PSYCH261 Chapter Notes - Chapter 4: Nocebo, Neuroimaging, Hypoventilation
SchoolUniversity of Waterloo
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Psycopharmacology and Drug Abuse
Chapters 4 and 18
Captain Cook and the Puffer Fish
“About three o’clock in the morning we found ourselves seized with an extraordinary
weakness and numbness all over our limbs. I had almost lost the sense of feeling; nor
could I distinguish between light and heavy bodies of such as I had strength to move, a
quart pot full of water and a feather being the same in my hand….”
*The process by which drugs are absorbed, distributed within the body,
metabolized, and excreted.
*Routes of Administration
*Intravenous (IV) Injection – injection of substances directly into a vein;
quickest acting method
*Intraperitoneal (IP) Injection – injection into peritoneal cavity (space
surrounding stomach, intestines, liver, etc.); not used in humans that much;
used when humans doesn’t have the veins available
*Intramuscular (IM) Injection – injection into muscle; injects athropin (stimulates
*Subcutaneous (SC) Injection – injection beneath the skin; injects botox –
causes the face to be kinda paralyzed which removes wrinkles
*Oral – administration by mouth (i.e., swallowing).
*Sublingual – administration by placing beneath the tongue (e.g., LSD).
*Inhalation – administration of a vaporous substance into the lungs; common
foe smoking or marijuana
*Topical – administration directly onto the skin (e.g. nicotine patch).
*Intracerebral/cerebroventricular – administration directly into brain or
Pharmacokinetics - important
*Dose-Response Curve –magnitude of a drug effect as a function of the amount
*Many drugs have more than one effect; e.g., morphine, codeine.
*Analgesic effect (desired reduction of pain) – e.g. morphine, at low doses, it
reduces pain but as soon as you increase the dose, it starts depressive
*Depressive effect (undesired reduction of heart rate, reduces breathing rate
and metabolism; used to reduce comas).
Tolerance and Sensitization
*Tolerance – decreased effectiveness of a drug that is administered repeatedly; the
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body Is adapting to the drug (e.g. cigar addiction)
* Sensitization – increased effectiveness of a drug that is administered repeatedly;
you’re becoming tolerant and sensitized at the same time
*Withdrawal Symptoms – symptoms opposite to those produced by a drug when the
drug is administered repeatedly and then suddenly no longer taken; opposite
effect that the drug have (e.g. when you inject cocaine, it makes you very happy
but when you stop taking cocaine, you feel the opposite)- because you felt
tolerance then your body went to a down stage once you stoped
*E.g., cocaine produces euphoria when repeatedly taken and dysphoria upon
*An inert substance given to an organism in lieu of a physiologically active drug;
*Commonly used experimentally to control for the effects of mere administration of
*May be disease specific
*May have greater effects for pain and anxiety disorders
*Can last for up to two and half years (rheumatoid arthritis)
*Nocebo effects – negative effects of an inert substance (e.g. alcohol study)
*Side effects – a placebo given after an opiate can lead to the same respiratory
depression seen after actually taking an opiate
*Withdrawal – women on placebo in a hormone replacement therapy trial – 40%
showed moderate to severe withdrawal symptoms
Sites of Drug Action
*Antagonist – the drug opposes/inhibits the effects of a neurotransmitter on the
postsynaptic cell. E.g. Tynol
*Agonist – the drug facilitates the effects of a neurotransmitter on the postsynaptic cell.
*Agonistic or antagonistic effects may influence production of neurotransmitters.
*Agonistic or antagonistic effects may influence storage and release of
Sites of Drug Action – SHORT ANS Q. – identify some of these sites where we can
have an agonist or antagonist e.g.: AlDOPA to Dopamine
Mechanisms of Drug Action
*Direct Agonist – drug binds with and activates a receptor.
*Mimics the agonist neurotransmitter
*Direct Antagonist – drug binds with receptor but does not activate it; prevents
binding of natural neurotransmitter.
*Receptor blockers, antagonists
Mechanisms of Drug Action
*Noncompetitive Binding – binding of drug to receptor site that does not interfere
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