What is meant by therapeutic index?

The therapeutic index (TI; also known as therapeutic ratio) is a ratio that compares the blood concentration at which a drug causes a therapeutic effect to the amount that causes death (in animal studies) or toxicity (in human studies) [1].

What is meant by therapeutic ratio or index?

The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxicity.

Why is the therapeutic index important?

The therapeutic index (TI) — which is typically considered as the ratio of the highest exposure to the drug that results in no toxicity to the exposure that produces the desired efficacy — is an important parameter in efforts to achieve this balance.

How do you find therapeutic index?

The therapeutic index formula T 1 = 3 W a × 10 – 4 was derived from T1 = LD50/ED50 and ED50 = L D 50 3 x W a × 10 – 4 . Findings have shown that, therapeutic index is a function of death reversal (s), safety factor (10−4) and weight of animal (Wa).

What is ed50 and td50?

ED50 is the dose required to produce a therapeutic effect in 50% of the population; TD50 is the dose required to produce a toxic effect in 50% of the population; both are calculated from dose–response curves.

What drug has a narrow therapeutic index?

Drugs with a narrow therapeutic index 4 We defined the following drugs to be NTI-drugs: aminoglycosides, ciclosporin, carbamazepine, digoxin, digitoxin, flecainide, lithium, phenytoin, phenobarbital, rifampicin, theophylline and warfarin.

What is meant by ED50?

Definition/Introduction The ED50 (median effective dose) is the dose of a medication that produces a specific effect in 50% of the population that takes that dose.

What is a safe therapeutic index?

The larger the therapeutic index (TI), the safer the drug is. If the TI is small (the difference between the two concentrations is very small), the drug must be dosed carefully and the person receiving the drug should be monitored closely for any signs of drug toxicity.

When two or more medications are prescribed that are highly protein bound What is the clinical outcome?

When two, highly protein-bound drugs (A and B) are added into the same biological system it will lead to an initial small increase in the concentration of free drug A (as drug B ejects some of the drug A from its proteins).

Quel est l’ index thérapeutique?

L’ index thérapeutique est, pour une substance, le rapport de deux quantités caractérisées, celles de la dose létale 50 (DL 50), soit la quantité d’une substance créant la mort chez 50 % des individus, et de la dose efficace 50 (DE 50) soit la dose nécessaire pour produire les effets désirés chez 50 % des individus.

Pourquoi l’index thérapeutique dépend de la tolérance?

Au numérateur, l’index thérapeutique dépend de l’efficacité (effet maximal) et non de la puissance (rapports de dose entre produits, issus des relations dose-effet). Au dénominateur, de multiples facteurs pharmacologiques influencent la tolérance.

Quel est le taux de fixation d’un médicament?

Le taux de fixation aux protéines d’un médicament dépend de trois facteurs : Concentration libre du médicament (fraction directement active) Son affinité par rapport aux sites de fixation sur les protéines (interactions) La concentration protéique (risque de majorer l’effet si hypoalbuminémie)