Pharmacology
Summary
Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are both primary classes of antidepressants. SSRIs, including fluoxetine, paroxetine, sertraline, and citalopram, function by inhibiting the presynaptic reuptake of serotonin (5-HT). Conversely, SNRIs such as venlafaxine and duloxetine, inhibit the reuptake of both serotonin and norepinephrine. SSRIs and SNRIs are first-line treatments for depression, generalized anxiety disorder (GAD), panic disorder, and PTSD. Moreover, SSRIs are especially useful in managing conditions like obsessive-compulsive disorder (OCD), bulimia, and social anxiety disorder, while SNRIs offer therapeutic benefits for diabetic neuropathy, neuropathic pain, and fibromyalgia.
SSRIs and SNRIs they typically require 1-2 months to reach their full therapeutic effect and are not intended for acute treatments. SSRIs may cause hyponatremia, stemming from SIADH, and can lead to sexual dysfunction, weight gain, and drowsiness. Both SSRIs and SNRIs are associated with the risk of serotonin syndrome, a condition marked by symptoms like hyperthermia, hypertension, and neuromuscular hyperactivity such as hyperreflexia. This syndrome's risk amplifies if combined with other drugs that elevate serotonin levels, like TCAs and MAO inhibitors. Cyproheptadine, a 5HT-2 antagonist, is employed to treat serotonin syndrome. Notably, SNRIs can induce hypertension. Discontinuing SSRIs and SNRIs can result in withdrawal symptoms, manifesting as flu-like symptoms.
Lesson Outline
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FAQs
SSRIs and SNRIs serve as primary therapeutic options for conditions such as depression, generalized anxiety disorder (GAD), panic disorder, and post-traumatic stress disorder (PTSD). Additionally, SSRIs find utility in treating obsessive-compulsive disorder (OCD), bulimia, and social anxiety disorder. Additionally, SNRIs are also indicated for managing diabetic neuropathy, various chronic pain types including neuropathic pain, and fibromyalgia.
Common side effects of SSRIs include hyponatremia (SIADH), sexual dysfunction, weight gain, and drowsiness. Additionally, these drugs can precipitate serotonin syndrome, marked by hyperthermia, hypertension, and neuromuscular hyperactivity. Both SSRIs and SNRIs can lead to withdrawal manifestations resembling flu-like symptoms, with SNRIs potentially causing hypertension as a side effect.
SSRIs function by inhibiting the presynaptic reuptake of serotonin (5-HT), enhancing its overall activity. In contrast, SNRIs block the presynaptic reuptake of both norepinephrine and serotonin, amplifying the actions of these neurotransmitters to elevate mood.
Serotonin syndrome arises as a critical adverse effect when using serotonergic agents like SSRIs and SNRIs, especially when concomitantly administered with other serotonin-elevating drugs. Serotonin syndrome presents with hyperthermia, hypertension, and neuromuscular hyperactivity such as hyperreflexia and clonus. The primary approach to treatment involves halting the offending medications and providing supportive care. Cyproheptadine, which functions as a 5HT-2 blocker, offers an additional treatment modality.
It's vital to understand that SSRIs and SNRIs require 1-2 months to manifest their full therapeutic effects and aren't designed for immediate symptom relief.
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