27 Psychoactive drugs Flashcards
27.01 PSYCHOMOTOR STIMULANTS
Amfetamine, methylenedioxymethamfetamine (MDMA), methylphenidate - actions
CNS stimulation: arousal, alertness, concentration
euphoria/excitement
stereotyped behaviour
anxiety
reduced appetite
sympathomimetic actions: tachycardia, pupillary dilation, etc.
27.01 PSYCHOMOTOR STIMULANTS
Amfetamine, methylenedioxymethamfetamine (MDMA), methylphenidate - MOA
inhibits neuronal reuptake of MA, inhibits MAO and vesicular MA transporter
raised cytosolic levels of MAs and release from nerve terminals, mainly by reverse operation of the MA transporter
increased MA levels in synapse
sympathomimetic actions due to release of NA in the periphery
27.01 PSYCHOMOTOR STIMULANTS
Amfetamine, methylenedioxymethamfetamine (MDMA), methylphenidate - abs/distrib/elim
orally active
amfetamine half-life 10h
renal excretion enhanced by urine acidification
methylphenidate is also administered by patch
27.01 PSYCHOMOTOR STIMULANTS
Amfetamine, methylenedioxymethamfetamine (MDMA), methylphenidate - clinical use
attention-deficit hyperactivity disorder (ADHD), narcolepsy
27.01 PSYCHOMOTOR STIMULANTS
Amfetamine, methylenedioxymethamfetamine (MDMA), methylphenidate - adverse effects
aggression, restlessness, insomnia, paranoia
anorexia, weight loss
psychotic states/hallucinations
dependence
dehydration/hyperthermia (MDMA)
hypertension
sudden death in patients with pre-existing cardiac abnormalities
27.02 PSYCHOMOTOR STIMULANTS
Methylxanthines: caffeine, theophylline - actions
psychomotor stimulant effects, mild diuresis, stimulation of cardiac muscle, relaxation of smooth muscle (especially bronchial muscle)
27.02 PSYCHOMOTOR STIMULANTS
Methylxanthines: caffeine, theophylline - MOA
antagonism of A2 purine receptors and part inhibition of phosphodiesterase
peripheral actions are exerted mainly on the heart, smooth muscle and kidney
27.02 PSYCHOMOTOR STIMULANTS
Methylxanthines: caffeine, theophylline - abs/distrib/elim
given orally
27.02 PSYCHOMOTOR STIMULANTS
Methylxanthines: caffeine, theophylline - clinical use
caffeine is included with aspirin in some preparations for treating headaches
treatment of apnoea of prematurity
theophylline is mainly used as a bronchodilator in severe asthma
27.02 PSYCHOMOTOR STIMULANTS
Methylxanthines: caffeine, theophylline - adverse effects
hyperglycaemia, tachycardia
caffeine withdrawal symptoms include headache and irritability
27.03 PSYCHOMOTOR STIMULANTS
Nicotine - actions
CNS stimulant
peripherally, stimulates autonomic ganglia
27.03 PSYCHOMOTOR STIMULANTS
Nicotine - MOA
central effects are on nicotinic acetylcholine receptors (nACRs), which are widely expressed in the brain
balance between activation of nACRs, causing neuronal excitation, and desensitisation, causing synaptic block
peripheral effects result from stimulation of autonomic ganglia and peripheral sensory receptors, mainly in the heart and lungs (tachycardia, increased cardiac output and arterial pressure, reduced GI motility, sweating)
27.03 PSYCHOMOTOR STIMULANTS
Nicotine - abs/distrib/elim
nicotine is metabolised to cotinine, mainly in the liver, within 1-2h
27.03 PSYCHOMOTOR STIMULANTS
Nicotine - clinical use
nicotine replacement therapy improves chances of giving up smoking
27.03 PSYCHOMOTOR STIMULANTS
Nicotine - adverse effects
tolerance develops rapidly to the effects of nicotine, giving rise to physical and psychological dependence
27.04 CNS DEPRESSANTS
Ethanol - actions
CNS depressant
27.04 CNS DEPRESSANTS
Ethanol - MOA
enhances GABA and glycine action
activates potassium channels
inhibits calcium channel opening, NMDA-type glutamate receptors and adenosine transport
27.04 CNS DEPRESSANTS
Ethanol - abs/distrib/elim
given orally
rapid absorption, substantial fraction cleared by first-pass metabolism
about 80% metabolised, 5-10% excreted unchanged in expired air and in urine
27.04 CNS DEPRESSANTS
Ethanol - clinical use
little or no therapeutic value, but widely used in many countries for its psychoactive properties
27.04 CNS DEPRESSANTS
Ethanol - adverse effects
neurological degeneration occurs with heavy and binge drinking, causing dementia and peripheral neuropathies
long-term ethanol consumption causes liver disease, progressing to cirrhosis and liver failure
physical and psychological dependence
ethanol misuse during pregnancy can result in impaired foetal development and foetal alcohol syndrome
27.04 CNS DEPRESSANTS
Ethanol - special notes
disulfiram can be used as aversion therapy to discourage ethanol excess
if combined with ethanol, it results in a severe reaction (flushing, tachycardia, hyperventilation and distress) due to excessive acetaldehyde accumulation in the bloodstream
27.05 OTHER PSYCHOACTIVE DRUGS
Cocaine
sympathomimetic action: inhibits uptake of dopamine, serotonin and noradrenaline transport
27.05 OTHER PSYCHOACTIVE DRUGS
Benzodiazepines
CNS depressant
27.05 OTHER PSYCHOACTIVE DRUGS
Zopiclone and other Z drugs
CNS depressant
27.05 OTHER PSYCHOACTIVE DRUGS
Gabapentin and pregabalin
CNS depressant
27.05 OTHER PSYCHOACTIVE DRUGS
Ketamine
blocks the NMDA-type glutamate receptor ion channel
misuse associated with ulcerative cystitis, liver damage and bladder pain
27.06 MAJOR PSYCHEDELIC DRUGS
Lysergic acid deithylamide (LSD)
interacts with 5-HT and dopamine receptors
psychotomimetic action attributed to 5-HT2A receptors enhancing glutamatergic transmission in the cerebral cortex is very potent - causes a long-lasting sense of dissociation and disordered thought
27.06 MAJOR PSYCHEDELIC DRUGS
Mescaline
agonist at 5-HT2A and other 5-HT receptors
related to amfetamine
derived from Mexican peyote cactus
27.06 MAJOR PSYCHEDELIC DRUGS
Psilocybin
metabolised to psilocin
related to 5-HT
active substance in magic mushrooms
27.06 MAJOR PSYCHEDELIC DRUGS
Salvinorin A
opioid receptor agonist
known as ‘herbal ecstasy’
contained in Salvia divinorum
