Learning Objectives
By the end of this session, the learner will be able to distinguish between Stimulant and Non-stimulant ADHD medications, explain the mechanism of action for Methylphenidate and Amphetamines, and identify the unique side effects of Alpha-2 agonists.
1. Stimulants (First-Line Therapy)
Stimulants are the most effective treatments for ADHD. They work by rapidly increasing the availability of catecholamines in the prefrontal cortex.
| Drugs | Mechanism of Action | Primary Side Effects |
|---|---|---|
| Methylphenidate, Amphetamine, Dextroamphetamine | Block reuptake and enhance the release of NE and Dopamine. | Insomnia, agitation, restlessness, and appetite suppression. |
2. Non-Stimulants (Alternatives)
Non-stimulants are used when stimulants are poorly tolerated, ineffective, or when there is a great concern for substance abuse.
| Drug Class | Example | Key Mechanism / Benefit |
|---|---|---|
| Selective NRI | Atomoxetine | Selective NE reuptake inhibitor; lacks abuse potential. |
 Agonists |
Clonidine, Guanfacine | Sympatholytic effect; often used for comorbid tics or aggression. |
3. High-Yield Side Effects & Toxicity
The side-effect profile of ADHD medications is a common target for board examinations, particularly regarding cardiovascular and autonomic effects.[Image comparing the sympathetic activation of stimulants vs the sympatholytic effect of alpha-2 agonists]
| Medication | Critical Side Effects | Clinical Warning |
|---|---|---|
| Stimulants | Cardiovascular toxicity (Tachycardia, Hypertension). | Potential for abuse and diversion (Schedule II). |
| $\alpha_2$ Agonists | Sedation, Hypotension, and constipation. | Monitor blood pressure; avoid abrupt withdrawal. |
Clinical Pearls:
- Growth Monitoring: Children on chronic stimulants should have their height and weight monitored due to appetite suppression.
- Abuse Potential: Atomoxetine is the preferred choice for ADHD in patients with a personal or strong family history of substance use disorder.