Medication Treatments for ADHD - Methylphenidate HCL and Sustained - Release Preparations

Written by Lewis Mehl-Madrona, MD, PhD

Methylphenidate HCL (Ritalin) and sustained-release preparations (Ritalin-SR, Concerta, Metadate CD):

Ritalin is said to affect as much as a 70% improvement in those affected with ADHD. Ritalin is supposed to induce hyperperfusion [increase blood supply] to the frontal lobes of the brain. Of all the ADHD medications, Ritalin is the most inconsistently absorbed. Some adults and children absorb as much as 80-90% of the medication, whereas others only absorb 30-40% of a medication dose.

Methylphenidate is derived from the same family as cocaine and increases blood flow to the basal ganglia and decreases flow to frontal and motoric regions. The basal ganglia are involved in the control of movement. Parkinson's disease, for example, is caused by a degeneration of certain neurons located in the mid-brain that send axons to parts of the basal ganglia. Cerebral studies in persons with ADHD have shown cerebral hypoperfusion in the frontal lobe and decreased blood flow to the caudate nucleus. The amygdala, considered by some anatomists to be part of the basal ganglia, is located within the temporal lobe near its rostral tip. The side effects of Methylphenidate include facial tics and a delay in the onset of action.

Some important facts to remember about Ritalin & Methylphenidate:

1. Its onset of action is rapid: 20-30 minutes.
2. It has the shortest duration of action of 2-4 hours. Many children only benefit for 3 hours from medication.
3. There may be a significant "rebound" when the medication wears off, constituted by over-agitation and/or anxiety.

Summary Drug Monograph:

Clinical Pharmacology:

The mode of action of Methylphenidate hydrochloride (Ritalin) in man is not completely understood, but methylphenidate presumably activates the brain stem arousal system and cortex to produce its stimulant effect.

There is neither specific evidence which clearly establishes the mechanism whereby methylphenidate produces its mental and behavioral effects in children, nor conclusive evidence regarding how these effects relate to the condition of the central nervous system.
Methylphenidate hydrochloride in extended-release tablets is more slowly but as extensively absorbed as in the regular tablets. Bioavailability of the MD Pharmaceutical Inc. methylphenidate hydrochloride extended-release tablet was compared to a sustained release reference product and an immediate-release product. The extent of absorption for the three products was similar, and the rate of absorption of the two sustained-release products was not statistically different.

Dosage and Aministration:
Children (6 years and over):

Methylphenidate hydrochloride should be initiated in small doses, with gradual weekly increments. Daily dosage above 60 mg is not recommended.

If improvement is not observed after appropriate dosage adjustment over a one-month period, the drug should be discontinued.

Tablets: Start with 5 mg twice daily (before breakfast and lunch) with gradual increments of 5 to 10 mg weekly.

Extended-Release Tablets: Methylphenidale hydrochloride extended-release tablets have a duration of action of approximately 8 hours. Therefore, the extended-release tablets may be used in place of the immediate-release tablets when the 8-hour dosage of methylphenidate hydrochloride extended-release tablets corresponds to the titrated 8-hour dosage of the immediate-release tablets. Methylphenidate hydrochloride extended-release tablets must be swallowed whole and never crushed or chewed.
If paradoxical aggravation of symptoms or other adverse effects occur, reduce dosage, or, if necessary, discontinue the drug.

Methylphenidate should be periodically discontinued to assess the child's condition. Improvement may be sustained when the drug is either temporarily or permanently discontinued. Drug treatment should not and need not be indefinite and usually may be discontinued after puberty.

Warnings:
Methylphenidate should not be used in children under six years, since safety and efficacy in this age group have not been established.