Clinical Dose Response Flashcards
can be constructed for responses that are measured on a continuous scale, eg, heart rate.
graded dose-response curve
relate the intensity of response to the size of the dose, and hence are useful for characterising the actions of drugs
graded dose-response curve
can be constructed for drugs and elicit an all-or-non response, eg, presence or absence of epileptic seizures.
quantal dose-response curve
The percentage of the population requiring a particular dose to exhibit the effect can be determined from this curve. When these data are plotted as a cumulative frequency distribution, a ____________ is generated.
sigmoidal dose-response curve
for most drugs, the doses that are required to produce a specified quantal effect in a population are log normally distributed, so that the frequency distribution of responses plotted against log dose is a?
Gaussian normal distribution curve
is the ratio of rate constants for the reverse
Kd
reaction between the drug receptor and the drug-receptor complex
K1
ratio of rate constants for the forward
K2
also the drug concentration at which receptor occupancy is half of maximum.
Kd
drugs with a high Kd dissociate rapidly from receptors
low affinity
drugs with a low kd dissociate slowly from receptors
high affinity
examples of specific drugs include?
✓ atropine
✓ salbutamol
✓ phenoxybenzamine
✓ cimetidine
muscarinic antagonist
atropine
a B2-adrenoceptor agonist
salbutamol
an a-alergic blocking agent
phenoxybenzamine
which causes blockade of D2-dopamine receptors, a-adregenic receptors and muscarinic receptors.
phenothiazine
a drug is the ration of the dose that results in an undesired effect to that which results in a desired effect
therapeutic index
the therapeutic index of a drug is usually define as the ratio of ____________ to ___________ which indicates how selective the drug is in resulting in its desired effect.
LD50 to ED50
Values of Ld50 and Ed50 for this purpose are derived from ______________ generated in animal studies.
quantal dose-response curves
the information obtained from __________ is critically important when choosing between drugs and when determining the dose to administer
dose-response curves
primary determinants of a drug’s clinical effectiveness
efficacy of the drug-receptor complex
is derived from a quantitative dose-response relationship for a single animal and varies among individuals
Emax
provides information concerning the dose range over which a drug elicits its effect.
slope of the graded dose-response curve
when quantal effects are being considered information concerning pharmacological potency, selectivity of a drug action, the margin of safety and the potential variability of responsiveness among individuals is obtained from?
quantal dose-response curves
an indication of the ability of drugs to reach the receptor is obtained for?
pharmacokinetic parameters
pharmacokinetics parameters characterize the;
absorption, distribution, and clearance of a drug
phenomenon is referred to as ___________ in the concentration-effect relationship.
hysteresis
observed of a drug such as digoxin
counterclockwise hysteresis loop
which distributes slowly to its site of action
digoxin
refers to the concentration or dose of a drug required to produce 50% of the drug’s maximal effect.
potency
how avidly the drug binds to the receptor
affinity
occurs between receptor occupancy and response, which results in the EC50 for response being much less
signal amplification
important only if it results in a need to administer the drug in large doses that are impractical
low potency
for a quantal dose-response relationship is the dose at which 50% of individuals exhibit the specified quantal effect.
ED50
also referred to as intrinsic activity. is the ability of drug to elicit a response when it binds to the receptor.
efficacy
is the concentration of an antagonist that reduces a specified response to 50% of the maximal possible effect
median inhibitory concentration or IC50
refers to a drug’s ability to preferentially produce a particular effect and is related to the structural specificity of drug binding to receptors
selectivity
a B-blocker, binds equally well to 1-adrenoreceptors
propranolol
a B-agonist used for treating asthma. binds selectively to B2-adrenoceptors.
salbutamol
