Methylphenidate is a central nervous system (CNS) stimulant of the phenethylamine and piperidine classes. It is a first-line pharmacological agent for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) and is also indicated for narcolepsy. It primarily acts by blocking the reuptake of dopamine and norepinephrine in the presynaptic neuron, increasing their concentration in the synaptic cleft. In India, it is a strictly regulated Schedule X drug under the Drugs and Cosmetics Act, 1940, requiring a special prescription.
Adult: ADHD: Start with 5mg once or twice daily (e.g., morning and noon). Titrate gradually by 5-10mg increments weekly based on response and tolerability. Typical effective dose range: 20-30mg/day in 2-3 divided doses. Maximum: 60mg/day. Narcolepsy: 20-30mg/day in divided doses.
Note: Administer orally, with or without food (food may delay absorption). Tablets should be swallowed whole with water. Doses are typically given in the morning and early afternoon to avoid insomnia. The last dose should not be taken after 4-6 PM. Do not crush or chew unless specifically instructed (some brands may have different formulations).
Methylphenidate is a potent blocker of the dopamine transporter (DAT) and norepinephrine transporter (NET). It binds to these transporters on the presynaptic neuronal membrane, inhibiting the reuptake of dopamine and norepinephrine from the synaptic cleft back into the presynaptic neuron. This leads to a significant increase in the extracellular concentrations of these neurotransmitters in key brain regions, particularly the prefrontal cortex and striatum.
Pregnancy: Pregnancy Category C (US FDA). Animal studies have shown adverse effects. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Neonates born to mothers dependent on methylphenidate may experience withdrawal symptoms.
Driving: May impair ability to drive or operate machinery, especially during initial treatment or dose adjustment. Patients should be cautioned until they are aware of how the medication affects them. Drowsiness or dizziness can occur.
| Monoamine Oxidase Inhibitors (MAOIs) - e.g., Phenelzine, Selegiline | Risk of hypertensive crisis, hyperpyrexia, serotonin syndrome. Potentially fatal. | Contraindicated |
| Anticoagulants (e.g., Warfarin) | Methylphenidate may inhibit metabolism of warfarin, increasing INR and bleeding risk. | Major |
| Anticonvulsants (e.g., Phenobarbital, Phenytoin, Primidone) | Methylphenidate may increase levels of these drugs, leading to toxicity. | Major |
| Tricyclic Antidepressants (TCAs - e.g., Imipramine, Desipramine) | Mutual inhibition of metabolism; increased levels of both drugs. Increased risk of cardiovascular effects. | Major |
| Pressor Agents (e.g., Dopamine, Epinephrine) | Additive pressor effects, leading to severe hypertension. | Major |
| Clonidine | Possible serious adverse events including sudden death reported (controversial, use with extreme caution). | Major |
| Alcohol | May alter the absorption profile of methylphenidate. CNS depression may be masked. Increases risk of cardiovascular side effects. | Major |