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HALF SINEMET CR is a brand name for Carbidopa. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Antiparkinson agent. Idiopathic Parkinson’s disease, in particular to reduce off-period in patients who previously have been treated with levodopa/decarboxylase inhibitors, or with levodopa alone and who have experienced motor fluctuations. The experience is limited with Sinemet CR and Half Sinemet CR in patients who…
Verbatim from this product's MHRA label. Tap a section to expand.
Sinemet CR and Half Sinemet CR tablets contain a 1:4 ratio of carbidopa to levodopa (Sinemet CR: carbidopa 50 mg/levodopa 200 mg, Half Sinemet CR 25mg/100mg per tablet). The daily dosage of Sinemet CR must be determined by careful titration.
Patients should be monitored closely during the dose adjustment period, particularly with regard to appearance or worsening of nausea or abnormal involuntary movements, including dyskinesias, chorea and dystonia. Route of administration: oral Sinemet CR and Half Sinemet CR may only be administered as whole tablets.
So that the controlled release properties of the product can be maintained, tablets should not be chewed, crushed, or halved. Standard antiparkinson drugs, other than levodopa alone, may be continued while Sinemet CR or Half Sinemet CR are being administered, although their dosage may have to be adjusted.
Since carbidopa prevents the reversal of levodopa effects caused by pyridoxine, Sinemet CR or Half Sinemet CR can be given to patients receiving supplemental pyridoxine (vitamin B6). Initial Dose Patients currently treated with conventional levodopa/decarboxylase inhibitor combinations Dosage with Sinemet CR should be substituted initially at an amount that provides no more than approximately 10% more levodopa per day when higher dosages are given (more than 900 mg per day).
The dosing interval between doses should be prolonged by 30 to 50% at intervals ranging from 4 to 12 hours. It is recommended to give the smaller dose, if divided doses are not equal, at the end of the day. The dose needs to be titrated further depending on clinical response, as indicated below under ‘Titration’.
Dosages that provide up to 30% more levodopa per day may be necessary. A guide for substitution of Sinemet CR treatment for conventional levodopa/decarboxylase inhibitor combinations is shown in the table below: Guideline for Conversion from Sinemet to Sinemet CR Sinemet Sinemet CR Daily Dosage Daily Dosage Levodopa (mg) Levodopa (mg) Dosage Regimen ________________________________________________________ 300 - 400 400 1 Tablet 2 x daily 500 - 600 600 1 Tablet 3 x daily 700 - 800 800 4 Tablets in 3 or more divided doses 900 - 1000 1000 5 Tablets in 3 or more divided doses 1100 - 1200 1200 6 Tablets in 3 or more divided doses 1300 - 1400 1400 7 Tablets in 3 or more divided doses 1500 - 1600 1600 8 Tablets in 3 or more divided doses Half Sinemet CR is available to facilitate titration when 100 mg steps are required.
In controlled clinical trials in patients with moderate to severe motor fluctuations 'Sinemet CR' did not produce side-effects which were unique to the modified-release formulation. The side-effect reported most frequently was dyskinesia (a form of abnormal involuntary movements).
A greater incidence of dyskinesias was seen with 'Sinemet CR' than with 'Sinemet'. Other side-effects that also were reported frequently (above 2%) were: nausea, hallucinations, confusion, dizziness, chorea and dry mouth. Side effects occurring less frequently (1-2%) were: dream abnormalities, dystonia, somnolence, insomnia, depression, asthenia, vomiting and anorexia.
Other side effects reported in clinical trials or in post-marketing experience include: Infections and infestations: urinary tract infections (frequency: very common) Body as a whole: chest pain, syncope. Cardiovascular: palpitation, orthostatic effects including hypotensive episodes.
Gastro-intestinal: constipation, diarrhoea, dyspepsia, gastro-intestinal pain, dark saliva. Hypersensitivity: angioedema, urticaria, pruritus. Metabolic: weight loss. 3 ‘Contraindications'), agitation, anxiety, decreased mental acuity, paraesthesia, disorientation, fatigue, headache, extrapyramidal and movement disorders, falling, gait abnormalities, muscle cramps, on-off phenomenon, increased libido, psychotic episodes including delusions and paranoid ideation.
Levodopa is associated with somnolence and has been associated very rarely with excessive daytime somnolence and sudden sleep onset episodes. Respiratory: dyspnoea Skin: flushing, alopecia, rash, dark sweat. Special Senses: blurred vision.
Urogenital: dark urine. Other side effects that have been reported with levodopa or levodopa/carbidopa combinations and may be potential side-effects with 'Sinemet CR' are listed below: Cardiovascular: cardiac irregularities, hypertension, phlebitis.
When patients are receiving levodopa monotherapy, levodopa must be discontinued at least eight hours before therapy with 'Sinemet CR' or 'Half Sinemet CR' is started (at least 12 hours if slow-release levodopa has been administered).
Dyskinesias may occur in patients previously treated with levodopa alone because carbidopa permits more levodopa to reach the brain and, thus, more dopamine to be formed. The occurrence of dyskinesias may require dosage reduction. 'Sinemet CR' and 'Half Sinemet CR' are not recommended for the treatment of drug-induced extrapyramidal reactions or for the treatment of Huntingdon’s chorea.
Based on the pharmacokinetic profile of 'Sinemet CR' the onset of effect in patients with early morning dyskinesias may be slower than with conventional 'Sinemet'. 2%) in advanced patients with motor fluctuations. 'Sinemet CR' or 'Half Sinemet CR' should be administered cautiously to patients with severe cardiovascular or pulmonary disease, bronchial asthma, renal, hepatic or endocrine disease, or with a history of peptic ulcer disease or of convulsions.
Care should be exercised in administering 'Sinemet CR' or 'Half Sinemet CR' to patients with a history of recent myocardial infarction who have residual atrial, nodal, or ventricular arrhythmia. In such patients, cardiac function should be monitored with particular care during the period of initial dosage administration and titration.
Levodopa has been associated with somnolence and episodes of sudden sleep onset. Sudden onset of sleep during daily activities, in some cases without awareness or warning signs, has been reported very rarely. Patients must be informed of this and advised to exercise caution while driving or operating machines during treatment with levodopa.
Patients who have experienced somnolence and/or an episode of sudden sleep onset must refrain from driving or operating machines. Furthermore a reduction of dosage or termination of therapy may be considered. As with levodopa, 'Sinemet CR' or 'Half Sinemet CR' may cause involuntary movements and mental disturbances.
Sinemet CR or Half Sinemet CR should not be given when administration of a sympathomimetic amine is contraindicated. Nonselective monoamine oxidase (MAO) inhibitors are contraindicated for use with Sinemet CR or Half Sinemet CR. These inhibitors must be discontinued at least two weeks prior to initiating therapy with Sinemet CR or Half Sinemet CR.
g. 5 ‘Interactions with other medicinal products and other forms of interaction’). Sinemet CR or Half Sinemet CR is contraindicated in patients with known hypersensitivity to any component of this medication, and in patients with narrow-angle glaucoma.
Because levodopa may activate a malignant melanoma, Sinemet CR or Half Sinemet CR should not be used in patients with suspicious undiagnosed skin lesions or a history of melanoma. Use in patients with severe psychoses.
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
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Patients currently treated with levodopa alone Levodopa must be discontinued at least eight hours before therapy with Sinemet CR is started. In patients with mild to moderate disease, the initial recommended dose is one tablet of Sinemet CR twice daily.
Patients not receiving levodopa In patients with mild to moderate disease, the initial recommended dose is one tablet of Sinemet CR twice daily. Initial dosages should not exceed 600 mg per day of levodopa, nor be given at intervals of less than six hours.
Titration Following initiation of therapy, doses and dosing intervals may be increased or decreased, depending upon therapeutic response. Most patients have been adequately treated with two to eight tablets per day of Sinemet CR administered as divided doses at intervals ranging from four to twelve hours during the waking day.
Higher doses (up to 12 tablets) and shorter intervals (less than four hours) have been used, but are not usually recommended. When doses of Sinemet CR are given at intervals of less than four hours, or if the divided doses are not equal, it is recommended that the smaller doses be given at the end of the day.
In some patients the onset of effect of the first morning dose may be delayed for up to one hour compared with the response usually obtained from the first morning dose of Sinemet. An interval of at least three days between dosage adjustments is recommended.
Maintenance Because Parkinson’s disease is progressive, periodic clinical evaluations are recommended and adjustment of the dosage regimen of Sinemet CR or Half Sinemet CR may be required. Addition of other antiparkinson medication Anticholinergic agents, dopamine agonists and amantadine can be given with Sinemet CR or Half Sinemet CR.
Dosage adjustment of Sinemet CR or Half Sinemet CR may be necessary when these agents are added to an existing treatment regimen for Sinemet CR or Half Sinemet CR. 4 ‘Special warnings and precautions for use’). Use in Children Safety and effectiveness of Sinemet CR or Half Sinemet CR in infants and children have not been established, and its use in patients below the age of 18 is not recommended.
Gastro-intestinal: bitter taste, sialorrhoea, dysphagia, bruxism, hiccups, gastro-intestinal bleeding, flatulence, burning sensation of tongue, development of duodenal ulcer. Haematologic: leucopenia, haemolytic and non-haemolytic anaemia, thrombocytopenia, agranulocytosis.
Nervous system/Psychiatric: ataxia, numbness, increased hand tremor, muscle twitching, blepharospasm, trismus, activation of latent Horner’s syndrome, euphoria, and dementia, depression with suicidal tendencies and Dopamine Dysregulation Syndrome.
Description of selected adverse reactions Dopamine Dysregulation Syndrome (DDS) is an addictive disorder seen in some patients treated with carbidopa/ levodopa. 4). 4. ‘Special warnings and precautions for use’) Skin: increased sweating.
Special senses: diplopia, dilated pupils, oculogyric crises. Urogenital: urinary retention, urinary incontinence, priapism. 3 Contraindications), Henoch-Schonlein purpura. Convulsions have occurred; however, a causal relationship with levodopa or levodopa/carbidopa combinations has not been established.
Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store
Patients with a history of severe involuntary movements or psychotic episodes when treated with levodopa alone or levodopa/decarboxylase inhibitor combination should be observed carefully when 'Sinemet CR' or 'Half Sinemet CR' is substituted.
These reactions are thought to be due to increased brain dopamine following administration of levodopa and use of 'Sinemet CR' or 'Half Sinemet CR' may cause recurrence. Dosage reduction may be required. All patients should be observed carefully for the development of depression with concomitant suicidal tendencies.
Patients with past or current psychoses should be treated with caution. A symptom complex resembling the neuroleptic malignant syndrome including muscular rigidity, elevated body temperature, mental changes, and increased serum creatine phosphokinase has been reported when antiparkinsonian agents were withdrawn abruptly.
Therefore, patients should be observed carefully when the dosage of carbidopa-levodopa combinations is reduced abruptly or discontinued, especially if the patient is receiving antipsychotics. Patients with chronic wide-angle glaucoma may be treated cautiously with 'Sinemet CR' or 'Half Sinemet CR', provided the intraocular pressure is well controlled and the patient monitored carefully for changes in intraocular pressure during therapy.
Periodic evaluations of hepatic, haematopoietic, cardiovascular and renal function are recommended during extended therapy. If general anaesthesia is required, 'Sinemet CR' or 'Half Sinemet CR' may be continued as long as the patient is permitted to take oral medication.
If therapy is interrupted temporarily, the usual dosage should be administered as soon as the patient is able to take oral medicine. Epidemiological studies have shown that patients with Parkinson's disease have a higher risk of developing melanoma than the general population (approximately 2-6 fold higher).
It is unclear whether the increased risk observed was due to Parkinson's disease, or other factors such as drugs used to treat Parkinson's disease. Therefore patients and providers are advised to monitor for melanomas on a regular basis when using 'Sinemet CR' for any indication.
, dermatologists). Laboratory Tests Abnormalities in various laboratory tests have occurred with carbidopa-levodopa preparations and may occur with 'Sinemet CR' or 'Half Sinemet CR'. These include elevations of liver function tests such as alkaline phosphatase, SGOT (AST), SGPT (ALT), LDH, bilirubin, blood urea nitrogen, creatinine, uric acid and positive Coombs’ test.
Carbidopa-levodopa preparations may cause a false-positive reaction for urinary ketone bodies when a test tape is used for determination of ketonuria. This reaction will not be altered by boiling the urine specimen. False-negative tests may result with the use of glucose-oxidase methods of testing for glycosuria.
Decreased haemoglobin and haematocrit, elevated serum glucose and white blood cells, bacteria and blood in the urine have been reported with standard 'Sinemet'. Dopamine Dysregulation Syndrome (DDS) is an addictive disorder resulting in excessive use of the product seen in some patients treated with carbidopa/ levodopa.
8). Impulse control disorders Patients should be regularly monitored for the development of impulse control disorders. Patients and carers should be made aware that behavioural symptoms of impulse control disorders including pathological gambling, increased libido, hypersexuality, compulsive spending or buying, binge eating and compulsive eating can occur […]