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Sunday, July 4, 2010

Amitriptyline

MEDICATION SAFETY ISSUES
Sound-alike/look-alike issues:
Amitriptyline may be confused with aminophylline, imipramine, nortriptyline
Elavil® may be confused with Aldoril®, Eldepryl®, enalapril, Equanil®, Mellaril®, Oruvail®, Plavix®

MEDICATION GUIDE — An FDA-approved patient medication guide, which is available with the product information and at http://www.fda.gov/downloads/Drugs/DrugSafety/ucm088622.pdf, must be dispensed with this medication for each new outpatient prescription and refill.

PHARMACOLOGIC CATEGORY
Antidepressant, Tricyclic (Tertiary Amine)

DOSING: ADULTS
Depression: Oral: 50-150 mg/day single dose at bedtime or in divided doses; dose may be gradually increased up to 300 mg/day.

Chronic pain management (unlabeled use): Oral: Initial: 25 mg at bedtime; may increase as tolerated to 100 mg/day.

Migraine prophylaxis (unlabeled use): Oral: Initial: 10-25 mg at bedtime; usual dose: 150 mg; reported dosing ranges: 10-400 mg/day

Post-traumatic stress disorder (PTSD) (unlabeled use): Oral: 75-200 mg/day

DOSING: PEDIATRIC

(For additional information see "Amitriptyline: Pediatric drug information")
Chronic pain management (unlabeled use): Oral: Initial: 0.1 mg/kg at bedtime, may advance as tolerated over 2-3 weeks to 0.5-2 mg/kg at bedtime

Depressive disorders:
Children (unlabeled use): Oral: Initial doses of 1 mg/kg/day given in 3 divided doses with increases to 1.5 mg/kg/day have been reported in a small number of children (n=9) 9-12 years of age; clinically, doses up to 3 mg/kg/day (5 mg/kg/day if monitored closely) have been proposed
Adolescents: Initial: 25-50 mg/day; may administer in divided doses; increase gradually to 100 mg/day in divided doses.

Migraine prophylaxis (unlabeled use): Oral: Initial: 0.25 mg/kg/day, given at bedtime; increase dose by 0.25 mg/kg/day to maximum 1 mg/kg/day. Reported dosing ranges: 0.1-2 mg/kg/day; maximum suggested dose: 10 mg.

DOSING: ELDERLY — Depression: Oral: Initial: 10-25 mg at bedtime; dose should be increased in 10-25 mg increments every week if tolerated; dose range: 25-150 mg/day. See Renal/Hepatic Impairment.

DOSING: RENAL IMPAIRMENT — Nondialyzable

DOSING: HEPATIC IMPAIRMENT — Use with caution and monitor plasma levels and patient response.

DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, as hydrochloride: 10 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg

DOSAGE FORMS: CONCISE
Tablet: 10 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg

GENERIC EQUIVALENT AVAILABLE — Yes

USE — Relief of symptoms of depression

USE - UNLABELED / INVESTIGATIONAL — Analgesic for certain chronic and neuropathic pain; prophylaxis against migraine headaches; treatment of depressive disorders in children; post-traumatic stress disorder (PTSD)

ADVERSE REACTIONS SIGNIFICANT — Anticholinergic effects may be pronounced; moderate to marked sedation can occur (tolerance to these effects usually occurs).

Frequency not defined.

Cardiovascular: Orthostatic hypotension, tachycardia, ECG changes (nonspecific), AV conduction changes, cardiomyopathy (rare), MI, stroke, heart block, arrhythmia, syncope, hypertension, palpitation

Central nervous system: Restlessness, dizziness, insomnia, sedation, fatigue, anxiety, cognitive function impaired, seizure, extrapyramidal symptoms, coma, hallucinations, confusion, disorientation, coordination impaired, ataxia, headache, nightmares, hyperpyrexia

Dermatologic: Allergic rash, urticaria, photosensitivity, alopecia

Endocrine & metabolic: Syndrome of inappropriate ADH secretion

Gastrointestinal: Weight gain, xerostomia, constipation, paralytic ileus, nausea, vomiting, anorexia, stomatitis, peculiar taste, diarrhea, black tongue

Genitourinary: Urinary retention

Hematologic: Bone marrow depression, purpura, eosinophilia

Neuromuscular & skeletal: Numbness, paresthesia, peripheral neuropathy, tremor, weakness

Ocular: Blurred vision, mydriasis, ocular pressure increased

Otic: Tinnitus

Miscellaneous: Diaphoresis, withdrawal reactions (nausea, headache, malaise)

Postmarketing and/or case reports: Neuroleptic malignant syndrome (rare), serotonin syndrome (rare)

CONTRAINDICATIONS — Hypersensitivity to amitriptyline or any component of the formulation (cross-sensitivity with other tricyclics may occur); use of MAO inhibitors within past 14 days; acute recovery phase following myocardial infarction; concurrent use of cisapride

WARNINGS / PRECAUTIONS
Boxed warnings: Suicidal thinking/behavior: .

Major psychiatric warnings:
• [U.S. Boxed Warning]: Antidepressants increase the risk of suicidal thinking and behavior in children, adolescents, and young adults (18-24 years of age) with major depressive disorder (MDD) and other psychiatric disorders; consider risk prior to prescribing. Short-term studies did not show an increased risk in patients >24 years of age and showed a decreased risk in patients ≥ 65 years. Closely monitor patients for clinical worsening, suicidality, or unusual changes in behavior, particularly during the initial 1-2 months of therapy or during periods of dosage adjustments (increases or decreases); the patient's family or caregiver should be instructed to closely observe the patient and communicate condition with healthcare provider. A medication guide concerning the use of antidepressants should be dispensed with each prescription. Amitriptyline is not FDA-approved for use in children <12 years of age. The possibility of a suicide attempt is inherent in major depression and may persist until remission occurs. Patients treated with antidepressants should be observed for clinical worsening and suicidality, especially during the initial few months of a course of drug therapy, or at times of dose changes, either increases or decreases. Worsening depression and severe abrupt suicidality that are not part of the presenting symptoms may require discontinuation or modification of drug therapy. Use caution in high-risk patients during initiation of therapy. Prescriptions should be written for the smallest quantity consistent with good patient care. The patient's family or caregiver should be alerted to monitor patients for the emergence of suicidality and associated behaviors such as anxiety, agitation, panic attacks, insomnia, irritability, hostility, impulsivity, akathisia, hypomania, and mania; patients should be instructed to notify their healthcare provider if any of these symptoms or worsening depression or psychosis occur. May worsen psychosis in some patients or precipitate a shift to mania or hypomania in patients with bipolar disorder. Monotherapy in patients with bipolar disorder should be avoided. Patients presenting with depressive symptoms should be screened for bipolar disorder. Amitriptyline is not FDA approved for the treatment of bipolar depression.

Concerns related to adverse effects: Anticholinergic effects: May cause anticholinergic effects (constipation, xerostomia, blurred vision, urinary retention); use with caution in patients with decreased gastrointestinal motility, paralytic ileus, urinary retention, BPH, xerostomia, or visual problems. The degree of anticholinergic blockade produced by this agent is high relative to other antidepressants. Hematologic effects: TCAs may rarely cause bone marrow suppression; monitor for any signs of infection and obtain CBC if symptoms (eg, fever, sore throat) evident. Orthostatic hypotension: May cause orthostatic hypotension (risk is very high relative to other antidepressants); use with caution in patients at risk of this effect or in those who would not tolerate transient hypotensive episodes (cerebrovascular disease, cardiovascular disease, hypovolemia, or concurrent medication use which may predispose to hypotension/bradycardia). Sedation: May cause sedation, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). The degree of sedation is very high relative to other antidepressants.

Disease-related concerns: Cardiovascular disease: Use with caution in patients with a history of cardiovascular disease (including previous MI, stroke, tachycardia, or conduction abnormalities); the risk of conduction abnormalities with this agent is high relative to other antidepressants. Diabetes: Use with caution in patients with diabetes mellitus; may alter glucose regulation. Hepatic impairment: Use with caution in patients with hepatic impairment. Renal impairment: Use with caution in patients with renal impairment. Seizure disorder: Use with caution in patients at risk of seizures, including those with a history of seizures, head trauma, brain damage, alcoholism, or concurrent therapy with medications which may lower seizure threshold. Thyroid dysfunction: Use with caution in patients with hyperthyroidism or those receiving thyroid supplementation due to concerns of pro-arrhythmogenesis.

Concurrent drug therapy issues: Anticholinergic and/or neuroleptic agents: Hyperpyrexia has been observed with TCAs in combination with anticholinergics and/or neuroleptics, particularly during hot weather. Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.

Special populations: Elderly: Use with caution in the elderly.

Other warnings/precautions: Discontinuation of therapy: Recommended to discontinue prior to elective surgery requiring general anesthesia. Therapy should not be abruptly discontinued in patients receiving high doses for prolonged periods. Electroconvulsive therapy: May increase the risks associated with electroconvulsive therapy; consider discontinuing, when possible, prior to ECT treatment.

METABOLISM / TRANSPORT EFFECTS — Substrate of CYP1A2 (minor), 2B6 (minor), 2C9 (minor), 2C19 (minor), 2D6 (major), 3A4 (minor); Inhibits CYP1A2 (weak), 2C9 (weak), 2C19 (weak), 2D6 (weak), 2E1 (weak)

DRUG INTERACTIONS
Acetylcholinesterase Inhibitors (Central): Anticholinergics may diminish the therapeutic effect of Acetylcholinesterase Inhibitors (Central). Acetylcholinesterase Inhibitors (Central) may diminish the therapeutic effect of Anticholinergics. If the anticholinergic action is a side effect of the agent, the result may be beneficial. Risk C: Monitor therapy

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy

Alfuzosin: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy

Alpha-/Beta-Agonists (Direct-Acting): Tricyclic Antidepressants may enhance the vasopressor effect of Alpha-/Beta-Agonists (Direct-Acting). Exceptions: Dipivefrin. Risk D: Consider therapy modification

Alpha1-Agonists: Tricyclic Antidepressants may enhance the vasopressor effect of Alpha1-Agonists. Risk D: Consider therapy modification

Alpha2-Agonists: Tricyclic Antidepressants may diminish the antihypertensive effect of Alpha2-Agonists. Exceptions: Apraclonidine; Brimonidine. Risk D: Consider therapy modification

Altretamine: May enhance the orthostatic effect of Tricyclic Antidepressants. Risk C: Monitor therapy

Amphetamines: Tricyclic Antidepressants may enhance the stimulatory effect of Amphetamines. Tricyclic Antidepressants may also potentiate the cardiovascular effects of Amphetamines. Risk C: Monitor therapy

Anticholinergics: May enhance the adverse/toxic effect of other Anticholinergics. Exceptions: Paliperidone. Risk C: Monitor therapy

Artemether: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination

Aspirin: Antidepressants (Tricyclic, Tertiary Amine) may enhance the antiplatelet effect of Aspirin. Risk C: Monitor therapy

Barbiturates: May increase the metabolism of Tricyclic Antidepressants. Risk D: Consider therapy modification

Beta2-Agonists: Tricyclic Antidepressants may enhance the adverse/toxic effect of Beta2-Agonists. Risk C: Monitor therapy

BuPROPion: May decrease the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

CarBAMazepine: May increase the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

Chloroquine: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy

Cimetidine: May decrease the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

Cinacalcet: May increase the serum concentration of Tricyclic Antidepressants. Risk C: Monitor therapy

Ciprofloxacin: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy

Cisapride: Amitriptyline may enhance the arrhythmogenic effect of Cisapride. Risk X: Avoid combination

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Risk C: Monitor therapy

CYP2D6 Inhibitors (Moderate): May decrease the metabolism of CYP2D6 Substrates. Risk C: Monitor therapy

CYP2D6 Inhibitors (Strong): May decrease the metabolism of CYP2D6 Substrates. Risk D: Consider therapy modification

Desmopressin: Tricyclic Antidepressants may enhance the adverse/toxic effect of Desmopressin. Risk C: Monitor therapy

Dexmethylphenidate: May decrease the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

Dronedarone: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Dronedarone. Risk X: Avoid combination

DULoxetine: May decrease the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

Gadobutrol: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk D: Consider therapy modification

Iobenguane I 123: Tricyclic Antidepressants may diminish the therapeutic effect of Iobenguane I 123. Risk X: Avoid combination

Lithium: May enhance the neurotoxic effect of Tricyclic Antidepressants. Risk C: Monitor therapy

Lumefantrine: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination

MAO Inhibitors: May enhance the serotonergic effect of Tricyclic Antidepressants. This may cause serotonin syndrome. Risk X: Avoid combination

MAO Inhibitors: May enhance the orthostatic effect of Orthostasis Producing Agents. Risk C: Monitor therapy

Methylphenidate: May decrease the metabolism of Tricyclic Antidepressants. Risk C: Monitor therapy

Nilotinib: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination

NSAID (COX-2 Inhibitor): Antidepressants (Tricyclic, Tertiary Amine) may enhance the antiplatelet effect of NSAID (COX-2 Inhibitor). Risk C: Monitor therapy

NSAID (Nonselective): Antidepressants (Tricyclic, Tertiary Amine) may enhance the antiplatelet effect of NSAID (Nonselective). Risk C: Monitor therapy

Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates. Risk C: Monitor therapy

Pimozide: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Pimozide. Risk X: Avoid combination

Pramlintide: May enhance the anticholinergic effect of Anticholinergics. These effects are specific to the GI tract. Risk D: Consider therapy modification

Propoxyphene: May enhance the CNS depressant effect of Tricyclic Antidepressants. Risk C: Monitor therapy

Protease Inhibitors: May increase the serum concentration of Tricyclic Antidepressants. Risk C: Monitor therapy

QTc-Prolonging Agents: May enhance the adverse/toxic effect of other QTc-Prolonging Agents. Their effects can be additive, causing life-threatening ventricular arrhythmias. Risk D: Consider therapy modification

QuiNIDine: Tricyclic Antidepressants may enhance the QTc-prolonging effect of QuiNIDine. QuiNIDine may decrease the metabolism of Tricyclic Antidepressants. Risk D: Consider therapy modification

QuiNINE: QTc-Prolonging Agents may enhance the QTc-prolonging effect of QuiNINE. QuiNINE may enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination

Selective Serotonin Reuptake Inhibitors: May decrease the metabolism of Tricyclic Antidepressants. Risk D: Consider therapy modification

Serotonin Modulators: May enhance the adverse/toxic effect of other Serotonin Modulators. The development of serotonin syndrome may occur. Risk D: Consider therapy modification

Sibutramine: May enhance the serotonergic effect of Serotonin Modulators. This may cause serotonin syndrome. Risk X: Avoid combination

St Johns Wort: May increase the metabolism of Tricyclic Antidepressants. The risk of serotonin syndrome may theoretically be increased. Risk D: Consider therapy modification

Sulfonylureas: Cyclic Antidepressants may enhance the hypoglycemic effect of Sulfonylureas. Risk C: Monitor therapy

Terbinafine: May decrease the metabolism of Tricyclic Antidepressants. Risk D: Consider therapy modification

Tetrabenazine: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Tetrabenazine. Risk X: Avoid combination

Thioridazine: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Thioridazine. Risk X: Avoid combination

TraMADol: Tricyclic Antidepressants may enhance the neuroexcitatory and/or seizure-potentiating effect of TraMADol. Risk C: Monitor therapy

Valproic Acid: May increase the serum concentration of Tricyclic Antidepressants. Risk C: Monitor therapy

Vitamin K Antagonists (eg, warfarin): Tricyclic Antidepressants may enhance the anticoagulant effect of Vitamin K Antagonists. Risk C: Monitor therapy

Yohimbine: Tricyclic Antidepressants may increase the serum concentration of Yohimbine. Risk C: Monitor therapy

Ziprasidone: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Ziprasidone. The risk of a severe arrhythmia may be increased. Risk X: Avoid combination

ETHANOL / NUTRITION / HERB INTERACTIONS
Ethanol: Avoid ethanol (may increase CNS depression).

Food: Grapefruit juice may inhibit the metabolism of some TCAs and clinical toxicity may result.

Herb/Nutraceutical: St John's wort may decrease amitriptyline levels. Avoid valerian, St John's wort, kava kava, gotu kola (may increase CNS depression).

PREGNANCY RISK FACTOR — C (show table)

PREGNANCY IMPLICATIONS — Teratogenic effects have been observed in animal studies. Amitriptyline crosses the human placenta; CNS effects, limb deformities and developmental delay have been noted in case reports.

LACTATION — Enters breast milk/not recommended (AAP rates "of concern")

BREAST-FEEDING CONSIDERATIONS — Generally, it is not recommended to breast-feed if taking antidepressants because of the long half-life, active metabolites, and the potential for side effects in the infant.

PRICING — (data from drugstore.com)
Tablets (Amitriptyline HCl)
25 mg (90): $11.99
50 mg (90): $12.99
75 mg (100): $14.44
100 mg (30): $13.99
150 mg (90): $21.98

MONITORING PARAMETERS — Monitor blood pressure and pulse rate prior to and during initial therapy; evaluate mental status, suicidal ideation (especially at the beginning of therapy or when doses are increased or decreased); monitor weight; ECG in older adults and patients with cardiac disease

REFERENCE RANGE — Therapeutic: Amitriptyline and nortriptyline 100-250 ng/mL (SI: 360-900 nmol/L); nortriptyline 50-150 ng/mL (SI: 190-570 nmol/L); Toxic: >0.5 mcg/mL; plasma levels do not always correlate with clinical effectiveness

CANADIAN BRAND NAMES — Apo-Amitriptyline®; Levate®; Novo-Triptyn; PMS-Amitriptyline

INTERNATIONAL BRAND NAMES — Adepril (IT); Amilit (IT); Amineurin (DE); Amiplin (TW); Amiprin (JP); Amitrip (NZ); Amitriptylinum (PL); Amytril (BR); Anapsique (MX); Antalin (CN); Conmitrip (TH); Domical (GB); Elatrol (IL); Elatrolet (IL); Elavil (FR); Endep (AU, NZ); Lantron (JP); Laroxyl (BF, BJ, CI, ET, FR, GH, GM, GN, IT, KE, LR, MA, ML, MR, MU, MW, NE, NG, SC, SD, SL, SN, TN, TZ, UG, ZA, ZM, ZW); Miketorin (JP); Neurotol (PY); Noriline (ZA); Pinsaun (TW); Protanol (BR); Psiquium (CO); Qualitriptine (HK); Redomex (BE); Saroten (BF, BJ, CI, CY, DE, DK, EE, ET, GH, GM, GN, GR, IR, KE, LR, MA, ML, MR, MU, MW, NE, NG, PT, SC, SD, SE, SL, SN, TN, TZ, UG, ZA, ZM, ZW); Saroten Retard (CH, MY, TW); Sarotena (IN); Sarotex (NL, NO, UY); Sarotex Retard (NO); Syneudon (DE); Teperin (HN, IQ, JO); Trepiline (ZA); Tridep (BG); Tripta (MY, TH); Triptanol (MX); Triptizol (IT); Trynol (TW); Tryptanol (AR, BR, JP, PE, TH); Tryptizol (AT, CH, EG, ES, GB, NL, PT, SE); Trytomer (IN); Uxen (AR)

MECHANISM OF ACTION — Increases the synaptic concentration of serotonin and/or norepinephrine in the central nervous system by inhibition of their reuptake by the presynaptic neuronal membrane

PHARMACODYNAMICS / KINETICS
Onset of action: Migraine prophylaxis: 6 weeks, higher dosage may be required in heavy smokers because of increased metabolism; Depression: 4-6 weeks, reduce dosage to lowest effective level

Distribution: Crosses placenta; enters breast milk

Metabolism: Hepatic to nortriptyline (active), hydroxy and conjugated derivatives; may be impaired in the elderly

Half-life elimination: Adults: 9-27 hours (average: 15 hours)

Time to peak, serum: ~4 hours

Excretion: Urine (18% as unchanged drug); feces (small amounts)

PATIENT INFORMATION — Do not discontinue medication abruptly. Full effect may not occur for 3-6 weeks. Avoid alcohol. May cause urine to turn blue-green. May cause drowsiness. Dry mouth may be helped by sips of water, sugarless gum, or hard candy.

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