Prozac (Fluoxetine)

$ 114.46$ 267.90

Category: Anti-Depressants
Commercial name: Prozac
Active ingredient: Fluoxetine
Production form: Pills
Available dosage: 20mg

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Description

Prozac (Fluoxetine). Dosage, Side Effects, Interactions

Prozac (Fluoxetine) is an antidepressant from the group of Selective Serotonin Reuptake Inhibitors (SSRIs) that primarily increases the concentration of serotonin in the synaptic cleft by inhibiting the serotonin transporter. Fluoxetine is used in the therapy of depression, obsessive-compulsive disorder and bulimia.

Prozac (Fluoxetine) is primarily used to treat depression . The antidepressant has an anxiolytic and mood-enhancing effect. Fluoxetine is also a strong CYP2D6 inhibitor and has a very long half-life.

Application areas

  • Major Depressive Episodes
  • obsessive compulsive disorder
  • bulimia

How Prozac (Fluoxetine) works

As a so-called selective serotonin reuptake inhibitor , the active ingredient fluoxetine , as the name suggests, inhibits the serotonin transporter and thus the reuptake of serotonin (5-HT) from the synaptic cleft into the presynapse, which increases the concentration of serotonin in the synaptic cleft . At higher concentrations, the drug also inhibits 5HT2C receptors.

Pharmacokinetics

 

absorption

  • After oral administration, fluoxetine is well absorbed from the gastrointestinal tract.
  • Bioavailability is not affected by food intake.

distribution

  • Fluoxetine is predominantly (approximately 95%) bound to plasma proteins and has a large volume of distribution (20-40 l/kg).
  • Steady-state plasma concentrations are reached after several weeks.
  • Long-term steady-state concentrations are comparable to those after 4 to 5 weeks.

biotransformation

  • Fluoxetine has a non-linear pharmacokinetic profile with a hepatic first-pass effect.
  • Peak plasma concentrations are generally reached after 6 to 8 hours.
  • Fluoxetine undergoes extensive metabolism via the polymorphic enzyme CYP2D6.
  • Fluoxetine is primarily metabolized in the liver by demethylation to the active metabolite norfluoxetine (demethylfluoxetine).

elimination

  • The elimination half-life is 4 to 6 days for fluoxetine and 4 to 16 days for norfluoxetine.
  • The long half-lives are responsible for the fact that the substance can still be found in the body 5 to 6 weeks after stopping treatment.
  • Excretion occurs mainly (about 60%) via the kidneys.
  • Fluoxetine passes into breast milk.

Dosage of Prozac (Fluoxetine)

In general, the long half-life of fluoxetine and the active metabolite norfluoxetine should be taken into account for all indications for adults, since the active substance still remains in the body 5 – 6 weeks after discontinuation. Doses greater than 80 mg/day have not been studied.

Major Depressive Episodes

In adult and elderly patients, the recommended dose is 20 mg/day. The dose should be reviewed within 3-4 weeks of starting treatment and adjusted individually if necessary. In some patients the dose can be increased gradually up to a maximum of 60 mg. In general, patients should be given the lowest effective dose. The duration of treatment should be at least 6 months.

In children and adolescents (8 years and older) the starting dose is 10 mg/day for moderate to severe major depressive episodes. Treatment should only be started and monitored under the supervision of a specialist. The dose should be adjusted individually. In general, patients should be given the lowest effective dose. The dose can be increased to 20 mg/day after one to two weeks. Clinical trials with daily doses over 20 mg and treatments longer than 9 weeks are limited. After 6 months, the need for continued therapy should be reviewed. Treatment should be reconsidered if clinical improvement is not achieved within 9 weeks.

obsessive compulsive disorder

In adult and elderly patients, the recommended dose is 20 mg/day. In some patients the dose may be increased gradually up to a maximum of 60 mg. Fluoxetine treatment should be reconsidered if there is no improvement within 10 weeks. The dose should be individually adjusted and the lowest effective dose should be given. There are no clinical studies on the duration of treatment. The need for treatment should be reviewed regularly. Concomitant behavioral therapy is recommended in patients who have responded well to pharmacotherapy.

bulimia

In adult and elderly patients, the recommended dose is 60 mg/day. Long-term effectiveness beyond 3 months has not been proven.

Elderly patients

Caution is required with each dose increase. A daily dose of 40 mg should not be exceeded. The maximum recommended dose is 60 mg/day.

Hepatic impairment/interactions with fluoxetine

Lower doses or more frequent dosing (e.g. 20 mg every other day) should be considered in patients with hepatic impairment or in patients taking other medicinal products that may interact with fluoxetine will.

Discontinuation symptoms upon discontinuation of treatment with SSRIs

To reduce the risk of withdrawal symptoms, when stopping therapy with fluoxetine, the dose should be reduced gradually over a period of at least one to two weeks. Avoid stopping suddenly. In the case of severely debilitating withdrawal symptoms, the last dose taken should possibly be taken again in order to then reduce it in smaller steps according to the doctor’s instructions.

 

Side effects of Prozac (Fluoxetine)

The most commonly reported side effects in patients treated with fluoxetine were:

  • headache
  • nausea
  • insomnia
  • fatigue
  • diarrhea

The severity and frequency of side effects may decrease with continued treatment and do not generally result in treatment discontinuation.

Interactions

  • Irreversible non-selective monoamine oxidase inhibitors → Contraindicated combination
  • Metoprolol (used in heart failure ) → Contraindicated combination since fluoxetine can increase the risk of side effects of metoprolol such as pronounced bradycardia by inhibiting metoprolol metabolism
  • Tamoxifen  → pharmacokinetic interaction between CYP2D6 inhibitors and tamoxifen with 65-75% reduction in plasma levels of endoxifene, one of the more active forms of tamoxifen, has been reported in the literature. Reduced efficacy of tamoxifen when used with some SSRI antidepressants has been reported in some studies.
  • alcohol
  • MAO-A inhibitors including linezolid and methylene blue.
  • Mequitazine → Increased risk of side effects from mequitazine (such as QT prolongation) since fluoxetine inhibits mequitazine metabolism.
  • Phenytoin → changes in blood levels possible.
  • Drugs with a serotonergic effect ( lithium , tramadol , triptans , tryptophan , selegiline (MAO-B inhibitors), St. John’s wort ( Hypericum perforatum ).
  • QT interval-prolonging compounds such as class IA and III antiarrhythmics , antipsychotics (e.g., phenothiazine derivatives, pimozide , haloperidol ), tricyclic antidepressants, certain antimicrobials ( e.g., sparfloxacin , moxifloxacin , erythromycin IV , pentamidine ), antimalarial drugs, in particular Halofantrine and certain antihistamines ( astemizole , mizolastine ).
  • Drugs that affect hemostasis (oral anticoagulants regardless of mechanism, antiplatelet drugs including acetylsalicylic acid and NSAIDs )
  • Cyproheptadine → There are isolated case reports of a reduced antidepressant effect of fluoxetine when fluoxetine is taken in combination with cyproheptadine.
  • Drugs that cause hyponatraemia (eg , diuretics , desmopressin , carbamazepine , and oxcarbazepine ).
  • Drugs that lower the seizure threshold (eg, tricyclic antidepressants, other SSRIs, phenothiazines, butyrophenones, mefloquine , chloroquine , bupropion , tramadol ).
  • Other drugs metabolized by CYP2D6 (such as flecainide , propafenone , and nebivolol ) and those that are dosed, but also with atomoxetine , carbamazepine , tricyclic antidepressants, and risperidone.

Contraindications

Fluoxetine is contraindicated in the following cases:

  • in case of hypersensitivity to the active substance
  • in combination with irreversible non-selective MAO inhibitors (e.g. tranylcypromine )
  • in combination with metoprolol when metoprolol is used in heart failure

Pregnancy

Some epidemiological studies suggest that the risk of birth defects in children is increased if the mother was treated with fluoxetine during the first trimester of pregnancy. The risk of cardiac malformations is of the order of two cases per 100 newborns treated with fluoxetine compared to one case per 100 newborns for the general population.

Data from epidemiological studies also suggest that the use of SSRIs during pregnancy, particularly in late pregnancy, may increase the risk of developing primary pulmonary hypertension of the newborn (PPHN, also known as persistent pulmonary hypertension). The observed risk was
approximately 5 cases per 1000 newborns. In the general population, there are 1 to 2 cases of PPHN per 1000 newborns.

Although fluoxetine can be given during pregnancy, caution is advised, particularly during late pregnancy and just before delivery, as the following effects have been reported in newborns:

  • irritability
  • Tremble
  • muscle hypotonia
  • persistent screaming
  • Difficulty sucking and sleeping

These symptoms can indicate either serotonergic effects or a withdrawal syndrome. The timing of onset and duration of symptoms may be related to the long half-life of fluoxetine (4-6 days) and its active metabolite, norfluoxetine (4-16 days).

In addition, observational data suggest an increased risk (less than 2-fold) for postpartum hemorrhage following exposure to SSRI/SNRI within
the month prior to delivery.

 

Lactation

Fluoxetine and its metabolite, norfluoxetine, are known to be excreted in human milk. Adverse reactions have been observed in breastfed infants. If treatment with fluoxetine is considered necessary, discontinuation of breast-feeding should be reconsidered. However, if breastfeeding is continued, the lowest effective dose of fluoxetine should be prescribed.

 

Driving ability

Fluoxetine has no or negligible influence on the ability to drive and use machines. Although fluoxetine has been shown not to affect psychomotor performance in healthy subjects, any drug with psychological effects could affect judgment or skills. Patients must be advised not to drive or operate hazardous machinery until they are satisfied that their ability to perform is not affected.

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Additional information

Dosage

10 mg, 20 mg, 40 mg, 60 mg

Quantity

30, 60, 90, 120, 180

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