Professor Linda Martin-Morris
Study Guide, Week II
Synergism, antagonism, incompatibility, additivity
Neuron, neuroglia [neuroglial cell], cell body, axon, dendrite, axon bulb
Electrical activity, resting potential, action potential
Na+ [sodium], K+ [potassium], Cl- [chloride]
Na+/K+ pump, Na+ channels, K+ channels
For negative drug interactions, the two terms include incompatibility and
In incompatibility, the drugs interfere with each other.
DRUG X + DRUG Y > DRUGS X + Y.
In positive drug interactions, the two terms
are additivity and synergism.
In additivity, DRUG X + DRUG Y = DRUGS X + Y.
In synergism, DRUG X + DRUG Y < DRUGS X + Y.
B. See graphs in Lecture Companion.
An example of incompatibility is when aspirin [temporary pain reliever, heart
strengthener, blood thinner] is taken with Metamucil [laxative].
absorption in the body.
In antagonism, If Valium [anxiety] is taken with caffeine,
there will be conflicting mechanisms because of the reaction between those two
In additivity, if aspirin and methotrexate [reduce inflammation] are taken
together, they attack the same symptoms, have different mechanisms, and have a
double edge approach.
In synergism, drugs such as alcohol and benzodiazepine
[sedative] which are taken together greatly increases disinhibition.