Generic Name: amitriptyline hydrochloride
Brands: Endep (CAN), Tryptanol (CAN)
Pregnancy Category D
Drug class
TCA; tertiary amine
Therapeutic actions
Mechanism of action unknown; TCAs inhibit the reuptake of the neurotransmitters norepinephrine and serotonin, leading to an increase in their effects; anticholinergic at CNS and peripheral receptors; sedative.
Indications
• Relief of symptoms of depression (endogenous most responsive); sedative effects may help when depression is associated with anxiety and sleep disturbance.
• Unlabeled uses: Control of chronic pain (eg, intractable pain of cancer, central pain syndromes, peripheral neuropathies, postherpetic neuralgia, tic douloureux); prevention of onset of cluster and migraine headaches; treatment of pathologic weeping and laughing secondary to forebrain disease (due to multiple sclerosis), insomnia.
Contraindications and cautions
• Contraindicated with hypersensitivity to any tricyclic drug; concomitant therapy with an MAOI; recent MI; myelography within previous 24 hr or scheduled within 48 hr; lactation.
• Use cautiously with electroshock therapy; preexisting CV disorders (severe coronary heart disease, progressive heart failure, angina pectoris, paroxysmal tachycardia); angle-closure glaucoma, increased IOP, urinary retention, ureteral or urethral spasm; seizure disorders; hyperthyroidism; impaired hepatic, renal function; psychiatric patients (schizophrenic or paranoid patients may exhibit a worsening of psychosis with TCA therapy); manic-depressive patients; elective surgery (discontinue as long as possible before surgery).
Available forms
Injection—10 mg/mL; tablets—10, 25, 50, 75, 100, 150 mg
Dosages
May be given IM if patients are unable or unwilling to take oral drug. Switch to oral drug as soon as possible.
ADULTS
• Depression, hospitalized patients: Initially, 100 mg/day PO in divided doses: gradually increase to 200–300 mg/day as required. May be given IM 20–30 mg qid, initially only in patients unable or unwilling to take drug PO. Replace with oral medication as soon as possible.
• Depression, outpatients: Initially, 75 mg/day PO, in divided doses; may increase to 150 mg/day. Increases should be made in late afternoon or hs. Total daily dosage may be administered hs. Initiate single daily dose therapy with 50–100 mg hs; increase by 25–50 mg as necessary to a total of 150 mg/day. Maintenance dose is 40–100 mg/day, which may be given as a single bedtime dose. After satisfactory response, reduce to lowest effective dosage. Continue therapy for 3 mo or longer to lessen possibility of relapse.
• Chronic pain: 75–150 mg/day PO.
• Prevention of cluster or migraine headaches: 50–150 mg/day PO.
• Prevention of weeping in MS patients with forebrain disease: 25–75 mg PO.
PEDIATRIC PATIENTS
< 12 yr: Not recommended.
12 yr: 10 mg tid PO and then 20 mg hs.
GERIATRIC PATIENTS
10 mg tid PO with 20 mg hs
Pharmacokinetics
|
Route |
Onset |
Peak |
Duration |
|
Oral |
Varies |
2–4 hr |
2–4 wk |
Metabolism: Hepatic; T1/2: 10–50 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Urine