Imipramine
Mechanism :
Imipramine is a tricyclic anti-depressant. The clinical effect is due to potentiation of adrenergic synapses by blocking uptake of norepinephrine at nerve endings.
Indication :
- Nocturnal enuresis
- Depression (off-label)
- Neuropathic pain
- Hyperactivity
- Chronic pain (off-label)
Contraindications :
Imipramine is contraindicated in patients who have shown prior hypersensitivity to it and in acute porphyria, hepatic impairment and cardiovascular disease.
Dosing :
Nocturnal enuresis:
6-12 years:
Start 10 mg and increase by 10 mg/day after 1-2 weeks, Maximum dose: 50 mg/day.
12-18 years:
Start 10 mg and increase by 10-25 mg/day after 1-2 weeks, Maximum dose: 75 mg/day.
Give 30 min before bedtime. Max period of treatment is 3 months. Review before giving further courses.
Hyperactivity:
6-12 years:
25-75 mg
12-17 years:
50-75 mg; once daily. Start at lower doses. Doses >1.5 mg/kg given in 2 divided doses.
Depression:
1.5 mg/kg/day given orally thrice a day and increased every 3-4 day by 1 mg/kg if required, Maximum dose: 5 mg/kg/day.
Neuropathic pain:
Start at 0.2-0.4 mg/kg to be taken orally and gradually increased upto 1.5 times; Maximum dose: 1-3 mg/kg orally at bedtime.
Adverse Effect :
Mainly anticholinergic effects, arrhythmia, sexual dysfunction, sedation, postural hypotension, tremor, increased appetite and weight gain, lowered seizure threshold and sweating.
Interaction :
MAOIs: Hyperpyretic crises, severe convulsions, and deaths have occurred in patients receiving tricyclic antidepressant and monoamine oxidase inhibiting drugs simultaneously
OCPs, Calcium Channel Blockers, Cimetidine, Phenothiazines, SSRIs: Plasma concentration of imipramine increased.
Rifampicin, Anti-Coagulants: Decreased plasma concentration of Imipramine.
Sedatives, Hypotensives, Drugs that prolong QT interval: Increased effects of these drugs.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in normal renal function |
| HD | Not dialysed. Dose as in normal renal function |
| HDF/High flux | Not dialysed. Dose as in normal renal function |
| CAV/VVHD | Not dialysed. Dose as in normal renal function |
Hepatic Dose :
Periodic monitoring of hepatic enzymes levels is recommended in patients with liver disease as it may cause jaundice or elevated transaminases. Drugs that activate the hepatic mono-oxygenase enzyme system (e.g. barbiturates, carbamazepine, phenytoin, nicotine, and oral contraceptives) may accelerate the metabolism and lower plasma concentrations of imipramine, resulting in decreased efficacy. Plasma levels of phenytoin and carbamazepine may increase, with corresponding adverse effects. It may be necessary to adjust the dosage of these drugs.