Cymbalta

Action

Unknown. May potentiate serotonergic and noradrenergic activity in CNS.

Availability

Capsules (delayed-release): 20 mg, 30 mg, 60 mg

Indications and dosages

➣ Major depressive disorder

Adults: 40 mg/day (20 mg b.i.d.) P.O. to 60 mg/day (once daily or as 30 mg b.i.d.) P.O. If needed, start at 30 mg P.O. once daily for 1 week so patient can adjust to drug before increasing to 60 mg/day. If dosage is increased above 60 mg/day, use increments of 30 mg/day. Some patients may require maintenance dosage of 60 mg once daily for several months or longer.

➣ Generalized anxiety disorder

Adults: For most patients, recommended starting dose is 60 mg P.O. once daily. If needed, start at 30 mg P.O. once daily for 1 week so patient can adjust to drug before increasing to 60 mg/day. If dosage is increased above 60 mg/day, use increments of 30 mg/day.

➣ Diabetic peripheral neuropathic pain

Adults: 60 mg P.O. once daily. For patients with unknown tolerance, consider starting at lower dosage.

➣ Fibromyalgia, chronic musculoskeletal pain

Adults: Initially, 30 mg P.O. daily for 1 week so patient can adjust to drug before increasing to 60 mg P.O. once daily. Some patients may respond to starting dosage. Base continued therapy on patient response.

Dosage adjustment

• Renal impairment

Contraindications

• MAO inhibitor use within past 14 days

• Uncontrolled narrow-angle glaucoma

Precautions

Use cautiously in:

• hepatic insufficiency, severe renal impairment, or chronic hepatic disease (use not recommended)

• hyponatremia, seizure disorder, controlled narrow-angle glaucoma, conditions that slow gastric emptying, urinary hesitancy and frequency

• history of mania

• concurrent use of potent CYP1A2 inhibitors (such as fluoroquinolones, thioridazine, or serotonin precursors) (avoid use)

• concurrent use of 5-hydroxytryptamine receptor agonist (triptan) or other CNS-acting drugs

• heavy alcohol use

• pregnant patients

• breastfeeding patients (use not recommended)

• children, adolescents, and young adults.

Administration

• Assess blood pressure before starting therapy.

• Give without regard to meals.

• Make sure patient swallows capsule whole without chewing or crushing it. Don't sprinkle contents onto food or mix with liquids.

See Don't give within 14 days of MAO inhibitors; don't give MAO inhibitors within 5 days of duloxetine withdrawal.

Adverse reactions

CNS: fatigue, somnolence, dizziness, asthenia, headache, agitation, abnormal dreams, tremor, insomnia, anxiety, worsening of depression, increased risk of suicide or suicidal ideation (especially in child or adolescent)

CV: orthostatic hypotension, syncope

EENT: blurred vision, mydriasis, nasopharyngitis, laryngopharyngeal pain

GI: nausea, vomiting, diarrhea, constipation, dyspepsia, dysgeusia, dry mouth

GU: abnormal orgasm, erectile or ejaculatory dysfunction, delayed ejaculation, decreased libido, frequent daytime urination

Hematologic: abnormal bleeding (ecchymoses, hematomas, epistaxis, petechiae, life-threatening hemorrhage)

Hepatic: hepatotoxicity

Musculoskeletal: muscle cramp, pain, and spasms

Respiratory: cough, upper respiratory tract infection

Skin: increased sweating, hot flashes, rash, pruritus

Other: pyrexia, seasonal allergy, yawning, decreased appetite, weight loss, serotonin syndrome

Interactions

Drug-drug. Aspirin, NSAIDs, other drugs that affect coagulation: increased risk of bleeding

Drugs metabolized by CYP2D6 (such as phenothiazines, tricyclic antidepressants, type 1C antiarrhythmics): increased blood levels of these drugs

Highly protein-bound drugs: increased free concentrations of these drugs, potentially causing adverse reactions

MAO inhibitors: serious and potentially fatal interactions

Potent CYP1A2 inhibitors (such as cimetidine, fluvoxamine, quinolone antibiotics), potent CYP2D6 inhibitors (such as fluoxetine, paroxetine, quinidine): increased duloxetine blood level

Serotonergic drugs (such as linezolid, lithium, tramadol, triptans): increased risk of serotonin syndrome

Thioridazine: increased risk of serious ventricular arrhythmias and sudden death

Warfarin: altered anticoagulant effect, including increased bleeding

Drug-diagnostic tests. ALP, ALT, AST, creatine kinase: increased levels

Sodium: decreased level

Drug-herbs. St. John's wort: increased risk of serotonin syndrome

Drug-behaviors. Alcohol use: increased risk of hepatic damage

Smoking: decreased duloxetine bioavailability

Patient monitoring

See Monitor patient's mental status carefully. Stay alert for mood changes and signs of suicidal ideation, especially in child or adolescent.

• Monitor liver function test results and creatinine level for evidence of hepatic impairment.

See Watch for potentially life-threatening serotonin syndrome, especially with concomitant use of serotonergic drugs (including triptans) or drugs that impair serotonin metabolism (including MAO inhibitors). Signs and symptoms may include mental status changes (agitation, hallucinations, coma), autonomic instability (tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (hyperreflexia, incoordination) and GI upset (nausea, vomiting, diarrhea).

• Monitor blood pressure periodically during therapy.

• Watch for signs and symptoms of hyponatremia, such as headache, poor concentration, memory impairment, confusion, weakness, and unsteadiness. If these occur, consider discontinuing drug and provide treatment as appropriate.

• Know that in diabetic patients, small increases in fasting blood glucose, glycosylated hemoglobin, and total cholesterol levels may occur.

• If concurrent triptan use is warranted, observe patient closely, especially at start of therapy and during dosage increases.

• Carefully monitor patient receiving warfarin when duloxetine is begun or discontinued.

See Don't stop drug abruptly. Taper dosage gradually.

Patient teaching

• Advise patient to take drug without regard to meals.

• Instruct patient to swallow capsules whole without chewing or crushing. Tell patient not to sprinkle contents onto food or mix with liquids.

See Advise patient (and parent or significant other as appropriate) to monitor mental status carefully and immediately report increased depression or suicidal thoughts or behavior (especially in child or adolescent).

See Instruct patient to report signs and symptoms of liver damage (unexplained flulike symptoms, itching, right upper abdominal tenderness, dark urine, or yellow skin).

See Tell patient not to stop taking drug abruptly and that dosage will be tapered gradually when drug is discontinued.

• Caution patient to avoid driving and other hazardous activities until drug's effects on concentration and alertness are known.

• Advise patient to rise slowly from a sitting or lying position to avoid sudden blood pressure drop.

• Instruct patient to avoid heavy alcohol use during therapy because of increased risk of liver damage.

• Caution patient to avoid NSAIDs, aspirin, and other drugs that affect coagulation unless prescriber approves.

• Instruct patient not to use herbs, especially St. John's wort, without consulting prescriber.

• Tell female patient to notify prescriber if she is pregnant or breastfeeding or plans to become pregnant or to breastfeed.

• 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.