Dexmethylphenidate

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Dexmethylphenidate, sold under the brand name Focalin among others, is a central nervous system (CNS) stimulant used in the treatment of attention deficit hyperactivity disorder (ADHD) in those over the age of five years.[1] It is taken by mouth.[1] The immediate-release formulation lasts up to five hours while the extended-release formulation lasts up to twelve hours.[2] It is the more active enantiomer of methylphenidate.[1]

Common side effects include abdominal pain, loss of appetite, and fever.[1] Serious side effects may include psychosis, sudden cardiac death, mania, anaphylaxis, seizures, and priapism.[1] Safety during pregnancy and breastfeeding is unclear.[3]

Dexmethylphenidate was approved for medical use in the United States in 2001.[4] It is available as a generic medication.[1] In 2022, it was the 109th most commonly prescribed medication in the United States, with more than 5Template:Nbspmillion prescriptions.[5][6] Template:TOC limit

Medical uses

Dexmethylphenidate is used as a treatment for attention deficit hyperactivity disorder (ADHD), usually along with psychological, educational, behavioral or other forms of treatment. It is proposed that stimulants help ameliorate the symptoms of ADHD by making it easier for the user to concentrate, avoid distraction, and control behavior. Placebo-controlled trials have shown that once-daily dexmethylphenidate XR was effective and generally well tolerated.[7]

Improvements in ADHD symptoms in children were significantly greater for dexmethylphenidate XR versus placebo.[7] It also showed greater efficacy than osmotic controlled-release oral delivery system (OROS) methylphenidate over the first half of the laboratory classroom day but assessments late in the day favoured OROS methylphenidate.[7]

Contraindications

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Adverse effects

Template:Transcluded section Products containing dexmethylphenidate have a side effect profile comparable to those containing methylphenidate.[8] Template:Trim

Interactions

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Pharmacology

Script error: No such module "Labelled list hatnote". Dexmethylphenidate has a 4–6 hour duration of effect. A long-acting formulation, Focalin XR, which spans 12 hours is also available and has been shown to be as effective as DL (dextro-, levo-)-TMP (threo-methylphenidate) XR (extended release) (Concerta, Ritalin LA), with flexible dosing and good tolerability.[9][10] It has also been demonstrated to reduce ADHD symptoms in both children[11] and adults.[12] d-MPH has a similar side-effect profile to MPH[8] and can be administered without regard to food intake.[13]

CTx-1301 is an experimental medication that is an extended-release formulation of dexmethylphenidate that has a half life more than an hour longer than extended-release dexmethylphenidate (d-MPH-ER). It is under development for ADHD.[14][15][16][17][18]

Mechanism of action

Methylphenidate is a catecholamine reuptake inhibitor that indirectly increases catecholaminergic neurotransmission by inhibiting the dopamine transporter (DAT) and norepinephrine transporter (NET),[19] which are responsible for clearing catecholamines from the synapse, particularly in the striatum and meso-limbic system.[20] Moreover, it is thought to "increase the release of these monoamines into the extraneuronal space."[21]

Although four stereoisomers of methylphenidate (MPH) are possible, only the threo diastereoisomers are used in modern practice. There is a high eudysmic ratio between the SS and RR enantiomers of MPH. Dexmethylphenidate (d-threo-methylphenidate) is a preparation of the RR enantiomer of methylphenidate.[22][23] In theory, D-TMP (d-threo-methylphenidate) can be anticipated to be twice the strength of the racemic product.[19][24]

Compd[25] DAT (Ki) DA (IC50) NET (Ki) (IC50)
D-TMP 161 23 206 39
L-TMP 2250 1600 >10K 980
DL-TMP 121 20 788 51

Notes

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References

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