Pharm Terminology Flashcards
What is the lock and key model of drug action?
We have variety of cell receptors in our cells. Drug get out of leaky blood vessel and target the receptors on the cell surfaces. This then causes inner cell signaling.
*Key word is : “leaky” blood vessels. In inflammation blood vessels become dilated and this makes the drug more likely to accumulate/target the specific tissue.
Define drug Affinity.
Potential for drug-receptor binding.
It is how much affinity the drug has for the receptor. So a drug with a high affinity will find the receptor. A drug with low affinity will have trouble finding the receptor and when it does it may not be very long before it falls off the receptor because of the weak integration.
Define Intrinsic activity.
This is the capacity of the drug to produce a biological effect. (Here biological effect means therapeutic effect).
Define Agonist.
SUBSTANCES that stimulate a receptor to produce a physiological reaction.
Agonist have intrinsic activity (aka beneficial biological effect) and affinity.
Define Antagonists
SUBSTANCES that oppose or interfere with the activity of a receptor and its endogenous substrate without producing a physiologic effect itself;
antagonists have affinity but LACK intrinsic activity.
Allostery
A stereospecific phenomenon whereby a bound ligand influences specificity of a second site.
*in allostery, the configuration of the protein/enzyme is changed.
Define Efficacy
Efficacy = [affinity] X [intrinsic activity]
-How well the drug finds its receptor and cause a biological effect.
Efficacy of a drug is dose INdependent. Unlike potency that is dose dependent.
*so the greater the affinity the drug has the greater the efficacy of the drug.
Thus the efficacy is zero for antagonists.
What is the difference between EC50 and ED50
EC50: this is the effective [concentration] in 50% of patients.
ED50: is the effective DOSE in 50% of patients.
**concentration is a laboratory measurement, dose is a clinical measurement. So we care more about EC50.
What is IC50?
IC50: This is the ‘inhibitory’ concentration in 50% of subjects.
*the term inhibition tells us that we are talking about antagonist.
Describe hypersensitivity in the context of pharmacology.
Hypersensitivity is the result of repeated or chronic antagonism.
*If you are exposed to something repeatedly, your body can become hypersensitive. So this is explaining a heightened sensitivity that some tissues can produce.
Example: in anisocoria, hypersensitivity allows us to diagnose which nerve it causing it?
What is maximum dose of a drug?
It is the MINIMUM amount of drug that produces the maximum therapeutic effect.
What is the difference between pharmacodynamics and pharmacokinetics?
Pharmacodynamics: Drug → Body *what the drug does to the body.
Pharmacokinetics: Body → Drug (ADME) *what the body does to the drug.
What is Partial agonist?
Low intrinsic activity with potency and affinity within therapeutic range.
*low potential to produce intrinsic activity (biological effect) with potency. but it has an affinity within a therapeutic range.
True or False: Potency is inversely related to both EC50 and IC50.
True.
- the lower the EC50 the higher the potency of the drug.
- the lower the IC50 the higher the potency.
What is Pharmacotherapeutics?
Pharmacotherapeutics: The study of the therapeutic uses and effects of drugs on diseases.
What is selectivity?
Ability of a drug to produce a desired effect versus adverse effect
What is specificity?
Ability of a drug to act at a specific receptor
What is the difference between pharmacodynamics vs pharmacokinetics.
Pharmodynamics: What the drug does to the body
Pharmokinetics: what the body does to the drug- ADME
What is Tachyphylaxis?
Rapidly decreasing therapeutic response.
*The effects of this is that the drug’s don’t work long enough. Drugs with tachyphylaxis are sometimes used in surgery, for short usage.
What is Teratogenesis?
The development of deformities in developing fetuses causing congenital malformation.
What is bioavailability?
The amount of active drug reaching target tissue.
Explain Therapeutic index.
In the lab, therapeutic dose is the lethal dose divided by the effective dose.
LD50:ED50 (lethal dose vs effective dose) or TD50:ED50 (toxic dose vs effective dose)
*A high therapeutic index is good. The higher the therapeutic index is the safer the drug.
What is the difference between DPA and TPA.
DPA: diagnostic pharmaceutical agent
TPA: therapeutic pharmaceutical agent
What is the difference between supplemental vs supportive drug types? Give an example of each.
Supplemental: therapy involves the addition of a substance that is normally required by the body but exists in insufficient amounts a achieve a desired state. Example: insulin.
Supportive:therapy is aimed at relieving symptoms or helping patients cope with them rather than focusing on a cure. Example: Glucose
What is a prophylactic drug. Give an example.
A drug intended to prevent disease. Example: low dose aspirin. i.e. Aspirin used to prevent coagulation in blood vessels to prevent heart disease.
What is a the difference between therapeutic drugs vs symptomatic drug? Give an example of each.
Symptomatic drug: This is a drug that relieves a patient’s symptoms. This does not necessary mean it is therapeutic.
*Example: olopatadine- artificial tears for dry eyes.
Therapeutic drug: drugs that cure symptoms.
*example: methotrexate -inhibits DNA synthesis in cells–> cures cancers
Give an example of a diagnostic drug.
fluorescein
*Exam question: What is the MOST COMMON receptor type targeted by ophthalmic drugs?
G-protein-coupled receptors
Example: ACh(M), rhodopsin
Give examples of Ion channels.
GABAA, AChN, glutamate
What are the five types of agonists?
- Direct: A drug that itself stimulates a receptor and produces the desired biological effects through its effects on the receptor. *Example: isoprotereno
- Indirect: A drug that causes a natural affect in the body to be amplified by promoting that through its interaction with the receptor. *example: Cocaine amplifies epinephrine by inhibiting its uptake.
- Mixed: has both agonist and antagonist properties.
example: Tamoxifen - Inverse:reversal of constitutive (basal) receptor activity
Example: Ro154513 - Partial: sub-maximal stimulation and efficacy (affinity may vary)
***Partial agonists are touted for their reduced dependency and withdrawal effects
What are uncompetitive antagonists?
*allosteric binding in PRESENCE of substrate slows ligand dissociation and response rate.
Explain Competitive antagonists.
Binding site is the same as endogenous agonist. The higher the concentrarion of the antagonist the better its effect.
