DOXEPIN: 4,021 Adverse Event Reports & Safety Profile

Doxepin hydrochloride, USP is one of a class of psychotherapeutic agents known as dibenzoxepin tricyclic compounds. The molecular formula of the compound is C 19 H 21 NO•HCl having a molecular weight of 315.84. It is a white crystalline powder freely soluble in water, in alcohol and methylene chloride.

Chemistry

Doxepin hydrochloride is a dibenzoxepin derivative and is the first of a family of tricyclic psychotherapeutic agents. Specifically, it is an isomeric mixture of: 1-Propanamine, 3-dibenz [ b , e ]oxepin-11(6 H )ylidene- N,N -dimethyl-, hydrochloride. It may be represented by the following structural formula: Each 10 mg, 25 mg, 50 mg, 75 mg and 100 mg Doxepin capsule for oral administration contains Doxepin hydrochloride equivalent to 10 mg, 25 mg, 50 mg, 75 mg and 100 mg of Doxepin, respectively and the following inactive ingredients: colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose, pregelatinized starch (corn) and sodium lauryl sulfate. The empty gelatin capsule shells contain D&C Yellow No. 10, gelatin and titanium dioxide. In addition, the 10 mg, 25 mg and 50 mg empty gelatin capsule shells contain FD&C Yellow No. 6 and the 75 mg and 100 mg empty gelatin capsule shells contain FD&C Green No. 3. The imprinting ink contains Shellac, Dehydrated Alcohol, Isopropyl Alcohol, Butyl Alcohol, Propylene Glycol, Strong Ammonia Solution, Potassium Hydroxide and Black Iron Oxide. FDA approved dissolution specifications differ from the USP. Doxepine

CHEMISTRY Doxepin hydrochloride is a dibenzoxepin derivative and is the first of a family of tricyclic psychotherapeutic agents. Specifically, it is an isomeric mixture of: 1-Propanamine, 3-dibenz [ b , e ]oxepin-11(6 H )ylidene- N,N -dimethyl-, hydrochloride. It may be represented by the following structural formula: Each 10 mg, 25 mg, 50 mg, 75 mg and 100 mg Doxepin capsule for oral administration contains Doxepin hydrochloride equivalent to 10 mg, 25 mg, 50 mg, 75 mg and 100 mg of Doxepin, respectively and the following inactive ingredients: colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose, pregelatinized starch (corn) and sodium lauryl sulfate. The empty gelatin capsule shells contain D&C Yellow No. 10, gelatin and titanium dioxide. In addition, the 10 mg, 25 mg and 50 mg empty gelatin capsule shells contain FD&C Yellow No. 6 and the 75 mg and 100 mg empty gelatin capsule shells contain FD&C Green No. 3. The imprinting ink contains Shellac, Dehydrated Alcohol, Isopropyl Alcohol, Butyl Alcohol, Propylene Glycol, Strong Ammonia Solution, Potassium Hydroxide and Black Iron Oxide. FDA approved dissolution specifications differ from the USP. Doxepine

INDICATIONS AND USAGE Doxepin Hydrochloride Capsules, USP are recommended for the treatment of: 1. Psychoneurotic patients with depression and/or anxiety. 2. Depression and/or anxiety associated with alcoholism (not to be taken concomitantly with alcohol). 3. Depression and/or anxiety associated with organic disease (the possibility of drug interaction should be considered if the patient is receiving other drugs concomitantly). 4. Psychotic depressive disorders with associated anxiety including involutional depression and manic-depressive disorders. The target symptoms of psychoneurosis that respond particularly well to doxepin hydrochloride capsules include anxiety, tension, depression, somatic symptoms and concerns, sleep disturbances, guilt, lack of energy, fear, apprehension and worry. Clinical experience has shown that doxepin hydrochloride capsules are safe and well tolerated even in the elderly patient. Owing to lack of clinical experience in the pediatric population, doxepin hydrochloride capsules are not recommended for use in children under 12 years of age.

AND ADMINISTRATION Prior to initiating treatment with doxepin hydrochloride, screen patients for a personal or family history of bipolar disorder, mania, or hypomania. ( 2.1 ) Recommended starting oral dosage is 25 mg three times daily or 75 mg once daily. ( 2.2 ) Recommended target total dosage range is between 75 mg/day and 150 mg/day (may be given once daily or in divided doses). ( 2.2 ) Maximum recommended dosage is 100 mg three times daily. ( 2.2 ) Wait at least 14 days after discontinuation of a monoamine oxidase inhibitor (MAOI) before initiating therapy with doxepin hydrochloride. ( 2.3 ) See the Full Prescribing Information for dosage modifications intended to reduce the risk of anticholinergic effects, for strong CYP2D6 inhibitors, and in known CYP2D6 and CYP2C19 poor metabolizers. ( 2.4 , 2.5 , 2.6 ) When discontinuing doxepin hydrochloride, gradually reduce the dosage until discontinued. ( 2.7 )

See Full Prescribing

Information for recommended preparation instructions for the oral solution. ( 2.8 )

2.1 Screen for Bipolar Disorder Prior to Starting Doxepin Hydrochloride Prior to initiating treatment with doxepin hydrochloride, screen patients for a personal or family history of bipolar disorder, mania, or hypomania <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.5 )]</span> .

2.2 Recommended Dosage The recommended starting oral dosage for doxepin hydrochloride is 25 mg three times daily or 75 mg once daily. The recommended target total oral dosage range for doxepin hydrochloride is between 75 mg/day and 150 mg/day (may be given once daily or in divided doses). The maximum recommended oral dosage for doxepin hydrochloride is 100 mg three times daily.

2.3 Switching Patients to or from a Monoamine Oxidase Inhibitor Wait at least 14 days after discontinuation of a monoamine oxidase inhibitor (MAOI) before initiating therapy with doxepin hydrochloride <span class="opacity-50 text-xs">[see Contraindications ( 4 ), Warnings and Precautions ( 5.2 ), and Drug Interactions ( 7 )]</span> . Wait at least 14 days after discontinuation of doxepin hydrochloride before initiating therapy with an MAOI <span class="opacity-50 text-xs">[see Contraindications ( 4 ), Warnings and Precautions ( 5.2 ), and Drug Interactions ( 7 )]</span> .

2.4 Dosage Modifications Intended to Reduce the Risk of Anticholinergic Effects If anticholinergic effects (e.g., dry mouth, blurred vision, constipation) develop, reduce the doxepin hydrochloride dosage <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.1 )]</span> .

2.5 Dosage Modifications for Strong CYP2D6 Inhibitors Reduce the doxepin hydrochloride dosage based on doxepin plasma concentrations when used concomitantly with strong CYP2D6 inhibitors <span class="opacity-50 text-xs">[see Drug Interactions ( 7 )]</span> .

2.6 Dosage Modifications in Known CYP2D6 and CYP2C19 Poor Metabolizers Reduce the doxepin hydrochloride dosage based on doxepin plasma concentrations in patients who are known CYP2D6 and CYP2C19 poor metabolizers <span class="opacity-50 text-xs">[see Use in Specific Populations ( 8.7 )]</span> .

2.7 Discontinuation of Doxepin Hydrochloride Treatment When discontinuing doxepin hydrochloride, gradually reduce the dosage until discontinued <span class="opacity-50 text-xs">[see Adverse Reactions ( 6 )]</span> .

2.8 Preparation of Doxepin Hydrochloride Oral Solution Recommended preparation instructions for the Doxepin Hydrochloride Oral Solution are as follows: Use the supplied calibrated dropper to measure the amount of Doxepin Hydrochloride Oral Solution needed. The calibrated dropper has markings at 5 mg, 10 mg, 15 mg, 20 mg, and 25 mg. Just prior to administration, mix doxepin hydrochloride with 120 mL of water, whole or skimmed milk, or orange, grapefruit, tomato, prune, or pineapple juice. Do not mix with other liquids. Administer the dose immediately after mixing.

4.

Contraindications

Hypersensitivity to doxepin hydrochloride, inactive ingredients, or other dibenzoxepines. ( 4.1 ) Co-administration with Monoamine Oxidase Inhibitors (MAOIs): Do not administer if patient is taking MAOIs or has used MAOIs within the past two weeks. ( 4.2 ) Untreated narrow angle glaucoma or severe urinary retention. ( 4.3 ) 4.1.

Hypersensitivity

Doxepin HCl Tablets is contraindicated in individuals who have shown hypersensitivity to doxepin HCl, any of its inactive ingredients, or other dibenzoxepines. 4.2. Co-administration with Monoamine Oxidase Inhibitors (MAOIs) Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Do not administer Doxepin HCl Tablets if patient is currently on MAOIs or has used MAOIs within the past two weeks. The exact length of time may vary depending on the particular MAOI dosage and duration of treatment. 4.3. Glaucoma and Urinary Retention Doxepin HCl Tablets is contraindicated in individuals with untreated narrow angle glaucoma or severe urinary retention.

REACTIONS The following serious adverse reactions are discussed in greater detail in other sections of labeling: Abnormal thinking and behavioral changes [see Warnings and Precautions ( 5.2 )]. Suicide risk and worsening of depression [see Warnings and Precautions ( 5.3 )].

Cns

Depressant effects [see Warnings and Precautions ( 5.4 )]. The most common treatment-emergent adverse reactions, reported in greater than or equal to 2% of patients treated with doxepin tablets, and more commonly than in patients treated with placebo, were somnolence/sedation, nausea, and upper respiratory tract infection. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Ajanta Pharma USA Inc. at 1-855-664-7744 and or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience The pre-marketing development program for doxepin tablets included doxepin HCl exposures in 1017 subjects (580 insomnia patients and 437 healthy subjects) from 12 studies conducted in the United States. 863 of these subjects (580 insomnia patients and 283 healthy subjects) participated in six randomized, placebo-controlled efficacy studies with doxepin tablets doses of 1 mg, 3 mg, and 6 mg for up to 3-months in duration. Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. However, data from the doxepin tablets studies provide the physician with a basis for estimating the relative contributions of drug and non-drug factors to adverse reaction incidence rates in the populations studied. Associated with Discontinuation of Treatment The percentage of subjects discontinuing Phase 1, 2, and 3 trials for an adverse reaction was 0.6% in the placebo group compared to 0.4%, 1.0%, and 0.7% in the doxepin tablets 1 mg, 3 mg, and 6 mg groups, respectively. No reaction that resulted in discontinuation occurred at a rate greater than 0.5%.

Adverse Reactions

Observed at an Incidence of greater than or equal to 2% in Controlled Trials Table 1 shows the incidence of treatment-emergent adverse reactions from three long-term (28 to 85 days) placebo-controlled studies of doxepin tablets in adult (N=221) and elderly (N=494) subjects with chronic insomnia. Reactions reported by Investigators were classified using a modified MedDRA dictionary of preferred terms for purposes of establishing incidence. The table includes only reactions that occurred in 2% or more of subjects who received doxepin tablets 3 mg or 6 mg in which the incidence in subjects treated with doxepin tablets was greater than the incidence in placebo-treated subjects.

Table

1 Incidence (%) of Treatment-Emergent Adverse Reactions in Long-term Placebo-Controlled Clinical Trials System Organ Class Preferred Term* Placebo (N=278) Doxepin tablets 3 mg (N=157) Doxepin tablets 6 mg (N=203)

Nervous System Disorders Somnolence/Sedation

4 6 9 Infections and Infestations Upper Respiratory Tract Infection/Nasopharyngitis 2 4 2 Gastroenteritis 0 2 0 Gastrointestinal Disorders Nausea 1 2 2 Vascular Disorders Hypertension 0 3 ˂1 * Includes reactions that occurred at a rate of greater than or equal to 2% in any doxepin tablets-treated group and at a higher rate than placebo. The most common treatment-emergent adverse reaction in the placebo and each of the doxepin tablets dose groups was somnolence/sedation. 6.2.

Studies

Pertinent to Safety Concerns for Sleep-promoting Drugs Residual Pharmacological Effect in Insomnia Trials Five randomized, placebo-controlled studies in adults and the elderly assessed next-day psychomotor function within 1 hour of awakening utilizing the digit-symbol substitution test (DSST), symbol copying test (SCT), and visual analog scale (VAS) for sleepiness, following night time administration of doxepin tablets. In a one-night, double-blind study conducted in 565 healthy adult subjects experiencing transient insomnia, doxepin tablets 6 mg showed modest negative changes in SCT and VAS. In a 35-day, double-blind, placebo-controlled, parallel group study of doxepin tablets 3 and 6 mg in 221 adults with chronic insomnia, small decreases in the DSST and SCT occurred in the 6 mg group. In a 3-month, double-blind, placebo-controlled, parallel group study in 240 elderly subjects with chronic insomnia, doxepin tablets 1 mg and 3 mg were comparable to placebo on DSST, SCT, and VAS. 6.3.

Other Reactions Observed

During the Pre-marketing Evaluation of Doxepin tablets Doxepin tablets were 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 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.

Clinical Worsening and Suicide Risk Patients with major depressive disorder (MDD), both adult and pediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior, whether or not they are taking antidepressant medications, and this risk may persist until significant remission occurs. Suicide is a known risk of depression and certain other psychiatric disorders, and these disorders themselves are the strongest predictors of suicide. There has been a long-standing concern, however, that antidepressants may have a role in inducing worsening of depression and the emergence of suicidality in certain patients during the early phases of treatment. Pooled analyses of short-term placebo-controlled trials of antidepressant drugs (SSRIs and others) showed that these drugs increase the risk of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults (ages 18 to 24) with major depressive disorder (MDD) and other psychiatric disorders. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction with antidepressants compared to placebo in adults aged 65 and older. The pooled analyses of placebo-controlled trials in children and adolescents with MDD, obsessive compulsive disorder (OCD), or other psychiatric disorders included a total of 24 short-term trials of nine antidepressant drugs in over 4,400 patients. The pooled analyses of placebo-controlled trials in adults with MDD or other psychiatric disorders included a total of 295 short-term trials (median duration of 2 months) of 11 antidepressant drugs in over 77,000 patients. There was considerable variation in risk of suicidality among drugs, but a tendency toward an increase in the younger patients for almost all drugs studied. There were differences in absolute risk of suicidality across the different indications, with the highest incidence in MDD. The risk differences (drug vs. placebo), however, were relatively stable within age strata and across indications. These risk differences (drug-placebo difference in the number of cases of suicidality per 1,000 patients treated) are provided in Table 1.

Table

1 Age Range Drug-Placebo Difference in Number of Cases of Suicidality Per 1,000 Patients Treated Increases Compared to Placebo < 18 14 additional cases 18 to 24 5 additional cases Decreases Compared to Placebo 25 to 64 1 fewer case ≥ 65 6 fewer cases No suicides occurred in any of the pediatric trials. There were suicides in the adult trials, but the number was not sufficient to reach any conclusion about drug effect on suicide. It is unknown whether the suicidality risk extends to longer-term use, i.e., beyond several months. However, there is substantial evidence from placebo-controlled maintenance trials in adults with depression that the use of antidepressants can delay the recurrence of depression. All patients being treated with antidepressants for any indication should be monitored appropriately and observed closely for clinical worsening, suicidality and unusual changes in behavior, especially during the initial few months of a course of drug therapy, or at times of dose changes, either increases or decreases. The following symptoms, anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania and mania, have been reported in adult and pediatric patients being treated with antidepressants for major depressive disorder as well as for other indications, both psychiatric and nonpsychiatric. Although a causal link between the emergence of such symptoms and either the worsening of depression and/or the emergence of suicidal impulses has not been established, there is concern that such symptoms may represent precursors to emerging suicidality. Consideration should be given to changing the therapeutic regimen, including possibly discontinuing the medication, in patients whose depression is persistently worse, or who are experiencing emergent suicidality or symptoms that might be precursors to worsening depression or suicidality, especially if these symptoms are severe, abrupt in onset, or were not part of the patient's presenting symptoms. Families and caregivers of patients being treated with antidepressants for major depressive disorder or other indications, both psychiatric and nonpsychiatric, should be alerted about the need to monitor patients for the emergence of agitation, irritability, unusual changes in behavior, and the other symptoms described above, as well as the emergence of suicidality, and to report such symptoms immediately to healthcare providers. Such monitoring should include daily observation by families and caregivers. Prescriptions for doxepin should be written for the smallest number of capsules consistent with good patient management, in order to reduce the risk of overdose.

Screening

Patients for Bipolar Disorder A major depressive episode may be the initial presentation of bipolar disorder. It is generally believed (though not established in controlled trials) that treating such an episode with an antidepressant alone may increase the likelihood of precipitation of a mixed/manic episode in patients at risk for bipolar disorder. Whether any of the symptoms described above represent such a conversion is unknown. However, prior to initiating treatment with an antidepressant, patients with depressive symptoms should be adequately screened to determine if they are at risk for bipolar disorder; such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression. It should be noted that doxepin is not approved for use in treating bipolar depression. Angle-Closure Glaucoma The pupillary dilation that occurs following use of many antidepressant drugs including doxepin hydrochloride capsules may trigger an angle closure attack in a patient with anatomically narrow angles who does not have a patent iridectomy.

Geriatric Use

The use of doxepin on a once a day dosage regimen in geriatric patients should be adjusted carefully based on the patient's condition (see PRECAUTIONS: GERIATRIC USE).

Pregnancy

Reproduction studies have been performed in rats, rabbits, monkeys and dogs and there was no evidence of harm to the animal fetus. The relevance to humans is not known. Since there is no experience in pregnant women who have received this drug, safety in pregnancy has not been established. There has been a report of apnea and drowsiness occurring in a nursing infant whose mother was taking doxepin.

Pediatric Use

The use of doxepin in children under 12 years of age is not recommended because safe conditions for its use have not been established.

Precautions

Information for Patients Prescribers or other health professionals should inform patients, their families and their caregivers about the benefits and risks associated with treatment with doxepin and should counsel them in its appropriate use. A patient Medication Guide about "Antidepressant Medicines, Depression and Other Serious Mental Illnesses and Suicidal Thoughts or Actions" is available for doxepin. The prescriber or health professional should instruct patients, their families and their caregivers to read the Medication Guide and should assist them in understanding its contents. Patients should be given the opportunity to discuss the contents of the Medication Guide and to obtain answers to any questions they may have. The complete text of the Medication Guide is reprinted at the end of this document. Patients should be advised of the following issues and asked to alert their prescriber if these occur while taking doxepin.

Clinical

Worsening and Suicide Risk Patients, their families and their caregivers should be encouraged to be alert to the emergence of anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, mania, other unusual changes in behavior, worsening of depression and suicidal ideation, especially early during antidepressant treatment and when the dose is adjusted up or down. Families and caregivers of patients should be advised to look for the emergence of such symptoms on a day to day basis, since changes may be abrupt. Such symptoms should be reported to the patient's prescriber or health professional, especially if they are severe, abrupt in onset, or were not part of the patient's presenting symptoms. Symptoms such as these may be associated with an increased risk for suicidal thinking and behavior and indicate a need for very close monitoring and possibly changes in the medication. Patients should be advised that taking doxepin hydrochloride capsules can cause mild pupillary dilation, which in susceptible individuals, can lead to an episode of angle-closure glaucoma. Pre-existing glaucoma is almost always open-angle glaucoma because angle-closure glaucoma, when diagnosed, can be treated definitively with iridectomy. Open-angle glaucoma is not a risk factor for angle-closure glaucoma. Patients may wish to be examined to determine whether they are susceptible to angle closure, and have a prophylactic procedure (e.g., iridectomy), if they are susceptible.

Drug Interactions Drugs

Metabolized by P450 2D6 The biochemical activity of the drug metabolizing isozyme cytochrome P450 2D6 (debrisoquin hydroxylase) is reduced in a subset of the Caucasian population (about 7% to 10% of Caucasians are so called "poor metabolizers"); reliable estimates of the prevalence of reduced P450 2D6 isozyme activity among Asian, African and other populations are not yet available. Poor metabolizers have higher than expected plasma concentrations of tricyclic antidepressants (TCAs) when given usual doses. Depending on the fraction of drug metabolized by P450 2D6, the increase in plasma concentration may be small, or quite large (8-fold increase in plasma AUC of the TCA). In addition, certain drugs inhibit the activity of this isozyme and make normal metabolizers resemble poor metabolizers. An individual who is stable on a given dose of TCA may become abruptly toxic when given one of these inhibiting drugs as concomitant therapy. The drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide). While all the selective serotonin reuptake inhibitors (SSRIs), e.g., citalopram, escitalopram, fluoxetine, sertraline, and paroxetine, inhibit P450 2D6, they may vary in the extent of inhibition. The extent to which SSRI-TCA interactions may pose clinical problems will depend on the degree of inhibition and the pharmacokinetics of the SSRI involved. Nevertheless, caution is indicated in the coadministration of TCAs with any of the SSRIs and also in switching from one class to the other. Of particular importance, sufficient time must elapse before initiating TCA treatment in a patient being withdrawn from fluoxetine, given the long half-life of the parent and active metabolite (at least 5 weeks may be necessary). Concomitant use of tricyclic antidepressants with drugs that can inhibit cytochrome P450 2D6 may require lower doses than usually prescribed for either the tricyclic antidepressant or the other drug. Furthermore, whenever one of these other drugs is withdrawn from cotherapy, an increased dose of tricyclic antidepressant may be required. It is desirable to monitor TCA plasma levels whenever a TCA is going to be coadministered with another drug known to be an inhibitor of P450 2D6. Doxepin is primarily metabolized by CYP2D6 (with CYP1A2 & CYP3A4 as minor pathways). Inhibitors or substrates of CYP2D6 (i.e., quinidine, selective serotonin reuptake inhibitors [SSRIs]) may increase the plasma concentration of doxepin when administered concomitantly. The extent of interaction depends on the variability of effect on CYP2D6. The clinical significance of this interaction with doxepin has not been systematically evaluated.

Mao

Inhibitors Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Therefore, MAO inhibitors should be discontinued at least 2 weeks prior to the cautious initiation of therapy with doxepin. The exact length of time may vary and is dependent upon the particular MAO inhibitor being used, the length of time it has been administered, and the dosage involved.

Cimetidine

Cimetidine has been reported to produce clinically significant fluctuations in steady-state serum concentrations of various tricyclic antidepressants. Serious anticholinergic symptoms (i.e., severe dry mouth, urinary retention and blurred vision) have been associated with elevations in the serum levels of tricyclic antidepressant when cimetidine therapy is initiated. Additionally, higher than expected tricyclic antidepressant levels have been observed when they are begun 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. Alcohol It should be borne in mind that alcohol ingestion may increase the danger inherent in any intentional or unintentional doxepin overdosage. This is especially important in patients who may use alcohol excessively. Tolazamide A case of severe hypoglycemia has been reported in a type II diabetic patient maintained on tolazamide (1 gm/day) 11 days after the addition of doxepin (75 mg/day).

Drowsiness

Since drowsiness may occur with the use of this drug, patients should be warned of the possibility and cautioned against driving a car or operating dangerous machinery while taking the drug. Patients should also be cautioned that their response to alcohol may be potentiated. Sedating drugs may cause confusion and over sedation in the elderly; elderly patients generally should be started on low doses of doxepin and observed closely (see PRECAUTIONS: GERIATRIC USE).

Suicide

Since suicide is an inherent risk in any depressed patient and may remain so until significant improvement has occurred, patients should be closely supervised during the early course of therapy. Prescriptions should be written for the smallest feasible amount.

Psychosis

Should increased symptoms of psychosis or shift to manic symptomatology occur, it may be necessary to reduce dosage or add a major tranquilizer to the dosage regimen.

Pediatric Use

Safety and effectiveness in the pediatric population have not been established (see BOX WARNING and WARNINGS: CLINICAL WORSENING AND SUICIDE RISK). Anyone considering the use of doxepin in a child or adolescent must balance the potential risks with the clinical need.

Geriatric

Use A determination has not been made whether controlled clinical studies of doxepin included sufficient numbers of subjects aged 65 and over to define a difference in response 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 over sedation in the elderly; elderly patients generally should be started on low doses of doxepin and observed closely. (See WARNINGS.)

PRECAUTIONS Information for Patients Prescribers or other health professionals should inform patients, their families, and their caregivers about the benefits and risks associated with treatment with doxepin hydrochloride and should counsel them in its appropriate use. A patient Medication Guide about “Antidepressant Medicines, Depression and other Serious Mental Illness, and Suicidal Thoughts or Actions” is available for doxepin hydrochloride. The prescriber or health professional should instruct patients, their families, and their caregivers to read the Medication Guide and should assist them in understanding its contents. Patients should be given the opportunity to discuss the contents of the Medication Guide and to obtain answers to any questions they may have. The complete text of the Medication Guide is reprinted at the end of this document. Patients should be advised of the following issues and asked to alert their prescriber if these occur while taking doxepin hydrochloride. Patients should be advised that taking doxepin hydrochloride capsules can cause mild pupillary dilation, which in susceptible individuals, can lead to an episode of angle-closure glaucoma. Preexisting glaucoma is almost always open-angle glaucoma because angle-closure glaucoma, when diagnosed, can be treated definitively with iridectomy. Open-angle glaucoma is not a risk factor for angle closure glaucoma. Patients may wish to be examined to determine whether they are susceptible to angle closure, and have a prophylactic procedure (e.g., iridectomy), if they are susceptible.

Clinical

Worsening and Suicide Risk: Patients, their families, and their caregivers should be encouraged to be alert to the emergence of anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, mania, other unusual changes in behavior, worsening of depression, and suicidal ideation, especially early during antidepressant treatment and when the dose is adjusted up or down. Families and caregivers of patients should be advised to look for the emergence of such symptoms on a day-to-day basis, since changes may be abrupt. Such symptoms should be reported to the patient's prescriber or health professional, especially if they are severe, abrupt in onset, or were not part of the patient's presenting symptoms. Symptoms such as these may be associated with an increased risk for suicidal thinking and behavior and indicate a need for very close monitoring and possibly changes in the medication. Patients should be advised that taking doxepin hydrochloride can cause mild pupillary dilation, which in susceptible individuals, can lead to an episode of angle closure glaucoma. Pre-existing glaucoma is almost always open-angle glaucoma because angle closure glaucoma, when diagnosed, can be treated definitively with iridectomy. Open-angle glaucoma is not a risk factor for angle closure glaucoma. Patients may wish to be examined to determine whether they are susceptible to angle closure, and have a prophylactic procedure (e.g., iridectomy), if they are susceptible.

Drug

Interactions: Drugs Metabolized by P450 2D6: The biochemical activity of the drug metabolizing isozyme cytochrome P450 2D6 (debrisoquin hydroxylase) is reduced in a subset of the Caucasian population (about 7 to 10% of Caucasians are so-called “poor metabolizers”); reliable estimates of the prevalence of reduced P450 2D6 isozyme activity among Asian, African and other populations are not yet available. Poor metabolizers have higher than expected plasma concentrations of tricyclic antidepressants (TCAs) when given usual doses. Depending on the fraction of drug metabolized by P450 2D6, the increase in plasma concentration may be small, or quite large (8-fold increase in plasma AUC of the TCA). In addition, certain drugs inhibit the activity of this isozyme and make normal metabolizers resemble poor metabolizers. An individual who is stable on a given dose of TCA may become abruptly toxic when given one of these inhibiting drugs as concomitant therapy. The drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide). While all the selective serotonin reuptake inhibitors (SSRIs), e.g., citalopram, escitalopram, fluoxetine, sertraline, and paroxetine, inhibit P450 2D6, they may vary in the extent of inhibition. The extent to which SSRI-TCA interactions may pose clinical problems will depend on the degree of inhibition and the pharmacokinetics of the SSRI involved. Nevertheless, caution is indicated in the co-administration of TCAs with any of the SSRIs and also in switching from one class to the other. Of particular importance, sufficient time must elapse before initiating TCA treatment in a patient being withdrawn from fluoxetine, given the long half-life of the parent and active metabolite (at least 5 weeks may be necessary). Concomitant use of tricyclic antidepressants with drugs that can inhibit cytochrome P450 2D6 may require lower doses than usually prescribed for either the tricyclic antidepressant or the other drug. Furthermore, whenever one of these other drugs is withdrawn from co-therapy, an increased dose of tricyclic antidepressant may be required. It is desirable to monitor TCA plasma levels whenever a TCA is going to be co-administered with another drug known to be an inhibitor of P450 2D6. Doxepin is primarily metabolized by CYP2D6 (with CYP1A2 & CYP3A4 as minor pathways). Inhibitors or substrates of CYP2D6 (i.e., quinidine, selective serotonin reuptake inhibitors [SSRIs]) may increase the plasma concentration of doxepin when administered concomitantly. The extent of interaction depends on the variability of effect on CYP2D6. The clinical significance of this interaction with doxepin has not been systematically evaluated.

Mao

Inhibitors: Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Therefore, MAO inhibitors should be discontinued at least two weeks prior to the cautious initiation of therapy with doxepin hydrochloride. The exact length of time may vary and is dependent upon the particular MAO inhibitor being used, the length of time it has been administered, and the dosage involved. Cimetidine: Cimetidine has been reported to produce clinically significant fluctuations in steady-state serum concentrations of various tricyclic antidepressants. Serious anticholinergic symptoms (i.e., severe dry mouth, urinary retention and blurred vision) have been associated with elevations in the serum levels of tricyclic antidepressant when cimetidine therapy is initiated. Additionally, higher than expected tricyclic antidepressant levels have been observed when they are begun 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. Alcohol: It should be borne in mind that alcohol ingestion may increase the danger inherent in any intentional or unintentional doxepin hydrochloride overdosage. This is especially important in patients who may use alcohol excessively. Tolazamide: A case of severe hypoglycemia has been reported in a type II diabetic patient maintained on tolazamide (1 gm/day) 11 days after the addition of doxepin (75 mg/day). Drowsiness: Since drowsiness may occur with the use of this drug, patients should be warned of the possibility and cautioned against driving a car or operating dangerous machinery while taking the 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 started on low doses of doxepin hydrochloride and observed closely. (See Error! Hyperlink reference not valid. .) Suicide: Since suicide is an inherent risk in any depressed patient and may remain so until significant improvement has occurred, patients should be closely supervised during the early course of therapy. Prescriptions should be written for the smallest feasible amount. Psychosis: Should increased symptoms of psychosis or shift to manic symptomatology occur, it may be necessary to reduce dosage or add a major tranquilizer to the dosage regimen.

Pediatric

Use -Safety and effectiveness in the pediatric population have not been established (see BOX WARNING and WARNINGS—Clinical Worsening and Suicide Risk ). Anyone considering the use of doxepin hydrochloride in a child or adolescent must balance the potential risks with the clinical need.

Geriatric

Use: A determination has not been made whether controlled clinical studies of doxepin hydrochloride included sufficient numbers of subjects aged 65 and over to define a difference in response 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 hydrochloride 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 started on low doses of doxepin hydrochloride and observed closely. (See WARNINGS .)

Drug Interactions: Drugs Metabolized by P450 2D6: The biochemical activity of the drug metabolizing isozyme cytochrome P450 2D6 (debrisoquin hydroxylase) is reduced in a subset of the Caucasian population (about 7% to 10% of Caucasians are so-called “poor metabolizers”); reliable estimates of the prevalence of reduced P450 2D6 isozyme activity among Asian, African and other populations are not yet available. Poor metabolizers have higher than expected plasma concentrations of tricyclic antidepressants (TCAs) when given usual doses. Depending on the fraction of drug metabolized by P450 2D6, the increase in plasma concentration may be small, or quite large (8-fold increase in plasma AUC of the TCA). In addition, certain drugs inhibit the activity of this isozyme and make normal metabolizers resemble poor metabolizers. An individual who is stable on a given dose of TCA may become abruptly toxic when given one of these inhibiting drugs as concomitant therapy. The drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide). While all the selective serotonin reuptake inhibitors (SSRIs), e.g., citalopram, escitalopram, fluoxetine, sertraline, and paroxetine, inhibit P450 2D6, they may vary in the extent of inhibition. The extent to which SSRI-TCA interactions may pose clinical problems will depend on the degree of inhibition and the pharmacokinetics of the SSRI involved. Nevertheless, caution is indicated in the co-administration of TCAs with any of the SSRIs and also in switching from one class to the other. Of particular importance, sufficient time must elapse before initiating TCA treatment in a patient being withdrawn from fluoxetine, given the long half-life of the parent and active metabolite (at least 5 weeks may be necessary). Concomitant use of tricyclic antidepressants with drugs that can inhibit cytochrome P450 2D6 may require lower doses than usually prescribed for either the tricyclic antidepressant or the other drug. Furthermore, whenever one of these other drugs is withdrawn from co-therapy, an increased dose of tricyclic antidepressant may be required. It is desirable to monitor TCA plasma levels whenever a TCA is going to be co-administered with another drug known to be an inhibitor of P450 2D6. Doxepin is primarily metabolized by CYP2D6 (with CYP1A2 & CYP3A4 as minor pathways). Inhibitors or substrates of CYP2D6 (i.e., quinidine, selective serotonin reuptake inhibitors [SSRIs]) may increase the plasma concentration of Doxepin when administered concomitantly. The extent of interaction depends on the variability of effect on CYP2D6. The clinical significance of this interaction with Doxepin has not been systematically evaluated.

Mao

Inhibitors: Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Therefore, MAO inhibitors should be discontinued at least two weeks prior to the cautious initiation of therapy with Doxepin. The exact length of time may vary and is dependent upon the particular MAO inhibitor being used, the length of time it has been administered, and the dosage involved. Cimetidine: Cimetidine has been reported to produce clinically significant fluctuations in steady-state serum concentrations of various tricyclic antidepressants. Serious anticholinergic symptoms (i.e., severe dry mouth, urinary retention and blurred vision) have been associated with elevations in the serum levels of tricyclic antidepressant when cimetidine therapy is initiated. Additionally, higher than expected tricyclic antidepressant levels have been observed when they are begun 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. Alcohol: It should be borne in mind that alcohol ingestion may increase the danger inherent in any intentional or unintentional Doxepin overdosage. This is especially important in patients who may use alcohol excessively. Tolazamide: A case of severe hypoglycemia has been reported in a type II diabetic patient maintained on tolazamide (1 gm/day) 11 days after the addition of Doxepin (75 mg/day). Drowsiness : Since drowsiness may occur with the use of this drug, patients should be warned of the possibility and cautioned against driving a car or operating dangerous machinery while taking the drug. Patients should also be cautioned that their response to alcohol may be potentiated. Sedating drugs may cause confusion and over sedation in the elderly; elderly patients generally should be started on low doses of Doxepin and observed closely. (See PRECAUTIONS−Geriatric Use.) Suicide : Since suicide is an inherent risk in any depressed patient and may remain so until significant improvement has occurred, patients should be closely supervised during the early course of therapy. Prescriptions should be written for the smallest feasible amount. Psychosis : Should increased symptoms of psychosis or shift to manic symptomatology occur, it may be necessary to reduce dosage or add a major tranquilizer to the dosage regimen.

Geriatric

Use: A determination has not been made whether controlled clinical studies of Doxepin included sufficient numbers of subjects aged 65 and over to define a difference in response 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 started on low doses of Doxepin and observed closely. (See WARNINGS.)