Dosage and Administration
Imipramine hydrochloride and imipramine pamoate are administered orally. Although imipramine hydrochloride has been administered in up to 4 divided doses throughout the day, it is long-acting and the entire oral daily dose may be administered at one time. Imipramine pamoate may also be used to administer the daily oral dose of imipramine, but it has no advantages over the hydrochloride. Administration of the entire daily dose at bedtime may reduce daytime sedation; patients who experience insomnia and stimulation may be given the entire daily dose in the morning.
Dosage of imipramine salts is expressed in terms of imipramine hydrochloride.
Patients should be monitored for possible worsening of depression, suicidality, or unusual changes in behavior, especially at the beginning of therapy or during periods of dosage adjustment. ()
Major Depressive Disorder
There is a wide range of oral dosage requirements, and dosage must be carefully individualized. Initial dosages of imipramine should be low and generally range from 75-100 mg daily, depending on the severity of the condition being treated. Dosage may be gradually adjusted to the level that produces maximal therapeutic effect with minimal toxicity and may range up to 300 mg daily. Hospitalized patients under close supervision may generally be given higher dosages than outpatients, and manufacturers state that dosages of greater than 200 mg daily are not recommended for outpatients. Geriatric patients should usually be given lower than average dosages. Manufacturers state that therapy should be initiated with 25-50 mg daily as imipramine hydrochloride (e.g., Tofranil) in these patients and that optimal dosage rarely exceeds 100 mg daily. If the daily dosage is established at 75 mg or more, imipramine pamoate (e.g., Tofranil PM) may be administered. Maximum antidepressant effects may not occur for 2 or more weeks after therapy is begun.
After symptoms are controlled, dosage should be gradually reduced to the lowest level that will maintain relief of symptoms. If maintenance therapy is necessary, manufacturers recommend an adult dosage of 50-150 mg daily. To avoid the possibility of precipitating withdrawal symptoms, imipramine should not be terminated abruptly in patients who have received high dosage for prolonged periods.
Functional Enuresis in Children
For the treatment of functional enuresis in children who are at least 6 years of age, the usual initial oral dosage of imipramine hydrochloride is 25 mg daily, administered 1 hour prior to bedtime. If a satisfactory response is not obtained within 1 week, dosage may be increased to 50 mg nightly for children younger than 12 years of age or 75 mg nightly for children 12 years of age and older. Dosages higher than 75 mg daily do not improve results and may increase the risk of adverse reactions. For children who are early-night bedwetters, better results may be obtained by administering 25 mg in midafternoon and again at bedtime. Dosage of imipramine hydrochloride for the treatment of functional enuresis in children should not exceed 2.5 mg/kg daily. Long-term effects of the drug in children have not been determined; therefore, after a satisfactory response has been maintained, imipramine hydrochloride should be gradually withdrawn. If dosage is gradually reduced after a favorable response of many weeks, relapses may be less frequent; children who relapse may not respond to subsequent treatment with imipramine. (
See Cautions: Pediatric Precautions.)