Tablets: Administer in divided doses 2 or 3 times daily, preferably 30 to 45 minutes before meals. Average dosage is 20 to 30 mg daily. Some patients may require 40 to 60 mg daily. In others, 10 to 15 mg daily will be adequate. Patients who are unable to sleep if medication is taken late in the day should take the last dose before 6 p.m.
# Children (6 years and over)
Ritalin should be initiated in small doses, with gradual weekly increments. Daily dosage above 60 mg is not recommended.
Tablets: Start with 5 mg twice daily (before breakfast and lunch) with gradual increments of 5 to 10 mg weekly.
SR Tablets: Ritalin-SR tablets have a duration of action of approximately 8 hours. Therefore, Ritalin-SR tablets may be used in place of Ritalin tablets when the 8-hour dosage of Ritalin-SR corresponds to the titrated 8-hour dosage of Ritalin. Ritalin-SR tablets must be swallowed whole and never crushed or chewed.
|Effects on the Brain||
Ritalin is just one brand name for methylphenidate. Sustained- or extended-release formulas of methylphenidate are sold as Ritalin SR, Ritalin LA, Metadate ER, Metadate CD, Methylin ER, and Concerta.
Like other stimulants, such as cocaine and amphetamine, Ritalin increases the activity of dopamine, a neurotransmitter associated with pleasure and important for reinforcement of behavior. While amphetamines stimulate the release of dopamine, cocaine and Ritalin block the transporters that reuptake dopamine into the neuron that released it. One of the theories as to why Ritalin helps people with ADHD is that they may have more dopamine transporters than others. The excess of transporters removes dopamine from the synapse before it can reach a dopamine reward receptor in the receiving neuron, so the attention circuitry in the ADHD brain is under stimulated. By blocking transporters, Ritalin allows more dopamine to reach receptors, thus increasing attention signaling, which helps people with ADHD to focus. Ritalin, when taken orally, slowly raises dopamine levels over the course of an hour or so. By contrast, when inhaled or injected, cocaine reaches the brain in seconds, producing a high
The effects of Ritalin, both adverse and desired, are similar to the effects of amphetamines. Like many substances, the effects of Ritalin are dose-dependent. Therapeutic dosage begins at 5 to 10 mg, one to three times a day, for children over six, but does not exceed 60 mg daily, even in adults. Heavily dependent recreational users may take hundreds of milligrams per day, increasing their dose as they build a tolerance to the desired effects.
The long-term effects of therapeutic doses of Ritalin are not clearly known. Some studies have shown long-term use of Ritalin may suppress growth in both height and weight, while other studies contradict this finding. Minor growth suppression and weight loss does occur in children under long-term psycho stimulant treatment, but some have suggested that weight loss may be more common in children who weigh more than the average for their height before they begin taking Ritalin, and growth deficits may be partly related to ADHD rather than the medication.
The effects of long-term Ritalin abuse are similar to those experienced by amphetamine users, including anxiety and sleeplessness. Ritalin abusers who inject high doses on a daily basis may experience a toxic state resembling acute paranoid schizophrenia. Additionally, the talcum filler in the tablets abusers crush and dissolve in water may cause lesions at the injection site.
|Tolerance, Dependence, & Withdrawal||
Children and adults prescribed Ritalin to treat ADHD or narcolepsy do not appear to develop tolerance to its therapeutic effects, but abusers develop tolerance to the effects they seek from the drug. Chronic heavy use can lead to physical dependence, and withdrawal symptoms include exhaustion and severe emotional depression. Ritalin abusers who become psychologically dependent may experience cravings for the drug and feelings of panic if the drug becomes temporarily unavailable.