion is one of the most stimulating antidepressants. It is unlikely to cause weight gain, and sometimes may cause weight loss6. Venlafaxine and trazodone are not likely to cause weight gain in the short term and have a low tendency to cause this problem over the long term. Sexual Side Effects In fact, sexual dysfunction is a common side effect of all classes of antidepressants, but remains highly unrecognized and underreported. Antidepressants produce a variety of sexual disturbances, including erectile dysfunction (impotence), delayed orgasm, anorgasmia, delayed ejaculation, and decreased libido. Although some side effects get milder or disappear after several weeks of antidepressant treatment, sexual difficulties rarely go away with time. The incidence of sexual dysfunction in men is higher than in women. Suggested causes of sexual side effects include increased serotonin, decreased dopamine, blockade of cholinergic and alpha-1 adrenergic receptors, inhibition of nitric oxide synthetase, and elevation of prolactin levels7. Serotonin tends to diminish sexual function, while dopamine tends to enhance sexual function. So drugs that enhance serotonin or block dopamine tend to decrease sexual activity. In most cases, once the offending medication is stopped, sexual functioning comes back to normal. But some people are faced with the persistent long-lasting symptoms called post-SSRI sexual dysfunction. Most likely to cause sexual problems: paroxetine, and to a lesser degree fluoxetine, citalopram, sertraline9. Least likely to cause sexual problems: The most "sex-friendly" antidepressant is thought to be bupropion8. It has stimulating properties. Mirtazapine and trazodone also are unlikely to affect sexual function. Withdrawal Symptoms Discontinuation syndrome (also known as withdrawal symptoms) occurs upon the abrupt discontinuation or a decrease in dosage of the antidepressant. Withdrawal symptoms include: irritability, agitation, anxiety, dizziness, flu-like symptoms, headache, nausea, insomnia, tingling sensations. Antidepressant discontinuation syndrome is more likely with a long-term treatment and a medication with shorter half-life. Most likely to cause withdrawal symptoms: Venlafaxine and paroxetine, both of which have short half-lives and wash out of the body most quickly. Least likely to cause withdrawal symptoms: Fluoxetine is the least likely to cause any discontinuation symptoms because it has the longest elimination half-life (7–15 days) and remains in the body longer. List of Antidepressants Selective serotonin reuptake inhibitors (SSRIs)
Serotonin and norepinephrine reuptake inhibitors (SNRIs) Norepinephrine and Dopamine Reuptake Inhibitors (NDRIs) Tricyclic antidepressants Noradrenergic and specific serotonergic antidepressants (NaSSAs) Other antidepressants Azaspirodecanedione anxiolytics References
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