"Scientists at the National Institutes of Health report they have discovered in mouse studies that a small molecule released in the spinal cord triggers a process that is later experienced in the brain as the sensation of itch.
Drowsiness occurs in over 20% of patients treated with Zonalon (doxepin) Cream, especially in patients receiving treatment to greater than 10% of their body surface area. Patients should be warned about the possibility of sedation and cautioned against driving a motor vehicle or operating hazardous machinery while being treated with Zonalon (doxepin) Cream.
If excessive drowsiness occurs it may be necessary to reduce the frequency of applications, the amount of cream applied, and/or the percentage of body surface area treated, or discontinue the drug. However, the efficacy with reduced frequency of applications has not been established. Keep this product away from the eyes.
Drowsiness: Since drowsiness may occur with the use of Zonalon (doxepin) Cream, patients should be warned of the possibility and cautioned against driving a car or operating dangerous machinery while using this drug. Patients should also be cautioned that their response to alcohol may be potentiated.
Sedating drugs may cause confusion and oversedation in the elderly; elderly patients generally should be observed closely for confusion and oversedation when started on Zonalon (doxepin) Cream. (See PRECAUTIONS -- Geriatric Use.)
Contact sensitization: Use of Zonalon (doxepin) Cream can cause Type IV hypersensitivity reactions (contact sensitization) to doxepin.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis, mutagenesis, and impairment of fertility studies have not been conducted with doxepin hydrochloride.
Pregnancy Category B
Reproduction studies have been performed in which doxepin was orally administered to rats and rabbits at doses up to 0.6 and 1.2 times, respectively, the estimated exposure to doxepin that results from use of 16 grams of Zonalon (doxepin) Cream per day (four applications of four grams of cream per day; dose multiples reflect comparisons made following normalization of the data on the basis of body surface area estimates) and have revealed no evidence of harm to rat or rabbit fetuses due to doxepin. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
Doxepin is excreted in human milk after oral administration. It is possible that doxepin may also be excreted in human milk following topical application of Zonalon (doxepin) Cream.
Because of the potential for serious adverse reactions in nursing infants from doxepin, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
The use of Zonalon (doxepin) Cream in pediatric patients is not recommended. Safe conditions for use of Zonalon (doxepin) Cream in children have not been established. One case has been reported of a 2.5 year old child who developed somnolence, grand mal seizure, respiratory depression, ECG abnormalities, and coma after treatment with Zonalon (doxepin) Cream. A total of 27 grams had been applied over three days for eczema. He was treated with supportive care, activated charcoal, and systemic alkalization and recovered.
Clinical studies of Zonalon (doxepin) Cream did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.
The extent of renal excretion of doxepin has not been determined. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selections.
Sedating drugs may cause confusion and oversedation in the elderly; elderly patients generally should be observed closely for confusion and oversedation when started on Zonalon (doxepin) Cream. (See WARNINGS.) An 80-year old male nursing home patient developed probable systemic anticholinergic toxicity which included urinary retention and delirium after Zonalon (doxepin) cream had been applied to his arms, legs and back three times daily for two days.
Last reviewed on RxList: 12/29/2008
This monograph has been modified to include the generic and brand name in many instances.
Additional Zonalon Information
- Zonalon Drug Interactions Center: doxepin top
- Zonalon Side Effects Center
- Zonalon Overview including Precautions
- Zonalon FDA Approved Prescribing Information including Dosage
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