What is the therapeutic index?
Most drugs have beneficial effects in performing measured doses, but may have undesirable or even harmful effects in larger quantities. Therefore, it may be useful to know the ratio of the average dose of the drug needed to the intended therapeutic effect compared to the average dose that can cause damage. This ratio is called a therapeutic index or therapeutic ratio.
In general, the doses used to calculate the therapeutic index are determined by scientific studies. They are known as the TD50 and ED50. The TD50 is the amount that is toxic to 50% of the individuals in the study, and the ED50 refers to the minimum dose that creates the desired effect in 50% of the studied. From there, the therapeutic ratio is administered as the TD50 divided by ED50.
When studies on animals are used to calculate the therapeutic index, the process is slightly different. In this case, a dose that causes 50 percent of animals in a study or LD50 is used by a pro -to -line. The therapeutic ratio is then found by Division of LD50 using ED50.
Studies that are used to find an effective dose for the therapeutic index measure this dose in terms of the amount of medicine in the bloodstream. This allows a more reliable dose estimate between individuals compared to oral doses. In addition, the effect caused by the dose is considered everything or nothing. In antihistamines drugs, the dose would have to alleviate the symptoms of allergy to be considered effective.
individuals can learn about the relative safety of the drug using a therapeutic index. The greater the toxic ratio to an effective dose, which is generally considered a safer medicine. A great therapeutic ratio means that a person would have to take an effective dose many times to experience harmful effects.
drugs with smaller therapeutic index can still be used, but often only taken under the supervision of a doctor. Determination of the right dose for one of these drugs may be taken into account by several aspects of a person such as weight, functionkidneys and other medicines. When taking a drug with a low therapeutic ratio, individuals may decide to monitor their plasma levels to make sure that the concentration of the drug in their bloodstream remains in a safe amount.