Prescription Drug Information: Doxepin Hydrochloride (Page 2 of 5)

6.3. Other Reactions Observed During the Pre-marketing Evaluation of Doxepin HCl Tablets

Doxepin HCl Tablets was administered to 1017 subjects in clinical trials in the United States. Treatment-emergent adverse reactions recorded by clinical investigators were standardized using a modified MedDRA dictionary of preferred terms. The following is a list of MedDRA terms that reflect treatment-emergent adverse reactions reported by subjects treated with Doxepin HCl Tablets.

Adverse reactions are further categorized by body system and listed in order of decreasing frequency according to the following definitions: Frequent adverse reactions are those that occurred on one or more occasions in at least 1/100 subjects; Infrequent adverse reactions are those that occurred in fewer than 1/100 subjects and more than 1/1000 subjects. Rare adverse reactions are those that occurred in fewer than 1/1000 subjects. Adverse reactions that are listed in Table 1 are not included in the following listing of frequent, infrequent, and rare AEs.

Blood and Lymphatic System Disorders: Infrequent: anemia; Rare: thrombocythemia.

Cardiac Disorders: Rare: atrioventricular block, palpitations, tachycardia, ventricular extrasystoles.

Ear and Labyrinth Disorders: Rare: ear pain, hypoacusis, motion sickness, tinnitus, tympanic membrane perforation.

Eye Disorders: Infrequent: eye redness, vision blurred; Rare: blepharospasm, diplopia, eye pain, lacrimation decreased.

Gastrointestinal Disorders: Infrequent: abdominal pain, dry mouth, gastroesophageal reflux disease, vomiting; Rare: dyspepsia, constipation, gingival recession, haematochezia, lip blister.

General Disorders and Administration Site Conditions: Infrequent: asthenia, chest pain, fatigue; Rare: chills, gait abnormal, edema peripheral.

Hepatobiliary Disorders: Rare: hyperbilirubinemia.

Immune System Disorders: Rare: hypersensitivity.

Infections and Infestations: Infrequent: bronchitis, fungal infection, laryngitis, sinusitis, tooth infection, urinary tract infection, viral infection; Rare: cellulitis staphylococcal, eye infection, folliculitis, gastroenteritis viral, herpes zoster, infective tenosynovitis, influenza, lower respiratory tract infection, onychomycosis, pharyngitis, pneumonia.

Injury, Poisoning and Procedural Complications: Infrequent: back injury, fall, joint sprain; Rare: bone fracture, skin laceration.

Investigations: Infrequent: blood glucose increased; Rare: alanine aminotransferase increased, blood pressure decreased, blood pressure increased, electrocardiogram ST-T segment abnormal, electrocardiogram QRS complex abnormal, heart rate decreased, neutrophil count decreased, QRS axis abnormal, transaminases increased.

Metabolism and Nutrition Disorders: Infrequent: anorexia, decreased appetite, hyperkalemia, hypermagnesemia, increased appetite; Rare: hypokalemia.

Musculoskeletal and Connective Tissue Disorders: Infrequent: arthralgia, back pain, myalgia, neck pain, pain in extremity; Rare: joint range of motion decreased, muscle cramp, sensation of heaviness.

Neoplasms Benign, Malignant and Unspecified (Including Cysts and Polyps): Rare: lung adenocarcinoma stage I, malignant melanoma.

Nervous System Disorders: Frequent: dizziness; Infrequent: dysgeusia, lethargy, parasthesia, syncope; Rare: ageusia, ataxia, cerebrovascular accident, disturbance in attention, migraine, sleep paralysis, syncope vasovagal, tremor.

Psychiatric Disorders: Infrequent: abnormal dreams, adjustment disorder, anxiety, depression; Rare: confusional state, elevated mood, insomnia, libido decreased, nightmare.

Reproductive System and Breast Disorders: Rare: breast cyst, dysmenorrhea.

Renal and Urinary Disorders: Rare: dysuria, enuresis, hemoglobinuria, nocturia.

Respiratory, Thoracic and Mediastinal Disorders: Infrequent: nasal congestion, pharyngolaryngeal pain, sinus congestion, wheezing; Rare: cough, crackles lung, nasopharyngeal disorder, rhinorrhea, dyspnea.

Skin and Subcutaneous Tissue Disorders: Infrequent: skin irritation; Rare: cold sweat, dermatitis, erythema, hyperhidrosis, pruritis, rash, rosacea.

Surgical and Medical Procedures: Rare: arthrodesis.

Vascular Disorders: Infrequent: pallor; Rare: blood pressure inadequately controlled, hematoma, hot flush.

In addition, the reactions below have been reported for other tricyclics and may be idiosyncratic (not related to dose).

Allergic: photosensitization, skin rash.

Hematologic: agranulocytosis, eosinophilia, leukopenia, purpura, thrombocytopenia.

7. DRUG INTERACTIONS

7.1. Cytochrome P450 Isozymes

Doxepin HCl Tablets is primarily metabolized by hepatic cytochrome P450 isozymes CYP2C19 and CYP2D6, and to a lesser extent, by CYP1A2 and CYP2C9. Inhibitors of these isozymes may increase the exposure of doxepin. Doxepin HCl Tablets is not an inhibitor of any CYP isozymes at therapeutically relevant concentrations. The ability of Doxepin HCl Tablets to induce CYP isozymes is not known.

7.2. Cimetidine

Doxepin HCl Tablets exposure is doubled with concomitant administration of cimetidine, a nonspecific inhibitor of CYP isozymes. A maximum dose of 3 mg is recommended in adults and elderly when cimetidine is co-administered with Doxepin HCl Tablets [see Clinical Pharmacology (12.3)]

7.3. Alcohol

When taken with Doxepin HCl Tablets, the sedative effects of alcohol may be potentiated [see Warnings and Precautions (5.2, 5.4)].

7.4. CNS Depressants and Sedating Antihistamines

When taken with Doxepin HCl Tablets, the sedative effects of sedating antihistamines and CNS depressants may be potentiated [see Warnings and Precautions (5.2, 5.4)].

7.5. Tolazamide

A case of severe hypoglycemia has been reported in a type II diabetic patient maintained on tolazamide (1 g/day) 11 days after the addition of oral doxepin (75 mg/day).

8. USE IN SPECIFIC POPULATIONS

8.1. Pregnancy

Risk Summary

Available data from published epidemiologic studies and postmarketing reports have not established an increased risk of major birth defects or miscarriage (see Data). There are risks of poor neonatal adaptation with exposure to tricyclic antidepressants (TCAs), including doxepin, during pregnancy (see Clinical Considerations). In animal reproduction studies, oral administration of doxepin to rats and rabbits during the period of organogenesis caused adverse developmental effects at doses 65 and 23 times the maximum recommended human dose (MRHD) of 6 mg/day based on AUC, respectively. Oral administration of doxepin to pregnant rats during pregnancy and lactation resulted in decreased pup survival and a delay in pup growth at doses 60 times the MRHD based on AUC (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of major birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Clinical Considerations

Fetal/Neonatal adverse reactions

Neonates exposed to TCAs, including doxepin, late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery. Reported clinical findings have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hyperreflexia, tremor, jitteriness, irritability and constant crying. These findings are consistent with either direct toxic effects of TCAs or possibly a drug discontinuation syndrome. Monitor neonates who were exposed to Doxepin HCl Tablets in the third trimester of pregnancy for poor neonatal adaptation syndrome.

Data

Human Data

Published epidemiologic studies of pregnant women exposed to TCAs, including doxepin, have not established an association with major birth defects, miscarriage or adverse maternal outcomes. Methodological limitations of these observational studies include small sample size and lack of adequate controls.

Animal Data

When doxepin (30, 100, and 150 mg/kg/day) was administered orally to pregnant rats during the period of organogenesis, developmental toxicity (increased incidences of fetal structural abnormalities consisting of non-ossified bones in the skull and sternum and decreased fetal body weights) and maternal toxicity were noted at ≥100 mg/kg/day, which produced plasma exposures (AUCs) of doxepin and nordoxepin (the primary metabolite in humans) approximately 65 and 53 times, respectively, the plasma AUCs at the MRHD. The plasma exposures at the no-effect dose for embryo-fetal developmental toxicity in rats (30 mg/kg/day) are approximately 6 and 5 times the plasma AUCs for doxepin and nordoxepin, respectively, at the MRHD. When doxepin (10, 30, and 60 mg/kg/day) was administered orally to pregnant rabbits during the period of organogenesis, fetal body weights were reduced at the highest dose in the absence of maternal toxicity, which produced plasma AUCs of doxepin and nordoxepin approximately 23 and 56 times, respectively, the plasma AUCs at the MRHD. The plasma exposures at the no-effect dose for developmental effects (30 mg/kg/day) are approximately 8 and 25 times the plasma AUCs for doxepin and nordoxepin, respectively, at the MRHD. Oral administration of doxepin (10, 30, and 100 mg/kg/day) to rats throughout pregnancy and lactation resulted in decreased pup survival and transient growth delay at the highest dose, which produced plasma AUCs of doxepin and nordoxepin approximately 60 and 39 times, respectively, the plasma AUCs at the MRHD. The plasma exposures at the no-effect dose for adverse effects on pre- and postnatal development in rats (30 mg/kg/day) are approximately 2 and 1 times the plasma AUCs for doxepin and nordoxepin, respectively, at the MRHD.

8.2. Lactation

Risk Summary

Data from the published literature report the presence of doxepin and nordoxepin in human milk. There are reports of excess sedation, respiratory depression, poor sucking and swallowing, and hypotonia in breastfed infants exposed to doxepin. There are no data on the effects of doxepin on milk production. Because of the potential for serious adverse reactions, including excess sedation and respiratory depression in a breastfed infant, clinicians should advise patients that breastfeeding is not recommended during treatment with Doxepin HCl Tablets .

Clinical Considerations

Infants exposed to Doxepin HCl Tablets through breast milk should be monitored for excess sedation, respiratory depression and hypotonia.

8.3. Females and Males of Reproductive Potential

Infertility

Based on results from animal fertility studies conducted in rats, doxepin may reduce fertility in females and males of reproductive potential [see Nonclinical Toxicology (13.1)]. It is unknown if the effects are reversible.

8.4. Pediatric Use

The safety and effectiveness of Doxepin HCl Tablets in pediatric patients have not been evaluated.

8.5. Geriatric Use

A total of 362 subjects who were ≥ 65 years and 86 subjects who were ≥ 75 years received Doxepin HCl Tablets in controlled clinical studies. No overall differences in safety or effectiveness were observed between these subjects and younger adult subjects. Greater sensitivity of some older individuals cannot be ruled out.

Sleep-promoting drugs may cause confusion and over-sedation in the elderly. A starting dose of 3 mg is recommended in this population and evaluation prior to considering dose escalation is recommended [see Dosage and Administration (2.2)].

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