Overview & Classes - Brain's Fast Lane
Psychostimulants: Drugs that ↑ alertness, wakefulness, & locomotor activity.
- Core MOA: Potentiate catecholamine (Dopamine, Norepinephrine) effects.
- Key Uses: ADHD, narcolepsy.
- Major Risk: High abuse potential.
Classification of Psychostimulants:
| Class | Examples | MoA (Primary) |
|---|---|---|
| Amphetamines | Amphetamine, Methamphetamine | ↑ DA/NE release & ↓ reuptake |
| Methylphenidate | Methylphenidate | Blocks DA/NE reuptake |
| Xanthines | Caffeine, Theophylline | Adenosine antag., PDE inhib. |
| Modafinil | Modafinil, Armodafinil | Atypical (?DAT inh.) |
| Cocaine | Cocaine | Blocks DA/NE/5-HT reuptake |
MoA & Pharmacokinetics - Neurotransmitter Party
- Mechanism of Action (MoA): General effect: ↑ synaptic Dopamine (DA), Norepinephrine (NE), & Serotonin (5-HT).
- 📌 Mnemonic: Stimulants ARE UP (Amphetamines Release Efflux; Uptake blocked by Phenidates/Cocaine).
- Amphetamines & derivatives: Promote NT release from presynaptic vesicles.
- Cocaine, Methylphenidate: Inhibit reuptake transporters (DAT, NET, SERT).
- Pharmacokinetics (PK):
- Absorption: Rapid (oral, IV, inhalation).
- Distribution: Highly lipid-soluble, readily cross Blood-Brain Barrier (BBB).
- Metabolism: Primarily hepatic (e.g., CYP2D6 for amphetamine).
- Excretion: Renal; urine pH influences amphetamine excretion (acidic pH ↑ excretion).
⭐ Cocaine is unique among psychostimulants for its additional action as a sodium channel blocker, leading to local anesthetic effects.
Specific Drugs & Indications - Focus & Wakefulness
| Drug | Primary MoA | Key Use(s) | Unique Side Effect/Note |
|---|---|---|---|
| Methylphenidate | NET & DAT block; ↑ DA/NE | ADHD, Narcolepsy | Insomnia, ↓Appetite, headache; 📌 MPH: More Productive Hours (less sleep/food) |
| Amphetamine | ↑ NE/DA release; NET/DAT block | ADHD, Narcolepsy, Binge eating disorder | Psychosis risk, Abuse potential, HTN; Growth delay (children) |
| Modafinil | Atypical DAT block; ↑ Histamine, Orexin; ↓ GABA | Narcolepsy, SWSD, OSA (adjunct) | SJS (rare), headache; Less abuse potential than amphetamines |
| Atomoxetine | Selective NET block (SNRI); ↑ NE in PFC | ADHD (esp. with substance abuse risk/tics) | Non-stimulant; Suicidal ideation (BBW); Hepatotoxicity, Somnolence |
Adverse Effects & Cautions - Handle With Care
- Common Adverse Effects:
- CNS: Insomnia, anxiety, irritability, nervousness, headache.
- CVS: Tachycardia, palpitations, ↑BP.
- GI: Anorexia, weight loss, dry mouth, nausea.
- Serious Adverse Effects:
- Dependence, tolerance, withdrawal symptoms.
- Psychotic episodes, hallucinations (especially with abuse).
- Seizures (may lower threshold).
- Cardiovascular events (MI, stroke, sudden death in those with pre-existing cardiac conditions).
- Growth suppression in children (monitor height/weight).
- Contraindications & Cautions: ⚠️
- Known hypersensitivity.
- Symptomatic cardiovascular disease (arrhythmias, severe hypertension).
- Glaucoma (angle-closure).
- Hyperthyroidism.
- Agitated states, severe anxiety.
- History of drug abuse.
- Tourette’s syndrome or tics.
- MAOI use (concurrently or within 14 days).
⭐ Concomitant use of psychostimulants (e.g., amphetamine, methylphenidate) with MAOIs is contraindicated. This combination poses a high risk of life-threatening hypertensive crisis due to synergistic increases in synaptic norepinephrine.
High‑Yield Points - ⚡ Biggest Takeaways
- Psychostimulants primarily ↑ DA & NE; cocaine blocks reuptake, amphetamines also promote release.
- Key uses: ADHD (methylphenidate, amphetamines), narcolepsy (modafinil, amphetamines).
- Methylphenidate: Common for ADHD, acts by blocking DAT and NET.
- Adverse effects: Sympathomimetic (tachycardia, HTN), insomnia, psychosis; risk of dependence & withdrawal.
- Cocaine uniquely blocks Na+ channels (local anesthetic effect) & causes coronary vasospasm.
- Modafinil is an atypical stimulant for narcolepsy with lower abuse potential than amphetamines.
Continue reading on Oncourse
Sign up for free to access the full lesson, plus unlimited questions, flashcards, AI-powered notes, and more.
CONTINUE READING — FREEor get the app
