15 Questions
What are the after effects of substances colloquially known as?
Hangover and afterglow
Which substances are typically associated with an 'afterglow' effect?
Cannabis, LSD, and ketamine
What law governs the binding of ligands (drugs) to receptors?
Law of mass action
What does the equilibrium dissociation constant (Kd) represent?
Equilibrium concentration of bound receptors
How are after effects defined in the text?
Residual effects remaining after the experience
What is the main focus of pharmacodynamics?
Studying how a drug affects an organism
Which equation represents a simplified model of drug-receptor interactions?
$L + R \rightleftharpoons LR$
What are the four principal protein targets with which drugs can interact?
Enzymes, ion channels, transporters, and receptors
Which action of a drug involves altering the production or metabolism of key endogenous chemicals?
Blocking
What is the therapeutic window of a medication?
The amount of medication between the effective dose and the adverse effects dose
What does the onset phase of a substance refer to?
The period until the very first changes in perception are able to be detected
What is the colloquial term for the typically positive, pleasant effect experienced after using substances like cannabis, LSD, and ketamine?
Afterglow
Which substances are commonly associated with negative after effects colloquially known as a 'hangover'?
Cocaine and MDMA
What law governs the binding of ligands (drugs) to receptors?
Law of Mass Action
What is the equilibrium dissociation constant (Kd) defined by in terms of the concentrations of ligands and receptors?
$K_d = [ L ] [ R ]$
Study Notes
Pharmacological Actions and Effects of Drugs
- Drugs can have 7 main actions: stimulating, depressing, blocking, stabilizing, exchanging, direct beneficial chemical reaction, and direct harmful chemical reaction.
- The desired activity of a drug is mainly due to successful targeting of cellular membrane disruption, chemical reactions with downstream effects, interaction with enzyme proteins, structural proteins, carrier proteins, ion channels, and ligand binding to receptors.
- General anesthetics were once thought to work by disordering neural membranes and altering Na+ influx, while antacids and chelating agents combine chemically in the body.
- Enzyme-substrate binding alters the production or metabolism of key endogenous chemicals, for example, aspirin irreversibly inhibits the enzyme prostaglandin synthetase.
- The widest class of drugs act as ligands that bind to receptors, eliciting their normal action (agonist), blocked action (antagonist), or even action opposite to normal (inverse agonist).
- The therapeutic window is the amount of medication between the effective dose and the amount that gives more adverse effects than desired effects.
- The duration of action of a drug is a function of several parameters including plasma half-life, the time to equilibrate between plasma and target compartments, and the off rate of the drug from its biological target.
- In recreational psychoactive drug spaces, duration refers to the length of time over which the subjective effects of a psychoactive substance manifest themselves.
- The total duration of a substance is the amount of time it takes for the effects of a substance to completely wear off into sobriety, starting from the moment the substance is first administered.
- The onset phase is the period until the very first changes in perception (i.e. "first alerts") are able to be detected.
- The "come up" phase is the period between the first noticeable changes in perception and the point of highest subjective intensity, colloquially known as "coming up."
- The peak phase is the period of time in which the intensity of the substance's effects is at its height.
Test your knowledge of Pharmacodynamics with this quiz! Explore the biochemical and physiological effects of pharmaceutical drugs on organisms, including humans and microorganisms. Brush up on key concepts in pharmacology and gain a deeper understanding of drug effects.
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