risperidone

risperidone

(ris peer' i dohn)

Risperdal, Risperdal Consta, Risperdal M-TAB

Pregnancy Category C

Drug classes

Antipsychotic

Benzisoxazole

Therapeutic actions

Mechanism of action not fully understood: Blocks dopamine and serotonin receptors in the brain, depresses the RAS; anticholinergic, antihistaminic, and alpha-adrenergic blocking activity may contribute to some of its therapeutic and adverse actions.

Indications

·        Treatment of schizophrenia

·        Delaying relapse in long-term treatment of schizophrenia

·        Short-term treatment of acute manic or mixed episodes associated with bipolar 1 disorder; alone or in combination with lithium or valproate (oral only)

Contraindications and cautions

·        Contraindicated with hypersensitivity to risperidone, lactation.

·        Use cautiously with CV disease, pregnancy, renal or hepatic impairment, hypotension.

Available forms

Tablets—0.25, 0.5, 1, 2, 3, 4 mg; oral solution—1 mg/mL; orally disintegrating tablets—0.5, 1, 2 mg; powder for injection—25, 37.5, 50 mg

Dosages

ADULTS

Schizophrenia

·        Initial treatment: 1 mg PO bid; then gradually increase with daily dosage increments of 1 mg bid on the second and third days to a target dose of 3 mg PO bid by the third day. Range, 4–8 mg/day or 25 mg IM q 2 wk; do not exceed 50 mg IM q 2 wk.

·        Reinitiation of treatment: Follow initial dosage guidelines, using extreme care due to increased risk of severe adverse effects with reexposure.

·        Switching from other antipsychotics: Minimize the overlap period and discontinue other antipsychotic before beginning risperidone therapy.

·        Delaying relapse time in long-term treatment: 3 mg PO bid.

Bipolar mania

2–3 mg/day PO as a once daily dose; range 1–6 mg/day.

PEDIATRIC PATIENTS

Safety and efficacy not established.

GERIATRIC PATIENTS OR PATIENTS WITH RENAL OR HEPATIC IMPAIRMENT

Initial dose of 0.5 mg PO bid; monitor patient for adverse effects and response.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	Varies	3–17 hr	Weeks

Metabolism: Hepatic; T_1/2: 20 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Insomnia, anxiety, agitation, headache, somnolence, aggression, dizziness, tardive dyskinesias

·        CV: Orthostatic hypotension, arrhythmias

·        Dermatologic: Rash, dry skin, seborrhea, photosensitivity

·        GI: Nausea, vomiting, constipation, abdominal discomfort, dry mouth, increased saliva

·        Respiratory: Rhinitis, coughing, sinusitis, pharyngitis, dyspnea

·        Other: Chest pain, arthralgia, back pain, fever, neuroleptic malignant syndrome, diabetes mellitus, hyperglycemia

Interactions

Drug-drug

·        Increased therapeutic and toxic effects with clozapine

·        Decreased therapeutic effect with carbamazepine

·        Decreased effectiveness of levodopa

Nursing considerations

Assessment

·        History: Allergy to risperidone, lactation, CV disease, pregnancy, renal or hepatic impairment, hypotension

·        Physical: T, weight; reflexes, orientation; P, BP, orthostatic BP; R, adventitious sounds; bowel sounds, normal output, liver evaluation; CBC, urinalysis, LFTs, renal function tests

Interventions

·        WARNING: Maintain seizure precautions, especially when initiating therapy and increasing dosage.

·        WARNING: Mix oral solution with 3–4 oz of water, coffee, orange juice, or low-fat milk. Do not mix with cola or tea.

·        Open blister units of orally disintegrating tablets individually; do not push tablet through the foil. Use dry hands to remove tablet—immediately place on tongue. Do not allow patient to chew tablet.

·        WARNING: Monitor patient regularly for signs and symptoms of diabetes mellitus.

·        Monitor T. If fever occurs, rule out underlying infection, and consult physician for appropriate comfort measures.

·        Advise patient to use contraception during drug therapy.

·        WARNING: Follow guidelines for discontinuation or reinstitution of the drug carefully.

Teaching points

·        Dosage will be increased gradually to achieve most effective dose. Do not take more than your prescribed dosage. Do not make up missed doses; contact your health care provider if this occurs. Do not stop taking this drug suddenly; gradual reduction of dosage is needed to prevent side effects.

·        Mix oral solution in 3–4 ounces of water, coffee, orange juice, or low-fat milk. Do not mix with cola or tea.

·        Remove orally disintegrating tablet with dry hands. Do not push tablet through foil. Immediately place tablet on tongue; do not split or chew tablet. The tablet will disintegrate within seconds and you can then swallow.

·        This drug cannot be taken during pregnancy. If you think you are pregnant or wish to become pregnant, contact your health care provider.

·        You may experience these side effects: Drowsiness, dizziness, sedation, seizures (avoid driving, operating machinery, or performing tasks that require concentration); dizziness, faintness on arising (change positions slowly; use caution); increased salivation (reversible); constipation; sensitivity to the sun (use a sunscreen or protective clothing).

·        Report lethargy, weakness, fever, sore throat, malaise, mouth ulcers, palpitations, increased thirst, increased urination, increased hunger.

Adverse effects in Italic are most common; those in Bold are life-threatening.