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.
What does the therapeutic index indicate?
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.
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 is a good therapeutic index?
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….Therapeutic index.
| Term | Meaning |
|---|---|
| TR | Therapeutic Ratio |
What does a 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.
What is wide therapeutic index?
Drugs with a high therapeutic index have a wide margin of safety and less danger of producing toxic effects. Plasma drug levels do not need to be monitored routinely for drugs with a high therapeutic index.
What is narrow and wide therapeutic index?
All categories. Name Narrow Therapeutic Index Drugs Accession Number DBCAT003972 Description. Narrow therapeutic index (NTI) drugs are defined as those drugs where small differences in dose or blood concentration may lead to dose and blood concentration dependent, serious therapeutic failures or adverse drug reactions.
How do you monitor narrow therapeutic index?
Here are three of the most effective ways to monitor patients who are taking these drugs.
- 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.
Why does digoxin have 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. Moreover, toxic symptoms can be evident with normal digoxin concentrations [25].
Does lithium have a narrow therapeutic index?
Lithium has a narrow therapeutic index; a large proportion of patients on chronic lithium therapy experience at least one episode of toxicity during treatment [8]. The highest intracellular lithium levels are found in the brain and the kidneys.
Does theophylline have a narrow therapeutic index?
Theophylline has an extremely narrow therapeutic window. Theophylline toxicity occurs when serum theophylline levels surpass the levels in the therapeutic range. This can occur by intentional overdose or unintentionally when metabolism and/or clearance of theophylline is altered due to certain physiological stressors.
Why is theophylline not used?
For maintenance therapy of asthma, theophylline may be obsolete because it is merely a relatively weak bronchodilator that adds little but side effects to dose- optimized inhaled ~2-agents and does not address the underlying inflammation, a fundamental charac- teristic of the disease.
What is a common side effect of aminophylline?
The most common adverse events with peak serum theophylline levels under 20 mcg/mL are transient caffeine-like events such as nausea, vomiting, headache, and insomnia.
Does gentamicin have a narrow therapeutic index?
Like other aminoglycosides, gentamicin has a narrow therapeutic index and therapeutic drug monitoring has proven to be beneficial, particularly in vulnerable populations such as the elderly.
Which antibiotics has high 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.