What is KB in pharmacology?

(iii) Kb refers to the equilibrium dissociation constant of a ligand (traditionally, a competitive antagonist) determined by means of a functional assay.

How do you calculate KB in pharmacology?

The value of KB was calculated according to the following new power equation: KB = IC50/(l + A(K)/Kp) = IC50/[l + (A/EC50)(K)], where IC50 is the concentration of the antagonist producing 50% inhibition, A is the concentration of the agonist against which the IC50 is being determined and KP is the apparent equilibrium …

What does a high KB value mean pharmacology?

The dose-response curve obtained in the presence of a competitive antagonist is parallel to the dose-response curve obtained in the absence of antagonist. If the Kb is small and the concentration high, the antagonist will have a more pronounced effect than if the Kb is large and the antagonist concentration is small.

What is pKB antagonist?

pKB. A measure of the potency of a competitive antagonist; the negative log of the molar concentration which at equilibrium would occupy 50% of the receptors in the absence of agonist.

What is Ka in pharmacology?

Ka is a measure of the affinity of the drug for the receptor. A drug with a low Kd value has a high Ka value and therefore high affinity for the receptor.

How do you calculate KB?

Solve the equation for Kb by dividing the Kw by the Ka. You then obtain the equation Kb = Kw / Ka. Put the values from the problem into the equation. For example, for the chloride ion, Kb = 1.0 x 10^-14 / 1.0 x 10^6.

What is affinity and efficacy?

Affinity describes strength of drug binding with receptor (“fit the lock”). Efficacy describes ability of drug-bound receptor to produce a response (“turn the key”). Agonists have both affinities for the receptor as well as efficacy but antagonists have only affinity for the receptors and no (zero) efficacy.

Does high potency mean high affinity?

The term potency is used as a comparative term for distinguishing which agonist has a higher affinity for a given receptor (Figure 2). The drug which can produce an effect at lower drug concentrations is “more potent” (in Figure 3, Drug A is the most potent, and Drug D is the least potent).

What does a high pA2 value mean?

The higher the value for pA2, the higher the affinity of B is to its receptor.

What is EC50 in pharmacology?

The EC50 (or ED50) is the concentration (or dose) effective in producing 50% of the maximal response and is a convenient way of comparing drug potencies. From: Medical Pharmacology and Therapeutics (Fifth Edition), 2018.

What is Emax and EC50?

E is the effect at drug concentration C, Emax is the maximal effect at high drug concentrations when all the receptors are occupied by the drug, and EC50 is the drug concentration to give the half-maximal effect.

What is difference between IC50 and EC50?

The EC50 is the concentration of a drug that gives half-maximal response. The IC50 is the concentration of an inhibitor where the response (or binding) is reduced by half.

What is potency and efficacy?

Results. Potency is an expression of the activity of a drug in terms of the concentration or amount of the drug required to produce a defined effect, whereas clinical efficacy judges the therapeutic effectiveness of the drug in humans.

What is the meaning of high potency?

A substance with high potency will have a big effect on the body, and something with low potency will have a smaller one. For example, some strains of cannabis have a higher potency than others.

Is High potency good?

Taking high-potency vitamin D-3 is generally considered safe. But taking doses greater than 4,000 international units for a long period of time may cause adverse effects such as excessively high levels of calcium.

What does low IC50 mean?

Low IC50 value means that the drug is effective at low concentrations, and thus will show lower systemic toxicity when administered to the patient.

Why is IC50 important?

Abstract. Half-maximal inhibitory concentration (IC50) is the most widely used and informative measure of a drug’s efficacy. It indicates how much drug is needed to inhibit a biological process by half, thus providing a measure of potency of an antagonist drug in pharmacological research.

How is IC50 used?

IC50 is commonly used as a measure of antagonist drug potency in pharmacological research. IC50 is comparable to other measures of potency, such as EC50 for excitatory drugs. EC50 represents the dose or plasma concentration required for obtaining 50% of a maximum effect in vivo.

What is a high IC50?

If you find high IC50, this means that the cell line is more resistant to drug1 than drug 2. If the drug 2 trigger less apoptosis, then it must kill the cells with different cell death pathway more than apoptosis.

What is good IC50 value?

In most cases, the IC50 of the best candidate compound should be lower to 10 micromolar, acceptable for NIH to screen the NCI60 program. In addition, the drug design should think over the related problem about the absorption, distribution, metabolism and excretion in our body.

What is IC50 in MTT assay?

The changing 50% inhibitory concentration (IC50) of cisplatin: a pilot study on the artifacts of the MTT assay and the precise measurement of density-dependent chemoresistance in ovarian cancer – PMC.

What is IC50 cell viability?

The IC50 value (that is, the concentration of drug which exhibited 50% cell viability for MCF-7 and MDA-MB-231 cells) were 15, 15, 10 μM, and 100 nM, respectively, for AZA, SAM, SFN, and TSA, respectively. Source publication.

What is the IC50 of doxorubicin?

The IC50 of doxorubicin in MCF-7/ADR was 1.9 microM.

What is the IC50 of cisplatin?

The mean IC50 of the four cell lines, evaluated by MTT assay, was 0.4 and 6.2 mg/ml for cisplatin and carboplatin, respectively.