Long-acting stimulants in ADHD
Concerta, Ritalin LA, and Vyvanse are all medications used to treat ADHD, but they use different delivery systems and mechanisms in the body. These medications have the benefit of providing single daily dosing, which is a consideration for children at school, as children can feel embarrassed having to take extra short-acting stimulants. Long-acting stimulants may also improve compliance with medication.
Concerta
Delivery System: Concerta uses an advanced osmotic-controlled release oral delivery system (OROS), which acts like a “micro pump” inside the body.
The tablet has a rugged, non-digestible shell with a laser-drilled hole at one end. After swallowing, a small amount of non-polymerised methylphenidate in the outer coating dissolves quickly, providing an initial rapid effect within 10–15 minutes. Water from the gastrointestinal tract enters the tablet through a semi-permeable membrane, gradually swelling a special “push compartment” made of an osmotically active polymer. As the polymer swells, it pushes the methylphenidate out through the tiny exit port at a controlled rate, resulting in a steady release of medication over 10–12 hours.
The internal structure is divided into two drug compartments: about 30% of the drug is in the first compartment (released earlier in the day), and 70% is in the second compartment (released later), creating an “ascending dose” profile that helps maintain symptom control throughout the day.
Ritalin LA: Immediate and Delayed Release Beads
Ritalin LA uses SODAS® (Spheroidal Oral Drug Absorption System) technology, which contains a mixture of two types of beads in each capsule.
50% of the beads are immediate release, providing a rapid onset like standard Ritalin tablets. The other 50% are enteric-coated, delayed-release beads that dissolve more slowly, releasing the second half of the dose about four hours later.
This design provides two peaks of medication in the bloodstream: one after taking the capsule and another several hours later, offering coverage for up to 8 hours.
If the capsule cannot be swallowed, it can be sprinkled onto apple puree or yoghurt in a teaspoon. It should not be chewed, as it can damage the outer coating, which is crucial for delayed release. It shouldn’t be mixed in water and swallowed, as it doesn’t dissolve, and the beads can stick to the sides of the glass, making it inefficient for delivering contents. The absorption can be affected by a high-fat diet, and fat can also damage the coating of the long-acting beads.
Lisdexamphetamine (Vyvanse)
Lisdexamphetamine is an inactive prodrug until it is metabolised in the body. Lis dexamphetamine is Amphetamine combined with the amino acid Lysine.
After ingestion, Lis dexamphetamine is absorbed into the bloodstream and then converted by enzymes in the body (mainly in the blood) into its active form, dexamphetamine. This conversion process results in a gradual onset and a long duration of action, typically lasting 10–14 hours. Because activation depends on metabolism, Lis dexamphetamine has a lower risk of abuse.
Lis dexamphetamine needs to be swallowed whole. The capsule can be opened, and the contents can be dissolved in water or yoghurt. Stir the liquid until it’s fully dissolved, then drink straight after. Depending on the dose the treating doctor advises, the dose can be adjusted as needed. It can be taken with or without food in the morning and generally starts to work in one to two hours. The effect will build up in the next few weeks.
The common side effects noted are poor appetite, poor sleep, headache, abdominal symptoms, dry mouth, dizziness, tachycardia, nervousness, and a change in mood. It’s not recommended to cease the medication abruptly, and if the child needs to come off it, it should be reduced over weeks.
In a combination form with Lysine, Dexamphetamine is rendered inactive. Once inside the body, it’s released slowly. Hence, it doesn’t give an immediate “high” if injected, sniffed or swallowed. And therefore, it doesn’t have the potential for abuse or addiction.
In clinical practice, the response to different agents is variable, as some patients’ reactions to the various agents are not predictable. Hence, the medicine is individualised to the patients and dose adjusted by clinicians based on several factors. Regular reviews with clinicians experienced in using these medications are essential for changing the dose and surveillance of side effects.
Acknowledgement: I thank Dr Aster Kuriakose, a General Paediatrician and Specialist in Developmental Paediatrics, for reviewing the article and providing immensely valuable contributions.
Disclaimer
Brand names are used in this article as clinicians and patients may be more familiar with them, but I have no affiliation with drug companies. The article is for information and is not peer-reviewed. It intends to provide information and share clinical experience. The choice of initiating the medication is carefully made by the concerned clinicians, considering various factors, and parents are advised to follow the clinicians’ advice for treating ADHD with these medications.
Suggested resources
Mark Selikowitz. Fast Facts. ADHD. Oxford University Press, 2021.
Christopher Green, Kit Chee. Understanding ADHD. Doubleday, 2001.