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PubMed2004

Effect of methylphenidate on vital signs and adverse effects in adults with traumatic brain injury.

OBJECTIVE: To study methylphenidate's adverse effects and impact on vital signs within the adult traumatic brain injury population. DESIGN: Thirty-five adults with traumatic brain injury enrolled in a double-blind, placebo-controlled, 6-wk crossover study of methylphenidate, given in a dose of 0.3 mg/kg/dose, twice a day. Vital signs were taken by trained clinicians and research assistants. Participants filled out weekly questionnaires pertaining to the adverse effects. RESULTS: Poor appetite was the only adverse effect related to methylphenidate. Other adverse effects commonly associated with methylphenidate, such as insomnia, rapid heart rate, and anxiety, were not found to be significantly related to the medication. The average rise in mean arterial pressure on methylphenidate was 2.5 mm. Methylphenidate showed a stronger impact on pulse, with an average increase of 7 beats/min. Baseline vital signs did not predict the degree of increase on methylphenidate. CONCLUSION: Methylphenidate appears to be safe for the adult population with traumatic brain injury. However, because a few individuals experienced significant changes in vital signs and adverse effects, all patients should be monitored.

Adult↗
PubMed2004

Methylphenidate does not improve cognitive function in healthy sleep-deprived young adults.

BACKGROUND: Abuse of methylphenidate, a treatment of attention-deficit/hyperactivity disorder, is reported to be increasing among students for the purpose of improving cognition. METHODS: A single capsule, containing methylphenidate (20 mg) or placebo, was administered to healthy young adults orally following 24 hours of sleep deprivation. Measurements included percent change in score from sleep-deprived baseline on four standardized tests of cognitive function: Hopkins Verbal Learning, Digit Span, Modified Stroop, and Trail Making tests. Measurements also included percent changes in blood pressure and heart rate from sleep-deprived baseline and plasma methylphenidate concentration. RESULTS: Differences in cognitive test performance were not observed between intervention groups. In subjects receiving methylphenidate, mean percent changes from baseline for systolic blood pressure and heart rate were increased relative to placebo between 90 and 210 minutes following capsule administration (maximum increases of 9.45% and 11.03%, respectively). The timing of peak differences in physiologic measures did not correlate with peak serum methylphenidate concentrations. Exit questionnaire ratings of "capsule effect" and perceived performance on the postcapsule administration of the most challenging cognitive test were both higher (p = .044 and p = .009, respectively) for the methylphenidate group than for the placebo group. CONCLUSIONS: Cognitive improvement among sleep-deprived young adults was not observed following methylphenidate administration. Benefits perceived by abusers may relate to increased confidence and sense of well-being, as well as to sympathetic nervous system stimulation. Moreover, methylphenidate administration results in physiologic effects that could be harmful to certain individuals.

Adult↗
PubMed1997

Effects of methylphenidate on regional brain glucose metabolism in humans: relationship to dopamine D2 receptors.

OBJECTIVE: The authors' goals were to determine whether baseline dopamine activity contributes to response to methylphenidate and to assess the pattern of metabolic responses associated with enhanced dopamine activity. METHOD: They used positron emission tomography with 2-deoxy-2[18F]fluoro-D-glucose to evaluate the effects of two sequential doses of methylphenidate on brain metabolism in 15 healthy subjects. Dopamine D2 receptor availability was measured with [11C]raclopride to evaluate its relation to methylphenidate-induced metabolic changes. RESULTS: Methylphenidate increased brain metabolism in six subjects, decreased it in two, and did not change it in seven; however, it consistently increased cerebellar metabolism. Methylphenidate significantly increased "relative" (region relative to the whole brain) metabolism in the cerebellum and decreased it in the basal ganglia. Regional metabolic changes in the cerebellum and the frontal and temporal cortices were significantly correlated with D2 availability. Frontal and temporal metabolism were increased in subjects with high D2 receptors and decreased in subjects with low D2 receptors. CONCLUSIONS: Methylphenidate induced variable changes in brain metabolism, but it consistently increased cerebellar metabolism. It also induced a significant reduction in relative metabolism in the basal ganglia. The significant association between metabolic changes in the frontal and temporal cortices and in the cerebellum and D2 receptors suggests that methylphenidate's metabolic effects in these brain regions are due in part to dopamine changes and that differences in D2 receptors may be one of the mechanisms accounting for the variability in response to methylphenidate.

Adult↗
PubMed2001

Effect of repeated methylphenidate administration on presynaptic dopamine and behaviour in young adult rats.

Methylphenidate, a dopamine reuptake inhibitor, is the most common treatment for attention-deficit hyperactivity disorder and may be prescribed for years, despite little evidence of any long-term benefit, nor knowledge of potential chronic side-effects. Therefore, this study examined the acute and longer-term behavioural effects and assessed striatal dopamine function following subchronic methylphenidate administration to adolescent rats. Male hooded Lister rats received methylphenidate (4 mg/kg i.p. twice daily for 4 days) or saline (1 ml/kg) and the acute locomotor and stereotype behaviour was monitored on days 1 and 4, novel object exploration on day 2 and, following 12 days drug withdrawal, the long-term effect examined on social interaction on day 16. Ex-vivo K+ (20 mM)- and methylphenidate (0.1 mM)-induced [3H]dopamine release from striatal slices and striatal monoamine content were measured on day 18. Compared with saline, methylphenidate induced mild hyperactivity without stereotypy but did not alter novel object exploration and, following withdrawal, had no long-term effect on social interaction. In striatal slices from controls, both K+ and methylphenidate elevated [3H]dopamine release (p < 0.01) while only combined treatment elevated release in methylphenidate pretreated rats, although striatal monoamine content was unaltered compared with control rats. In summary, a repeated dose of methylphenidate that had acute behavioural effects produced no long-term alteration in social interaction but attenuated presynaptic striatal dopamine function.

Animals↗
PubMed2003

The efficacy of 2 different dosages of methylphenidate in treating adults with attention-deficit hyperactivity disorder.

OBJECTIVE: To evaluate the efficacy of methylphenidate in treating adults with attention-deficit hyperactivity disorder (ADHD), using subjective (self-report) and objective (computerized test) measures. METHOD: This double-blind crossover trial of placebo vs methylphenidate included subjects with childhood and current ADHD symptoms, IQs above 80, no other psychiatric condition explaining their difficulties or requiring other treatment, and no substance abuse in the previous 6 months. We administered 10 mg 3 times daily of medication (that is, placebo or methylphenidate) for 2 weeks. On the final day, subjects completed self-report measures and were tested on computerized tests. We then increased dosage to 15 mg 3 times daily for 2 weeks and administered a complete reassessment on the final day. Following a 1-week washout, we repeated this process on the second medication (that is, placebo or methylphenidate). RESULTS: Thirty adults with ADHD participated. Self-report measures and computerized tests showed significant improvements in ADHD symptoms on methylphenidate, compared with placebo. Other psychiatric symptoms (notably, anxiety and depression) were alleviated with methylphenidate. There was no significant difference between the 2 dosages of methylphenidate. CONCLUSION: Methylphenidate is effective in improving ADHD symptoms in adults with ADHD, is well tolerated, and has minimal side effects.

Adolescent↗
PubMed2006

The incidence of methylphenidate use by Canadian children: what is the impact of socioeconomic status and urban or rural residence?

OBJECTIVE: To examine socioeconomic, demographic, and behavioural factors that influence the incidence of methylphenidate use among children aged 4 to 13 years. METHOD: A total of 11,316 children, aged 2 through 11 years, from Cycle 1 (1994-95) of the National Longitudinal Survey of Children and Youth were followed up 2 years later in Cycle 2 (1996-97). The outcome measure was methylphenidate use in Cycle 2. Individual-level explanatory variables included sex, age, socioeconomic status (SES), mother's age at birth of child, lone-parent family status, parental working status, and hyperactivity-impulsivity and inattention probabilities. Area-level explanatory variables included income and rural or urban residence. We used hierarchical linear modelling to examine individual- and area-level factors that predicted methylphenidate use. RESULTS: The strongest predictors of methylphenidate use were behavioural: children with high hyperactive-impulsive and (or) inattention behaviours in 1994, compared with children low on these behaviours, were 4.5 to 6 times more likely to use methylphenidate 2 years later. SES remained a significant predictor of the incidence of methylphenidate use, even when other significant predictors were held constant, with lower SES being associated with higher use. Area-level income also predicted methylphenidate use. CONCLUSION: Even when children with similar behavioural symptoms and demographic characteristics were compared, socioeconomic factors had a significant impact on incidence of methylphenidate use.

Adolescent↗
PubMed2003

Prevalence of and change in the prescription of methylphenidate in Israel over a 2-year period.

INTRODUCTION: The use of methylphenidate for the treatment of attention deficit-hyperactivity disorder (ADHD) has increased dramatically in the past decade in some countries in Europe and North America. In response to a public debate in Israel, several Knesset members introduced a legislative initiative that aims to limit the prescription of methylphenidate by physicians. The objective of this study was to examine the rate methylphenidate prescriptions dispensed for the treatment of ADHD in children in northern and central Israel in 1999 and 2001. PATIENTS AND STUDY DESIGN: The population included all children aged 0-18 years living in central or northern Israel and insured by the largest national health management organisation who were prescribed methylphenidate at least once in 1999 or 2001. This was a population-based prevalence study comparing the two timepoints using data from the health management organisation and descriptive statistics. RESULTS: The overall 1-year prevalence of methylphenidate prescriptions dispensed to children was 1.01% in 1999 and 1.22% in 2001 (relative risk [RR] 1.21, 95% CI 1.15-1.26), an increase of 21%. Seventy-seven percent of those prescribed methylphenidate were boys. The prescription rate ranged from 0.2% (RR 1.24, 95% CI 0.76-2.05) in Arabic cities to 5.99% (RR 1.19, 95% CI 1.09-1.30) in kibbutzim; this wide variation by type of residence apparently involved cultural, racial and economic factors. CONCLUSION: Israel shows no unusual or unexpected patterns in methylphenidate prescriptions dispensed to children and a lesser increase over time than other developed countries. This suggests that limiting physician freedom to prescribe methylphenidate to children may not be justified.

Adolescent↗
PubMed2006

Methylphenidate controlled-delivery capsules (EquasymXL, Metadate CD): a review of its use in the treatment of children and adolescents with attention-deficit hyperactivity disorder.

Controlled-delivery methylphenidate (methylphenidate CD) [EquasymXL, Metadate CD], an oral stimulant, is approved in the US and EU to treat children aged>or=6 years who have been diagnosed with attention-deficit hyperactivity disorder (ADHD). Once-daily methylphenidate CD is generally well tolerated and effective in the treatment of children and adolescents with ADHD. Methylphenidate CD resulted in superior control of ADHD symptoms compared with osmotic release oral system (OROS) methylphenidate over a time period corresponding to that of an average school day in a laboratory classroom. In 3-week clinical trials conducted in a community setting, methylphenidate CD was superior to placebo and noninferior to methylphenidate immediate-release (IR) in the treatment of children and adolescents with ADHD. Thus, methylphenidate CD should be considered an important primary treatment on its own or in addition to behavioral and psychosocial interventions, for when a reduction in ADHD symptoms is required during the school day in preference to the evening.

Adolescent↗
PubMed2000

Ethylphenidate formation in human subjects after the administration of a single dose of methylphenidate and ethanol.

Ethylphenidate was recently reported as a novel drug metabolite in two overdose fatalities where there was evidence of methylphenidate and ethanol coingestion. This study explores the pharmacokinetics of ethylphenidate relative to methylphenidate and the major metabolite ritalinic acid, in six healthy subjects who received methylphenidate and ethanol under controlled conditions. Subjects (three males, three females) received a single oral dose of methylphenidate (20 mg; two 10-mg tablets) followed by consumption of ethanol (0.6 g/kg) 30 min later. Methylphenidate, ritalinic acid, and ethylphenidate were quantified using liquid chromatography-tandem mass spectrometry. Ethylphenidate was detectable in the plasma and urine of all subjects after ethanol ingestion. The mean (+/-S.D.) area under the concentration versus time curve for ethylphenidate was 1.2 +/- 0.7 ng/ml/h, representing 2.3 +/- 1.3% that of methylphenidate (48 +/- 12 ng/ml/h). A significant correlation was observed between the area under the concentration versus time curve of methylphenidate and that of ethylphenidate. In view of the known dopaminergic activity of racemic ethylphenidate, it remains possible that under certain circumstances of higher level dosing, e.g., in the abuse of methylphenidate and ethanol, the metabolite ethylphenidate may contribute to drug effects.

Adult↗
PubMed1992

Methylphenidate and seizure frequency in brain injured patients with seizure disorders.

BACKGROUND: Psychostimulant drugs such as methylphenidate are increasingly being used in patients with traumatic brain injury or other brain injuries for a variety of cognitive and behavioral problems. However, there is some reluctance among clinicians and family members to use methylphenidate in brain injured patients because of warnings of seizure occurrence, which are prominently reported by the product labeling included in the Physicians' Desk Reference. METHOD: We retrospectively studied the use of methylphenidate in 30 consecutive patients with active seizure disorders. We compared the seizure frequency in the 3 months before and after methylphenidate with the seizure frequency during methylphenidate treatment, using the Wilcoxon signed-rank test. RESULTS: Overall, the findings demonstrated a trend toward a lesser incidence of seizures in patients during methylphenidate treatment. Only 4 patients had greater seizure frequency during methylphenidate treatment, and 3 of these 4 were receiving tricyclic antidepressants. CONCLUSION: Methylphenidate can be safely used in brain injured patients, even those at high risk for seizures, as it was associated with a trend toward reduction (rather than increase) in seizure frequency in this population.

Adult↗
PubMed1976

The existence of tolerance to and cross-tolerance between d-amphetamine and methylphenidate for their effects on milk consumption and on differential-reinforcement-of-low-rate performance in the rat.

Administration of d-amphetamine (2.5 mg/kg) or methylphenidate (20 mg/kg) decreased milk consumption in rats. When these drugs were administered daily, tolerance developed to this effect over the course of 20 days. Cross-tolerance to the effects on milk consumption occurred between d-amphetamine and methylphenidate over a 4-fold range of dose of both drugs. Administration of d-amphetamine (1.5 mg/kg) or methylphenidate (10 mg/kg) disrupted responding under differential-reinforcement-or-low-rate (DRL) contingencies. Both drugs increased response rate, decreased frequency of reinforcement and shifted the mode of the inter-response time distribution to the left. When the drugs were administered daily, tolerance developed to all these effects over the course of 20 days. Cross-tolerance to the effects on DRL behavior occurred between d-amphetamine and methylphenidate over a 4-fold range of dose of both drugs. Daily administration of d-amphetamine (2.5 mg/kg) but not of methylphenidate (20 mg/kg) resulted in decreased norepinephrine (NE) levels in brain; the decreased norepinephrine levels, which occur with repeated d-amphetamine administration, are believed to result from the storage in noradrenergic neurons of p-hydroxynorephedrine, a metabolite of d-amphetamine. Radioactivity was not detectable in brain 24 hours after the last of 15 daily doses of radiolabeled methylphenidate. These results suggest that d-amphetamine, but not methylphenidate, is metabolized to a compound which is stored in noradrenergic neurons. The existence of behavioral cross-tolerance between d-amphetamine and methylphenidate is therefore inconsistent with the hypothesis that tolerance to the behavioral effects of d-amphetamine is due to the metabolism of d-amphetamine to p-hydroxynorephedrine, a false transmitter in noradrenergic neurons.

Animals↗
PubMed1993

Effects of methylphenidate on sleep in children with attention-deficient hyperactivity disorder. An activity monitor study.

OBJECTIVE: To assess the effects of methylphenidate hydrochloride on sleep patterns in children diagnosed as having attention-deficit hyperactivity disorder (ADHD). DESIGN: A double-blind, controlled drug-placebo cross-over design. SETTING: Home. SUBJECTS: Ten children (aged 6 years 9 months to 12 years & months) diagnosed as having ADHD were consecutively recruited and compared with age- and sex-matched normal controls. TREATMENT: Methylphenidate hydrochloride (0.3 to 0.4 mg/kg) or placebo was administered at 7:30 AM. MEASUREMENTS AND RESULTS: Each child underwent activity monitoring at home during 6 days of no treatment (baseline) followed by placebo and methylphenidate treatment. The results of the three trial stages, as well as those of the 20 age- and sex-matched normal controls, were compared. A shorter total sleep duration was evident during the methylphenidate treatment compared with that of baseline and placebo treatment. The amount of quiet sleep was lower (however, not significantly) among the study group compared with controls, whereas no such difference was noted during methylphenidate treatment. Night-to-night sleep pattern stability was found. No other differences were found either between children with ADHD and controls or between on and off stages of methylphenidate treatment. CONCLUSIONS: These results support the notion that ADHD is a centrally generated disorder attributable to hypoarousal, which subsequently stimulates motor overactivity. Methylphenidate does not appear to affect sleep patterns adversely and possibly normalizes them in patients with ADHD.

Analysis of Variance↗
PubMed1999

Comparable changes in synaptic dopamine induced by methylphenidate and by cocaine in the baboon brain.

Though the blockade of dopamine transporters (DAT) is associated with cocaine's and methylphenidate's reinforcing effects, it is the stimulation of dopamine (DA) receptors, achieved by increases in synaptic DA, that enables these effects to occur. Positron emission tomography (PET) and [11C]raclopride were used to assess the levels of occupancy of DA D2 receptors by dopamine achieved by doses of cocaine or methylphenidate previously documented to block over 70% of DAT. Studies were performed in five baboons using a paired scan protocol designed to measure DA D2 receptor availability (Bmax/Kd) at baseline conditions and after intravenous administration of either cocaine or methylphenidate. Cocaine (1-2 mg/kg) or methylphenidate (0.5 mg/kg) administered 5 min prior to [11C]raclopride decreased Bmax/Kd by 29+/-3% and 32 + 4%, respectively. Smaller reductions in Bmax/Kd (13% for cocaine given 30 min before [11C]raclopride and 25+/-10% for methylphenidate given 40 min before [11C]raclopride) were seen with longer periods between drug and radioligand. These observations are consistent with the slower striatal clearance kinetics of [11C]methylphenidate than [1C]cocaine observed in previous PET experiments and with the approximately twofold higher potency of methylphenidate than cocaine in in vitro experiments. Though the elevation of synaptic DA induced by >70% occupancy of DAT by these drugs lead to a modest increase in occupancy of D2 receptors (25-30%), further studies are required to assess if this is an underestimation because of differences in D2 receptor binding kinetics between raclopride and DA.

Animals↗
PubMed2003

Bioavailability of modified-release methylphenidate: influence of high-fat breakfast when administered intact and when capsule content sprinkled on applesauce.

Ritalin, an immediate release form of racemic methylphenidate hydrochloride, has been available in the USA since 1955 and is used for the treatment of ADHD. The objective of this study was to evaluate the pharmacokinetics of modified-release methylphenidate (highest single dose), Ritalin LA, when administered under fasting condition, with a high-fat breakfast, and when sprinkled on applesauce in healthy adult subjects. Blood samples were drawn for 24 h following a 40 mg oral administration. Most subjects appeared to produce a bimodal methylphenidate plasma concentration profile. In all three treatment groups, methylphenidate was rapidly absorbed with an initial average t(max(0-4)) of 1.3-2.4 h and an average peak plasma concentration [C(max(abs))] of 14.4-15.2 ng/ml. On average, both the rate [C(max(abs)) and t(max(abs))] and the extent of absorption (AUC(0- infinity)) of methylphenidate were similar when the capsule was given with a high fat breakfast and when the capsule contents were sprinkled onto applesauce, compared with the fasting state. No dose dumping was observed when the capsule was given with a high fat breakfast or when sprinkled onto applesauce. The dose was safe and generally well tolerated. Coadministration of a single oral dose of 40 mg methylphenidate capsule whether administered intact with a high-fat breakfast or sprinkled on applesauce did not affect the overall rate or extent of absorption of methylphenidate compared with the fasted condition.

Administration, Oral↗
PubMed2005

Comparing effects of methylphenidate, sertraline and placebo on neuropsychiatric sequelae in patients with traumatic brain injury.

BACKGROUND: This study aimed to investigate the effects of methylphenidate and sertraline compared with placebo on various neuropsychiatric sequelae associated with traumatic brain injury (TBI). METHODS: This was a 4 week, double-blind, parallel-group trial. Thirty patients with mild to moderate degrees of TBI were randomly allocated to one of three treatment groups (n = 10 in each group) with matching age, gender and education, i.e. methylphenidate (starting at 5 mg/day and increasing to 20 mg/day in a week), sertraline (starting at 25 mg/day and increasing to 100 mg/day in a week) or placebo. At the baseline and at the 4 week endpoint, the following assessments were administered: subjective (Beck Depression Inventory) and objective (Hamilton Depression Rating Scale) measures of depression; Rivermead Postconcussion Symptoms Questionnaire for postconcussional symptoms; SmithKline Beecham Quality of Life Scale for quality of life; seven performance tests (Critical Flicker Fusion, Choice Reaction Time, Continuous Tracking, Mental Arithmetic, Short-Term memory, Digit Symbol Substitution and Mini-Mental State Examination); subjective measures of sleep (Leeds Sleep Evaluation Questionnaire) and daytime sleepiness (Epworth Sleepiness Scale). All adverse events during the study period were recorded and their relationships to the drugs were assessed. RESULTS: Neuropsychiatric sequelae seemed to take a natural recovery course in patients with traumatic brain injury. Methylphenidate had significant effects on depressive symptoms compared with the placebo, without hindering the natural recovery process of cognitive function. Although sertraline also had significant effects on depressive symptoms compared with the placebo, it did not improve many tests on cognitive performances. Daytime sleepiness was reduced by methylphenidate, while it was not by sertraline. CONCLUSIONS: Methylphenidate and sertraline had similar effects on depressive symptoms. However, methylphenidate seemed to be more beneficial in improving cognitive function and maintaining daytime alertness. Methylphenidate also offered a better tolerability than sertraline.

Adult↗
PubMed2005

Methylphenidate analogs with behavioral differences interact differently with arginine residues on the dopamine transporter in rat striatum.

The methylphenidate analogs N-methyl-4-methyl-methylphenidate and N-benzylmethylphenidate are believed to interact differently with the dopamine transporter (DAT) in vitro and in vivo. Herein, we report that methylphenidate and N-methyl-4-methyl-methylphenidate, but not N-benzylmethylphenidate, protect the rat striatal DAT from the arginine-selective chemical modifying agent, phenylglyoxal. This suggests that methylphenidate and N-methyl-4-methyl-methylphenidate, but not N-benzylmethylphenidate, interact with the guanidine groups of arginine residues in the DAT of rat striatum. This differential interaction may, at least in part, explain the in vitro and in vivo differences between N-methyl-4-methyl-methylphenidate and N-benzylmethylphenidate.

1-Methyl-4-phenylpyridinium↗
PubMed1982

Sensitization of mice to methylphenidate.

Mice that received five daily injection of methylphenidate HCl, 10-75 mg/kg, showed an increased running response to methylphenidate, cocaine, and amphetamine. Sensitization to methylphenidate persisted for at least 50 days. Repeated IP injections of methylphenidate into mice with unilateral striatal lesions increased ipsilateral turning in response to methylphenidate, but decreased contralateral turning after apomorphine. The climbing response to apomorphine in intact, methylphenidate-sensitized mice was also decreased. There was no change in either basal or dopamine-stimulated adenyl cyclase activity in the striata of sensitized mice, but there was a 36% increase in the specific binding of haloperidol. The rate of turnover of striatal dopamine was increased in sensitized mice. These results suggest that pretreatment with methylphenidate may alter the sensitivity of presynaptic dopamine receptors.

Adenylyl Cyclases↗
PubMed1984

Effects of methylphenidate (Ritalin) on information processing in hyperactive children.

The effect of methylphenidate on information-processing efficiency was studied in 12 hyperactive, nonretarded children. Performance on six efficiency tasks (Posner Letter Matching, Reaction Time, Memory Search, Category Verification, Item Identification, and Word-Span) and a general measure of on-task behavior were compared for children receiving methylphenidate or a placebo. The median drug dosage was .38 mg/kg, and it was ingested 1 1/2 hours prior to testing. Children blind to the drug-placebo condition were tested on 4 days. In general, methylphenidate-related improvements in attention to on-task behaviors were found. An overall analysis of processing speed suggested that methylphenidate improved efficiency. Methylphenidate significantly decreased reaction times to simple and complex stimulus arrays; differences due to the drug remained even when on-task attentive behaviors were statistically removed. Significantly fewer identification errors occurred on the Posner task in the methylphenidate condition. Results indicated that methylphenidate improved general attentional behaviors and positively influenced processes that define perceptual efficiency.

Adolescent↗