GENERIC NAME: paroxetine
BRAND NAME: Paxil
DRUG CLASS AND MECHANISM: Paroxetine is an anti- depressant medication that affects the chemicals that nerves in the brain use to send messages to one another. These chemical messengers, called neurotransmitters, are released by one nerve and taken up by other nerves. Neurotransmitters that are released but not taken up by other nerves are taken up by the nerves that release them ("reuptake"). Many experts believe that it is an imbalance among the amounts of the different neurotransmitters that are released that causes depression. Paroxetine works by inhibiting the reuptake of serotonin by the nerves that release it, an action which allows more serotonin to be available to be taken up by other nerves. Paroxetine is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs), a class that also contains fluoxetine (Prozac) and sertraline (Zoloft).
GENERIC AVAILABLE: no
PREPARATIONS: Tablets (oval): 10mg (yellow), 20mg (pink), 30mg (blue), and 40mg (green).
STORAGE: Tablets should be kept at room temperature, 15- 30C (59-86F).
PRESCRIBED FOR: Paroxetine is indicated for the management of depression, obsessive-compulsive disorders, and panic disorders.
DOSING: Paroxetine is given as a single daily dose, usually in the morning. As with all antidepressants, 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 are often 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.
DRUG INTERACTIONS: All SSRIs, including paroxetine, should not be taken with any of the MAO (mono-amine oxidase) inhibitor- class of antidepressants [for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane). Such combinations may lead to confusion, high blood pressure, tremor, and increased activity. This same type of interaction may also occur with selegiline (Eldepryl), fenfluramine (Pondimin), and dexfenfluramine (Redux). The anti-ulcer medication, cimetidine (Tagamet) can increase the amount of paroxetine in the blood, possibly leading to side effects. Paroxetine may increase the risk of bleeding in patients taking warfarin (Coumadin) although the mechanism for the interaction is not known. Tryptophan can cause headaches, nausea, sweating, and dizziness when taken with any SSRI. Phenytoin (Dilantin) and phenobarbital may decrease the amount of paroxetine in the body, possibly reducing its effectiveness.
PREGNANCY: There are no adequate studies of paroxetine in pregnant women.
NURSING MOTHERS: It is not known if paroxetine is secreted in breast milk.
SIDE EFFECTS: The most commonly noted side effects associated with paroxetine are anxiety, sweating, nausea, decreased appetite, somnolence (sleepiness), dizziness, insomnia, and male sexual disturbances. Dry mouth occurs in about 18% of patients taking Paxil.
The withdrawal of treatment with many antidepressants has been associated with troublesome symptoms. Symptoms have been particularly frequent with antidepressants classified as selective serotonin reuptake inhibitors (SSRI's). Specifically, the incidence of symptoms upon withdrawal is between 17% and 30% with the SSRI's, paroxetine (Paxil) and fluvoxamine (Luvox), but less than 5% with other SSRI's.
The most common symptoms of withdrawal have been dizziness, tiredness, tingling of the extremities, nausea, vivid dreams, irritability, and poor mood. Other symptoms have included visual disturbances and headaches.
Withdrawal reactions have been reported after an average of 12 to 36 weeks of treatment, but after as few as 5 weeks. Although most authorities have recommended that treatment be discontinued by tapering the dose (by gradually reducing the dose), symptoms have occurred despite tapering. Symptoms generally appear within a few days of discontinuing medication and persist for an average of 12 days (up to 21 days). They are relieved within 24 hours by re-administering the medication that was discontinued.