In drug delivery assays, it is important to determine the optimal dose range for a particular drug or drug candidate. This information is critical for selecting the most promising drug candidates for further development and for optimizing dosing and administration. This is an important aspect of drug development because it helps finding the lowest most effective concentration of the compound of interest. In a real application of cancer treatments, high levels of chemotherapeutic compounds can harm other functions in the body and can kill normal cells along with the cancerous cells. To minimize the harmful effects, it is critical to find the lowest effective dose for the treatment.

Understanding Drug Behavior

One way to understand how the drug behaves in a biological system is by determining the IC₅₀ value of the drug compound. IC₅₀, or the half-maximal inhibitory concentration is a value in which a drug concentration inhibits half the functions of the target cells of interest. Typically, this experiment is run over a range of concentrations and is graphed based on their maximal and minimal inhibitory functions. From obtaining the range of values, we determine the 50%, or half value of the inhibitory response found in treating the cells with the drug compound. This often relates to a specific cellular activity such as cell growth or protein activity. Similarly, EC₅₀, or the half-maximal effective concentration is used for compounds that induces a response rather than inhibit them. This is also calculated over the range of concentrations treated onto cells of interest and graphed the response to obtain the half value of activity.

Due to the nature of the drug compounds and their capabilities in interacting with other biological systems, it is ideal to have IC₅₀ or EC₅₀ values of drug compounds low, around micro to even nanomolar. This not only allows us to understand the potency of the drug compound but also how effective it is in treating diseases with a small concentration. It gives a better understanding of the optimal way to dose and administer the drug compounds. Understanding their mechanism of action and the appropriate parameters for certain compounds and their effects on biological functions is important in developing drugs. It is a long and arduous process but a necessary one. Factors such as pharmacokinetics, pharmacodynamics, and toxicity should also be considered when determining the optimal dose range of a drug or drug candidate. Here in Visikol, we run various types of assays, including those of the cytotoxicity and terminal ATP assays that help us understand the effects of the compounds of interest. Reach out today to inquire about a specific assay of interest.

The pharmaceutical industry relies on the products it develops. A major factor that heavily affects the success of these products are the effectiveness of each pharmaceutical drug. It is believed that the five main factors to affect success of pharmaceutical products are-

1. Unmet need and burden of disease
2. Clinical efficacy
3. Comparators
4. Safety
5. Price

Clinical efficacy is second on the list, which is how well the treatment succeeds in its purpose. For example, an anti-cancer drug should inhibit cancer cell growth. Drug effectiveness is most often determined by IC50 in drug discovery and pharmacology studies.

IC50

IC (inhibitory concentration) curves are dose response curves used to determine the specific drug concentration required to reduce the population of viable cells by a particular percentage when compared to cells grown with no exposure to the drug. The IC50 stands for inhibitory concentration at 50% which means this is one half the maximal inhibitory concentration of a compound. It is important to use the IC50 value because it indicates how much of a drug is needed to inhibit a biological process by half. The IC curves show a change in population because of increased cell death or decreased cell proliferation.

Finding the IC50 can mean much more than only inhibiting the growth of cells or increased death of cells. In cancer, using certain drugs at the IC50 concentration means inhibit growth of a tumor by half. When testing for the IC curves, if the IC50 is found at a lower concentration, this means that the drug will be effective at lower concentrations and therefore will cause lower systemic toxicity when given to patients for treatment. Using the IC50 concentration can mean killing cancer cells and stopping cancer cell growth, while having a less toxic effect on the healthy cells in the body.

IC50 and Assays

Scientific research models require the best concentration of the compound for the assay and cell type in use. For models such as blood brain barrier, the health of the cells which form the barrier is critical. The Blood Brain Barrier model is used to represent the semipermeable barrier in vitro and, therefore, one of the main goals of this model is to keep the cells of the barrier alive while introducing compounds to the model to assess the permeability of the membrane formed. If a concentration is too high, it can be toxic to the cells, destroy the membrane, and allow all compounds to pass which would end in false results. The IC50 is crucial to models like this and others which is why the scientists at Visikol highly recommend finding the IC curves and determining the IC50 prior to working with new fewer known compounds to ensure the 2D and 3D assays perform to the best of their ability.

Researchers in Visikol’s Pharmacology and Drug Discovery division are skilled in toxicity assessment and screening in 2D and 3D cellular based assays. Visikol suggests determining the proper concentration to use in the desired assays through dose range and IC50 determination. This process uses a 2D assay of the cell line of interest. The cells are plated and treated with various concentrations of the test compounds which is typically an eight point dose range, as well as, vehicle and media only controls. Cell viability is assessed through a luminescent ATP assay or immunolabeling endpoints.

If you are interested in learning more about this technique or any of the other many research opportunities at Visikol, please reach out to our team. We are always interested in working together with our clients as a team to develop customized assays to best suit their needs.