Pharmacodynamics 1 Flashcards
pharmacodynamics: study of what 3 things
what drugs do to the body, mechanisms of action, quantification of drug responses
how do drugs elicit effects in the body
drugs interact with target macromolecules - modify physiological or biochemical events
7 potential drug targets
regulatory proteins in cell membranes (Receptors, channels, transporters). intracellular proteins. nuclear receptors. RNA/DNA. small molecules. nonspecific physical/chemical targets. non human targets
membrane receptors as drug targets: usually have a? response initiated when?
have a natural endogenous activator aka a ligand: neurotransmitter, hormone or autacoid. Response is initiated when receptor activated
membrane receptors as drug targets: two consequences of drug binding?
agonist = initiation of response. antagonist = blockade of response.
membrane receptors as drug targets: limitation?
receptors present in finite numbers = limitation to maximal possible effect
4 major classes of membrane receptors + examples
ligand or voltage gated ion channels (GABA-A, Na channels. GPCRs (B-adrenoreceptors). nuclear hormone receptors (estrogen). catalytic receptors (Receptor tyrosine kinases for insulin).
opioid receptors: 3 types? activated by? 3 classical agonists?
mu, kappa, delta: activated by endogenous peptides called enkephalins. morphine, fentanyl. codeine
opioid receptors: 4 effects
u, k, d = analgesia. u/d = euphoria and dependence. u = respiratory depression. u = GI motility.
adverse effects of opioid receptor agonists (5)
stimulates histamine release = itch. severe respiratory depression. constipation, urinary retention, anti-tussive (suppresses cough), vomiting.
W18
more potent than fentanyl but actually don’t act at opioid receptors
chemical antagonism + 2 examples
one drug inactivates another to reduce its effects: Ca carbonate neutralizes gastric H+, EDTA binds Ca2+ in chelation therapy
physiological antagonism + example
one drug exerts its actions to oppose another: works via distinct sites + mechanisms. adrenaline for allergic bronchoconstriction.
antibodies as receptor blockers: example for blood clots?
abciximab binds to glycoprotein IIb/IIIa receptors on platelets = prevents platelet aggregation + thrombosis, useful with angioplasty to prevent restenosis
antibodies as agonist inactivators: how do they work?
bind and inactivate the endogenous agonist
TNF-a: what? key component of? causes? inactivated by? treatment?
endogenous chemical aka cytokine, key component of autoimmune reaction, causes inflammation. bound/inactivated by anti-TNF antibodies like infliximab, useful to treat inflammatory conditions like Crohn’s or rheumatoid arthritis
drugs can potentiate agonist actions in what ways?
allosteric mechanism to enhance receptor affinity. inhibit agonist inactivation
example of allosteric potentiation of agonist actions? (for GABA)
benzodiazepines enhance GABA-mediated neural inhibition.
benzodiazepine effects: sequence + 3 other effects?
dose-related: anti-anxiety, sedation, hypnosis, coma, resp depression/death. other effects: skeletal muscle relaxation, anti-convulsant, tolerance and dependence.
benzodiazepine antagonist
flumanezil
