Prozac
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Prozac
[pro´zak]fluoxetine hydrochloride
Pharmacologic class: Selective serotonin reuptake inhibitor
Therapeutic class: Antidepressant
Pregnancy risk category B
Action
Selectively inhibits serotonin reuptake in CNS; has little to no effect on norepinephrine and dopamine reuptake
Availability
Capsules: 10 mg, 15 mg, 20 mg, 40 mg
Capsules (delayed-release): 90 mg
Oral solution: 20 mg/5 ml
Tablets: 10 mg, 15 mg, 20 mg
Indications and dosages
➣ Major depressive disorder (MDD)
Adults: 20 mg/day P.O. in morning. After several weeks, may increase by 20 mg/day at weekly intervals. Give dosages above 20 mg/day in two divided doses (morning and noon); don't exceed 80 mg/day. Patients stabilized on 20 mg/day may be switched to 90-mg/week delayed-release capsules (Prozac Weekly) 7 days after last 20-mg dose.
Children ages 8 to 18: Initially, 10 to 20 mg/day P.O. After 1 week at 10 mg daily, dosage should be increased to 20 mg/day. However, because of higher plasma levels in lower-weight children, starting and target dose in this group may be 10 mg/day. Dosage increase to 20 mg/day may be considered after several weeks if insufficient clinical improvement occurs.
➣ Obsessive-compulsive disorder (OCD)
Adults: Initially, 20 mg/day P.O. in morning. After several weeks, may increase dosage. Give doses above 20 mg/day once daily (morning) or in two divided doses b.i.d. (morning and noon). Dosage range of 20 to 60 mg/day is recommended; however, dosages of up to 80 mg/day have been well tolerated. Don't exceed 80 mg/day.
Children ages 7 to 17: Initially, 10 mg/day P.O. in morning in adolescents and higher-weight children; after 2 weeks, may increase dosage to 20 mg/day. Additional dosage increases may be considered after several more weeks if insufficient clinical improvement occurs. Dosage range of 20 to 60 mg/day is recommended. Initially, 10 mg/day P.O. in lower-weight children; may increase dosage after several more weeks if insufficient clinical improvement occurs. Dosage range of 20 to 30 mg/day is recommended. Experience with daily doses greater than 20 mg is very minimal; there is no experience with doses greater than 60 mg.
➣ Acute treatment of depressive episodes associated with bipolar I disorder
Adults: Initially, 20 mg fluoxetine P.O. with 5 mg olanzapine P.O. daily; dosage range of fluoxetine is 20 to 50 mg; olanzapine, 5 to 12.5 mg. Safety of fluoxetine doses above 75 mg and olanzapine doses above 18 mg haven't been established
➣ Bulimia nervosa
Adults: 60 mg/day P.O.; may be titrated upward over several days
➣ Panic disorder
Adults: 10 mg/day P.O. for 1 week; then, if needed, increase to 20 mg/day. Dosage increases of up to 60 mg/day may be considered after several weeks if patient doesn't respond to lower dosage.
➣ Premenstrual dysphoric disorder
Adults: 20 mg/day (Sarafem) P.O., not to exceed 80 mg/day
Dosage adjustment
• Hepatic impairment
• Concurrent disease or multiple concomitant medications
• Pregnant women during third trimester
• Elderly patients
Off-label uses
• Diabetic peripheral neuropathy
• Alcoholism
• Bipolar II disorder
• Borderline personality disorder
• Narcolepsy
• Posttraumatic stress disorder
• Schizophrenia
• Social phobia
Contraindications
• Hypersensitivity to drug
• MAO inhibitor use within past 14 days
• Concurrent use of thioridazine or within 5 weeks of discontinuing fluoxetine
• Concurrent use of pimozide
Precautions
Use cautiously in:
• hepatic or renal impairment, diabetes mellitus, cardiovascular disease, concomitant illness, acute narrow-angle glaucoma
• history of seizures, serotonin syndrome or neuroleptic malignant syndrome, clinical worsening and suicidal thinking and behavior, activation of mania or hypomania
• hyponatremia in association with syndrome of inappropriate antidiuretic hormone secretion
• concurrent use of NSAIDs, aspirin, warfarin, or other drugs that affect coagulation
• concurrent use of tryptophan (use not recommended)
• pregnant patients (third trimester)
• breastfeeding patients (use not recommended)
• children younger than age 7 (in OCD use), younger than age 8 (in MDD use), younger than age 18 for all other uses (safety and efficacy not established).
Administration
☞ Be aware that drug should be discontinued 5 weeks before MAO inhibitor or thioridazine therapy begins.
• Give before 2 P.M. to prevent nighttime insomnia.
• Be aware that drug should be gradually reduced rather than abruptly stopped whenever possible.
Adverse reactions
CNS: anxiety, drowsiness, headache, insomnia, abnormal dreams, dizziness, fatigue, nervousness, hypomania, mania, weakness, tremor, seizures, suicidal ideation
CV: chest pain, palpitations, prolonged QTc interval
EENT: visual disturbances, stuffy nose, sinusitis, pharyngitis
GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth, anorexia
GU: urinary frequency, sexual dysfunction, dysmenorrhea
Metabolic: hypouricemia, hypocalcemia, hyponatremia, hyperglycemia, hypoglycemia
Musculoskeletal: joint, back, or muscle pain
Respiratory: cough, upper respiratory tract infection, dyspnea, respiratory distress
Skin: diaphoresis, pruritus, erythema nodosum, flushing, rash
Other: abnormal taste, weight loss, fever, flulike symptoms, hot flashes, serotonin syndrome, neuroleptic malignant syndrome (NMS), allergic reactions, hypersensitivity reactions
Interactions
Drug-drug. Adrenergics: increased sensitivity to adrenergics, increased risk of serotonin syndrome
Alprazolam: decreased metabolism and increased effects of alprazolam
Antihistamines, opioids, other antidepressants, sedative-hypnotics: additive CNS depression
Aspirin, NSAIDs, warfarin, other drugs that affect coagulation: increased risk of GI or other bleeding
Buspirone: potentiation of fluoxetine effects, increased risk of seizures
Carbamazepine, clozapine, digoxin, haloperidol, lithium, phenytoin, warfarin: increased blood levels of these drugs, greater risk of adverse reactions
CYP450-2D6 inducers: increased effects of these drugs
Cyproheptadine: decrease in or reversal of fluoxetine effects
Digoxin, warfarin, other highly protein-bound drugs: increased risk of adverse reactions to either drug
Efavirenz, ritonavir, saquinavir, other CYP450 inhibitors: serotonergics, triptans: increased risk of serotonin syndrome
MAO inhibitors: confusion, agitation, seizures, hypertension, and hyperpyrexia (serotonin syndrome)
Pimozide: increased risk of drug interaction or QTc-interval prolongation
Thioridazine: increased risk of QTc-interval prolongation or potential for elevated thioridazine plasma level
Other antidepressants, phenothiazines, risperidone, tryptophan: increased risk of adverse reactions
Ritonavir: increased ritonavir blood level
Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, creatine kinase, electrolytes, glucose: increased levels
Sodium: decreased level
Drug-herbs. St. John's wort: increased risk of serotonin syndrome
Drug-behaviors. Alcohol use: additive CNS depression
Patient monitoring
☞ Monitor patient for signs and symptoms of depression. Assess for suicidal ideation.
☞ Evaluate neurologic status, watching especially for seizures.
☞ Monitor cardiovascular status, particularly for prolonged QTc interval.
• Assess weight regularly. Watch for signs of eating disorders.
☞ Monitor patient for signs and symptoms of allergic reactions, serotonin syndrome, or NMS-like reactions. Discontinue drug immediately and initiate supportive treatment if these reactions occur.
Patient teaching
• Encourage patient to establish effective bedtime routine to minimize sleep disorders.
• Tell patient drug may take 4 weeks or longer to be fully effective.
☞ Instruct patient to contact prescriber if he develops worsening depression or has suicidal thoughts.
☞ Instruct patient to immediately stop drug and report signs and symptoms of allergic reactions (rash), serotonin syndrome, or neuroleptic malignant syndrome-like reactions.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Tell female patient to inform prescriber if she is pregnant or breastfeeding.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.