pKI values of known histamine agonists and antagonists
| Compound | pKI |
|---|---|
| N-methylhistamine | −9.8 |
| Imetit | −9.7 |
| Immepip | −9.7 |
| Clobenpropit | −9.3 |
| Histamine | −8.5 |
| Thioperamide | −7.7 |
| Ranitidine | >−5 |
| Diphenhydramine | >−5 |
| Clozapine | >−5 |
| Cirazoline | >−5 |
| Mepyramine | >−5 |
| Imidazole | >−5 |
Values were determined by competition binding withR-α-methyl[3H]histamine to GPCR97-expressing cell membranes.