Drugs of Abuse Flashcards
What are the factors that limit the therapeutic usefulness of drugs?
Tolerance
Physical dependence
Psychological dependence
What are examples of drugs that are commonly abused?
CNS stimulants
Hallucinogens
Opioid analgesics
CNS depressants
Sedative-hypnotics
Inhalants
What are examples of CNS stimulants?
Cocaine, amphetamines, nicotine
What category do LSD, marijuana, mescaline, and phencyclidine fall under?
Hallucinogens
What are examples of opioid analgesics?
Morphine and heroin
What kind of drug is ethanol?
CNS depressant
What are examples of sedative-hypnotics?
Alprazolam and diazepam
What kind of drugs are toluene, nitrous oxide and amyl nitrate?
Inhalants
What are CNS stimulants?
Drugs that have a chemical structure similar to monoamine neurotransmitters
How do CNS stimulants produce their actions?
Stimulating the release and blocking the reuptake of monoamine neurotransmitters
What are the effects of cocaine on CNS?
Enhances the activity of dopamine by binding tightly at the dopamine transporter forming a complex that blocks the transporter’s function.
What happens if the transporter’s function is blocked?
It can no longer perform its reuptake function thus increasing the amount of dopamine available
What is responsible for the addictive property of cocaine?
The stimulation of the pleasure centre of the human brain
What does cocaine do in relation to norepinephrine?
Blocks reuptake of norepinephrine and serotonin and pre-synaptic neurons
Why is cocaine also considered a local anaesthetic agent?
Produces a direct effect on cell membranes by blocking sodium channel activity, preventing the generation and conduction of nerve impulses.
What is the half-life of cocaine?
0.7 to 1.5 hours
How is cocaine metabolised?
By cholinesterase enzymes in liver
What is the metabolism process of cocaine?
Metabolised to benzoylecgonine and ecgonine methyl ester, both excreted in urine
What happens if cocaine is taken while consuming alcohol?
Cocaethylene is formed which is more euphoric and toxic than cocaine itself.
What are the side effects of cocaine intake?
Psychiatric complaints, hyperthermia, chest pain, agitation, convulsion.
How is cocaine toxicity treated?
Calming and cooling the patient, benzodiazepines could be used to calm an agitated patient.
What is amphetamine?
A sympathetic amine that shows neurologic and clinic effects very similar to ccocaine
What is the mechanism of action when it comes to amphetamine?
Inhibiting weakly the reuptake transport
Releasing intracellular stores of catecholamines
Inhibiting monoamine oxidase responsible for the catabolism of monoamines
What does the consumption of amphetamine lead to?
Elevation of catecholamine neurotransmitters in synaptic spaces induces stimulation of the entire cerebrospinal axis and leads to increased alertness, decreased fatigue, and insomnia.
Where is amphetamine metabolised?
In the liver
Where is amphetamine excreted?
In the urine
How long does the euphoria of amphetamine last?
4 to 6 hours
What are some side effects of amphetamine?
Dependence tolerance and drug-seeking behaviour.
What are some additional side-effects of both cocaine and amphetamine?
Increased norepinephrine (increased heart rate, blood pressure, mydriasis and hyperactivity)
Increased dopamine (paranoia, hallucinations, and endocrine disturbances)
Increased serotonin (aggressiveness, dyskinesia, decreased appetite)
What is the common name of methylenedioxymethamphetamine?
Ecstasy or Molly
What is MDMA?
Synthetic substance that does not exist in nature
What is the difference between MDMA and amphetamine?
There is a methylenedioxy group attached to the aromatic ring of MDMA.
What is the mechanism of action of MDMA?
Interferes with the storage of serotonin, and increases the amount of serotonin available to be released. Acts of serotonin transported and promotes the release of serotonin in synapse.
What does MDMA act as?
Indirect monoaminergic agonist
What does MDMA cause?
Significant increase in synaptic serotonin levels
What is the relation between MDMA and dopamine?
MDMA blocks the dopamine transporter and enhances the release of dopamine noradrenaline
Why can’t MDMA be inhaled?
Because the methylenedioxy group raises the boiling point.
What is the elimination half-life of MDMA?
7 hours
Where is MDMA absorbed?
Really absorbed from the GI tract
Where is MDMA metabolised?
In the liver
What are some side effects of MDMA?
Hyperthermia and movement disorders are known as serotonin syndrome.
Dehydration and renal failure.
Why are benzodiazepines given to MDMA patients?
To calm and cool the patients
What drug is given to treat the serotonin syndrome symptoms?
Cyproheptadine
What is the effect of khat?
Increase the release and inhibit the reuptake of catecholamines
What other drugs is khat similar to?
Cocaine and amphetamine
What are the drugs that bind to transporters of biogenic amines?
CNS stimulants: cocaine, amphetamine, MDMA, khat
What are examples of hallucinogens?
LSD, marijuana, synthetic cannabinoids
What is LSD?
Acts as a partial agonist at serotonin receptors
How long do the effects of LSD last?
Between 6 and 12 hours
Where is the drug eliminated?
In the urine: 1% as unchanged and 13% as the major metabolite (O-H-LSD)
What are the side effects of LSD?
Hallucinations, mood alterations, sleep disturbances, and anxiety, loss of judgment, and impaired reasoning
What is the mechanism of action of marijuana?
THC is the main active ingredient in marijuana and it binds to and activates specific receptors.
What are the receptors the THC binds to called?
Cannabinoid receptors.
Where are the cannabinoid receptors found?
Parts of the brain that control memory, thought and concentration.
How does marijuana affect the reward system?
By inducing the release of endorphins in the brain
By acting as a dopamine agonist
What is the effect of inducing the release of endorphins?
Produces the feeling of pleasure and reward
What is the effect of marijuana acting as a dopamine agonist?
Stimulating reinforcement regions in the mesh-telencephalic dopamine system
Why does marijuana accumulate in the milk?
Due to its lipophilic qualities
What are the two main signs of marijuana use?
Increased heart rate and conjunctival reddening, however, decrease in blood pressure and in psychomotor performance can also occur
What are synthetic cannabinoids?
Synthetic forms of different nolecular structure from cannabinoids found in marijuana plants, they can produce 800 times greater effects
What are the most common examples of opioids?
Morphine, heroine, codeine, oxycodone
What kind of individuals often develop an addiction to opioids?
Those who take them for recreational purposes.
What are the effects of opioids?
Euphoria, analgesia, sedation, cough suppression and constipation
What are the toxicity effects of opioids?
Respiratory depression, nausea, and vomiting.
What are the withdrawal symptoms of opioid use?
Lacrimation, yawning, sweating, restlessness, muscle cramping, and diarrhea.
What do opioids bind onto?
μ-DOR, δ-DOR or κ-DOR
What leads to the distinct and sometimes opposing effects of opioids?
Distinct signalling and expression of opioid receptors through the brain
What does the activation of μ-DOR in the VTA cause and how is that different from the activation of κ-DOR?
Activation of μ-DOR causes an inhibition of GABA which leads to a disinhibition of dopamine neurons. While activation of κ-DOR receptors inhibit directly dopamine neurons.
What are the drugs that activate G protein-coupled receptors?
Hallucinogens, opioids
What is the mechanism of action for ethanol?
Modulating the activity of inotropic rectors such as GABA, glutamate receptors, MDMA receptors, glycine receptors, and the serotonin receptors.
How does alcohol exert its desired and toxic effects?
- Increasing the effects of inhibitory neurotransmitter GABA
- Releasing endogenous opioids in the reward system
What happens if the inhibitory neurotransmitter GABA is increased?
Suppression of the activity of the CNS
What happens if ethanol is consumed in high doses and why?
Coma and respiratory depression, because it is a general CNS depressant.
What kind of drug is ethanol?
Drug that mediates its effect via inotropic receptors
What are the side effects of ethanol consumption?
Nausea, vomiting and hypotension
What can chronic ethanol abuse cause?
Profound hepatic, cardiovascular, pulmonary, hematologic, endocrine, metabolic, and CNS damage
What does treatment of ethanol withdrawal rely on ?
Benzodiazepines
What is used to treat the dependence of ethanol?
Naltrexone: white still consuming ethanol
Disulfiram and Acamprosate: once abstinence is achieved
What is the function of naltrexone?
Blockade of μ-opioid receptors; therefore blocks normal reaction of the part of the brain that produces the feeling of pleasure and reward
What is the function of acamprosate?
Modulation of the glutamate (excitatory) and GABA (inhibitory) neurotransmission restore imbalance between neuron excitation and inhibition
What is the function of disulfiram?
Inhibits aldehyde dehydrogenase and prevents the metabolism of acetaldehyde.
Why should disulfiram not be taken while consuming ethanol?
It causes the accumulation of acetaldehyde in the blood which causes sweating, headache, and flushing.
