Fluoxetine

Fluoxetine hydrochloride is the first agent of the class of antidepressants known as selective serotonin-reuptake inhibitors (SSRIs). Fluoxetine is a racemic mixture of the R- and S- enantiomers and are of equivalent pharmacologic activity. Despite distinct structural differences between compounds in this class, SSRIs possess similar pharmacological activity. As with other antidepressant agents, several weeks of therapy may be required before a clinical effect is seen. SSRIs are potent inhibitors of neuronal serotonin reuptake. They have little to no effect on norepinephrine or dopamine reuptake and do not antagonize α- or β-adrenergic, dopamine D₂ or histamine H₁ receptors. During acute use, SSRIs block serotonin reuptake and increase serotonin stimulation of somatodendritic 5-HT_1A and terminal autoreceptors. Chronic use leads to desensitization of somatodendritic 5-HT_1A and terminal autoreceptors. The overall clinical effect of increased mood and decreased anxiety is thought to be due to adaptive changes in neuronal function that leads to enhanced serotonergic neurotransmission. Side effects include dry mouth, nausea, dizziness, drowsiness, sexual dysfunction and headache. Side effects generally occur within the first two weeks of therapy and are usually less severe and frequent than those observed with tricyclic antidepressants. Fluoxetine may be used to treat major depressive disorder (MDD), moderate to severe bulimia nervosa, obsessive-compulsive disorder (OCD), premenstrual dysphoric disorder (PMDD), panic disorder with or without agoraphobia, and in combination with olanzapine for treatment-resistant or bipolar I depression. Fluoxetine is the most anorexic and stimulating SSRI.

Symptoms of overdose include agitation, restlessness, hypomania, and other signs of CNS excitation. LD₅₀=284mg/kg (orally in mice). The most frequent side effects include: nervous system effects such as anxiety, nervousness, insomnia, drowsiness, fatigue or asthenia, tremor, and dizziness or lightheadedness; GI effects such as anorexia, nausea, and diarrhea; vasodilation; dry mouth; abnormal vision; decreased libido; abnormal ejaculation; rash; and sweating. Withdrawal symptoms include flu-like symptoms, insomnia, nausea, imbalance, sensory changes and hyperactivity.

Labeled indication include: major depressive disorder (MDD), moderate to severe bulimia nervosa, obsessive-compulsive disorder (OCD), premenstrual dysphoric disorder (PMDD), panic disorder with or without agoraphobia, and combination treatment with olanzapine for treatment-resistant or bipolar I depression. Unlabeled indications include: selective mutism, mild dementia-associated agitation in nonpsychotic patients, post-traumatic stress disorder (PTSD), social anxiety disorder, chronic neuropathic pain, fibromyalgia, and Raynaud’s phenomenon.