Packed with the Ester PC Ligand phase, IAM Fast-Screen Mini columns are a rapid and economically viable screening method for the high throughput estimation of drug permeability. Their benefits include excellent reproducibility, short analysis time, and low cost. This can be of great use in characterizing large libraries of compounds.

The IAM.PC Fast-Screen Mini Column, 1 cm in length by 3.0 mm in internal diameter, and was specifically designed by Regis for rapid estimation of drug permeability in high-throughput screening programs. When connected to an HPLC system with an autosampler, a single column can be used in the analysis of hundreds of samples per day with highly reproducible results.

The 1 cm Fast-Screen Mini Column is offered not as a separation tool, but rather as a tool for characterizing the chromatographic retention factor (k') of individual analytes. The measured k' of analytes on this column can be used to estimate a value for drug permeability.

Excellent Correlation to Traditional Methods

The traditional means of predicting permeability includes use of Caco-2 cell line cultures, intestinal tissue or liposome assays. These are laborious and costly to perform. Data obtained from the IAM Fast-Screen Mini Column correlate well to data obtained from traditional assays. This is summarized in Table 1.

Method
Number of Compounds Evaluated Correlation (r) with IAM Fast-Screen Mini Column
Partitioning into liposomes 23 0.831
Intestinal drug permeability 12 0.839
Caco-2 cell permeability 8 0.909

Table 1. Comparing k'IAM data with other methods for estimating permeability.

The measured k' of analytes on this column can be used to estimate a value for drug permeability.

Chromatographic Conditions:
Column: IAM Fast-Screen Mini Column 1 cm x 3.0 mm i.d.
Mobile Phase: 0.01 M DPBS Buffer, pH 7.4
Flow Rate: 0.5 mL/min
Load: 10 µl
Detection: UV 220 nm

Drugs studied: 1. Propanol; 2. Alprenolol; 3. Warfarin; 4. Metoprolol; 5. Hydrocortisone; 6. Terbutaline; 7. Atenolol; and 8. (AVP) Arginine-Vasopressin
 

Intestinal Tissue Correlation
Table 2 shows that drug permeability predicted by inverted rat intestines correlates well to drug retention factors, k'IAM measured on the IAM Fast-Screen Mini Columns. Note the short retention times. 

Compound % Absorption of Inverted Rat Intestine IAM Fast Screen Mini Column Retention Time
 
m-nitroaniline 77 133.1 15.29
p-nitroaniline 68 177.9 21.84
salicylic acid 60 93.8 9.54
p-toluidine 59 79.7 7.48
aniline 54 52.1 3.45
m-nitrobenzoic acid 53 68.1 5.79
phenol 51 94.6 9.66
benzoic acid 51 43.7 2.22
acetanilide 42 76.2 6.97
antipyrine 32 51.8 3.40
theophyline 29 39.3 1.58
acetylsalcylic acid 20 36.1 1.11
r (correlation factor)     0.8385

Table 2. Correlating drug partitioning into IAM with rat intestinal drug absorption.
*r is calculated by plotting k' vs. log % absorption of inverted rat intestine.


Rapid Indication of Drug Absorption
IAM Chromatography is a more rapid alternative to other methods. In a recent study completed by Regis, k'IAMs of 12 compounds were compared with absorption data obtained in situ using rat intestines. Retention times for the compounds tested were between 20 and 190 seconds, while retention factors correlated well to the intestinal absorption data.

High Sample Throughput
IAM Chromatography is of increasing importance in combinatorial chemistry, where it is used to provide an initial estimate of a drug candidates' membranes permeability. Hundreds of samples can be injected into a single Fast-Screen Mini Column using an automated HPLC system. Recently a group of 12 test analytes was evaluated in 10 runs over the course of eight hours. Total run time for the 12 test analytes was only 42 minutes.

Highly Reproducible Results
The measured values for k'IAM show excellent reproducibility, both from run to run and from day to day.

Durability
IAM Fast-Screen Mini Columns are extremely durable. Correlation factors,r, for the original k', and k' after 5000 column volumes were identical.

Cost Effectiveness
Because the IAM Fast-Screen Mini Column is inexpensive, has a very short analysis time, and provides drug permeability estimates for hundreds of drug candidates in a fraction of time of conventional methods, the IAM Fast-Screen Mini Column becomes the economical alternative for high throughput screening.

Ability to Establish Permeability Zones for High Throughput Screening
Permeability zones can be determined for different analytes when performing large-scale drug absorption screening. Thus, rapid IAM analyses can characterize a drug as having low, medium, or high membrane permeability.

Email the Chromatography Department (chromsales@registech.com) for more information on how IAM Fast-Screen Mini Columns can help with your project.

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