CNS stimulants Flashcards
What are the 3 main categories of harm from drugs?
Physical harm;
- Acute vs chronic risks
- Route of administration (both primary and secondary risk)
Dependence;
- Intensity of pleasure (“rush”, “high”)
- Tolerance, craving, withdrawal
- Physical vs psychological dependence
Social harms
What is the UK misuse of drugs act?
It classifies controlled drugs into 3 classes;
Class A;
- Deemed “most dangerous”
- Carry the harshest punishments
Class B
Class C;
- Deemed to have “least capacity for harm”
- Act demands more lenient punishment
What are the types of CNS stimulants we have ?
Convulsants & respiratory stimulants;
- Doxapram
Psychotomimetic drugs;
- Hallucinogens (LSD, psilocybin, mesacaline, MDMA)
- Dissociative anaesthetics (ketamine, PCP)
- Cannabis
Psychomotor stimulants;
- Amphetamines, khat, cocaine, nicotine
- Methylxanthines (caffeine, theophylline)
What are some features of Convulsants and Respiratory Stimulants ?
Convulsants and Respiratory Stimulants
A diverse group of drugs that have little clinical use
Doxapram;
- Short acting respiratory stimulant used in respiratory failure, e.g;
- Post-operative respiratory depression
- Acute respiratory failure
- Neonatal apnoea
What are the features of Psychotomimetic drugs?
Psychotomimetic drugs
Relating to or denoting drugs which are capable of producing an effect on the mind similar to a psychotic state
Hallucinogens !
Drugs that after on 5HT receptors and transporters;
- LSD (D-lysergic acid diethylamine)
- Psiolocybin (magic mushrooms)
- Mescaline
- MDMA (Ecstasy)
Where do serotonin pathways in the brain go?
5-HT was identified as a neurotransmitter in the serotonin pathway thanks to LSD
Locus coeruleus - Sensory signals
Raphe nuclei - Sleep, wakefulness and mood
What are the pharmacological effects of Hallucinogens ?
The main effect are on mental processes;
- alter perception of sights and sounds
- hallucinations (visual, auditory, tactile or olfactory)
- sounds can be perceived as visions
- thought processes illogical and disconnected
‘Bad trip’
- hallucinations can take on menacing quality
- may be accompanied by paranoid delusions
‘Flashbacks’
- can be reported weeks or months later
Some say due to environment, some say due to mental health issues etc
What is Tolerance, Dependence and Risks associated with Hallucinogens ?
Tolerance;
- develops quickly (plus cross-talk between drugs)
There is no physical withdraw syndrome;
- Psychological effects (“flashbacks”, psychosis)
Risks;
- Risk of injury and accidental death while intoxicated
- Poisoning due to mistaken identity
- Adrenergic effects with LSD (can cause cardio risk as well)
- GI effects with psilocybin
Not drug itself, due to behaviour when taking to or taking something else that you thought was LSD
What are the features of Dissociative anaesthetics ?
Phencyclidine (PCP, ‘Angel Dust’)
- synthesised as a possible i.v general anaesthetic
- found to produce disorientation and hallucinations
Ketamine;
- used for induction and maintenance of anaesthesia
Effects resemble those of other psychotomimetic drugs;
- also an analgesic
- causes stereotyped motor behaviour like amphetamine
- can give a ‘bad trip’ as LSD
Both are NMDA receptor antagonists (similar effects but different mechanisms)
What is the Tolerance, Dependence and Risks involved with Dissociative anaesthetics ?
Tolerance;
- Rapid over regular, repeated doses
Dependence (physical & psychological) and withdrawal syndromes with PCP
Risks;
- Accidents / Loss of control / Autonomic behaviour
- PCP: Hyperthermia, convulsions
- Ketamine: Overdose with heart attack / respiratory failure (rare)
What is another big Psychotomimetic drug?
Cannabis ! (THC)
What are some Psychomotor stimulants and their features ?
Psychomotor stimulants;
“drugs that act on the CNS to increase alter ness, elevate mood, and produce a sense of well being”
Amphetamine, dextroamphetamine and methylamphetamine (crystal meth)
- Very similar chemical and pharmacological properties
Main effects are;
- Locomotor stimulations
- Euphoria and excitement
- Insomnia
- Anorexia (diminishes with continued use)
- Stereotypic behaviours (chronic use)
Methylphenidate, 3,4-methylenedioxymethamphetamine (MDMA)
- Chemically related, but considered separately
What are the actions of Amphetamine ?
Behavioural effects portably due to the release of dopamine rather than noradrenaline
- Subjects becomes 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
What is the mode of Action of Amphetamines?
- Competitive inhibitors of monamine uptake
- Displace monoamines (i.e noradrenaline, dopamine) from vesicles into cytoplasm
- Inhibits MAO at high concentrations
- Cause NET to work in “reverse”
Displace monoamine and catecholamine
NET - norepinephrine transport - usually takes back into cells to get packaged into vesicles but acts as pump to push into synaptic region and prevent reuptake
What the 3 simplified dopamine pathways in the Brain?
Nigrostiatal;
- Motor control
Mesolimibc & mesocortiyal;
- Behaviours effects
Tuberohypophyseal system
- Endocrine control
If target dopamine affect all of these pathways
High uses of amphetamine can lead to schizophrenia states in brain
What the 2 simplified noradrenaline pathways in the Brain?
Locus coeruleus;
- Wakefulness, alterness
Medulla / hypothalamus;
- Blood pressure regulation
What are the features of Methyxanthines ?
Various beverages (e.g tea, coffee, cocoa) contain methyxanthines which have mild CNS stimulant effects = STARBUCKS!
Main two are caffeine & theophylline
- CNS stimulants
- Diuretics
- Cardiac muscle stimulants
- Smooth muscle relaxants (especially bronchial - use in airway dilation)
Main psychological effects are to reduce fatigue and improve mental performance without any euphoria
What are Eugeroics and their features?
Eugeroics are “wakefulness-promoting agents” - clinically used in treatment of narcolepsy
Not 100% in the “psychostimulant” category, but have some commonalities and prone to abuse (“smart drugs”)
Modafinil;
- Mechanisms not 100% clear but has some activity as a DA reuptake inhibitor
Solriamfetol;
- NA and DA reuptake inhibitor
Pitolisant;
- H3 receptor antagonist
