Imipramina

Imipramina, also known as imipramine, is a tricyclic antidepressant (TCA) used to treat major depressive disorder and, in some cases, nocturnal enuresis (bedwetting) in children. It works mainly by inhibiting the reuptake of serotonin and norepinephrine, increasing their levels in the synaptic cleft. The drug also antagonizes several receptor systems, including muscarinic acetylcholine, histamine H1, and alpha-1 adrenergic receptors, which contributes to both its therapeutic effects and its adverse effects.

Indications include major depressive disorder; historically it has been used for nocturnal enuresis in children, though this use is less common today due to safety and tolerability concerns. Imipramine is usually not a first-line antidepressant in modern practice.

Pharmacokinetics and metabolism: Imipramina is taken by mouth and is extensively metabolized in the liver to desipramine, an active metabolite. The elimination half-life is variable and can be prolonged with chronic use. Steady-state plasma levels are typically reached after one to two weeks, with full antidepressant effects often taking several weeks to appear.

Adverse effects and safety: Common adverse effects include dry mouth, constipation, blurred vision, urinary retention, drowsiness, weight gain, orthostatic hypotension, and tachycardia. The anticholinergic and sedative properties can be problematic, especially in the elderly. Overdose is potentially fatal due to cardiotoxicity and seizures. Interactions include monoamine oxidase inhibitors and other serotonergic or sedative medications, as well as agents that prolong the QT interval.

Contraindications: Known hypersensitivity; concurrent MAOI therapy or recent MAOI use; recent myocardial infarction or certain conduction abnormalities; glaucoma. Pregnancy category varies by country.