Indications
Fluoxetine is indicated in-
- Depressive illness
- Bulimia nervosa and anorexia nervosa
- Obsessive compulsive disorders
- Pre-menstrual syndrome
Therapeutic Class
Pharmacology
Fluoxetine Hydrochloride is a phenylpropylamine derivative antidepressant for oral administration, it is chemically unrelated to tricyclic, tetracycline or other available antidepressants.
Fluoxetine has been shown to selectively inhibit the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane which causes increased synaptic concentration of serotonin in the CNS. This results in numerous functional changes associated with enhanced serotonergic neurotransmission.
Fluoxetine appears to have no effect on the reuptake of norepinephrine and dopamine and does not exhibit antihistaminic or alpha1 adrenergic blocking activity at usual therapeutic doses.
Dosage & Administration
Initial treatment: Recent studies suggest that 20 mg/day of Fluoxetine may be sufficient to obtain satisfactory antidepressant response. Consequently, a dose of 20 mg/day administered in the morning is recommended as the initial dose.
A dose increase may be considered after several weeks if no clinical improvement is observed. Dosage above 20 mg/day, should be administered on a bid schedule (i.e. morning and noon) and should not exceed a maximum dose of 80 mg/day. As with other antidepressants, the full antidepressant effect may be delayed until 4 weeks of treatment or longer. As with many other medications, a lower or less frequent dosage should be used in patients with renal and/or hepatic impairment.
A lower or less frequent dosage should also be considered for patients, such as elderly, with concurrent disease or on multiple medication. A recommended maximum dose for elderly patients is 60 mg per day.
Maintenance treatment: It is generally agreed among expert psychopharmacologists that acute episode of depression requires several months or longer sustained pharmacologic therapy. Fluoxetine is also used in dosage of 60 mg daily for the management of bulimia nervosa.
Interaction
May lead to serotonin syndrome with serotonergic drugs (e.g. triptans, TCAs, fentanyl, tramadol, lithium, buspirone, tryptophan). May increase risk of bleeding with aspirin, NSAIDs, warfarin and other anticoagulants. May increase plasma levels of phenytoin.
Potentially Fatal:Â May increase risk of serotonin syndrome with concomitant admin or within 14 days of MAOIs withdrawal. May increase the QTc prolonging effect of pimozide and thioridazine.
Contraindications
known to be hypersensitive to it.Monoamine oxidase inhibitors: There have been reports of serious, sometimes fatal reactions (including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs and changes of mental status that include extreme agitation progressing to delirium and coma) in patients receiving Fluoxetine in combination with monoamine oxidase inhibitors (MAOIs), and in patients who have recently discontinued Fluoxetine and are then started on MAOIs. Some cases presented with features resembling neuroleptic malignant syndrome. Therefore, Fluoxetine should not be used in combination with MAOI, or within 14 days of discontinuing therapy with MAOI. Since Fluoxetine and its major metabolites have very long elimination half-lives, at least 5 weeks should be allowed after stopping Fluoxetine and before starting MAOI.
Side Effects
Gastrointestinal:Â Nausea, vomiting, dyspepsia, dry mouth, and diarrhoea.
Neurological:Â Anxiety, nervousness, insomnia/ drowsiness and fatigue.
Others: Excessive sweating, pruritus, skin rashes associated with liver, kidney and lung involvement. It has therefore been advised that Fluoxetine therapy should be discontinued in any patient who develops a skin rash.
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