Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methylphenidate is a first-line therapy for attention deficit hyperactivity disorder, the most prevalent neuropsychiatric disorder of childhood. The compound is a piperidine and the D-threo-isomer is considered the biologically active form. The compound is available in multiple short- and long-acting preparations, having different delivery systems leading to varying kinetics without clear superiority in efficacy or tolerability at the group level. Common adverse effects are insomnia, appetite disturbance, stomach ache, headache and dizziness. Its mechanism of action is linked to the monoamines dopamine and norepinephrine. The compound appears to predominantly increase the synaptic concentration of dopamine, presumably via inhibition of the dopamine transporter DAT1. There also appears to be effects on presynaptic vesicular trafficking and distribution of dopamine. Both immediate- and sustained-release preparations of methylphenidate have proven efficacy in children and adults with attention deficit hyperactivity disorder. Analysis of the National Institutes of Health-sponsored multimodal treatment study of attention deficit hyperactivity disorder supports a combined medication and behavioral therapy approach.
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PMID:Methylphenidate HCl: therapy for attention deficit hyperactivity disorder. 1593 65

(1) Narcolepsy is characterised by sudden, overwhelming daytime drowsiness, sometimes associated with cataplexy (more or less complete loss of muscle tone during an emotional reaction). (2) Modafinil moderately reduces daytime drowsiness but has no effect on cataplexy. Methylphenidate, an amphetamine psychostimulant, seems to act on both drowsiness and cataplexy, although its clinical evaluation is limited to observational series. (3) Oxybic acid, long used in general anaesthesia, but also misused for recreational and criminal purposes (chemical or drug-induced submission), has been approved to treat adults with both narcolepsy and cataplexy, in the form of an oral solution of sodium oxybate. (4) The rationale behind the use of sodium oxybate is to re-establish a near-normal pattern of the different phases of sleep. Because of its short-lasting action, sodium oxybate has to be taken once at bedtime and then again 2.5 to 4 hours later. (5) Clinical evaluation mainly consists of 4 double-blind placebo-controlled trials of sodium oxybate. Three short-term trials, involving 136 patients treated for 4 weeks and 228 and 270 patients treated for 8 weeks, showed that sodium oxybate at a dose of 4.5 g to 9 g a day reduced the number of cataplexy attacks but that a dose of at least 6 g was needed to reduce daytime drowsiness. A trial involving 56 patients who had been taking sodium oxybate for nearly 2 years, assessed the effects of stopping versus continuing treatment. The results suggest that sodium oxybate is effective in the long term. (6) During clinical trials, 61% of patients had adverse effects attributed to sodium oxybate. These included gastrointestinal disorders (nausea (18%)), neurological disorders (dizziness (15%), headache (6%)), confusion (3%), and enuresis (7%). (7) Altered consciousness and respiratory depression occurred after a single intake of a dose two or three times higher than the recommended dose. (8) Misuse, especially to obtain chemical or drug-induced submission (i.e. as a 'date rape' drug), is facilitated by the odourless and colourless nature of the oral solution. (9) In practice, for some patients who are seriously affected by persistent episodes of cataplexy or drowsiness, despite treatment of narcolepsy, sodium oxybate is preferable to methylphenidate, which has been less thoroughly evaluated. However, the risks of misuse and overdose mean that this drug should only be proposed to patients in whom the benefits are likely to outweigh the risks.
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PMID:Sodium oxybate: new drug. Fewer attacks of cataplexy in some patients. 1758 23