CNS Stimulants Flashcards
What are the three main categories of harm associated with CNS Stimulants
- Physical harm (route of administration),
- Dependency (tolerance, craving and withdrawal) drugs that act quickly and give a big high are more likely to be a risk of dependency,
- Social Harms
What are the categories of CNS stimulants and examples
Convulsant and respiratory stimulants (Doxapram),
- Psychotomimetic drugs (Hallucinogens, Dissociative anaesthetics (eg, ketamine) and cannabis).
- Psychomotor stimulants (amphetamines and methylxanthines)
Describe features of Doxapram
It is a short acting respiratory stimulant used in respiratory failure such as post-op resp depression, acute respiratory failure and neonatal apnoea.
What are psychotomimetic drugs?
Relating to or denoting drugs which are capable of producing an effect on the mind similar to psychotic state
Name and describe hallucinogens
- They are drugs such on the 5-HT receptors and transporters. Examples include;
- LSD,
- Psilocybin,
- Mescaline,
- MDMA (Ecstasy)
Where are the key areas that 5-HT acts?
- Locus coeruleus (sensory signals),
- Raphe Nuclei (effects sleep, wakefulness and mood)
So drugs interact with serotonin
What are the pharmacological effects of hallucinogens?
They have main effects on mental processes such as;
- Altering perception of sights and sounds,
- Hallucinations (visual, auditory, tactile or olfactory) they can take on a menacing quality and can be accompanied by paranoid delusions,
- Sounds can be perceived as visions,
- Thought processes illogical and disconnected.
- Flashbacks which can be reported weeks or months later
What are the risks of hallucinogens?
- Tolerance develops quickly however there is no physical withdrawal.
- There are risks of injury and accidental death whilst intoxicated, risk of poisoning due to mistaken identity, risk of adrenergic effects with LSD and GI effects with Psilocybin.
Name examples of Dissociative anaesthetics and their uses and effects
- Phencyclidine which produces disorientation and hallucinations.
- Ketamine which is used for induction and maintenance of anaesthesia.
- They can be an analgesic, cause sterotypes motor behaviour seen with amphetamine use and can cause ‘bad trips’.
What type of drugs are dissociative anaesthetics?
NMDA receptor antagonists
What are the risks and tolerances of dissociative anaesthetics?
Tolerance develops rapidly with repeated doses which can lead to dependence and withdrawal syndrome (PCP).
- Risks include; accidents/loss of control/automatic behaviour, with PCP can have hyperthermia and convulsions. Ketamine can cause overdose with heart attack/respiratory failure.
What is cannabis?
Tetrahydrocannabinol (THC)
What are psychomotor stimulants?
Drugs that act on the central nervous system to increase alertness, elevate mood, and produce a sense of well-being. Examples include amphetamine, methylamphetamine.
What are the main effects of amphetamines?
- Locomotor stimulation,
- Euphoria and excitement,
- Insomnia,
- Anorexia (diminishes with continued use),
- Steryotypic behaviour
What are the behavioural effects of amphetamines?
Thought to be due to release of dopamine and can cause;
- subjects to become more confident, hyperactive and talkative,
- Enhanced sex drive,
- Fatigue is reduced,
- Does not hence mental performance but does improve ability to concentrate for longer.
What is the mode of action of amphetamines?
They are competitive inhibitors of monoamine (Noradrenaline, dopamine) uptake and can also displace monoamines from vesicles into cytoplasm. At high concentrations can inhibit MAO. and causes NET to work in reverse (causing pumping out of noradrenaline)
Name the main areas where dopamine acts?
- Nigrostriatal (motor control),
- Mesolimbic and mesocortical (behavioural effects,
- Tuberohypophyseal system (endocrine control)
Where are the main areas of the brain where noradrenaline works?
- Locus coeruleus (wakefulness, alertness),
- Medulla/hypothalamus (Blood pressure regulation)
explain the tolerance, dependence and risks associated with amphetamine use
- Has rapid tolerance to euphoric and anorexic effects but slowly to others.
- Moderate dependence due to euphoric effect.
- Risks are amphetamine psychosis (occurs if repeatedly over days), vascular accidents, cerebral convulsions and coma, excitation syndrome, anorexia, chronic paranoid psychosis, cognitive impairment and personality/mood changes.
What are the clinical uses of amphetamines?
- Lisdexamfetamine mesylate is used in Attention deficit hyperactivity disorder (ADHD),
- Phentermine is used in weight loss (prescription only, not offered in NHS but private clinics)
Other than amphetamines, name two other psychomotor stimulants
Khat (contains cathinone which is an amphetamine like substance),
Nicotine
What is cocaine and its effects
- Potent inhibitor of catecholamine uptake into nerve terminals (especially dopamine),
- Its effects are; Euphoria, alertness and wakefulness, increased confidence and strength, heightened sexual feelings and indifferent to concerns/care
What are the dependency, tolerance and risks associated with cocaine?
- Nasal administration can damage nasal mucosa and septum,
- Tolerance develops rapidly, with mild physical dependence and strong psychological dependence.
- Risks include CV ( increased BP, tachycardia, ventricular fibrillation, heart attack, resp arrest and stroke), muscle spasms and tremor, hyperthermia, seizures, headaches and excited delirium, personality /mood changes, malnutrition and weight loss, decreased libido and impotence and toxic syndrome/
What are methylxanthines? Name two key ones and their effects
Psychomotor stimulants which are found in various beverages and have a milf CNS stimulant effect. Caffeine and theophylline which act as CNS stimulants, diuretics, cardiac muscle stimulants and smooth muscle relaxants. They reduce fatigue and improve mental performance without euphoria.
What is the mechanism of action of methylxanthines?
- Inhibit cAMP/cGMP phosphodiesterases,
- Block purine receptors (adenosine receptors of A1 and A1),
- Diuresis is thought to be due to vasodilation of afferent glomerular arterioles causing an increase in GFR
What can theophylline be used for?
Bronchodilator in severe asthma attacks
What are Eugeroics and name some examples
- Wakefulness-promoting agents which are clinically used in the treatment of narcolepsy.
Examples are Modafinil, Solriamfetol (NA and DA reuptake inhibitor) and pitolisant (H3 receptor antagonsit)
