Fluoxetine and paroxetine

Fluoxetine and paroxetine

Drug monograph · NCLEX study reference
Trade names	Prozac, Paxil
Therapeutic class	Antidepressant, antianxiety
Pharmacologic class	SSRIs
Onset / peak / duration	Mood effect over 2 to 4 weeks.
Half-life / level	Fluoxetine half-life 1 to 4 days (active metabolite up to 16 days); paroxetine about 21 hours.
Routes	PO (oral)
High-alert (ISMP)	No
Black box warning	Yes (see Safety)
Antidote / reversal	Supportive care.
Pregnancy / lactation	Paroxetine generally avoided in pregnancy; others case by case.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Fluoxetine and paroxetine (brand names Prozac, Paxil) — Antidepressant, antianxiety; SSRIs.

Identification

• Therapeutic class: Antidepressant, antianxiety.
• Pharmacologic class: SSRIs.

Pharmacology

• Mechanism of action: Block serotonin reuptake; fluoxetine has a very long half-life, paroxetine the shortest and most withdrawal-prone.
• Onset / peak / duration: Mood effect over 2 to 4 weeks.
• Half-life / therapeutic level: Fluoxetine half-life 1 to 4 days (active metabolite up to 16 days); paroxetine about 21 hours.

Clinical use

• Indications: Depression, OCD, panic, anxiety; fluoxetine also bulimia and premenstrual dysphoric disorder.
• Usual dose, route, frequency: PO once daily (fluoxetine often morning to limit insomnia).
• Maximum dose / adjustments: Taper to stop, especially paroxetine; paroxetine reduced in elderly.

Safety

• Contraindications: MAO inhibitor within 14 days; paroxetine in pregnancy (cardiac defect risk).
• Black box warning: Suicidality in those under 25 (SSRI class).
• Interactions: Strong CYP2D6 inhibition (raises many drugs), serotonergic drugs, NSAIDs and anticoagulants.
• Pregnancy / lactation: Paroxetine generally avoided in pregnancy; others case by case.
• High-alert: No.

Adverse effects

• Common side effects: Nausea, insomnia (fluoxetine), sedation and weight gain (paroxetine), sexual dysfunction.
• Serious effects to report: Suicidal thoughts, serotonin syndrome, hyponatremia, bleeding.
• Antidote / reversal: Supportive care.

Nursing process

• Assessment before administration: Mood and suicide risk, pregnancy status, serotonergic drugs.
• Interventions during therapy: Taper paroxetine carefully; fluoxetine self-tapers due to long half-life.
• Monitor: Mood, suicidality, sodium, bleeding.
• Evaluation / expected outcome: Improved mood.

Patient teaching

• Patient teaching: Fluoxetine in the morning; do not stop paroxetine abruptly.
• Notify provider if: Suicidal thoughts, agitation with fever, unusual bleeding.
• Administration tips: Consistent timing; with food if GI upset.