hERG IC50 Concentration Response Assays
(GLP and non-GLP)
The manual patch clamp hERG assay is the “gold standard” for assessment of drug interactions with the hERG potassium channel responsible for IKr, the rapid delayed rectifier current that mediates cardiac action potential repolarization, and is the primary target for drugs that prolong the QT interval. In this assay, solubility pre-testing, concentration range-finding, and continuous superfusion of cells to reach a steady-state effect improves the accuracy of the measurement, even for difficult (e.g., “sticky”) compounds. Moreover, recordings can be performed at physiologic temperature and in compliance with GLP guidelines, including concentration verification by chemical analysis of the superfusate. The concentration-response assay (either GLP or non-GLP) determines an IC50 value that, in the context of intended therapeutic levels, provides an important benchmark for cardiac risk assessment.
Assay Features:
- Quantitative assessment of inhibitory potency
- Physiological temperature standard
- Concentration and solubility pre-testing standard
- Concentration verification available
- Three week turnaround time with concentration analysis
Ion Channel |
Assay |
Positive Contol |
| hERG |
GLP Assays: GLP protocol conducted at either physiological or room temperature; recommended for IND submissions Non-GLP Assays: GLP-type protocol & report, including concentration pre-testing & GLP-level compound exposure times, but without QAU inspection and auditing required by the GLP protocol |
Cisapride or Terfenadine |
| Assay Parameters: | hERG IC50 (GLP) |
hERG IC50 (non-GLP)
|
| Number of concentrations | 4 -6 |
3 - 6 |
| Number of replicates per concentration | ≥3 |
2 - 3 |
| Positive control (n ≥ 2) | 2 |
2 |
| Vehicle control (1 concentration n ≥ 3) | included |
optional |
| Solubility pre-test | ||
| Assay temp: room (RT) or physiological (PT) | PT (standard); RT (optional) |
RT (standard); PT (optional) |
| Concentration range-finding pre-test | included |
included |
| Protocol & report | GLP |
GLP-type |
| Cumulative curves | standard |
standard |
| Collection of analytical samples | standard |
optional |
| Electronic (pdf) report provided | standard |
optional |
HERG concentration-response assay
A: Superimposed patch clamp recordings (upper section) obtained before (control) and during application of 10 and 100 nM cisapride. At the end of the recording period 500 nM E-4031, a selective hERG channel blocker, was applied. The lower section of the figure shows the stimulus voltage pattern.
hERG concentration-response assay.
B: Peak current amplitude versus time during repetitive stimulation at 0.1 pulses/second.
hERG concentration-response assay.
C: Concentration-response relationship. Mean ± SEM, n = 4 cells/concentration. IC50 = 0.0234 μM.
Optional assays:
- Dose Solution Analysis – GLP & non-GLP; verify applied concentrations with analytical sample testing of doses
- Use-dependence analysis
- Temperature-dependence analysis
Additional options:
- Additional copies of final report
- Copies of solution worksheets & data-collection forms
- Integrated Risk Assessment Summary – dose-response, repolarization, in vivo data compiled in one report
For a quote or additional information, please email inquiries@chantest.com or call 216-332-1665.
Additional Cardiac Safety Assays:
