Risgen is a light orange to orange film coated tablet, round, biconvex, plain on one side and bisected on the other side.
Each film-coated tablet contains: Risperidone 2 mg.
Risperidone is a benzisoxazole antipsychotic reported to be an antagonist at dopamine (D2) and serotonin (5-HT2), adrenergic (α1 and α2) and histamine (H1) receptors. It is described as an atypical antipsychotic.
Pharmacology: Pharmacodynamics: Risperidone is a benzisoxazole derivative with antipsychotic property. It selectively antagonizes serotonin effects via cortical 5-HT2 receptor, and to a lesser extent, competes with dopamine at the limbic dopamine D2 receptor. This leads to decreased psychotic effects.
Pharmacokinetics: Risperidone is readily absorbed after oral doses, peak plasma concentrations being reached within 1 to 2 hours. It is extensively metabolized in the liver by hydroxylation to its main active metabolite, 9-hydroxyrisperidone; oxidative N-dealkylation is a minor metabolic pathway. Hydroxylation is mediated by the cytochrome P450 isoenzyme CYP2D6 and is the subject of genetic polymorphism.
Excretion is mainly in the urine and to a lesser extent, in the feces. Risperidone and 9-hydroxyrisperidone are about 88% and 77% bound to plasma protein, respectively.
For the treatment of schizophrenia and other psychoses.
The usual initial dose of Risperidone is 2 mg in 1 or 2 divided doses on day one. This may be increased to 4 mg in 1 or 2 divided doses on day two and subsequently adjusted further as required in increments and decrements of 1 or 2 mg daily, or as prescribed by the physician.
Signs and Symptoms: The reported signs and symptoms are result of the drug's exaggerated pharmacological effects. These include drowsiness and sedation, tachycardia and hypotension and extrapyramidal symptoms.
Treatment: There is no specific antidote to risperidone, therefore, appropriate supportive measures should be initiated. In cases of severe extrapyramidal symptoms, anticholinergic medication should be administered.
Risperidone is contraindicated in patients with known hypersensitivity to the product.
Risperidone is contraindicated in patients with pre-existing CNS depression or coma, bone marrow suppression, pheochromocytoma, or
prolactin-dependent tumors. It should be used with caution or not at all in patients with impaired liver, kidney, cardiovascular, cerebrovascular and respiratory function and in those with angle-closure glaucoma, history of jaundice, parkinsonism, diabetes mellitus, hypothyroidism, myasthenia gravis, paralytic ileus, prostatic hyperplasia or urinary retention. Care is required in patients with epilepsy or history of seizures.
The sedative effects of risperidone are most marked during the first few days of administration; affected patients should not drive or operate machines.
Risperidone is generally not recommended late in pregnancy as such may be associated with intoxication of the neonates.
Pregnancy: Pregnancy category C.
There are no adequate or well-controlled studies conducted in pregnant women.
Risperidone should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Lactation: In animal studies, risperidone and its metabolite, 9-hydroxyrisperidone are excreted in human breast milk. Therefore, women receiving risperidone should not breast-feed.
Anxiety, dizziness, dystonic reactions, extrapyramidal reactions, headache, neuroleptic malignant syndrome, tardive dyskinesia; abnormal t-waves with prolonged ventricular repolarization, arrhythmias, orthostatic hypotension, amenorrhea, galactorrhea, gynecomastia, sexual dysfunction; weight gain; constipation, nausea, cholestatic jaundice, agranulocytosis, overflow incontinence, priapism, urinary retention, altered temperature regulation.
Centrally-Acting Drugs and Alcohol: Risperidone should be used with caution when taken in combination with other centrally-acting drugs and alcohol given the primary CNS effects of risperidone.
Drugs with Hypotensive Effects: Because of its potential for inducing hypotension, risperidone may enhance the hypotensive effects of other therapeutic agents with this potential.
Levodopa and Dopamine Agonists: Risperidone may antagonize the effects of levodopa and dopamine agonist.
Cimetidine and Ranitidine: Cimetidine and ranitidine increased the bioavailability of risperidone by 64% and 26%. Cimetidine did not affect the AUC of risperidone, whereas ranitidine increased the AUC of risperidone and 9-hydroxyrisperidone combined by 20%.
Clozapine: Chronic administration of clozapine with risperidone may decrease the clearance of risperidone.
CYP Enzyme Inducers: Co-administration of risperidone with enzyme inducers (e.g. carbamazepine, rifampin, phenytoin, and carbamazepine) may cause decrease in the combined plasma concentration of risperidone and 9-hydroxyrisperidone, which could lead to decreased efficacy of risperidone treatment.
Store at temperatures not exceeding 30°C.
N05AX08 - risperidone ; Belongs to the class of other antipsychotics.
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