TABLE 3.

Concentration-response model for opioid craving in the phase 3 study.

Parameter	Description	Estimate (RSE%)	IIV (RSE%)#
α1	Intercept at logit level for zero craving (300/300 mg and PBO)	−2.41 (6.8)	2.10 (4.7)
α1 (300/100)	Intercept at logit level for zero craving (300/100 mg)	−1.87 (11)	−
δ1	Delta between α2 and α1	2.28 (1.7)	−
δ2	Delta between α3 and α2	1.85 (2.5)	−
Emax	Maximal BUP effect	2.87 (7.2)	101 (7.0)
EC50	BUP concentration yielding 50% of Emax	2.45 (15)	−
βEmax (BMI)	Coefficient for BMI (power model) on Emax	0.853 (37)	−

#IIV was modeled assuming a normal distribution for α₁ (SD shown) and a log-normal distribution for E_max (CV% shown). For the log-normal distribution, CV% was calculated as $100\times \sqrt{\exp \left({\omega }^2\right)-1}$ where ${\omega }^2$ was the variance of the related subject-specific random effect.

BMI, body mass index; BUP, buprenorphine; CV, coefficient of variation; IIV, interindividual variability; PBO, placebo; RSE, relative standard error; SD, standard deviation.