paroxetine hydrochloride
Meaning of paroxetine hydrochloride: The salt form of an SSRI, notable for its strength against anxiety and for a difficult stop when it is withdrawn.
Definition of paroxetine hydrochloride
Paroxetine hydrochloride is the salt form of paroxetine, an antidepressant belonging to the group known as selective serotonin reuptake inhibitors. It blocks the pump that pulls serotonin back into the nerve ending that released it, so more of the messenger stays available between nerve cells. It is prescribed for depression and for several anxiety disorders.
Why does the name include hydrochloride?
Many drugs are unstable or poorly soluble in their pure form, so they are paired with an acid or a base to make a salt. Hydrochloride is the commonest such partner. The salt dissolves better, keeps longer and behaves predictably in a tablet, and once swallowed it separates, leaving the same paroxetine molecule to do the work. The salt part changes handling, not effect, though the strength printed on a package refers to the salt and differs slightly from other salt forms of the same drug.
What is it used for?
Depression was the first use, but the drug is prescribed at least as often for anxiety. It is licensed across panic disorder, social anxiety disorder, obsessive-compulsive disorder, generalized anxiety and post-traumatic stress disorder, which is a wider anxiety range than most drugs in the class carry. A low dose form is also approved for hot flashes at menopause in people who cannot take hormones. As an antidepressant it is slow to show its full effect, taking several weeks, while its anxiolytic effect can be preceded by a period of increased restlessness.
How does it differ from other SSRIs?
| Feature | What it means in practice |
|---|---|
| Strongest blocker of the serotonin pump in the class | Effective, but withdrawal effects are more pronounced |
| Short stay in the body, no lasting active breakdown product | Levels fall quickly if a dose is missed |
| Some drying, anticholinergic activity | Dry mouth, constipation and drowsiness are more common |
| Strong inhibitor of a major liver enzyme | Interacts with drugs that depend on that enzyme |
| Weight gain more likely than with others in the group | A frequent reason for changing treatment |
What happens when it is stopped?
Because levels drop fast, stopping abruptly often brings dizziness, brief electric shock sensations in the head, irritability, vivid dreams and a flu-like feeling. This is a discontinuation reaction, not addiction, and it settles as the body readjusts. Reducing the dose in slow steps is the usual approach for that reason.
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Used in a sentence
Paroxetine hydrochloride was reduced in slow steps rather than stopped outright.
Good to know
Paroxetine strongly inhibits the liver enzyme that converts tamoxifen into its active form, and its rapid clearance makes abrupt withdrawal more likely to cause dizziness and electric shock sensations than with other drugs in its class.