Psychomotor Stimulants Overview

Psychomotor Stimulants

• Mechanism of Action: These drugs cause excitement, euphoria, reduced fatigue, and increased motor activity.

• Examples: Amphetamine, Atomoxetine, Caffeine, Cocaine, Methylphenidate, Modafinil, Nicotine, Theobromine, Theophylline

• Duration of Action (Half-life): Varies significantly: Amphetamine (12-36 hours), Methamphetamine (8-17 hours), Ecstasy (7-9 hours), Cocaine (45-90 minutes).

• Methylxanthines (Subcategory): Theophylline, Theobromine, Caffeine

  • Mechanism of Action: Inhibit phosphodiesterase and block adenosine receptors.
  • Effects (Caffeine): Low doses decrease fatigue and enhance mental alertness. High doses (1.5g+) cause anxiety and tremors.
  • Gastrointestinal Effects: Stimulate HCl secretion, caution for peptic ulcer patients.
  • Therapeutic Uses: Bronchodilation (Theophylline, less common now), migraine treatment (Caffeine + Ergot alkaloid).
  • Pharmacokinetics: Oral administration, crosses blood-brain barrier and placenta.
  • Side Effects (Moderate Doses): Insomnia, anxiety, agitation. High doses lead to emesis and convulsions.
  • Caffeine Toxicity: Lethal dose around 10g (100+ cups), causes cardiac arrhythmias. Withdrawal includes fatigue and sedation.

• Nicotine (Subcategory):

  • Mechanism of Action: Low doses stimulate, high doses block ganglionic transmission.
  • CNS Effects: Low doses: euphoria, arousal, relaxation. Improved attention, learning, problem-solving. High doses: respiratory paralysis, severe hypotension.
  • Peripheral Effects: Increased heart rate, blood pressure, pupillary constriction. High doses: decreased blood pressure, GI/bladder paralysis.
  • Toxicity: Acute lethal dose around 60mg. High absorption rate in smoke.
  • Side Effects: Tremors, intestinal cramps, diarrhea, increased heart rate and blood pressure.
  • Withdrawal Syndrome: Severe physical dependence, characterized by irritability, anxiety, difficulty concentrating, headaches, insomnia, and GI pain.
  • Treatment Options: Transdermal/chewable/inhaled nicotine, Cystisine, Varenicline, Bupropion, Mecamylamine, Naltrexone.

• Cocaine and Amphetamine: Classified as drugs of abuse (detailed information not included)

• Methylphenidate: Schedule II drug, ADHD treatment (children 6-16), also used for narcolepsy. Increases dopamine availability for children with ADHD.

  • **Mechanism of Action:**Increases dopamine availability
  • Side Effects: GI problems, anorexia, insomnia, nervousness, fever
  • Contraindications: Glaucoma
  • Drug Interactions: Potential interaction with metabolism of Warfarin, diphenylhydantoin, phenobarbital, primidone, and TCAs

Hallucinogens

• Mechanism of Action: Produce profound changes in thought patterns and mood, have minimal effect on brainstem and spinal cord.
• Examples: Lysergic acid diethylamide (LSD), Phencyclidine (PCP), Rimonabant, Tetrahydrocannabinol (THC)
• Consequences: Impair rational decision-making due to altered thought processes. (Detailed information not included)

Explore the mechanisms of action, examples, and effects of psychomotor stimulants such as amphetamines and caffeine. This quiz covers the pharmacokinetics, therapeutic uses, and important considerations regarding these drugs. Test your understanding of how these substances work and their implications on health.