GENERAL DESCRIPTION
Fluoxetine is an antidepressant and classified in serotonin reuptake inhibitors (SSRIs). Fluoxetine was the first SSRI to reach general clinical use.
GENERIC NAME: Fluoxetine
BRAND NAME: Prozac
MECHANISM OF ACTION
Fluoxetine work by elevating serotonin neurotransmitter in the brain. At presynaptic serotonergic neuron, this interact with postsynaptic neuron which have postsynaptic receptors which are 5-HT. serotonin is synthesized from amino acid tryptophan by serotonergic neurons. These serotonin is stored in vesicles for regulated release.
At presynaptic noradrenergic neuron, this interact with postsynaptic neuron which have postsynaptic receptors which are β and α1. Norepinephrine is synthesized from amino acid tyrosine by noradrenergic neurons and stored in vesicles awaiting regulated release.
When serotonin and NE release from the neuron they stimulate their receptors and at the same time they transported back to their neurons by a process called reuptake. Serotonin is reuptake by serotonin transporter or SERT and norepinephrine is transported back to their neuron by norepinephrine transporter or NET. Once both chemicals reabsorb they partially repacked in synaptic vesicles in partially broken down into inactive metabolites by an enzyme monoamine oxidase or MAO.
As from the name of group described fluoxetine selectively inhibit reuptake of serotonin by blocking the SERT which resulted in increased levels of serotonin available to bind postsynaptic 5-HT receptors.
PHARMACOKINETICS
Fluoxetine is an orally active antidepressant. It is metabolized by hepatic CYP2D6 and 2C9. The half-life of fluoxetine is 53 hours and its active metabolite is norfluoxetine which has half-life of 240 hours i.e. 10 days. It has 70% bioavailability and 94% protein binding.
INDICATIONS
Depression
Generalized anxiety
Post-traumatic stress disorder
Obsessive compulsive disorder
Premenstrual dysphoric disorder
Bulimia nervosa
CONTRAINDICATIONS
NSAIDs
Hepatic failure
Renal failure
Epilepsy
Lithium, MAOIs, tryptophan
SIDE EFFECTS & ADVERSE EFFECTS
Manic episodes
Decrease libido
Weight gain
Insomnia
Increase in anxiety
Irritability
Sexual side effects include erectile dysfunction
Nausea
Vomiting
Diarrhea
Abrupt with drawl may cause temporary deficiency of serotonin which may lead to headache, nausea, vomiting, agitation, sleep disturbance.
Serotonin syndrome
DRUG INTERACTION
Nefazodone may cause acute hypotension and weakness when given with fluoxetine.
Cyproheptadine may cause oppose the antidepressant effect of fluoxetine
Grape juice can increase the plasma levels and may cause serotonin like syndrome when given with fluoxetine.
Clarithromycin may cause acute fluoxetine toxicity when given concurrently.
Serotonin syndrome may cause when metoclopramide, efavirenz, hydromorphone, oxycodone, pentazocine, pethidine, tramadol, morphine given with fluoxetine.
Fluoxetine may increase the plasma level of protease inhibitors like, ritonavir.
Tryptophan may cause central and peripheral toxicity when given with fluoxetine.
NURSING INTERVENTIONS
Enquire the complete health history of the patient including allergy, drug interactions, and family background of depression
Check lab test for CBC, blood glucose, BUN, creatinine, platelets, electrolytes, LFT
Check and identify if any neurological disorder like seizure etc.
Monitor blood pressure and pulse before and during treatment
Administer medicine at night or bed time to avoid drowsiness at day time
Observe mood swing during the treatment
Observe s/s for serotonin syndrome, if any
Observe cardiovascular or neurologic s/s for any disorder, if any
Avoid to administer MAOIs with tyramine containing food
Observe sleep-wake cycle of the patients.
PATIENT EDUCATION
IF taken MAOIs, forbid patient to take any fermented or aged food or containing tyramine.
Advise to take medicine at night or bed time to avoid drowsiness at day time and take morning dose early to avoid insomnia.
Advise patient not to discontinue treatment because it may take 2-4 weeks to start antidepressant effects
Inform the patients about the possible side effects of medication specially serotonin syndrome which may be life threatening.
Report immediately if feeling bradycardia, urinary retention, blurred vision, chest pain, and diaphoresis.
Advice to take care and slow change of posture due to dizziness and danger of fall or injuries.
Avoid driving if feeling drowsiness or dizziness.
Do not breast breast feed while taking medicine.
Do not take NSAIDs or pain killer with or till 2 weeks after treatment with fluoxetine.