Blog Date 29 March, 2023


Paroxetine is a phenylpiperidine derivative. It is composed of a secondary amine in the piperidine ring, which is connected to benzodioxol and fluorophenyl groups. Paroxetine is enantiomerically pure with chemical name (3S,4R)-3-[(2H-1,3-benzodioxol-5-yloxy)methyl]-4-(4-fluorophenyl)piperidine hydrochloride hemihydrate and empirical formula of C19H20FNO3.HCl 2H2O.

Paroxetine is an odorless, off-white powder, having a melting point ranging between 120 and 1380C. Paroxetine is a relatively small molecule with molecular weight of 374.8 g/mol (329.4 g/mol )as free base. In addition to hydrochloride, paroxetine mesylate(P080000A) is also available. 

Paroxetine exists in two crystal forms, i.e., a stable hemihydrate referred to as form I and the anhydrous form called form II. FTIR, NMR and MS data clearly show that each of the three rings present in paroxetine structure is located on a different plane, so the structure of this compound is a highly nonplanar molecule. Paroxetine is slightly soluble in H2O, sparingly soluble in Me2Cl2 and EtOH but soluble in MeOH.

What is Paroxetine?

Paroxetine is an antidepressant. It belongs to a class of medications called selective serotonin reuptake inhibitors, or SSRIs.

Paroxetine is approved by the FDA as a treatment for several other mental illnesses, including:

• Generalized anxiety disorder (GAD)

• Social anxiety disorder (SAD)

• Panic disorder

• Post-traumatic stress disorder (PTSD)

• Obsessive-compulsive disorder (OCD)

• Premenstrual dysphoric disorder (PMDD)

Mechanism of Action

Paroxetine is one of several depression medications referred to as selective serotonin reuptake inhibitors. It works by increasing levels of serotonin, an important neurotransmitter, in your brain and body.

Serotonin is a chemical nerve cells produce, and it sends signals between your nerve cells. Serotonin is found in many parts of your body: in your digestive system, blood platelets, and throughout the central nervous system. It has a role in regulating your mood.Serotonin is made from the essential amino acid tryptophan. This amino acid must enter your body through your diet and is commonly found in foods such as meat, dairy products, eggs, and nuts.Serotonin impacts every part of you, from your emotions to your body and motor skills. It helps with sleeping, healing, and digesting. Serotonin is also thought to be a natural mood stabilizer.

Serotonin helps your body to :

• regulate anxiety

• experience happiness

• heal wounds

• stimulate nausea

As a neurotransmitter, serotonin is responsible for regulating certain aspects of your moods and feelings. Research has linked serotonin to happiness and anxiety. High levels of serotonin may reduce feelings of arousal, while low levels of serotonin are associated with depression.

Serotonin also affects other aspects of your health, including your sleep-wake cycle, your wound healing abilities and certain parts of your digestive system function.

As an SSRI, paroxetine increases serotonin levels and changes your mental balance. This can help to improve your moods and make many symptoms of depression, anxiety and other mental illnesses less severe.


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