Dosing and uses of Asendin (amoxapine)
Adult dosage forms and strengths
tablet
- 25mg
- 50mg
- 100mg
- 150mg
Depression
Initiate at low dose (25 mg q8-12hr) and gradually titrate upward every 5-7 days up to 200-300 mg PO qHs
If dose exceeds 300 mg/day, administer in divided doses q12hr
Outpatient: Not to exceed 400 mg/day
Inpatient: May require higher doses, up to 600 mg/day divided q12hr
Pediatric dosage forms and strengths
Not recommended
Geriatric dosage forms and strengths
Use caution; avoid use
Depression
Initiate at low dose (25 mg q8-12hr) and gradually titrate upward every 5-7 days up to 200-300 mg PO qHs
If dose exceeds 300 mg/day, administer in divided doses q12hr
Outpatient: Not to exceed 400 mg/day
Inpatient: May require higher doses, up to 600 mg/day divided q12hr
Asendin (amoxapine) adverse (side) effects
>10%
Constipation (12-14%)
Dry mouth (12-14%)
Sedation (12-14%)
1-10%
Anxiety
Ataxia
Blurred vision
Confusion
Dizziness
Edema
Headache
Fatigue
Nausea
Nervousness/restlessness
Prolactin levels increased
Rash
Sweating
Tremor
Weakness
<1%
Agranulocytosis
Diarrhea
ECG changes
EPs
Flatulence
Galactorrhea
Hypertension
Leukopenia
Menstrual irregularity
Mydriasis
Orthostatic hypotension
Seizure
Urinary retention
Urticaria
Vomiting
Tachycardia
Sexual dysfunction
Frequency not defined
neuroleptic malignant syndrome (rare)
Warnings
Black box warnings
In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (<24 yr of age) taking antidepressants for major depressive disorders and other psychiatric illnesses
This increase was not seen in patients aged >24 years; a slight decrease in suicidal thinking was seen in adults >65 years
In children and young adults, risks must be weighed against the benefits of taking antidepressants
Patients should be monitored closely for changes in behavior, clinical worsening, and suicidal tendencies; this should be done during initial 1-2 months of therapy and dosage adjustments
The patient’s family should communicate any abrupt changes in behavior to the healthcare provider
Worsening behavior and suicidal tendencies that are not part of the presenting symptoms may require discontinuation of therapy
This drug is not approved for use in pediatric patients
Contraindications
Hypersensitivity
Severe cardiovascular d/o
Uncorrected narrow angle glaucoma
Within 14 day of MAOIs (risk of serotonin syndrome); if linezolid or IV methylene blue (MAOIs) must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity; may resume 24 hr after last linezolid or methylene blue dose, or after 2 weeks of monitoring, whichever comes first
Any drugs or conditions that prolong QT intervaL
Acute recovery post-MI
Cautions
BPH, urinary/GI retention, incr IOP, hyperthyroidism, opne angle glaucoma, seizure d/o, brain tumor, respiratory impairment, hyperthyroidism
Clinical worsening & suicide ideation may occur despite medication in adolescents & young adults (18-24 yo)
Risk of anticholinergic side effects
Possibility of tardive dyskinesia & NMs
Pregnancy and lactation
Pregnancy category: C
Lactation: enters breast milk; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Asendin (amoxapine)
Mechanism of action
Neurotransmitter (esp NE & serotonin) reuptake inhibitor; anticholinergic
Pharmacokinetics
Half-Life: 8-30 hr
Peak Plasma Time: 90 min
Bioavailability: Almost complete absorption
Metabolites: 8-hydroxyamoxapine
Vd: 0.9-1.2 L/kg
Protein binding: 90%
Excretion: Urine (60%); Feces: (18%)
