Antagonism lecture 5

Question 1

chemical antagonism

Answer 1

agonist chemically altered by the antagonist so cannot bind to receptor
heavy metal poisoning (chelator)

Question 2

pharmacokinetic antagonism

Answer 2

reduction in conc of drug absorbed, metabolised or excreted
- Opiates reduce gut motility therefore gut absorption
- Warfarin taken with some antibiotics, ^ metabolism of warfarin therefore reduce effective conc. in blood
- Diuretics- ^ excretion and may get rid of administered drugs

Question 3

physiological antagonism

Answer 3

interaction of two drugs with opposing action on body
- Noradrenaline and histamine
- nor ^ arterial BP by acting on heart and peripheral blood vessels
- histamine v arterial pressure by vasodilation

Question 4

non-competitive antagonism

Answer 4

bind in different place to agonist but indirectly stops signaling
blocks some step in process between receptor activation and response
- antihypertensives inhibit voltage gated Ca2+ channel, stopping contraction and reducing pressure (treat high BP)