The affinity of triptans
Analyzing In Vitro Results for the 5-HT Ligands
The affinity of triptans for 5-ht subtypes
The key reference drugs of the 5-HT1B/D agonist sub-family of the triptans are almotriptan, naratriptan, rizatriptan and sumatriptan. The full activity profile for these drugs is visualized in a Heatmap (Figure 2). Extensive data are available on sumatriptan and the Heatmap clearly displays the selectivity profile of that drug.
The pX values for almotriptan, naratriptan, rizatriptan and sumatriptan for 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, 5-HT1F, 5-HT6 and 5-HT7 were selected using Analysis View and viewed as a Heatmap (Figure 3).
A large number of binding data points are available for naratriptan, rizatriptan and particularly for sumatriptan against all of the targets selected, especially the 5-HT1B and 5-HT1D receptors (Figure 4). pX values extracted from the literature show a large variation, especially for sumatriptan against the 5-HT1B and 5-HT1D receptors.
The large number of data points available for sumatriptan on 5-HT1B resulted in significant differences in reported pX values. Differences in the experimental conditions under which these data were obtained could explain the discrepancies. Figure 5 illustrates the analysis of these data points by receptor species and by human cell line used in the assay.