Module 2

• An SUD is a substance use disorder. Someone is usually considered to have an SUD if they have at least 2 criteria
• The 5 criteria of SUD include:

  Social impairments, risky use, impaired control, withdrawal, tolerance.
• Addiction is a state in which stopping or abruptly reduce the dose of a given drug produces non-physical symptoms.
• The dopamine hypothesis explains addiction:

  • Misused drugs increase dopamine in the reward systems of the brain (limbic system)
  • Dopaminergic systems are responsible for natural rewards such as food and sex, as well as video gaming and gambling. But it is also associated with addictive drugs such as cocaine
• LSD and ecstasy are addictive because it produces a sense of novelty, while benzodiazepines and barbiturates are addictive because they reduce anxiety.
• Drug withdrawal is an abnormal psychological state that happens when drug use is repetitive and creates a withdrawal syndrome when the drug is stopped
• Symptoms of withdrawal in stimulants (cocaine, amphetamines) include sleepiness, muscle pain, anxiety, tremors, low mood, suicidal ideations and cardiovascular problems
• Symptoms of withdrawal in opioids (heroin, morphine, oxycodone) include sweating, muscle aches, agitation, diarrhea, abdominal cramping, and vomiting.
• Drug tolerance is defined as a state in which repeated administration of a given dose of a drug has progressively less pharmacological effect
• Cross tolerance is the tolerance to one drug because of resistance to a similar drug. For example, if someone is tolerant to CNS depressant alcohol, they will be tolerant to CNS depressant benzodiazepine, even though they have never taken it before.
• There are 4 factors that can influence SUD:

  Genetic factors, pre-existing disorders, environmental factors, and developmental factors.
• Stigmatization can lead to isolation and low self esteem in SUD individuals, leading to them not receiving the medical or social help they need.
• Harm reduction is a method that seeks to prevent negative consequences from substance use, eliminating discrimination and judgement, without stopping substance use
• Misuse is defined as using the prescribed drug in ways or amounts other than that was prescribed, or against social norms.
• Misuse potential is determined by 5 factors:

  Nature of the drug, route of administration, amount/frequency of use, availability, inherent harmfulness.
• There are 5 drug classes: opioids (morphine, heroin), CNS stimulants (cocaine, amphetamines), CNS depressants (ethanol), hallucinogens (LSD, are the only class that do not lead to withdrawal), and cannabis (THC)
• Amphetamine drug class includes amphetamine, dextroamphetamine, and methamphetamine (and ecstasy and ritalin as related compounds)
• Amphetamines are synthetic organic compounds, and are structurally similar to endogenous transmitters like norepinephrine and dopamine.
• Amphetamines have four effects:

  1. a decreased threshold for transmitting sensory input to the cerebral cortex, leading to excitation
  2. A feeling of euphoria and reward
  3. Appetite suppression due to temperature regulation being ticked off
  4. An increase in aggressive behaviour and mood swings.
• Amphetamine short term effects:

  • Chest pain, cardiovascular collapse, increased respiratory rate

  Long term effects:

  • Chronic sleeping problems, poor appetite, anxiety, elevated blood pressure
• Therapeutic uses of amphetamines include treatment for narcolepsy (sleeping disorders) and ADHD
• Cocaine is classified as a local anesthetic and a CNS stimulant, but is also known as being a narcotic. It is almost indistinguishable from amphetamine in its effects and toxicity.
• Cocaine has a duration of 1h compared to amphetamines which last 12h
• Cocaine causes CNS stimulation on a dose-dependent manner. It causes the inhibition of serotonin and dopamine transporters, preventing them from entering the presynaptic neuron. This increases their concentration in the synaptic cleft, increasing activation of the postsynaptic neuron receptors.
• Cocaine therapeutic use is very limited. It is sometimes used as a local anesthetic for mouth and throat, but is rarely used as there are better alternatives.
• Long-term cocaine use can lead to paranoia, hallucinations, permanent brain damage, high blood pressure, changes to the nasal mucosa, etc.
• Cocaethylene is a metabolite formed when taking both alcohol and cocaine together, which increases euphoria, aggressive thoughts, and poor judgement.
• Cocaine has the one of the highest misuse potentials of all drugs because it can be injected and absorbed readily into the blood
• Tobacco is the leading cause of death in Canada, and contains a naturally occurring substance known as nicotine responsible for addiction.
• Nicotine comes from smoking cigarettes and is absorbed through the lungs, GI tract, skin, and oral mucosa. The dose of nicotine can be controlled by managing depth of inhalation and frequency of smoking.
• Nicotine is distributed throughout the body and is rapidly accessed by the brain
• Nicotine is metabolized in the liver
• The half-life of nicotine is about 2 hours, and is excreted through the kidneys (urine)
• Nicotine activates nicotinic receptors at the synapse, increasing motor activity, cognitive function, attention, and memory. In large doses, it can cause tremors and seizures.
• Nicotine is only used therapeutically for maintaining high blood nicotine levels in patients trying to combat addiction, and are served through nicotine gums.
• Short-term effects of nicotine:

  Mild euphoria, arousal, increased ability to concentrate, relaxation, and dizziness, headaches and nausea in non-regular smokers.

  Long-term effects of nicotine:

  Cardiovascular disease, lung disease, and cancer
• Misuse potential of nicotine is very high, as quitting smoking is very difficult, due to the craving of nicotine being so great
• Caffeine is taken orally and is rapidly absorbed. Blood levels are significant after 30 minutes, and at its peak at 2h. Caffeine distributes to all parts of the body and freely passes through the brain and placenta
• Genetics explain why caffeine keeps some individuals awake and not other due to the speed of caffeine metabolism, which happens in the liver
• the half-life of caffeine varies from 2.5 to 10h due to genetic differences in individuals, and is excreted through the kidney (urine)