paroxetine, Paxil, Paxil CR, Pexeva
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Medical and Pharmacy Editor:
GENERIC NAME: paroxetine
BRAND NAME: Paxil, Paxil CR, Pexeva
DRUG CLASS AND MECHANISM: Paroxetine is an oral drug that is used for treating depression. It is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs), a class that also contains fluoxetine (Prozac), citalopram (Celexa), and sertraline (Zoloft). Paroxetine affects neurotransmitters, the chemicals that nerves within the brain use to communicate with each other. Neurotransmitters are manufactured and released by nerves and then travel and attach to nearby nerves. Thus, neurotransmitters can be thought of as the communication system of the brain. Serotonin is one neurotransmitter that is released by nerves in the brain. The serotonin either travels across the space that lies between nerves and attaches to receptors on the surface of nearby nerves or it attaches to receptors on the surface of the nerve that produced it, to be taken up by the nerve and released again (a process referred to as re-uptake).
Many experts believe that an imbalance among neurotransmitters is the cause of depression. Paroxetine works by preventing the reuptake of one neurotransmitter, serotonin, by nerve cells after it has been released. Since reuptake is an important mechanism for removing released neurotransmitters and terminating their actions on adjacent nerves, the reduced uptake caused by paroxetine increases free serotonin that stimulates nerve cells in the brain. The FDA approved paroxetine in December 1992.
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 10, 20, 30, and 40 mg; Paxil CR Tablets: 12.5, 25, and 37.5 mg; Suspension: 10 mg/5ml
STORAGE: Tablets should be kept at room temperature, 59-86 F (15- 30 C). The suspension and controlled release tablets should be stored at or below 77 F (25 C).
PRESCRIBED FOR: Paroxetine is used for the management of depression, obsessive-compulsive disorders (OCD), panic disorders, post traumatic stress disorder (PTSD), premenstrual dysphoric disorder (PMDD), and social anxiety disorder.
DOSING: The recommended dose is 20-60 mg daily of immediate release tablets or 12.5-75 mg daily using controlled release tablets. Paroxetine is given as a single daily dose, usually in the morning. As with all anti-depressants, the full effect may not occur until after a few weeks of therapy. Doses for obsessive-compulsive disorders and panic disorders are often higher than those for depression. Doses often are adjusted to find the optimal dose. Elderly patients, debilitated persons, and patients with certain kidney or liver diseases may need lower doses because they metabolize and eliminate paroxetine more slowly and, therefore, are prone to develop high blood levels and toxicity.
DRUG INTERACTIONS: All SSRIs, including paroxetine, should not be taken with any of the monoamine oxidase inhibitor (MAOI) class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Eldepryl, Carbex), and procarbazine (Matulane) or other drugs that inhibit monoamine oxidase, for example, linezolid (Zyvox). Such combinations may lead to confusion, high blood pressure, tremor, hyperactivity, coma, and death. (A period of 14 days without treatment should lapse when switching between paroxetine and MAOIs.) Similar reactions occur when paroxetine is combined with other drugs [for example, tryptophan, St. John's wort, meperidine (Demerol), tramadol (Ultram) that increase serotonin in the brain.
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