Presentation: Tab 1 mg (white, film coated, half-scored, oblong)
10tabs x 6 strips, 2mg (orange, film coated, half-scored, oblong) 10tabs x 6
Action: Risperidone is a novel antipsychotic belonging to a new
class of antipsychotic, the benzisoxazole class.
Pharmacodynamic: Risperidone is a selective monoaminergic
antagonist with high affinity for serotoninergic 5-HT2 and
dopaminergic D2 receptors. Risperidone binds also to alpha,
adrenergic receptors, with lower affinity to H1, histaminergic
and alpha2 adrenergic receptors. Risperidone has no affinity for
Pharmacokinetics: Risperidone is completely absorbed after oral
administration, reaching peak plasma concentration within 1 to 2 hours. The
absorption is not affected by food. Risperidone is metabolised by cytochrome
P-450 IID6 to 9-hydroxy-risperidone which has similar pharmacological
properties as risperidone. Elimination half-life of' risperidone is about 3
hours while that of 9-hydroxy-risperidone and the anlipsychotic fraction is
24 hours. Steady state of risperidone is usually I day and of
9-hydroxy-risperidone is 4-5 days. A slower elimination is expected in renal
insufficiency patients and in the elderly.
Indications: Risperidone is indicated for the treatment of
schizophrenia including first episode psychoses, acute schizophrenia
exacerbations, chronic schizophrenia and other psychotic conditions in which
positive symptoms and/or negative symptoms are present. Risperidone also
alleviates affective symptoms like depression, anxiety and guilt feelings
associated with schizophrenia.
Dosage and administration: Schizophrenia: adults should start with
2mg/day in 2 divided doses and titrated accordingly to between 4-6mg per
day. Some patients may benefit from a lower optimal dose. For sonic patients
such as first episode patients, a slower titration phase and a lower
starting and maintenance dose may be appropriate. Doses above 10mg/day
generally have not been shown to provide additional efficacy and may
increase risk of extrapyramidal symptoms. Use of Risperone in children below
15 years is not established.
For patients with renal and liver disease or elderly: a starting dose of
0.5mg twice a day is recommended with of 0.5mg bd increments to 1-2mg bd per
Contraindications: Patients with a known hypersensitivity to
risperidone or any other ingredients in the product.
Warning and Precautions: Risperone is not recommended for the
treatment of behavioural symptoms of dementia due to an increased risk of
cerebrovaseular events. Treatment of acute psychoses in patients with a
history of dementia should be limited to short term only. Caution to be
taken when treating patients with known cardiovascular disease or associated
risk factors. Orthostalic hypotension may occur in the initial dose
All antipsychotic drugs should be discontinued if signs and symptoms of
tardive dyskinesia (rhythmical involuntary movement, predominantly of face
and tongue) or neuroleptic malignant syndrome (hyperthermia, muscle
rigidity, autonomic instability, altered consciousness and elevated CPK
Risperone should be used with caution in patients with known
cardiovascular disease, renal and liver disease, Parkinson's disease and
epilepsy. It is recommended to halve both the starting and subsequent dose
increments in geriatric patients and patients with renal or Beer
insufficiency. Hyperglycaemia or exacerbation of pre-existing diabetes has
been reported very rarely. Patients are advised not to drive or operate
machineries if Risperone interfere with their mental alertness.
Gradual withdrawal of antipsychotics are advised to minimise the
recurrence of psychotic symptoms and the emergence of involuntary movement
Interactions: Caution if
used in combination with other centrally acting drugs including alcohol.
Hepatic enzyme inducers like carbamazepine may reduce the plasma level of
risperidone. Phenotiazines, tricyclic antidepressants and some beta-blockers
may increase the plasma concentration of risperidone. Fluoxetine and
paroxetine, CYP2D6 inhibitors may increase the plasma concentration of
risperidone but less of the active antipsychotic fraction. The same
interaction may occur with haloperidol.
Amitriptyline does not affect the pharmacokinetics of risperidone.
Cimetidine and ranitidine increase the bioavailability of risperidone but
marginally of the antipsychotic fraction. Erythromycin, a CYP 3A4 inhibitor,
does not change the pharmacokinetics of risperidone and the active
When taken with other highly bound drugs, there is no clinically relevant
displacement of either drug. Risperone does not show a clinically relevant
effect on the pharmacokinetics of valproate. In patients on long term
lithium and older/typical neuroleptic therapy, there is no significant
change in the pharmacokinetics of lithium after substitution of the
concomitant neuroleptic with risperidone. Food does not affect the
absorption of risperidone.
Use in pregnancy and lactation: The safety of risperidone for use in
human pregnancy has not been established. In animal studies, although no
teratogenic effects were noted, some prolactin and CNS-mediated effects such
as delayed oestrus and changes in mating and nursing behaviour were observed
in rats. Risperidone and 9-hydroxyrisperidone are excreted in human breast
milk. Therefore, women receiving Risperone should not breast feed.
Adverse events: Generally, risperidone is well tolerated and in many
instances it has been difficult to differentiate adverse events from
symptoms of the underlying disease. Common side effects are insomnia,
agitation, anxiety and headache. Less common: somnolence, fatigue,
dizziness, impaired concentration, constipation, dyspepsia, nausea/vomiting,
abdominal pain, blurred vision, priapsim, erectile dysfunction, ejaculatory
dysfunction, orgasmic dysfunction, urinary incontinence, rhinitis, rash and
other allergic reactions. In some cases, extrapyramidal symptoms may occur.
Occasionally, orthostatic hypotension and cerebrovascular accidents has been
Risperidone can induce a
dose-dependent increase in plasma prolactin concentration with possibly
galactorrhoea, gynaecomastia, disturbances of the menstrual cycle and
Weight gain, oedema, increased hepatic enzyme levels decrease in neutrophil
and/or thrombocyte count as well as hyperglycaemia have been observed during
treatment. As with classical neuroleptics, rare cases of the following have
been reported in schizophreia patients: water intoxication with
hyponatraemia, either due to polydipsia or to the syndrome of inappropriate
secretion of antidiuretic hormone; tardive dyskinesia, body temperature
dysregulation and seizures. Sedation, generally transient and mild has been
reported more frequently in children and adolescents.
Symptoms and treatment for overdose: Symptoms include drowsiness,
sedation, tachycardia and hypotension, and extrapyramidal symptoms and rare
eases of QT prolongation. There is no specific antidote.
Appropriate supportive treatment
including gastric larvage and administration of activated charcoal and
laxative should be considered. Cardiovascular monitoring should include
continuous electrocardiography monitoring.
Storage: Store below 25C in a dry place. Keep out of reach of children.