A higher therapeutic index is preferable to a lower one: a patient would have to take a much higher dose of such a drug to reach the toxic threshold than the dose taken to elicit the therapeutic effect.
Is a higher therapeutic index better?
A ratio that compares the blood concentration at which a drug becomes toxic and the concentration at which the drug is effective. The larger the therapeutic index (TI), the safer the drug is.
What does low therapeutic index mean?
Some drugs have a narrow therapeutic index, which means that there is only a small difference between the minimum effective concentrations and the minimum toxic concentrations in the blood . With such drugs, small increases in dose or in blood/serum concentrations could lead to toxic effects.
How do you interpret therapeutic index?
- therapeutic index of a drug is the ratio of the dose that produces toxicity to the dose that produces a clinically desired or effective response.
- TD50 = the dose of drug that causes a toxic response in 50% of the population.
- ED50 = the dose of drug that is therapeutically effective in 50% of the population.
What is therapeutic index and why is it 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.
What is an NTI drug?
Introduction. Narrow therapeutic index drugs are drugs where small differences in dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions that are life-threatening or result in persistent or significant disability or incapacity.
What therapeutic index is safe?
Drugs with TI’s greater than 10 are considered relatively safe while those with TI’s less than 3 typically require tighter controls on manufacturing (to ensure that the dosing is accurate) and patient monitoring.
Why are medications with the highest therapeutic index the safest medications?
A higher therapeutic index is preferable to a lower one: a patient would have to take a much higher dose of such a drug to reach the toxic threshold than the dose taken to elicit the therapeutic effect .
Is high mortality applicable to Type B?
Type B reactions are idiosyncratic, bizarre or novel responses that cannot be predicted from the known pharmacology of a drug and are associated with low morbidity and high mortality .
How would you monitor a patient with a narrow therapeutic index?
- Assays. Assays are one of the most basic methods of therapeutic drug testing. ...
- Automation. There are now technologies available that automate many aspects of the therapeutic drug monitoring process. ...
- Microsampling.
What does low distribution mean?
This means that most of the drug is in the tissue, and very little is in the plasma circulating . The larger the volume of distribution, the more likely that the drug is found in the tissues of the body. The smaller the volume of distribution, the more likely that the drug is confined to the circulatory system.
How is the therapeutic index calculated?
The therapeutic index formula T 1 = 3 W a × 10 – 4 was derived from T 1 = LD 50 /ED 50 and ED 50 = 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 the difference between therapeutic window and therapeutic index?
Therapeutic window is also termed as safety window and can be quantified by therapeutic index. Therapeutic Index (TI): Therapeutic index (TI) describes a relationship between the doses of a drug that causes lethal or toxic effects with the dose that causes therapeutic effects . It is also called as therapeutic ratio.
What is a major disadvantage of the therapeutic ratio?
01) What is a major disadvantage of the therapeutic ratio? Feedback: The therapeutic ratio is an indication of the relative dose levels of a drug which will be effective , versus those which will be lethal. It gives no indication of chronic or non-lethal toxicity.
What is therapeutic range of a drug?
The therapeutic range of a drug is the dosage range or blood plasma or serum concentration usually expected to achieve the desired therapeutic effect .
What is minimum effective concentration?
Minimum effective concentration (MEC) is the minimum plasma concentration of a drug needed to achieve sufficient drug concentration at the receptors to produce the desired pharmacologic response , if drug molecules in plasma are in equilibrium with drug molecules in the various tissues (Figure 1.3).
Is digoxin a narrow therapeutic index?
Digoxin has a narrow therapeutic index [1, 23, 25] so small variations in plasma concentration may readily result in toxic or sub therapeutic concentrations. Thus, consistency in bioavailability is important.
What is drug toxicity?
‘Drug toxicity’ can be defined as a diverse array of adverse effects which are brought about through drug use at either therapeutic or non-therapeutic doses .
Does carbamazepine have a narrow therapeutic index?
Background and objectives: Carbamazepine is among those drugs that have been considered to have a narrow therapeutic plasma concentration range , that is, a narrow therapeutic index.
Does aspirin have a narrow therapeutic index?
Most readers would not consider aspirin or another salicylate as a nar- row therapeutic index drug. However, when used in large doses to treat inflammatory disease, it is a narrow thera- peutic index drug because of its nonlinear elimination kinetics in humans.
What is the therapeutic index of ibuprofen?
The maximum recommended daily dose is 3200 mg, and the therapeutic window of ibuprofen is wide: 10-50 mg/L and the toxic concentration is high (>100 mg/L).
When a drug has a low therapeutic index that drug should be?
4 Moreover, despite the lack of definite lists of NTI-drugs, the understanding of which drugs should belong to the NTI group are by and large similar among drug experts. NTI-drugs have been shown to be a major cause of emergency department visits .
Why are drugs with a wide therapeutic window considered safer to use?
A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication , so the drug is relatively safe.
Which adverse effect might the patient develop if treated with primaquine?
The main adverse effect of primaquine is oxidant haemolysis . Although some red cell loss may occur in normal subjects, patients who are G6PD deficient are particularly vulnerable. It is the potential for toxicity in G6PD deficiency that has limited the use of primaquine.
In which person incidence ADR is highest?
Patients aged greater than 65 years (29.6% vs. 20.5% for younger patients) and females (26.2% vs. 20% for males) were at higher risk for ADR development (p < 0.05).
Which 3 organs are most likely to be affected by ADRs?
organ systems most commonly involved in ADRs were gastrointestinal (47.5%), followed by liver (29.6%) and skin (14.1%) (Figure 1).
Which antibiotic has the narrowest therapeutic index?
Most antibiotics, such as the β-lactams, macrolides and quinolones have a wide therapeutic index and therefore do not require therapeutic drug monitoring. Some, such as the aminoglycosides and vancomycin , have a narrow therapeutic index, and toxicity may be severe and irreversible.
Does warfarin have a narrow therapeutic range?
In this context, warfarin is the most widely prescribed oral anticoagulant agent for preventing and treating these events. This medication has a narrow therapeutic range and, consequently, patients usually have difficulty in achieving and maintaining stable target therapeutics.
Why is the difference between therapeutic index and therapeutic window important?
The therapeutic index is an important ratio to determine how close a toxic dose is to an effective one . Note that the term therapeutic index is often used more loosely, not just in these formulatic terms, and is often conflated with the therapeutic window, which we’ll define soon.
What are Type B drugs?
Class B. Class B drugs are considered by Parliament to be less harmful than Class A drugs and include amphetamines, barbiturates, cannabis and dihydrocodeine . Certain Class B drugs are reclassified to Class A if they have been prepared for injection. These include amphetamines, dihydrocodeine and codeine.
What is the therapeutic range for digoxin?
Therapeutic levels of digoxin are 0.8-2.0 ng/mL . The toxic level is >2.4 ng/mL.
What is MEC and MTC?
The minimum effective concentration (MEC) of a drug is the lowest concentration of the drug required to achieve the therapeutic benefit. On the other hand, the maximum therapeutic concentration or minimum toxic concentration (MTC) is the concentration at which a drug produces unwanted side effects.
What are hit and run drugs?
The hit-and-run drugs’ are – (Mnemonic: MOGRA): MAO inhibitors, Omeprazole (Other PPIs also) Guanethidine, Reserpine and Aspirin .
What does a high Vd mean?
A drug with a high Vd has a propensity to leave the plasma and enter the extravascular compartments of the body, meaning that a higher dose of a drug is required to achieve a given plasma concentration. (High Vd -> More distribution to other tissue ) ... (Low Vd -> Less distribution to other tissue)
Which drug has highest volume of distribution?
| Drug V D Comments | Warfarin 8 L Reflects a high degree of plasma protein binding. | Theophylline, Ethanol 30 L Represents distribution in total body water. | Chloroquine 15000 L Shows highly lipophilic molecules which sequester into total body fat. | NXY-059 8 L Highly charged hydrophilic molecule. |
|---|
Why distribution channel is important to the business?
Distribution channels are important to businesses as they allow for the smooth delivery of goods or services to a customer . ... Creating an efficient process from warehouse to customer can make a huge difference in how customers view your business.
What does it mean when a drug is 50% protein bound?
Answer: The percentage of drug NOT protein bound is the amount of drug that is free to work as expected. In this case, 50% is unable to be effective , because it is protein-bound. Protein binding has nothing to do with the destruction of protein, drug excretion, or protein in the diet.
What does low therapeutic index mean?
Some drugs have a narrow therapeutic index, which means that there is only a small difference between the minimum effective concentrations and the minimum toxic concentrations in the blood . With such drugs, small increases in dose or in blood/serum concentrations could lead to toxic effects.
