CNS Stimulants Overview - The Kickstarters
CNS stimulants are drugs that ↑ alertness, attention, energy, and wakefulness. They primarily act by enhancing central neurotransmission, especially involving catecholamines.
⭐ Most CNS stimulants act by enhancing catecholaminergic (Dopamine, Norepinephrine) transmission.
Major Categories:
| Category | Examples | Core Mechanisms / Effects |
|---|---|---|
| Psychomotor Stimulants | Amphetamine, Cocaine, Methylphenidate | ↑ DA & NE (release/reuptake block); euphoria |
| Methylxanthines | Caffeine, Theophylline, Theobromine | Adenosine R antagonist; PDE inhibition |
| Analeptics | Doxapram, Nikethamide (obsolete) | Direct brainstem stimulation (historical use) |
| Cognitive Enhancers | Modafinil, Armodafinil, Piracetam | Promote wakefulness; enhance cognition |
- Key Indications: ADHD, narcolepsy, fatigue; some for cognitive enhancement.
- Common Adverse Effects: Insomnia, restlessness, tachycardia, hypertension, abuse potential.
Psychomotor Stimulants - Amped Up!
| Drug | MOA | Uses | Key ADRs | Abuse Potential |
|---|---|---|---|---|
| Amphetamine | Promotes DA & NE release, inhibits reuptake | ADHD, narcolepsy, binge eating disorder | Insomnia, hypertension, anorexia, psychosis, palpitations, dependence | High |
| Methylphenidate | Blocks DA & NE reuptake transporters | ADHD, narcolepsy | Insomnia, anorexia, headache, irritability, growth suppression, tachycardia | High |
| Modafinil | Atypical DA reuptake inhibitor; ↑Histamine, orexin, glutamate; ↓GABA | Narcolepsy, shift work sleep disorder, OSA adjunct | Headache, anxiety, nausea, insomnia; rare: SJS/TEN | Lower |
| Cocaine | Blocks DA, NE, & 5-HT reuptake transporters | Topical anesthetic, vasoconstrictor (ENT) | Myocardial infarction, arrhythmias, stroke, seizures, psychosis, nasal septal perforation | Very High |
⭐ Methylphenidate and amphetamines are first-line for ADHD, but carry a risk of dependence and cardiovascular side effects.
Methylxanthines & Analeptics - Perk & Prod
- Caffeine/Theophylline (Methylxanthines)
- MOA: Adenosine A1/A2A receptor antagonism, phosphodiesterase (PDE) inhibition (↑cAMP).
- Uses: Apnea of prematurity (caffeine citrate), mild CNS stimulant, bronchodilator (theophylline).
- ADRs: Insomnia, anxiety, tremors, arrhythmias, GI upset. Theophylline: narrow therapeutic index.
- Doxapram (Analeptic)
- MOA: Stimulates peripheral carotid chemoreceptors & central respiratory centers.
- Uses: Post-anesthetic respiratory depression, COPD (short-term). Limited use.
- ADRs: Hypertension, tachycardia, arrhythmias, seizures.
⭐ Caffeine's stimulant effect is primarily due to antagonism of adenosine A1 and A2A receptors.
Cognitive Enhancers - Brain Boosters
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Alzheimer's Disease Management: 📌 Alzheimer's Drugs: AChEIs (Donepezil, Rivastigmine, Galantamine) for mild-moderate; NMDA Antagonist (Memantine) for moderate-severe.
Feature Acetylcholinesterase Inhibitors (AChEIs) NMDA Receptor Antagonist Drugs Donepezil, Rivastigmine, Galantamine Memantine MOA Reversibly inhibit AChE, ↑ACh at synapse Non-competitive NMDA antagonist, ↓$Ca^{2+}$ influx, ↓glutamate excitotoxicity Key Uses Mild to moderate Alzheimer's; symptomatic relief Moderate to severe Alzheimer's; neuroprotective; often with AChEIs Common ADRs GI upset (nausea, vomiting, diarrhea), insomnia, dizziness, bradycardia Dizziness, headache, confusion, agitation, constipation ⭐ Donepezil is a commonly used acetylcholinesterase inhibitor for mild to moderate Alzheimer's, while Memantine is used for moderate to severe stages.
-
Other Nootropics:
- Piracetam: A nootropic; proposed MOA includes AMPA receptor modulation & improved neuronal membrane fluidity. Clinical efficacy for cognitive enhancement remains controversial.
High‑Yield Points - ⚡ Biggest Takeaways
- Methylphenidate & Atomoxetine: Key for ADHD; differing mechanisms (DAT/NET block vs NRI).
- Amphetamines: ↑ DA/NE release; for ADHD, narcolepsy; high abuse risk.
- Modafinil: For narcolepsy; atypical stimulant, lower abuse potential than amphetamines.
- Caffeine: Methylxanthine; adenosine receptor antagonist; mild CNS stimulant.
- Cocaine: Blocks DA, NE, 5-HT reuptake; potent sympathomimetic, highly addictive.
- Alzheimer's drugs: Cholinesterase inhibitors (Donepezil) for mild-moderate; Memantine (NMDA antagonist) for moderate-severe_._
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