Paper I
Question
Amphetamine
Answer
Amphetamine is an indirectly acting sympathomimetic and CNS stimulant.
Mechanism of action
- Promotes release of stored catecholamines (dopamine, noradrenaline) from presynaptic nerve terminals
- Also weakly inhibits monoamine oxidase and blocks reuptake of catecholamines
- Crosses the blood-brain barrier readily, producing marked CNS stimulation
Actions
- CNS: wakefulness, alertness, elevated mood, decreased appetite (anorexiant), improved physical performance/reduced fatigue
- Peripheral: sympathomimetic effects — increased heart rate and blood pressure
Uses
- Attention-deficit hyperactivity disorder (ADHD, e.g., dextroamphetamine)
- Narcolepsy
Adverse effects
- Insomnia, restlessness, anxiety
- Tolerance and dependence (high abuse potential)
- Tachycardia, hypertension
- Psychosis with chronic high-dose use
- Anorexia, weight loss