CNS Stimulants

Question 1

three categories of drug

Answer 1

1. convulsants & respiratory stimulants
2. Psychotomimetric drugs
3. Psychomotor stimulants

Question 2

Misuse of drugs act

Answer 2

A - deemed most dangerous
B
C - Deemed to have least capacity for harm
- act demands more lenient punishment

Question 3

Convulsants & respiratory stimulants

Answer 3

– Doxapram

– short-acting respiratory stimulant used in respiratory failure, e.g.
• post-operative respiratory depression
• acute respiratory failure • neonatal apnoea

Question 4

Psychotomimetic drugs - relating to or denoting drugs which are capable of producing an effect on the mind similar to a psychotic state

Answer 4

– Hallucinogens (LSD, psilocybin, mescaline, MDMA)
– Dissociative anaesthetics (ketamine, PCP)
– Cannabis

Question 5

Psychomotor stimulants

Answer 5

– Amphetamines, khat, cocaine, nicotine

– Methylxanthines (caffeine, theophylline)

Question 6

Hallucinogens

Answer 6

Drugs that act on 5-HT receptors and transporters: 
– LSD (D-lysergic acid diethylamine)
– Psilocybin
– Mescaline
– MDMA (Ecstasy)

Question 7

where does serotonin work in the brain

Answer 7

Locus coeruleus
• (sensory signals) Raphe nuclei
• (sleep, wakefulness and mood)

Question 8

main effects of hallucinogens

Answer 8

– alter perception of sights and sounds
– hallucinations (visual, auditory, tactile or olfactory)
– sounds can be perceived as visions
– thought processes illogical and disconnected

Question 9

‘Bad trip‘

Answer 9

– hallucinations can take on a menacing quality

– may be accompanied by paranoid delusions

Question 10

tolerance and risks of halluncinogens

Answer 10

Tolerance
– develops quickly (plus cross-talk between drugs)

There is no physical withdrawal syndrome

Risks
– Psychological effects (“flashbacks”, psychosis)
– Risk of injury and accidental death whilst intoxicated
– Poisoning due to mistaken identity
– Adrenergic effects with LSD
– GI effects with psilocybin

Question 11

Dissociative anaesthetics

Answer 11

Phencyclidine (PCP, ‘Angel Dust’)

Ketamine

Both are NMDA receptor antagonists

Question 12

tolerance to dissociative anaesthetics

Answer 12

Tolerance
– Rapid over regular, repeated doses
Dependence (physical & psychological) and withdrawal
syndromes with PCP

Risks
– Accidents/loss of control/automatic behaviour
– PCP: hyperthermia, convulsions
– Ketamine: overdose with heart attack/respiratory failure (rare)

Question 13

Cannabis (Cannabis sativa, indica)

Answer 13

Tetrahydrocannabinol (THC) and 11-hydroxy-THC

Question 14

Psychomotor Stimulants - “drugs that act on the central nervous system (CNS) to increase alertness, elevate mood, and produce a sense of well-being”

Answer 14

Amphetamine, dextroamphetamine and methylamphetamine

Question 15

main effects of Psychomotor Stimulants

Answer 15

– Locomotor stimulation
– Euphoria and excitement
– Insomnia
– Anorexia (diminishes with continued use) – Stereotypic behavior (chronic use)

Question 16

Action of Amphetamine on behaviour

Answer 16

probably due to the release of dopamine rather than noradrenaline

– Subjects become confident, hyperactive and talkative
– Sex drive is said to be enhanced
– Fatigue (both physical and mental) is reduced
– Does not enhance mental performance, just ability to concentrate for longer

Question 17

Mode of Action of Amphetamines

Answer 17

Competitive inhibitors of monoamine uptake

Displace monoamines (i.e. noradrenaline, dopamine) from vesicles into cytoplasm

Inhibit MAO at high concentrations

Cause NET to work in “reverse”

Question 18

what are the dopamine pathways in the brain

Answer 18

Nigrostriatal
• (motor control) Mesolimbic & Mesocortical
• (behavioural effects) Tuberohypophyseal system
• (endocrine control)

Question 19

Simplified noradrenaline pathways in the brain

Answer 19

Locus coeruleus
• (wakefulness, alterness) Medulla/hypothalamus
• (blood pressure regulation)

Question 20

Amphetamines: Tolerance, Dependence, Risks

Answer 20

Rapid tolerance to euphoric and anorexic effects, slowly for other effects.
Moderate dependence potential due euphoria it produces.
“Amphetamine psychosis”
– If taken repeatedly over a few days
– Almost indistinguishable from an acute schizophrenic attack
– Stereotypic behaviour
– After cessation, usually a period of deep sleep
• After which subject may feel lethargic, depressed, anxious & often very
hungry

Question 21

risks of an amphetamines

Answer 21

– Vascular accidents (e.g. tachycardias, arrhythmias, ↑BP) 
– Cerebral convulsions & coma
– Excitation syndrome (hyperthermia/tachycardia)
– Anorexia
– Chronic paranoid psychosis 
– Cognitive impairment
– Personality/mood
– Chronic paranoid psychosis

Question 22

Lisdexamfetamine mesylate - like amphetamine

Answer 22

• Attention-deficit hyperactivity disorder

Question 23

Phentermine and diethylpropion - like amphetamine

Answer 23

• Weight loss

* Prescription-only, not on NHS (i.e. private only)

Question 24

Khat - Psychomotor Stimulants

Answer 24

Contains cathinone, an amphetamine-like stimulant

Question 25

Cocaine - Erythroxylum Coca

Answer 25

Potent inhibitor of catecholamine uptake into nerve terminals – (especially dopamine) Effects resemble that of amphetamine: – Euphoria (related to↓dopamine and 5-HT re uptake) – Alertness and wakefulness – Increased confidence and strength – Heighted sexual feelings – Indifference to concerns/cares Readily absorbed by many routes – Nasal administration damages the nasal mucosa and septum – Free-base form (‘crack’) can be smoked

Question 26

Cocaine: Tolerance, Dependence

Answer 26

Tolerance to occurs rapidly. Physical dependence mild. Strong psychological dependence occurs. Risks (acute) – Cardiovascular (↑BP, tachycardia, ventricular fibrillation, heart attack, respiratory arrest, stroke) – Muscle spasms, tremor – Hyperthermia – Seizures, headaches, excited delirium

Question 27

risks of cocaine

Answer 27

– Heart attacks due to furring of coronary arteries – Malnutrition & weight loss – Decreased libido and impotence – Personality/mood • (e.g. anxiety, depression, repetitive behaviours, delusions, psychosis) – “Toxic syndrome” • similar to acute paranoid schizophrenia

Question 28

Methylxanthines

Answer 28

Various beverages (e.g. tea, coffee, cocoa) contain methylxanthines which have mild CNS stimulant effects Main two are caffeine & theophylline – CNS stimulants – Diuretics – Cardiac muscle stimulants – Smooth muscle relaxants (especially bronchial) Main psychological effects are to reduce fatigue & improve mental performance without any euphoria

Question 29

Methylxanthines mechanism of action

Answer 29

– Inhibit cAMP/cGMP phosphodiesterases – Block purine receptors • adenosine receptors of the A1 and A2 subtype – Diuresis possibly due to vasodilation of the afferent glomerular arterioles causing ↑ GFR Tolerance and habituation develop to a small extent Few clinical uses for caffeine but theophylline can be used as a bronchodilator in severe asthma attacks

Question 30

Eugeroics

Answer 30

Not 100% in the “psychostimulant” category, but have some commonalities and prone to abuse (“smart drugs”) Modafinil • Mechanism not 100% clear, but has some activity as a DA reuptake inhibitor Solriamfetol • NA and DA reuptake inhibitor Pitolisant • H3 receptor antagonist