RISPERIDONE

RISPERIDONE
(ris-per'i-done)
Risperdal, Risperdal M-TAB, Risperdal Consta
Classifications: psychotherapeutic, antipsychotic, atypical;
Therapeutic: antipsychotic, atypical
Prototype: Clozapine
Pregnancy Category: C

Availability

0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg tablets; 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg quick-dissolving tablets; 1 mg/mL solution; 12.5 mg, 25 mg, 37.5 mg, 50 mg injection

Action

Interferes with binding of dopamine to D₂-interlimbic region of the brain, serotonin (5-HT₂) receptors, and alpha-adrenergic receptors in the occipital cortex. It has low to moderate affinity for the other serotonin (5-HT) receptors.

Therapeutic Effect

Effective in controlling symptoms of schizophrenia as well as other psychotic symptoms.

Uses

Treatment of schizophrenia; treatment of bipolar disorder; irritability associated with autism.

Unlabeled Uses

Management of patients with dementia-related psychotic symptoms. Adjunctive treatment of behavioral disturbances in patients with mental retardation.

Contraindications

Hypersensitivity to risperidone; elderly with dementia-related psychosis; QT prolongation, Reye's syndrome, brain tumor, severe CNS depression, head trauma; suicidal ideation, tardive dyskinesia; sunlight (UV) exposure, tanning beds; pregnancy (category C), lactation, children <15 y.

Cautious Use

Older adults; arrhythmias, hypotension, breast cancer, blood dyscrasia, cardiac disorders, cerebrovascular disease, hypotension, dehydration, diabetes mellitus, diabetic ketoacidosis, hyperglycemia, hypokalemia, hypomagnesemia, hyponatremia, MI, obesity, orthostatic hypotension, mild or moderate CNS depression, coma; GI obstruction, dysphagia; electrolyte imbalance, ethanol intoxication, heart failure, renal or hepatic dysfunction; seizure disorder, seizures, stroke, Parkinson's disease.

Route & Dosage

Schizophrenia
Adult/Adolescent (>13 y): PO 1–2 mg/d in 1 or 2 doses, then titrate up (max: 8 mg/d) IM 25 mg once q2wk (max: 50 mg)
Geriatric: PO Start 0.5 mg b.i.d. and increase by 0.5 mg b.i.d. daily to an initial target of 1.5 mg b.i.d. (max: 4 mg/d) IM 25 mg once q2wk (max: 25 mg)

Bipolar Disorder
Adult/Adolescent (>10 y): PO 2–3 mg once daily for up to 3 wk (max: 6 mg/d)
Geriatric: PO Start with 0.5 mg b.i.d. and increase by 0.5 mg b.i.d. daily to an initial target of 1.5 mg b.i.d. (max: 4 mg/d). May convert to once daily dosing after stabilized in b.i.d. 2–3 d.

Irritability Associated with Autism
Adolescent/Child (≥5 y, ≥20 kg): PO 0.5 mg q.d.; after 4 d, increase to 1 mg q.d.; can increase by 0.5 mg q2wk
Child (≥5 y, <20 kg): PO 0.25 mg q.d.; after 4 d, increase to 0.5 mg q.d.; can increase by 0.25 mg q2wk

Renal Impairment
Cl_cr <30 mL/min: start with 0.5 mg b.i.d., increase by 0.5 mg b.i.d. daily to an initial target of 1.5 mg b.i.d., may increase by 0.5 mg b.i.d. at weekly intervals (max: 6 mg/d); lower IM dose may be required

Hepatic Impairment
Start with dose of 0.5 mg b.i.d.

Administration

Oral

Note that quick-dissolving tablets dissolve rapidly when placed on tongue.
Do not exceed increases/decreases of 1 mg b.i.d. in normal populations or 0.5 mg b.i.d. in older adults or the debilitated during dosage adjustments.
Make further increases at 1-wk or longer intervals after the target dose of 3 mg b.i.d. in normal populations and 1.5 mg b.i.d. in older adults or the debilitated are reached.
Store at 15°–30° C (59°–86° F).

Intramuscular

Reconstitute the 25, 37.5, or 50 mg vial using the supplied 2 mL prefilled syringe. Shake vigorously for at least 10 sec to produce a uniform, thick, milky suspension. If 2 min or more pass before injection, shake vial again.
Give deep IM into the upper-outer quadrant of the gluteal muscle with the supplied needle; do not substitute. Follow the manufacturer's instructions for use of the SmartSite Needle-Free Vial Access Device and Needle-Pro device.
Store unopened vials at 2°–8° C (36°–46° F). Protect from light.

Adverse Effects (≥1%)

Body as a Whole: Orthostatic hypotension with initial doses, sweating, weakness, fatigue. CNS: Sedation, drowsiness, headache, transient blurred vision, insomnia, disinhibition, agitation, anxiety, increased dream activity, dizziness, catatonia, extrapyramidal symptoms (akathisia, dystonia, pseudoparkinsonism), especially with doses >10 mg/d, neuroleptic malignant syndrome (rare), increased risk of stroke in elderly. CV: Prolonged QT_c interval, tachycardia. GI: Dry mouth, dyspepsia, nausea, vomiting, diarrhea, constipation, abdominal pain, elevated liver function tests (AST, ALT). Endocrine: Galactorrhea. Metabolic: Hyperglycemia, diabetes mellitus. Respiratory: Rhinitis, cough, dyspnea. Skin: Photosensitivity. Urogenital: Urinary retention, menorrhagia, decreased sexual desire, erectile dysfunction, sexual dysfunction male and female.

Diagnostic Test Interference

Liver function tests (AST, ALT) are elevated.

Interactions

Drug: Risperidone may enhance the effects of certain antihypertensive agents. May antagonize the antiparkinson effects of bromocriptine, cabergoline, levodopa, pergolide, pramipexole, ropinirole. Carbamazepine , phenytoin, phenobarbital, rifampin may decrease risperidone levels. Clozapine may increase risperidone levels.

Pharmacokinetics

Absorption: Rapidly; not affected by food. Onset: Therapeutic effect 1–2 wk. Peak: 1–2 h. Distribution: 0.7 L/kg; in animal studies, risperidone has been found in breast milk. Metabolism: Primarily in liver by cytochrome P450 with an active metabolite, 9-hydroxyrisperidone. Elimination: 70% in urine; 14% in feces. Half-Life: 20 h for slow metabolizers, 30 h for fast metabolizers.

Nursing Implications

Assessment & Drug Effects

Monitor diabetics for loss of glycemic control.
Reassess patients periodically and maintain on the lowest effective drug dose.
Monitor closely neurological status of older adults.
Monitor cardiovascular status closely; assess for orthostatic hypotension, especially during initial dosage titration.
Monitor closely those at risk for seizures.
Assess degree of cognitive and motor impairment, and assess for environmental hazards.
Lab tests: Monitor periodically blood glucose, serum electrolytes, liver function, and complete blood counts.

Patient & Family Education

Carefully monitor blood glucose levels if diabetic.
Do not engage in potentially hazardous activities until the response to drug is known.
Be aware of the risk of orthostatic hypotension.
Learn adverse effects and report to physician those that are bothersome.
Wear sunscreen and protective clothing to avoid photosensitivity.
Notify physician if you intend to or become pregnant.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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