Imipramine Hydrochloride 25 MG Oral Tablet

Generic Name: IMIPRAMINE HYDROCHLORIDE
Brand Name: Imipramine Hydrochloride
  • Substance Name(s):
  • IMIPRAMINE HYDROCHLORIDE

WARNINGS

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 9 antidepressant drugs in over 4400 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 1000 patients treated) are provided in Table 1.

Table 1 Age Range Drug-Placebo Difference in Number of Cases of Suicidality per 1000 Patients Treated Increases Compared to Placebo <18 14 additional cases 18 – 24 5 additional cases Decreases Compared to Placebo 25 – 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 health care providers.

Such monitoring should include daily observation by families and caregivers.

Prescriptions for imipramine hydrochloride tablets should be written for the smallest quantity of tablets 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 imipramine hydrochloride is not approved for use in treating bipolar depression.

Angle-Closure Glaucoma – The pupillary dilation that occurs following use of many antidepressant drugs including imipramine hydrochloride tablets may trigger an angle-closure attack in a patient with anatomically narrow angles who does not have a patent iridectomy.

Children – A dose of 2.5 mg/kg/day of imipramine hydrochloride should not be exceeded in childhood.

ECG changes of unknown significance have been reported in pediatric patients with doses twice this amount.

Extreme caution should be used when this drug is given to: patients with cardiovascular disease because of the possibility of conduction defects, arrhythmias, congestive heart failure, myocardial infarction, strokes, and tachycardia.

These patients require cardiac surveillance at all dosage levels of the drug; patients with history of urinary retention, or history of narrow-angle glaucoma because of the drug’s anticholinergic properties; hyperthyroid patients or those on thyroid medication because of the possibility of cardiovascular toxicity; patients with a history of seizure disorder because this drug has been shown to lower the seizure threshold; patients receiving guanethidine, clonidine, or similar agents, since imipramine may block the pharmacologic effects of these drugs; patients receiving methylphenidate hydrochloride.

Since methylphenidate hydrochloride may inhibit the metabolism of imipramine hydrochloride, downward dosage adjustment of imipramine hydrochloride may be required when given concomitantly with methylphenidate hydrochloride.

Imipramine may enhance the CNS depressant effects of alcohol.

Therefore, it should be borne in mind that the dangers inherent in a suicide attempt or accidental overdosage with the drug may be increased for the patient who uses excessive amounts of alcohol ( see PRECAUTIONS ).

Since imipramine may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as operating an automobile or machinery, the patient should be cautioned accordingly.

DRUG INTERACTIONS

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., 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.

The plasma concentration of imipramine may increase when the drug is given concomitantly with hepatic enzyme inhibitors (e.g., cimetidine, fluoxetine) and decrease by concomitant administration with hepatic enzyme inducers (e.g., barbiturates, phenytoin), and adjustment of the dosage of imipramine may therefore be necessary.

In occasional susceptible patients or in those receiving anticholinergic drugs (including antiparkinsonism agents) in addition, the atropine-like effects may become more pronounced (e.g., paralytic ileus).

Close supervision and careful adjustment of dosage is required when imipramine hydrochloride is administered concomitantly with anticholinergic drugs.

Avoid the use of preparations, such as decongestants and local anesthetics, that contain any sympathomimetic amine (e.g., epinephrine, norepinephrine), since it has been reported that tricyclic antidepressants can potentiate the effects of catecholamines.

Caution should be exercised when imipramine hydrochloride is used with agents that lower blood pressure.

Imipramine hydrochloride may potentiate the effects of CNS depressant drugs.

Patients should be warned that imipramine hydrochloride may enhance the CNS depressant effects of alcohol ( see WARNINGS ).

OVERDOSAGE

Deaths may occur from overdosage with this class of drugs.

Multiple drug ingestion (including alcohol) is common in deliberate tricyclic overdose.

As the management is complex and changing, it is recommended that the physician contact a poison control center for current information on treatment.

Signs and symptoms of toxicity develop rapidly after tricyclic overdose.

Therefore, hospital monitoring is required as soon as possible.

Children have been reported to be more sensitive than adults to an acute overdosage of imipramine hydrochloride.

An acute overdose of any amount in infants or young children, especially, must be considered serious and potentially fatal.

Manifestations These may vary in severity depending upon factors such as the amount of drug absorbed, the age of the patient, and the interval between drug ingestion and the start of treatment.

Critical manifestations of overdose include cardiac dysrhythmias, severe hypotension, convulsions, and CNS depression including coma.

Changes in the electrocardiogram, particularly in QRS axis or width, are clinically significant indicators of tricyclic toxicity.

Other CNS manifestations may include drowsiness, stupor, ataxia, restlessness, agitation, hyperactive reflexes, muscle rigidity, athetoid and choreiform movements.

Cardiac abnormalities may include tachycardia and signs of congestive failure.

Respiratory depression, cyanosis, shock, vomiting, hyperpyrexia, mydriasis, and diaphoresis may also be present.

Management Obtain an ECG and immediately initiate cardiac monitoring.

Protect the patient’s airway, establish an intravenous line and initiate gastric decontamination.

A minimum of 6 hours of observation with cardiac monitoring and observation for signs of CNS or respiratory depression, hypotension, cardiac dysrhythmias and/or conduction blocks, and seizures is necessary.

If signs of toxicity occur at any time during this period, extended monitoring is required.

There are case reports of patients succumbing to fatal dysrhythmias late after overdose: these patients had clinical evidence of significant poisoning prior to death and most received inadequate gastrointestinal decontamination.

Monitoring of plasma drug levels should not guide management of the patient.

Gastrointestinal Decontamination – All patients suspected of tricyclic overdose should receive gastrointestinal decontamination.

This should include large volume gastric lavage followed by activated charcoal.

If consciousness is impaired, the airway should be secured prior to lavage.

Emesis is contraindicated.

Cardiovascular – A maximal limb-lead QRS duration of ≥0.10 seconds may be the best indication of the severity of the overdose.

Intravenous sodium bicarbonate should be used to maintain the serum pH in the range of 7.45 to 7.55.

If the pH response is inadequate, hyperventilation may also be used.

Concomitant use of hyperventilation and sodium bicarbonate should be done with extreme caution, with frequent pH monitoring.

A pH >7.60 or pCO 2 < 20 mmHg is undesirable.

Dysrhythmias unresponsive to sodium bicarbonate therapy/hyperventilation may respond to lidocaine, bretylium, or phenytoin.

Type 1A and 1C antiarrhythmics are generally contraindicated (e.g., quinidine, disopyramide, and procainamide).

In rare instances, hemoperfusion may be beneficial in acute refractory cardiovascular instability in patients with acute toxicity.

However, hemodialysis, peritoneal dialysis, exchange transfusions, and forced diuresis generally have been reported as ineffective in tricyclic poisoning.

CNS – In patients with CNS depression, early intubation is advised because of the potential for abrupt deterioration.

Seizures should be controlled with benzodiazepines, or if these are ineffective, other anticonvulsants (e.g., phenobarbital, phenytoin).

Physostigmine is not recommended except to treat life-threatening symptoms that have been unresponsive to other therapies, and then only in consultation with a poison control center.

Psychiatric Follow-up – Since overdosage is often deliberate, patients may attempt suicide by other means during the recovery phase.

Psychiatric referral may be appropriate.

Pediatric Management – The principles of management of child and adult overdosages are similar.

It is strongly recommended that the physician contact the local poison control center for specific pediatric treatment.

DESCRIPTION

Imipramine hydrochloride, USP is supplied in tablet form for oral administration.

Imipramine hydrochloride USP, the original tricyclic antidepressant, is a member of the dibenzazepine group of compounds.

It is designated 5-[3-(dimethylamino) propyl] -10,11-dihydro-5 H-dibenz [ b,f]-azepine monohydrochloride.

Its structural formula is: Imipramine hydrochloride tablets are available in 10 mg, 25 mg and 50 mg for oral administration.

Imipramine hydrochloride USP is a white to off-white, odorless, or practically odorless crystalline powder.

It is freely soluble in water and in alcohol; soluble in acetone; and insoluble in ether and in benzene.

Imipramine HCl tablets, 10 mg contain the following inactive ingredients: colloidal silicon dioxide, D & C red No.

30 aluminum lake, D & C yellow No.

10 aluminum lake, dibasic calcium phosphate, FD & C blue No.

2 aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, sodium starch glycolate, and titanium dioxide.

Imipramine HCl tablets, 25 mg contain the following inactive ingredients: colloidal silicon dioxide, dibasic calcium phosphate, FD & C blue No.

2 aluminum lake, FD & C red No.

40 aluminum lake, FD & C yellow No.

6 aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, sodium starch glycolate, and titanium dioxide.

Imipramine HCl tablets, 50 mg contain the following inactive ingredients: colloidal silicon dioxide, D & C yellow No.

10 aluminum lake, dibasic calcium phosphate, FD & C blue No.

1 aluminum lake, FD & C yellow No.

6 aluminum lake, hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, sodium starch glycolate, and titanium dioxide.

Chemical Structure

HOW SUPPLIED

Imipramine hydrochloride tablets, USP are available as follows: 10 mg – round, yellow film coated tablets, debossed MP 4 Bottles of 100 NDC 54738-912-01 25 mg – round, brown film coated tablets, debossed MP 8 Bottles of 100 NDC 54738-913-01 50 mg – round, green film coated tablets, debossed MP 79 Bottles of 100 NDC 54738-914-01 Store at 20° to 25°C (68° to 77°F).

[See USP Controlled Room Temperature] DISPENSE IN TIGHT, LIGHT-RESISTANT CONTAINER.

GERIATRIC USE

Geriatric Use In the literature, there were four well-controlled, randomized, double-blind, parallel group comparison clinical studies done with imipramine in the elderly population.

There was a total number of 651 subjects included in these studies.

These studies did not provide a comparison to younger subjects.

There were no additional adverse experiences identified in the elderly.

Clinical studies of imipramine in the original application did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.

Post-marketing clinical experience has not identified differences in responses between the elderly and younger subjects.

In general, dose selection for the elderly should be cautious, usually starting at the low end of the dosing range, reflecting greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

( See also DOSAGE AND ADMINISTRATION, Adolescent and Geriatric Patients.

) ( See also PRECAUTIONS, General.

)

MECHANISM OF ACTION

The mechanism of action of imipramine is not definitely known.

However, it does not act primarily by stimulation of the central nervous system.

The clinical effect is hypothesized as being due to potentiation of adrenergic synapses by blocking uptake of norepinephrine at nerve endings.

The mode of action of the drug in controlling childhood enuresis is thought to be apart from its antidepressant effect.

INDICATIONS AND USAGE

Depression – For the relief of symptoms of depression.

Endogenous depression is more likely to be alleviated than other depressive states.

One to three weeks of treatment may be needed before optimal therapeutic effects are evident.

Childhood Enuresis – May be useful as temporary adjunctive therapy in reducing enuresis in children aged 6 years and older, after possible organic causes have been excluded by appropriate tests.

In patients having daytime symptoms of frequency and urgency, examination should include voiding cystourethrography and cystoscopy, as necessary.

The effectiveness of treatment may decrease with continued drug administration.

PEDIATRIC USE

Pediatric Use Safety and effectiveness in the pediatric population other than pediatric patients with nocturnal enuresis have not been established ( see BOX WARNING and WARNINGS, Clinical Worsening and Suicide Risk ).

Anyone considering the use of imipramine hydrochloride in a child or adolescent must balance the potential risks with the clinical need.

The safety and effectiveness of the drug as temporary adjunctive therapy for nocturnal enuresis in pediatric patients less than 6 years of age has not been established.

The safety of the drug for long-term, chronic use as adjunctive therapy for nocturnal enuresis in pediatric patients 6 years of age or older has not been established; consideration should be given to instituting a drug-free period following an adequate therapeutic trial with a favorable response.

A dose of 2.5 mg/kg/day should not be exceeded in childhood.

ECG changes of unknown significance have been reported in pediatric patients with doses twice this amount.

PREGNANCY

Pregnancy Animal reproduction studies have yielded inconclusive results ( see also ANIMAL PHARMACOLOGY & TOXICOLOGY ).

There have been no well-controlled studies conducted with pregnant women to determine the effect of imipramine on the fetus.

However, there have been clinical reports of congenital malformations associated with the use of the drug.

Although a causal relationship between these effects and the drug could not be established, the possibility of fetal risk from the maternal ingestion of imipramine cannot be excluded.

Therefore, imipramine should be used in women who are or might become pregnant only if the clinical condition clearly justifies potential risk to the fetus.

NUSRING MOTHERS

Nursing Mothers Limited data suggest that imipramine is likely to be excreted in human breast milk.

As a general rule, a woman taking a drug should not nurse since the possibility exists that the drug may be excreted in breast milk and be harmful to the child.

BOXED WARNING

Suicidality and Antidepressant Drugs Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders.

Anyone considering the use of imipramine hydrochloride or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need.

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 in risk with antidepressants compared to placebo in adults aged 65 and older.

Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide.

Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behavior.

Families and caregivers should be advised of the need for close observation and communication with the prescriber.

Imipramine hydrochloride is not approved for use in pediatric patients ( see WARNINGS, Clinical Worsening and Suicide Risk; PRECAUTIONS, Information for Patients; and PRECAUTIONS, Pediatric Use).

INFORMATION FOR PATIENTS

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 imipramine 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 imipramine 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 imipramine hydrochloride.

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 imipramine 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.

DOSAGE AND ADMINISTRATION

Depression Lower dosages are recommended for elderly patients and adolescents.

Lower dosages are also recommended for outpatients as compared to hospitalized patients who will be under close supervision.

Dosage should be initiated at a low level and increased gradually, noting carefully the clinical response and any evidence of intolerance.

Following remission, maintenance medication may be required for a longer period of time, at the lowest dose that will maintain remission.

Usual Adult Dose Hospitalized Patients – Initially, 100 mg/day in divided doses gradually increased to 200 mg/day as required.

If no response after two weeks, increase to 250 to 300 mg/day.

Outpatients – Initially, 75 mg/day increased to 150 mg/day.

Dosages over 200 mg/day are not recommended.

Maintenance, 50 to 150 mg/day.

Adolescent and Geriatric Patients – Initially, 30 to 40 mg/day; it is generally not necessary to exceed 100 mg/day.

Childhood Enuresis Initially, an oral dose of 25 mg/day should be tried in children aged 6 and older.

Medication should be given one hour before bedtime.

If a satisfactory response does not occur within one week, increase the dose to 50 mg nightly in children under 12 years; children over 12 may receive up to 75 mg nightly.

A daily dose greater than 75 mg does not enhance efficacy and tends to increase side effects.

Evidence suggests that in early night bedwetters, the drug is more effective given earlier and in divided amounts, i.e., 25 mg in midafternoon, repeated at bedtime.

Consideration should be given to instituting a drug-free period following an adequate therapeutic trial with a favorable response.

Dosage should be tapered off gradually rather than abruptly discontinued; this may reduce the tendency to relapse.

Children who relapse when the drug is discontinued do not always respond to a subsequent course of treatment.

A dose of 2.5 mg/kg/day should not be exceeded.

ECG changes of unknown significance have been reported in pediatric patients with doses twice this amount.

The safety and effectiveness of imipramine hydrochloride as temporary adjunctive therapy for nocturnal enuresis in children less than 6 years of age has not been established.