Theoretical relationship between half-maximal drug response and the operational efficacy and affinity of a drug (Black et al. 2010) | (6) |

or |

(7) |

Anticipated experimental of reference agonist | Since , eq. 6 becomes | Since , eq. 6 becomes |

(8a) | (8b) |

Anticipated experimental of a test agonist | | Since , eq. 6 becomes |

(9a) | (9b) |

Experimental implementation of operational model to determine affinity | |

Implementation of the operational model assumes eq. 7 to be valid for experimentally measured values; in other words, |

(10) |

Experimental determination of affinity, , of a test agonist | |

Substituting eqs. 5a and 9a | | Substituting eqs. 5b and 9b |

| | |

(11a) | | (11b) |