Generic Name: Fluoxetine

What is Fluoxetine?

In addition, fluoxetine is a potent CYP2D6 inhibitor, and increased concentrations of antiarrhythmic drugs metabolized via the same pathway, including propafenone, can occur. Propoxyphene: Fluoxetine may inhibit the metabolism of propoxyphene.

Propranolol: Propranolol is significantly metabolized by CYP2D6 isoenzymes. Protriptyline: Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering fluoxetine with other drugs that have serotonergic properties such as tricyclic antidepressants.

Quazepam: Fluoxetine could theoretically inhibit CYP3A4 metabolism of oxidized benzodiazepines, including quazepam. Quetiapine: According to the manufacturer of quetiapine, the drug should not be used with other drugs having an association with QT prolongation. In addition, the metabolite of fluoxetine is a moderate CYP3A4 inhibitor and may decrease the clearance of CYP3A4 substrates such as quetiapine.

Decreased metabolism of quetiapine may lead to clinically important adverse reactions such as extrapyramidal symptoms.

Quinine: Quinine inhibits CYP2D6 and may theoretically increase concentrations of other drugs metabolized by this enzyme. Caution is recommended when administering quinine with other CYP2D6 substrates, such as fluoxetine, that have a narrow therapeutic range or where large increases in serum concentrations may be associated with severe adverse reactions.

Therefore, unlike tricyclic antidepressant drugs TCAfluoxetine lacks the three-fused ring system. Fluoxetine is very selective and has minimal effects on other systems. Additionally, in receptor binding studies, fluoxetine was shown to have only weak affinity for several receptors, including opiate, serotonergic 5-HT1 and 5-HT2, dopaminergic, beta, alpha-1 and alpha-2 adrenoceptors, histaminergic, and muscarinic receptors. Fluoxetine preferentially inhibits the reuptake of serotonin into brain synaptosomes and platelets in rats and humans.

Fluoxetine is metabolized to norfluoxetine, which is equipotent as an inhibitor of the serotonin transporter and CYP2D6 has a much longer half-life. Human Pharmacokinetics Fluoxetine hydrochloride is readily absorbed from the gastrointestinal tract with peak plasma concentrations appearing from 6-8 hours after oral administration. Fluoxetine is extensively metabolized in the liver to a desmethyl metabolite, nor-fluoxetine, which has activity similar to fluoxetine.

Pharmacokinetic Properties Value Units Prep. Reference Comments Absorption Fluoxetine is rapidly absorbed from the GI tract with peak plasma concentrations appearing from 4-6 hours after oral administration Saletu and Grunberger 1985. Food slows the rate, but not extent of absorption. The brain to plasma ratio of fluoxetine in patients is 2.

The V of fluoxetine is one of the highest among SSRIs Catterson and Preskorn 1996due to a great extent to accumulation in the lungs. On the other hand, the brain to plasma ratio of fluoxetine is lower than for many SSRIs.

How should I take Fluoxetine?

The most common side effects with Prozac include abnormal dreams, abnormal ejaculation, anorexia, anxiety, asthenia weaknessdiarrhea, dry mouth, dyspepsia, flu syndrome, impotence, insomnia, libido decreased, nausea, nervousness, pharyngitis, rash, sinusitis, somnolence, sweating, tremor, vasodilatation, and yawn.

With antidepressants, it is possible to have a worsening of symptoms. Do not change the amount of medication you take without talking to your doctor first.

Sarah Lewis, PharmDA: Prozac fluoxetine is a selective serotonin reuptake inhibitor SSRI antidepressant. Food and Drug Administration FDAfor the treatment of major depressive disorder, depressive episodes associated with bipolar disorder, obsessive-compulsive disorder OCDbulimia nervosa, and panic disorder.

Some of the most common side effects associated with Prozac include insomnia, headache, weakness, nausea, runny nose, drowsiness, diarrhea, and anorexia. According to the prescribing information for Prozac, abnormal vision and visual field defects were reported as potential side effects occurring in 4 percent and less than 1 percent respectively of patients taking Prozac during clinical trials.

What should I avoid while taking Fluoxetine?

Fluoxetine must not be taken at the same time as monoamine oxidase inhibitor antidepressants MAOIs such as phenelzine, isocarboxazid or tranylcypromine, or with selegiline or rasagiline, which are also MAOIs and are used to treat Parkinson's disease. If you have been taking one of these MAOIs you should not start treatment with fluoxetine until at least 14 days after stopping the MAOI.

Treatment with these MAOIs, or with the related antidepressant moclobemide, should not be started until at least five weeks after fluoxetine has been stopped. Linezolid is an antibiotic that is also an MAOI. This medicine can be given in combination with fluoxetine, provided that there are facilities for close observation of symptoms of serotonin syndrome and monitoring of blood pressure.

Fluoxetine can reduce the effectiveness of tamoxifen and it should be avoided wherever possible in people taking tamoxifen.

Fluoxetine may increase the blood levels of the following medicines, and for this reason your doctor may prescribe a lower dose of these if you are taking them with fluoxetine, or if you have taken fluoxetine in the previous five weeks:If fluoxetine is taken with lithium it may cause the blood level of lithium to rise, or there may be an increased risk of side effects.

Fluoxetine side effects

The brain to plasma ratio of fluoxetine in patients is 2. The V of fluoxetine is one of the highest among SSRIs Catterson and Preskorn 1996due to a great extent to accumulation in the lungs. On the other hand, the brain to plasma ratio of fluoxetine is lower than for many SSRIs. Plasma Protein Binding 94.

Aronoff et al 1984 Metabolism It appears that fluoxetine is metabolized primarily by CYP2C9, as possibly CYP2C19 and CYP3A von Moltke et al 1997. Patients receiving high doses over long periods of time may exhibit prolonged elimination half-lives.

Common Fluoxetine ide effects may include:

  • In Study 2, patients receiving PROZAC experienced mean reductions of approximately 4 to 9 units on the YBOCS total score, compared with a 1-unit reduction for placebo patients.

  • Fluoxetine is also used to reduce or eliminate the symptoms of obsessive-compulsive disorder OCD as well as to treat the eating disorder, bulimia nervosa.

  • During pregnancy, this medication should be used only when clearly needed.

  • Switching A Patient To Or From A Monoamine Oxidase Inhibitor MAOI Intended To Treat Psychiatric Disorders At least 14 days should elapse between discontinuation of an MAOI intended to treat psychiatric disorders and initiation of therapy with PROZAC.

However, it may be started at a lower dose then gradually increased to a maximum dose of 60mg a day. Some people might need to take a lower dose of fluoxetine, or to take it less often. If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways that are suitable for you and your medicines.

Where can I get more information?

  • View ArticlePubMedGoogle ScholarAnderson IM: Meta-analytical studies on new antidepressants.

  • Rasagiline: It is recommended to avoid concurrent use of rasagiline and antidepressants, including selective serotonin reuptake inhibitors SSRIs.