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PubMed2005

Responses to methylphenidate in adolescent AD/HD: evidence from concurrently recorded autonomic (EDA) and central (EEG and ERP) measures.

This paper aims to examine the effects of methylphenidate (MPH) on integrated baseline and event-related psychophysiological measures in AD/HD. Thirty-four unmedicated AD/HD adolescents (11-17 years; 6 females) were first compared to 34 age- and sex-matched controls, and then re-tested at least 4 weeks after methylphenidate (MPH) medication. In each testing session, EDA was recorded simultaneously with EEG during a resting eyes open condition, and with ERPs during an auditory oddball task. Unmedicated AD/HD subjects were compared to controls and then AD/HD subjects were compared pre- and post-medication. Correlations between the change in EEG theta and the remaining psychophysiological variables were undertaken to provide information about post MPH treatment changes. In the unmedicated state, AD/HD was characterized by abnormally enhanced theta, across fronto-central sites, generally reduced P2 responses, with larger non-specific and oddball-elicited SCRs and poor behavioural performance on the oddball task. Following treatment, AD/HD showed a 'normalization' of theta activity (particularly in the right hemisphere), a reduction in the rate of decrement of EDA and a general increase in P3 amplitude. These findings suggest that methylphenidate is associated with a robust 'normalization' of low frequency EEG activity during the resting brain state, but has less impact on task-related brain activity or phasic changes in autonomic function. This dissociation of resting and task-related activity may prove to be useful in elucidating the effects of stimulant versus new non-stimulant medications in AD/HD.

Adolescent↗
PubMed2004

Prevalence and correlates of illicit methylphenidate use among 8th, 10th, and 12th grade students in the United States, 2001.

The prevalence and correlates of illicit methylphenidate use were examined within a nationally representative U.S. sample of 8th, 10th, and 12th graders. The annual prevalence of illicit methylphenidate use was 4%. Race, grade level, geographical region, grade point average, and substance use were all significantly associated with illicit methylphenidate use.

Adolescent↗
PubMed2004

Dopaminergic ventral tegmental neurons modulated by methylphenidate.

Treatment of psychostimulants leads to the development of behavioral sensitization, an augmented behavioral response to drug re-administration. The induction of behavioral sensitization to psychostimulants such as amphetamine and cocaine occurs at the ventral tegmental area's dopaminergic neurons (VTA-DA). Currently, there is limited experimental data about the physiological properties of methylphenidate (MPD) on VTA-DA neurons. Behavioral and electrophysiological experiments using male rats were performed before and after MPD treatment. The behavioral experiment included dose-response (0.6, 2.5, and 10.0 mg/kg MPD) study to select the most effective dose for the electrophysiological study. Methylphenidate increased locomotion in typical dose response characteristics. Based on this experiment, the 10.0 mg/kg MPD was used in two types of electrophysiological recordings: 1) intracellular recording of neuronal activity performed on horizontal 275-300 microm brain slices and 2) whole-cell patch clamping before and after electrical stimulation to study post-synaptic currents on neurophysiologically identified VTA-DA neurons. Methylphenidate suppressed the neuronal activity of these neurons for 210 +/- 30 sec. Stimulation of the prefrontal cortex afferent fibers to these VTA-DA neurons in the presence of TTX, saclofen, and picrotoxin led to the conclusion that this input is mediated via NMDA and kainate/AMPA receptors and may participate to induce behavioral sensitization to psychostimulants.

Afferent Pathways↗
PubMed2006

Effectiveness and safety of methylphenidate in adult attention deficit hyperactivity disorder in patients with epilepsy: an open treatment trial.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness and safety of methylphenidate treatment in epilepsy patients with comorbid adult attention deficit hyperactivity disorder (ADHD). METHODS: Six of 156 consecutive patients attending a tertiary epilepsy clinic for diagnostic evaluation of new seizures, 3 patients with epilepsy and 3 patients with psychogenic non-epileptic seizures, were diagnosed with comorbid adult ADHD. These 6 patients entered an open trial of methylphenidate 10 mg twice daily. Clinical improvement was assessed at 6 weeks of follow-up. RESULTS: Both groups showed clinical improvement of ADHD symptoms during treatment. None of the patients with comorbid epilepsy experienced adverse effects on seizure control or antiepileptic drug use. CONCLUSION: In this open trial methylphenidate was safely used in patients with epilepsy and adult ADHD. It was effective against adult ADHD, and there were no adverse effects on seizure severity and frequency. A randomized study is needed to further establish effectiveness and safety.

Adolescent↗
PubMed1977

The effect of the stimulant drugs, dextroamphetamine and methylphenidate, on secretion of growth hormone in hyperactive children.

The stimulant effect of L-dopa (125 to 500 mg) was compared to dextroamphetamine and methylphenidate, 15, and 20 mg, respectively, on growth hormone secretion in 20 hyperactive children. All three stimulants were responsible for peak GH concentration in serum at 60 minutes after drug ingestion; there was no significant difference between the mean GH level at any time of sampling. Seven of the children were retested with L-dopa and dextroamphetamine after six to eight months of treatment with methylphenidate. After treatment, there was a tendency to higher zero time levels of GH, and to delayed and/or paradoxical response to dextroamphetamine. The findings indicate an acute and a probably long-term effect of dextroamphetamine and methylphenidate on the homeostasis of growth hormone. The possible long-term adverse effects of these drugs on the growth of children indicates the need for caution to the widespread use of these agents.

Adolescent↗
PubMed1982

Methylphenidate in severely retarded residents and the clinical significance of stereotypic behavior.

An attempt was made to evaluate a model predicting stimulant drug response based on attentional characteristics of the participants. Twenty-eight severely and profoundly mentally retarded residents took part in a double blind, placebo controlled trial of methylphenidate (Ritalin). Methylphenidate was administered, for one week each, in a low dose of 0.3 mg/kg and a high dose of 0.6 mg/kg. The results failed to show any clinically relevant differences between placebo and active drug conditions with the exception that methylphenidate caused a significant reduction in food consumption. A variety of subject characteristics, including level of stereotypy, hyperactivity, and IQ were unrelated to drug effect. One positive finding, unrelated to drug effects, was that subdivision of the group by degree of stereotypy provided substantial clinical information about individual subjects.

Adolescent↗
PubMed1985

Gas chromatographic-mass spectrometric analysis of methylphenidate and p-hydroxymethylphenidate using deuterated internal standards.

A gas chromatography-mass spectrometry assay is described for the simultaneous determination of threo-dl-methylphenidate and threo-dl-p-hydroxymethylphenidate in plasma and urine using selected ion monitoring of electron impact generated fragments of their pentafluoropropionyl derivatives. The use of recently available deuterated analogues as internal standards improves overall performance relative to previous methods. The practical limit of quantifiable detection of the assay is 0.5 ng/ml for both methylphenidate and p-hydroxymethylphenidate. p-Hydroxymethylphenidate appears to be a significant urinary metabolite of methylphenidate in rats but not in humans.

Adult↗
PubMed1998

Quantitative capillary electrophoresis-ion-trap mass spectrometry determination of methylphenidate in human urine.

A quantitative capillary electrophoresis-mass spectrometry method has been demonstrated for the determination of methylphenidate in human urine over a dynamic range of 640. The samples were prepared by liquid-liquid extraction using 4 ml of human urine. The extracts were analyzed using a Finnigan LCQ ion-trap mass spectrometer in a two-event, positive-ion full-scan MS and tandem MS selected reaction monitoring mode. The lower level of quantitation was determined to be 1.5 ng/ml methylphenidate in human urine. The intra-assay precision had a relative standard deviation less than 6.8%. The intra-assay accuracy was less than +/-14.7% bias from the nominal concentration for the full-scan MS analysis, and less than +/-26.5% bias for the tandem MS analysis. Six incurred human urine samples containing methylphenidate were analyzed and a simple pharmacokinetic curve is presented.

Dopamine Uptake Inhibitors↗
PubMed2002

Methylphenidate treatment.

Methylphenidate is the psychotropic drug most commonly used to treat individuals suffering from developmental attention-deficit-hyperactivity disorder. Additional attention deficit is part of numerous neurologic diseases in childhood. Despite the vast extent of scientific research on methylphenidate, the use of this stimulant in the treatment of cognitive and behavioral dysfunction in children with epilepsy, brain tumor, leukemia, closed brain injury, encephalitis, meningitis, or mental retardation continues to be controversial. Only few data exist about the efficacy and side effects of methylphenidate treatment in children with this neurologic illness or history. The aim of the present study is to provide a review of this important clinical topic and perhaps to stimulate further controlled investigations.

Attention Deficit Disorder with Hyperactivity↗
PubMed1998

Neuroleptic malignant syndrome and methylphenidate.

A 1-year-old female presented with neuroleptic malignant syndrome probably caused by methylphenidate. She had defects in the supratentorial brain including the basal ganglia and the striatum (multicystic encephalomalacia) due to severe perinatal hypoxic-ischemic encephalopathy, which was considered to be a possible predisposing factor causing neuroleptic malignant syndrome. A dopaminergic blockade mechanism generally is accepted as the pathogenesis of this syndrome. However, methylphenidate is a dopamine agonist via the inhibition of uptake of dopamine, and therefore dopaminergic systems in the brainstem (mainly the midbrain) and the spinal cord were unlikely to participate in the onset of this syndrome. A relative gamma-aminobutyric acid-ergic deficiency might occur because diazepam, a gamma-aminobutyric acid-mimetic agent, was strikingly effective. This is the first reported patient with neuroleptic malignant syndrome probably caused by methylphenidate.

Brain↗
PubMed1998

Differences in regional brain metabolic responses between single and repeated doses of methylphenidate.

Studies investigating the acute effects of drugs of abuse on human brain metabolism have measured single doses whereas these drugs are mostly taken repeatedly. Here we compared the brain metabolic response to intravenous methylphenidate when given after a single dose to that when given after two sequential doses. Methylphenidate-induced changes in metabolism differed; whereas single doses tended to decrease metabolism, repeated doses tended to increase it, and these differences were significant in frontal, parietal and occipital cortices and hippocampus. This indicates that methylphenidate's metabolic effects vary with acute previous exposure and highlights the importance of studying drugs after single and repeated administration.

Adult↗
PubMedDate not supplied

Methylphenidate: increased abuse or appropriate use?

OBJECTIVE: To address the question of the significant increase in methylphenidate (MPD) prescriptions being written and to make recommendations for health care providers involved in providing care for patients with attention deficit hyperactivity disorder (ADHD) and their families. DATA SOURCES: Medline search 1966-1998 for professional articles using the following search terms--methylphenidate, children, adolescents, abuse; Internet search using MPD, Ritalin, and ADHD; and Paper Chase search using methylphenidate. DATA EXTRACTION: The available literature regarding potential abuse or diversion of MPD consists of case reports, review articles, newspaper articles, and a Drug Enforcement Administration (DEA) publication. All available literature sources were used. DATA SYNTHESIS: Although the media and DEA report significant abuse and diversion of prescribed MPD, a review of the available literature did not reveal data to substantiate these claims. Nonetheless, there are reasons to suspect that abuse and diversion occur. A potential contributing factor to abuse is the reported similarities in pharmacodynamics and pharmacokinetics between MPD and cocaine. Recommendations are made to decrease the possibility of abuse and diversion of prescribed MPD. CONCLUSION: A balanced middle ground must be found regarding the benefits of MPD and its abuse potential. Education of clinicians, patients, and family members is key in ensuring that MPD is used appropriately.

Adolescent↗
PubMed2002

EEG differences between good and poor responders to methylphenidate in boys with the inattentive type of attention-deficit/hyperactivity disorder.

OBJECTIVES: This study investigated electroencephalographic (EEG) differences between good and poor responders to methylphenidate in boys with the Inattentive type of Attention-Deficit/Hyperactivity Disorder (ADHD). METHODS: Twenty good and 15 poor responders to methylphenidate, based on the results of a continuous performance task, and 35 age- and sex-matched control subjects, participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. RESULTS: EEG differences were found between the ADHD children and controls which were compatible with previous literature on the Inattentive type. Differences were also found between the good and poor responders to methylphenidate. CONCLUSIONS: Good responders had EEG profiles that suggested that they were more cortically hypoaroused than poor responders.

Adolescent↗
PubMed1987

Which boys respond to stimulant medication? A controlled trial of methylphenidate in boys with disruptive behaviour.

Thirty-eight boys, referred for psychiatric treatment because of serious problems of behaviour, underwent a double-blind, placebo-controlled, crossover trial of methylphenidate and placebo. Methylphenidate was an effective treatment over a 3-week period. A good response to methylphenidate was predicted by higher levels of inattentive and restless behaviour, impaired performance on tests of attention, clumsiness, younger age and by the absence of symptoms of overt emotional disorder. DSM-III and ICD-9 diagnoses of 'hyperactivity' were not good predictors. The results support the validity of a construct of hyperactivity in describing childhood psychopathology, but emphasize the need for a refinement of diagnostic criteria.

Attention↗
PubMed2004

Lacunar stroke associated with methylphenidate abuse.

BACKGROUND: Methylphenidate is a central nervous system stimulant used for the treatment of attention deficit hyperactivity disorder and narcolepsy and like other psychostimulants has a potential for abuse. CASE STUDY: A young man with a cerebral lacunar infarction following chronic oral abuse of methylphenidate is presented. CONCLUSIONS: The experience of our patient and a review of the literature suggest that cerebral infarction is a potential side effect of chronic consumption of methylphenidate.

Adult↗
PubMed2003

Methylphenidate-induced obsessive-compulsive symptoms in an elderly man.

An 82-year-old man with treatment-resistant depression and early Alzheimer's disease was started on methylphenidate. Significant obsessive-compulsive behavior ensued but diminished over several weeks when methylphenidate was replaced by fluvoxamine. The patient had no prior psychiatric history, but he had a sister with obsessive-compulsive disorder. It appears that methylphenidate precipitated the patient's pathological behavior.

Aged↗
PubMed2003

Synthesis and evaluation of dopamine and serotonin transporter inhibition by oxacyclic and carbacyclic analogues of methylphenidate.

Methylphenidate (Ritalin) binds stereoselectively and enantioselectively to the dopamine transporter (DAT) and inhibits dopamine reuptake with in vitro and in vivo potency similar to that of cocaine. Unlike cocaine, it manifests little, if any, tolerance or addiction liability. Since this compound has a substantial clinical history, it provides an excellent template from which to design potential medications for cocaine abuse. It has long been assumed that a nitrogen, such as exists in cocaine and methylphenidate, is essential for interaction with monoamine transporters. We previously demonstrated that an amine nitrogen in phenyltropane analogues of cocaine is not necessary for conferring high DAT binding affinity. We now report the synthesis of oxacyclic and carbacyclic analogues of methylphenidate, including the four enantiomerically pure isomers of 2-(3,4-dichlorophenyl)-2-(tetrahydropyran-2-yl)acetic acid methyl ester. The threo isomers are potent and selective inhibitors of the DAT. This is the first generalization of the principle that the presence of nitrogen is not a necessity for DAT inhibition.

Animals↗
PubMed2007

Slow-onset, long-duration, alkyl analogues of methylphenidate with enhanced selectivity for the dopamine transporter.

Methylphenidate analogues, in which the carbomethoxy has been replaced by an alkyl group and with different phenyl substituents, have been synthesized and tested in monoamine transporter assays. As predicted from a pharmacophore model, most of the RR/SS diastereomers showed high potency as dopamine reuptake inhibitors. Analogues with a 4-chlorophenyl group and an unbranched initial alkyl atom had consistently enhanced selectivity for the dopamine transporter. The most potent compounds were those with a three- or four-carbon chain. The "inactive" RS/SR diastereomers showed substantial activity when the phenyl substituent was 3,4-dichloro. On a locomotor assay, one compound was found to have a slow onset and a long duration of action. The activity of these compounds provides additional evidence for a conformational/superposition model of methylphenidate with cocaine-like structures. A ketone analogue, obtained by hydrogenating a previously described vinylogous amide, had activity similar to that of methylphenidate.

Animals↗