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-HT1A and terminal autoreceptors. Fluoxetine is marketed under the trade names Prozac and Sarafem among others. It is also marketed for the treatment of premenstrual dysphoric disorder (Sarafem®, fluoxetine hydrochloride). PROZAC is a selective serotonin reuptake inhibitor indicated for: • Acute and maintenance treatment of Major Depressive Disorder (MDD) in adult and pediatric patients aged 8 to 18 years • Acute and maintenance treatment of Obsessive Compulsive Disorder (OCD) in adult and pediatric patients aged 7 to 17 years • Acute and maintenance treatment of Bulimia Nervosa in adult patients • Acute treatment of Panic Disorder, with or without agoraphobia, in adult patients. Studies at clinically relevant doses in man have demonstrated that fluoxetine blocks the uptake of serotonin into human platelets. Studies in animals also suggest that fluoxetine is a much more potent uptake inhibitor of serotonin than of norepinephrine. Antagonism of muscarinic, histaminergic, and α1-adrenergic receptors has been hypothesized to be associated with various anticholinergic, sedative, and cardiovascular effects of classical tricyclic antidepressant (TCA) drugs. Fluoxetine binds to these and other membrane receptors from brain tissue much less potently in vitro than do the tricyclic drugs.

Amitriptyline is a derivative of dibenzocycloheptadiene and a tricyclic antidepressant (TCA) and is mainly used to treat symptoms of depression. It works on the central nervous system (CNS) by inhibiting the membrane pump mechanism responsible for uptake of norepinephrine and serotonin in adrenergic and serotonergic neurons. Amitriptyline has been frequently used as an active comparator in clinical trials on newer antidepressants. It is rarely used as a first-line antidepressant nowadays due to its high degree of toxicity in overdose and generally poorer tolerability than the newer antidepressants.

Melitracen (HCl) is a tricyclic antidepressant with actions and effects similar to amitriptyline.Melitracen (HCl) is given orally in the treatment of depression. It should be withdrawn gradually to reduce the risk of withdrawl symptoms. Melitracen (HCl) is primarily indicated in conditions like Anxiety, Asthenia, Depression, gastro-intestinal disorders associated with anxiety and agitation. Melitracen is marketed in Europe and Japan by Lundbeck and Takeda, respectively, for the treatment of depression and anxiety. In addition to single drug preparations, it is also available as Deanxit, a combination product containing both melitracen and flupentixol. The way this drug works hasn’t been thoroughly researched, but some hypothesize that it may work similarly to the drugs Imipramine and Amitriptyline. In comparison to older TCAs, this drug is thought to work more quickly with more favorable side effects.