Antidepressant drugs

Antidepressant drugs
Depression is characterized by intense feeling of sadness, hopelessness, inability to experience pleasure, changes in sleep patterns and appetite, loss of energy, and suicidal thoughts. Mania is characterized by the opposite behavior that includes rapid thought and speech patterns, extreme self-confidence, and impaired judgment.

Mechanism of Antidepressant Drugs
Most antidepressant drugs potentiate, either directly or indirectly, the actions of in the brain. This led to the amine theory, which states that depression is due to a deficiency of monoamines, such as norepinephrine and serotonin, at certain sites in the brain. Conversely, the theory states that mania is caused by an overproduction of these neurotransmitters. The pharmacologic effects of any of the antidepressant and antimania drugs on neurotransmission occur immediately, whereas the therapeutic response occurs over several weeks. Decreased the uptake of neurotransmitter is only an initial effect of the drugs, which may not be directly responsible for the antidepressant effects. It has been proposed that presynaptic inhibitory receptor densities in the brain decrease over a 2- to 4-week period with antidepressant drug use. This down-regulation of inhibitory receptors permits greater synthesis and release of neurotransmitters into the synaptic cleft leading to a therapeutic response.


selective serotonin reuptake inhibitors (SSRI)
Serotonin-Norepinephrine Reuptake Inhibitors
Atypical Antidepressants
Tricycli antidepressants(TCAs):
Monoamine oxidase inhibitors(MAOIs)

Treatment of Mania and Bipolar Disorder
Lithium salts are used prophylactically for treating manic-depressive patients and in the treatment of manic episodes and, thus, is considered as mood stabilizer. Lithium is believed to attenuate signaling via receptors coupled to the phosphatidylinositol bisphosphate (PIP2) second-messenger system. Lithium interferes with the resynthesis (recycling) of PIP2, leading to its relative depletion in neuronal membranes of the CNS. PIP2 levels in peripheral membranes are unaffected by lithium. Lithium salts have therapeutic index are extremely Low comparable to those of digitalis. Common adverse effects may include headache, dry mouth, polydipsia, polyuria, polyphagia, gastrointestinal distress (give lithium with food), tremor, dizziness, fatigue, dermatologic reactions, and sedation. Adverse effects due to higher plasma levels may include ataxia, slurred speech, coarse tremors, confusion, and convulsions. Several antiepileptic drugs, including carbamazepine, valproic acid, and lamotrigine, have been identified as mood stabilizers and have been used in the treatment of bipolar disorder. The atypical antipsychotics (risperidone, olanzapine, ziprasidone, aripiprazole, and quetiapine) also used in the management of mania.