Doxepin HCl

 Action Moderately blocks reuptake of norepinephrine and weakly blocks reuptake of serotonin; also produces antihistaminic and anticholinergic activity.

 Indications Treatment of psychoneurotic patients with depression or anxiety; depression or anxiety associated with alcoholism (not to be taken concomitantly with alcohol); depression or anxiety associated with organic disease (the possibility of drug interaction should be considered if the patient is receiving other drugs concomitantly); psychotic depressive orders with associated anxiety including involutional depression and manic-depressive disorders. Unlabeled use(s): Neurogenic pain; peptic ulcer disease. Topical use: Pruritus.

 Contraindications Hypersensitivity to tricyclic antidepressants; use during acute recovery phase after MI; angle-closure glaucoma; risk of urinary retention; concomitant use with monoamine oxidase (MAO) inhibitor; Dibenzoxepines may produce cross-sensitivity.

 Route/Dosage

Depression

ADULTS: PO Initial dose: 75 mg/day, increasing as tolerated. Maximum daily dose: 150 mg for outpatients, 300 mg for inpatients. Maximum single daily dose: 150 mg given at bedtime. FOR MILD CASES WITH ORGANIC DISEASES: PO 25 to 50 mg/day.

Pruritus

ADULTS: Topical Apply thin film qid with ³ 3 to 4 hr between applications. Not recommended for > 8 days.

 Interactions

Alcohol/CNS depressants: CNS and respiratory depression may be potentiated. Anticoagulants: Anticoagulant action may increase. Cimetidine: May inhibit metabolism of doxepin, leading to increased concentrations. Clonidine: Concurrent use may lead to dangerous increases in BP. Fluoxetine: May increase serum concentrations of doxepin; effect may occur up to 5 wk after discontinuation of fluoxetine. Guanethidine: Hypotensive action may be inhibited. MAO inhibitors: Concurrent use may lead to severe seizures, hyperpyretic crisis and fatal reactions. Generally, allow 7 to 10 days between discontinuation of one drug and start of other. Sympathomimetics (eg, dopamine, epinephrine): Pressor response may increase or decrease; arrhythmias may occur.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Orthostatic hypotension; hypertension; fainting; tachycardia; arrhythmias; MI; heart block, precipitation of CHF; stroke. CNS: Dizziness; drowsiness; headache; confusion; weakness; tremors; convulsions. EENT: Mydriasis; photophobia; blurred vision; increased IOP; unpleasant taste. GI: Nausea; constipation; dry mouth; paralytic ileus. GU: Urinary retention; nocturia; painful ejaculation; altered libido; impotence; dysmenorrhea. HEPA: Hepatitis. HEMA: Agranulocytosis; eosinophilia; purpura; thrombocytopenia; leukopenia. META: Increased appetite; weight gain; syndrome of inappropriate secretion of antidiuretic hormone. RESP Bronchospasms; dyspnea. OTHER: Hyperthermia. Topical use: Local burning or stinging; dry or tight skin. Results in significant plasma levels; drowsiness and other adverse effects are possible.

 Precautions

Pregnancy: Oral form: Safety not established. Lactation: Excreted in breast milk. Children: Not recommended for children < 12 yr. Special risk patients: Use drug with caution in patients with history of seizures, urinary retention, urethral spasm, angle-closure glaucoma or increased IOP, cardiovascular disorders, hyperthyroidism (or those receiving thyroid medication), hepatic or renal impairment, schizophrenia or paranoia. Topical use: For external use only; do not use ophthalmically, orally or intravaginally. Because of absorption of drug, drowsiness often occurs.

 Administration/Storage

• Administer with or after meals to decrease GI upset.
• Have patient take capsule with full glass of water.
• If patient is unable to swallow capsule, open capsule and mix contents with food or fluids.
• Dilute concentrate with 120 ml of liquid (water, milk, fruit juice). Do not mix with carbonated beverages.
• If oversedation occurs when divided doses are given during the day, administer total daily dose at bedtime.
• Do not prepare or store bulk dilutions.
• Store at room temperature in tight container and protect from sunlight.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Assess BP (lying, standing) and pulse q 4 hr. If systolic BP drops significantly, withhold drug and notify physician.
• Weigh patient weekly. Appetite may be increased.
• Monitor ECG before and during therapy, especially in elderly patients or patients with current cardiac condition or history of cardiac disease.
• Monitor blood studies: CBC, leukocytes and differential before and during therapy.
• Monitor liver function studies: AST, ALT, bilirubin and serum phosphatase.
• Monitor for urinary retention and constipation. Increase fluids and bulk in diet if constipation or urinary retention occurs.
• Assess patient's mental status: mood, sensorium, affect, suicidal tendencies, increased depression or panic.
• Observe for signs of extrapyramidal syndrome especially in elderly patients: rigidity, dystonia, akathisia.
• If drug is discontinued abruptly, observe patient for withdrawal symptoms: headache, nausea, vomiting, muscle pain, weakness.
• If drowsiness or dizziness occurs, assist patient with ambulation. Use siderails for safety, especially with elderly patients.

 Patient/Family Education

• Warn patient of risk of seizure.
• Emphasize that therapeutic effect may take up to 4 to 6 wk.
• Advise patient to monitor dietary intake because increased appetite may lead to weight gain.
• Instruct patient to increase fluid and bulk intake if constipation occurs.
• Explain that if daytime drowsiness occurs, patient should ask physician about taking total dose at bedtime. Explain that sedative effect tends to disappear with prolonged therapy.
• Caution patient not to stop taking drug abruptly since withdrawal symptoms may occur.
• Emphasize importance of follow-up appointments and lab tests.
• Instruct patient to report urinary retention to physician.
• Advise patient to take sips of water frequently, suck on ice chips or sugarless hard candy or chew sugarless gum if dry mouth occurs.
• Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.