PS268 Chapter Notes - Chapter 5: Pharmacodynamics, Pharmacokinetics, Metabolite
Module I: Introduction to Psychoactive Drugs, Behaviour, and the Brain
(Chapter Five
−
How Drugs Work: Mechanisms of Action)
5.1 − Sources and Names of Drugs
- Most drugs come from plants or derived from plant substances
- Names of Drugs
o Chemical Name: name that specifies a complete chemical description of a drug
o Generic Name: name that specifies a particular chemical but not a particular brand
▪ Ex. ibuprofen
o Brand Name: name that specifies a particular formation and manufacturer of a drug
▪ Ex. Tylenol
▪ Controlled by Health Canada
5.2 − Categories of Drugs
- Psychoactive/Psychotropic Drugs
o Have effects on the brain that result in temporary changes in thought processes,
mood, and behaviour
o Can be used recreationally to affect a person’s consciousness, as entheogen for
spiritual purposes, and as medication
- CNS Stimulants
o Amphetamines, cocaine, and nicotine
o In moderate doses, produce wakefulness and a sense of energy and well-being
o More powerful stimulants can at high doses produce a manic state of excitement
combined with paranoia and hallucinations
- CNS Depressants
o Barbiturates and alcohol use
o Regular use can lead to withdrawal syndrome
▪ Characterized by restlessness, shakiness, hallucinations, and convulsions
when intake of drug is reduced
- Analgesics (Pain Relievers)
o Morphine and codeine
o Include opioid drugs that produce relaxed, dreamlike state
▪ Cause clouding of consciousness
▪ Withdrawal symptoms include diarrhea, cramps, chills, and profuse sweating
- Hallucinogens (Psychedelics)
o LSD, ecstasy/MDMA, and PCP/angel dust
- Psychotherapeutics
o Used to treat psychological disorders
o Ritalin
▪ Treats ADHD
o Used for control of mental health problems
▪ Neuroleptics can calm people experiencing psychosis
▪ Antidepressants help people recover from seriously depressed mood states
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▪ Lithium used to control manic episodes and prevent mood swings in bipolar
disorder
5.3.a − Pharmacodynamics
- Pharmacodynamics
o Includes drug action and drug effects
▪ Drug Action: interaction of drug with receptors
▪ Drug Effects: resulting behavioural, cognitive, and emotional changes
produced following drug action
o Drug Effects
▪ Drugs can’t have an effect until it is taken
▪ To have a drug effect, drug must be brought together with a living organism
▪ What the drug does to the body is often the reason the drug is taken
o Nonspecific (Placebo) Effect
▪ Expectancy, experience, and setting important determinants to the drug’s effect
▪ Nonspecific Effects: effects that derive from user’s unique background and
perception of the world
• Placebo Effect: can be produced by an inactive chemical that user
believes to be a drug
▪ Tests for effectiveness of new drug must be done using double-blind
procedure
• Double-Blind Procedure: neither evaluators not participants know
who is in the control group
▪ Placebo effects have been shown in treating pain and treating psychological
depression
• Nonspecific effects not caused by chemicals in drugs, but still real
effects that have biological basis
- Dose-Response Relationship
o The strongest demonstration of the specific effect of a drug is obtained when the
dose is varied → size of effect varies
▪ Low doses, no-little effects
▪ As dose increase, effect of drugs increases
o As dose increases, increasing people show slowing of reaction time
o Ataxia: staggering or inability to walk straight
▪ As reaction time slows, ataxia appears
o As dosage increases even further, they start to become comatose
▪ Comatose: pass out and cannot be aroused
o Estimating safety margin is important for animal testing before it can be tested on
humans
▪ Therapeutic Index = LD50/ED50
• LD50: effective dose for half of the animals tested
• ED50: lethal dose for half of the animals tested
o Larger than effective dose
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Module i: introduction to psychoactive drugs, behaviour, and the brain (chapter five how drugs work: mechanisms of action) Most drugs come from plants or derived from plant substances. Psychoactive/psychotropic drugs mood, and behaviour: have effects on the brain that result in temporary changes in thought processes, can be used recreationally to affect a person"s consciousness, as entheogen for spiritual purposes, and as medication. Cns stimulants: amphetamines, cocaine, and nicotine. In moderate doses, produce wakefulness and a sense of energy and well-being: more powerful stimulants can at high doses produce a manic state of excitement combined with paranoia and hallucinations. Cns depressants: barbiturates and alcohol use, regular use can lead to withdrawal syndrome, characterized by restlessness, shakiness, hallucinations, and convulsions when intake of drug is reduced. Analgesics (pain relievers: morphine and codeine. Include opioid drugs that produce relaxed, dreamlike state: cause clouding of consciousness, withdrawal symptoms include diarrhea, cramps, chills, and profuse sweating. Hallucinogens (psychedelics: lsd, ecstasy/mdma, and pcp/angel dust.
