Zonalon (Doxepin HCl)



Doxepin HCl

Antipruritic Agent

Action And Clinical Pharmacology: Doxepin, a dibenzoxepin-derivative tricyclic compound, is a topical antipruritic. While the exact mechanism of antipruritic activity is unknown, doxepin exhibits potent histamine H1 and H2 receptor antagonist activity. Although the sedative effect of systemically absorbed doxepin may contribute to the drug’s antipruritic activity, the antipruritic efficacy of doxepin reportedly does not appear to depend on a sedative effect. tag_IndicationsIndications

Indications And Clinical Uses: For the short-term (up to 8 days) topical relief of histamine mediated pruritus of moderate severity accompanying conditions such as eczematous dermatitis.

Contra-Indications: In individuals who have shown hypersensitivity to the drug or to other dibenzoxepin compounds.

Children: Doxepin cream is not recommended in children under the age of 12 because safety and efficacy in this age group have not been established.

Because doxepin has an anticholinergic effect and because significant plasma levels of doxepin are detectable after topical doxepin cream application, the use of doxepin cream is contraindicated in patients with glaucoma or a tendency to urinary retention.

Doxepin cream is contraindicated in individuals who have shown previous sensitivity to any of its components.

Manufacturers’ Warnings In Clinical States: Pregnancy and Lactation: The safety of doxepin cream during pregnancy and lactation has not been established and therefore, it should not be used in women of childbearing potential or nursing mothers unless in the opinion of the physician, the potential benefit to the patient outweighs the possible hazards to the fetus.

Occupational Hazards: Drowsiness occurs in over 20% of patients treated with doxepin cream, especially in patients receiving treatment to greater than 10% of their body surface area. Patients should be warned of this possibility and cautioned against driving a motor vehicle or operating hazardous machinery while being treated with doxepin cream.

If excessive drowsiness occurs it may be necessary to reduce the number of applications, the amount of cream applied, and/or the percentage of body surface area treated.

Drug Interactions: MAO Inhibitors: Serious side effects and even death have been reported following the concomitant use of certain orally administered drugs chemically related to doxepin and MAO inhibitors. Therefore, MAO inhibitors should be discontinued at least 2 weeks prior to the initiation of treatment with doxepin cream.

Cimetidine: Cimetidine has been reported to produce clinically significant fluctuations in steady-state serum concentrations of various tricyclic antidepressants when taken orally. Serious anticholinergic symptoms have been associated with elevations in serum levels of orally administered tricyclic antidepressants when cimetidine therapy is initiated. Higher than expected tricyclic antidepressant levels have been observed in patients already taking cimetidine. In patients who have been reported to be well-controlled on tricyclic antidepressants receiving concurrent cimetidine therapy, discontinuation of cimetidine has been reported to decrease established steady-state serum tricyclic antidepressant levels and compromise their therapeutic effects.

The relevance of concurrent administration of cimetidine on the antipruritic effectiveness of doxepin cream, applied topically, is not known.

Alcohol: Alcohol ingestion has exacerbated the potential sedative effects of doxepin cream, particularly in those individuals who use alcohol excessively.

CNS Drugs: CNS drugs patient should be warned that the effects of other drugs acting on the CNS such as barbiturates and other CNS depressants, are potentiated by doxepin cream.

Precautions: Studies have not been done examining drug interactions with doxepin cream. In an 8-day 40-patient percutaneous absorption study, none of the patients who applied doxepin cream 4 times each day had blood levels which reached the antidepressant therapeutic range for oral doxepin.

Patients should also be warned that the effects of alcoholic beverages can be potentiated when using doxepin cream.

Local adverse effects have been reported infrequently with the use of topical doxepin, but may occur more frequently with the use of occlusive dressings. Occlusive dressings may increase the absorption of most topical drugs, therefore occlusive dressings should not be used with doxepin cream.

Adverse Reactions: Local reactions are listed in a decreasing order of occurrence and include: burning, stinging, irritation, tingling and local rash.

Systemic effects which have been observed with the topical use of doxepin cream, include anticholinergic effects: dry mouth, thirst, taste changes, dry eyes. CNS effects including drowsiness, asthenia, headaches, fever, dizziness and gastrointestinal effects were nausea, dyspepsia, vomiting and diarrhea.

Dosage And Administration: Doxepin cream should be applied to the affected area in a thin film 3 to 4 times daily with at least 3- or 4-hour intervals between applications. Doxepin cream should be used for a short term no longer than 8 days. Chronic use beyond 8 days may result in higher systemic levels.

Clinical experience has shown that drowsiness is significantly more common in patients applying treatments to over 10% of body surface area, body surface area (BSA), therefore patients with over 10% of BSA affected should be especially cautioned concerning possible drowsiness.

If excessive drowsiness occurs it may be necessary to reduce BSA treated, reduce the number of applications per day, and/or reduce the amount of cream applied.

Occlusal dressing may also increase the absorption of most topical drugs therefore occlusive dressing should not be used with doxepin cream.

Availability And Storage: Each tube of cream contains: doxepin HCl. Aluminum tubes of 30 g.

ZONALON Medicis Doxepin HCl Antipruritic Agent

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