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Respal

Afrab-Chem Ltd
No. 22, Abimbola Street, Isolo Industrial Estate, Isolo, P.O. Box 1647, Lagos, Nigeria.
Email: info@afrabchem.com
Tel: 234-1-2700057
Fax: 234-1-4520328
Website: http://afrabchem.com/

Brand Name

Respal

Manufacturer

Joswe Medicals, Na'ur Jordan.

Therapeutic Class

Antipsychotics

Dosage Form, Composition & NAFDAC Registration Number (NRN)

Tablet (NRN:04-5731): Risperidone 1 mg; film coated tablet.

Pack size: 20's

 

Tablet (NRN:04-8629): Risperidone 2 mg; film coated tablet.

Pack size: 20's

repal 2 

Tablet (NRN:04-8628): Risperidone 4 mg; film coated tablet.

Pack size: 20's

Pharmacology

Pharmacodynamics:

Risperidone is a selective monoaminergic antagonist with unique properties. It has a high affinity for serotoninergic 5-HT2 and dopaminergic D2 receptors. Risperidone binds also to alpha1-adrenergic receptors, and with lower affinity to H1-histaminergic and alpha2-adrenergic receptors. Risperidone has no affinity for cholinergic receptors. Although risperidone is a potent D2 antagonist, which is considered to improve the positive symptoms of schizophrenia, it causes less depression of motor activity and induction of catalepsy than classical neuroleptics. Balanced central serotinin and dopamine antagonism may reduce extrapyramidal side effects and extend the therapeutic activity to the negative and affective symptoms of schizonphrenia.

Pharmacokinetics:

Risperidone is completely absorbed after oral administration, reaching peak plasma concentrations within 1 to 2 hours. The absorption is not affected by food and thus risperidone can be given with or without meals. Risperidone is metabolized by cytochrome P-450 2D6 to 9-hydroxy-risperidone which has a similar pharmacological activity as risperidone. Risperidone plus 9-hydroxy-risperidone form the active antipsychotic fraction. Another metabolic pathway of risperidone is N-dealkylation. After oral administration to psychotic patients, risperidone is eliminated with a half life of about 3 hours.

The elimination half life of 9-hydroxy-risperidone is reached within 4-5 days of dosing. Risperidone plasma concentrations are dose-proportional within the therapeutic dose range. Risperidone is rapidly distributed. The volume of distribution is 1-2 L/kg. In plasma, risperidone is bound to albumin and alpha1-acid glycoprotein. The plasma protein binding of risperidone is 88%, that of 9-hydroxy-risperidone represent 35-45% of the dose. The remainder are inactive metabolites. A single dose study showed higher active plasma concentrations and a slower elimination of risperidone in the elderly and in patients with renal insufficiency. Risperidone plasma concentrations were normal in patients with liver insufficiency.

Indications

Respal is indicated for the treatment of acute and chronic schizophrenic psychoses, and other psychotic conditions, in which positive symptoms such as hallucinations, delusions, thought disturbances, hostility, suspiciousness and/or negative symptoms (such as blunted affect, emotional and social withdrawal, poverty of speech) are prominent.

Respal also alleviates affective symptoms (such as depression, guilt feelings, anxiety) associated with schizophrenia.

Contra-indications

Hypersensitivity to Risperidone.

Precautions/Warnings

Due to the alpha-blocking activity of Risperidone (orthostatic) hypotension can occur, especially during the initial dose titration period. Risperidone should be used with caution in patients with known cardiovascular disease (e.g. heart failure, myocardial infarction, conduction abnormalities, dehydration, hypovolaemia, or cerebrovascular diseases) and the dosage should be gradually titrated as recommended. A dose reduction should be considered if hypotension occurs.

Drugs with dopamine receptor antagonistic properties have been associated with the induction of tardive dyskinesia characterized by rhythmical involuntary movements, predominantly of the tongue and/or face. It has been reported that the occurrence of extrapyrimidal symptoms is a risk factor for the development of tardive dyskinesia. Because Riperidone has a lower potential to induce extrapyramidal symptoms than classical neuroleptics, it should have a reduced risk of inducing tardive dyskinesia as compared to classical neuroleptics.

If signs and symptoms of tardive dyskinesia appear, the discontinuation of all antipsychotic drugs should be considered. The Neuroleptic Malignant Syndrome, characterized by hyperthermia, muscle rigidity, autonomic instability, altered consciousness and elevated CPK levels has been reported to occur with classical neuroleptics. In this event, all antipsychotic drugs, including Riperidone should be discontinued. It is recommended to halve both the starting dose and the subsequent dose increments in geriatric patients and in patients with renal or liver insufficiency.

Caution is also used when prescribing Risperidone to patients with Parkinson's disease since, theoretically, it might cause a deterioration of the disease. Classical neuroleptics are known to lower the seizure threshold. Caution is recommended when treating patients with epilepsy. Patients may be advised to refrain from excessive eating in view of the possibility of weight gain.

Pregnancy and lactation: The safety of Risperidone for use during human pregnancy has not been established. Although, in experimental animals, risperidone did not show direct reproductive toxicity, some indirect, prolactin-and CNS mediated effects were observed. No teratotogenic effect of risperidone was noted in any study. Therefore, Risperidone should only be used during pregnancy if the benefits outweigh the risks. In animal studies, risperidone and 9-hydroxy-risperidone are excreted in the milk. It has been demonstrated that risperidone and 9-hydroxy-risperidone are also excreted in human breast milk. Therefore, women receiving Risperidone should not breast feed.

Effects on ability to drive and use machines: Risperidone may interfere with activities requiring mental alertness. Therefore, patients should be advised not to drive or operate machinery until their individual susceptibility is known.

Interactions

The risk of using Risperidone in combination with other drugs have been systemically evaluated. Given the primary CNS effects of Risperidone it should be used with caution in combination with other centrally acting drugs.

Risperidone may antagonize the effect of levodopa and other dopamine agonists. Carbamazepine has been shown to decrease to plasma levels of the active antipsychotic fraction of Risperidone. Similar effects may be observed with other hepatic enzyme inducers. On discontinuation of carbamazepine or other hepatic enzyme inducers, the dosage of Risperidone should be re-evaluated and if necessary decreased.

Phenothiazines, tricyclic antidepressants and some beta blockers may increase the plasma concentrations of risperidone but not those of the antipsychotic fraction. Fluoxetine may increase the plasma concentration of risperidone but less so of the antipsychotic fraction.

When risperidone is taken together with other highly protein bound drugs, there is no clinically relevant displacement of either drug from the plasma proteins.

Adverse Effects

Risperidone is generally well tolerated. In many instances, it has been difficult to differentiate adverse events from symptoms of the underlying disease. Adverse events observed in association with the use of Riperidone are:

Common: Insomina, agitation, anxiety, headache

Less common: Somnolence, fatigue, dizziness, impaired concentration, constipation, dyspepsia, nausea/vomiting, abdominal pain, blurred vision, priapism, erectile dysfunction, ejaculatory dysfunction, orgastic dysfunction, urinary incontinence, rhinitis, rash and other allergic reactions. Risperidone has a lower propensity to induce extrapyramidal symptoms than classical neuroleptics, however, in some cases the following extrapyramidal symptoms may occur: tremor, rigidity, hypersalivation, bradykinesia, akathisia, acute dystonia. These are usually mild and are reversible upon dose reduction and/or administration of antiparkinson medication, if necessary.

Occasionally, (orthostatic) hypotension, (reflex) tachycardia or hypertension have been observed following administration of Risperidone. A mild fall in neutrophil and/or thrombocyte count has been reported. Risperidone can induce a dose-dependent increase in plasma prolactin concentration. Possible associated manifestation are: galactorrhoea, gynaecomastia, disturbances of the menstrual cycle and amenorrhoa.

Weight gain (see Warnings & Precautions), oedema and increased hepatic enzyme levels have been observed during treatment with Risperidone.

As with classical neuroleptics, the following have occasionally been reported in psychotic patients: water intoxication due to either polydipsia or the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), tardive dyskinesia, neuroleptic malignant syndrome, body temperature disregulation and seizures.

Dosage & Administration

Switching from other antipsychotics: When medically appropriate, gradual discontinuation of the previous treatment while Riperidone therapy is initiated is recommended. Also if medically appropriate when switching patients from depot antipsychotics, initiate Risperidone therapy in place of the next schedule injection. The need for continuing existing anti-parkinson medications should be re-evaluated periodically.

Adults: Respal may be given once daily or twice daily. Patients should be titrated to 6 mg gradually over three days. Acute or chronic patients should start with 2 mg/day Risperidone. The dosage should be increased to 4 mg on the second day and 6 mg on the third day. From then on the dosage can be maintained unchanged, or further individualized, if needed. The usual optimal dosage is 4 to 8 mg/day.

However, some patients may benefit from lower doses. A slower titration phase may be medically appropriate. Doses above 10 mg/day have not been shown to be superior in efficacy to lower doses and may cause extrapyramidal symptoms. Since the safety of doses above 16 mg/day has not been evaluated, doses above this level should not be used. A benzodiazepine may be added to Risperidone when additional sedation is required.

Elderly: A starting dose of 0.5 mg b.i.d. is recommended. The dosage can be individually adjusted with 0.5 mg b.i.d. increments to 1 to 2 mg b.i.d. Risperidone is well tolerated by the elderly.

Overdosage:

Symptoms: These include drowsiness and sedation, tachycardia and hypotension, and extrapyramidal symptoms. Overdosages of up to 360 mg have been reported. The available evidence suggests a wide safety margin. In overdose, rare cases of QT-prolongation have been reported. In case of acute overdosage, the possibility of multiple drug involvement should be considered.

Treatment: Establish and maintain a clear airway and ensure adequate oxygenation and ventilation. Gastric lavage (after intubation, if the patient is unconscious) and administration of activated charcoal together with a laxative should be considered. Cardiovascular monitoring should commence immediately and should include continous electrocardiographic monitoring to detect possible arrythmias. There is no specific antidote to Risperidone. Therefore, appropriate supportive measures should be instituted.

Hypotension and circulatory collapse should be treated with appropriate measures such as Intravenous fluids and/or sympathomimetic agents. In case of severe extrapyramidal symptoms, anticholinergic medication should be administered. Close medical supervision and monitoring should continue until the patient recovers.

Storage/Handling Recommendations

Store below or at room temperature.

Keep away from the reach of children.

Review Date

2017-09-28 07:21:37