PRINCIPLE 1: BINDING
Specific targets of drug action
Drug action is explained in terms of CONVENTIONAL
CHEMICAL INTERACTIONS
Low [D] still involve large numbers of molecules
Avogadro’s number = number of molecules found in 1 mole
of a substance
1 drop of a [D] = 10-10 mol/l contains 1010 drug molecules
Drug molecules must get so CLOSE to other molecules
that they exert a CHEMICAL INFLUENCE on them
Drug distribution = at random,
interaction (with particular cellular molecule) = negligble
D/R INTERACTION:
Depends on [D] and [R]
D-R amount determines the RESPONSE MAGNITUDE
Threshold: minimum number of D-R complexes
response
↑ [D] ↑D-R ↑ EFFECT
SATURATION = NO FURTHER ↑R
LAW OF MASS ACTION APPLIES TO D-R INTERACTION
A DRUG WILL NOT WORK UNLESS IT IS BOUND!!
, TARGETS OF DRUG ACTION:
1) SIMPLE CHEMICAL NEUTRALISATION - antacid
2) ENZYME INHIBITORS – antibiotics
o Inhibitor normal reaction INHIBITED
o False substrate ABNORMAL METABOLITE produced
o Pro-drug ACTIVE drug produced
3) R OCCUPYING DRUGS – related to NTs
o Agonist direct ion channel OPENING/CLOSING
o Agonist transduction Enzyme +/-, ion channel
modulation, DNA transcription
o Antagonist NO EFFECT, endogenous mediators BLOCKED
4) MODULATORS OF CERTAIN TRANSPORT SYSTEMS –
Na+/K+-ATPase
o NORMAL TRANSPORT
o Inhibitor transport BLOCKED
o False substrate ABNORMAL COMPUNDS accumulate
5) ION CHANNEL INTERACTION – local anesthetics
o Blockers permeation BLOCKED
o Modulators ↑/↓ opening
Specific targets of drug action
Drug action is explained in terms of CONVENTIONAL
CHEMICAL INTERACTIONS
Low [D] still involve large numbers of molecules
Avogadro’s number = number of molecules found in 1 mole
of a substance
1 drop of a [D] = 10-10 mol/l contains 1010 drug molecules
Drug molecules must get so CLOSE to other molecules
that they exert a CHEMICAL INFLUENCE on them
Drug distribution = at random,
interaction (with particular cellular molecule) = negligble
D/R INTERACTION:
Depends on [D] and [R]
D-R amount determines the RESPONSE MAGNITUDE
Threshold: minimum number of D-R complexes
response
↑ [D] ↑D-R ↑ EFFECT
SATURATION = NO FURTHER ↑R
LAW OF MASS ACTION APPLIES TO D-R INTERACTION
A DRUG WILL NOT WORK UNLESS IT IS BOUND!!
, TARGETS OF DRUG ACTION:
1) SIMPLE CHEMICAL NEUTRALISATION - antacid
2) ENZYME INHIBITORS – antibiotics
o Inhibitor normal reaction INHIBITED
o False substrate ABNORMAL METABOLITE produced
o Pro-drug ACTIVE drug produced
3) R OCCUPYING DRUGS – related to NTs
o Agonist direct ion channel OPENING/CLOSING
o Agonist transduction Enzyme +/-, ion channel
modulation, DNA transcription
o Antagonist NO EFFECT, endogenous mediators BLOCKED
4) MODULATORS OF CERTAIN TRANSPORT SYSTEMS –
Na+/K+-ATPase
o NORMAL TRANSPORT
o Inhibitor transport BLOCKED
o False substrate ABNORMAL COMPUNDS accumulate
5) ION CHANNEL INTERACTION – local anesthetics
o Blockers permeation BLOCKED
o Modulators ↑/↓ opening
