Methylphenidate: Drug Effects, Side Effects, Dosage and Uses

Products

Methylphenidate is commercially available in many countries in the form of tablets, film-coated tablets, sustained-release tablets, and sustained-release capsules (e.g., Ritalin, Concerta, Medikinet, Equasym, generics). It has been approved since 1954. The drug is subject to strict control as a narcotic and is available only by prescription. The isomer dexmethylphenidate (Focalin XR) is also commercially available.

Structure and properties

Methylphenidate (C14H19NO2, Mr = 233.3 g/mol) is a piperidine derivative of the stimulant amphetamine. In pharmaceuticals, it exists as methylphenidate hydrochloride, a white, odorless, crystalline powder that is highly soluble in water. It has two chiral centers and four isomers are possible. However, only the two D,L-threo forms are used in practice. The pure D-threo isomer dexmethylphenidate is also approved in many countries and is considered to be mainly pharmacologically active.

Effects

Methylphenidate (ATC N06BA04) has central stimulant and sympathomimetic properties. Its effects in ADHD are thought to be due in part to increases in synaptic dopamine and norepinephrine in the central nervous system. Methylphenidate inhibits the reuptake of these neurotransmitters into the presynaptic neuron.

Indications

For the treatment of attention-deficit/hyperactivity disorder ADHD and for the treatment of narcolepsy. Methylphenidate should be prescribed for ADHD as part of a comprehensive treatment program.

Dosage

According to the SmPC. The maximum daily dose ranges from 5 to 60 mg. Because of the short half-life of only two hours, sustained-release dosage forms are increasingly used today, which are taken as a single dose in the morning and release the active ingredient continuously throughout the day.

Abuse

There are numerous reports of abuse of methylphenidate as a central nervous stimulant in everyday life and at work, as a party drug, and as an intoxicant and stimulant. This is also reflected in popular culture. In one episode of the television series, the overwhelmed mother Lynette Scavo swallows her children’s ADHD medication in order to better manage the household. Methylphenidate is also abused by students as a so-called “smart drug” for cognitive performance enhancement to improve academic performance. It is applied orally and intravenously or snorted. The dose is often higher than therapeutic use, which is why more adverse effects and symptoms of overdose and chronic intoxication occur. Due to the release of dopamine, the effects are similar to those of cocaine and lead to a “high” and euphoria (especially with parenteral and intranasal application) and increased performance. Due to acute and chronic adverse effects and the development of dependence, it must be strongly discouraged. Withdrawal symptoms such as lethargy, apathy, depression, and paranoia may occur upon discontinuation. Abusive use is not advised.

Contraindications

Numerous precautions must be observed during use. Full precautions can be found in the drug label.

Interactions

Methylphenidate is biotransformed by the carboxylesterase CES1A1 and does not interact with CYP450. Drug-drug interactions have been described with MAO inhibitors (contraindicated), antihypertensive agents, halogenated anesthetics, vitamin K antagonists, antiepileptics, antidepressants, clonidine, antihypertensives, and alcohol.

Adverse effects

The most common possible adverse effects include:

Methylphenidate, as an amphetamine, can potentially cause numerous adverse effects, can be overdosed and abused. Possible consequences of long-term treatment on health are not fully known (growth retardation, mental illness, development of substance dependence?).Many parents are reluctant to use psychotropic drugs on their children.