Table 2.

Pharmacokinetics of omeprazole (100 µg orally) and its metabolite 5-OH-omeprazole alone (baseline), during CYP2C19 inhibition with fluconazole, and during induction with rifampicin in 20 healthy study participants

100 µg omeprazole	Baseline		Fluconazole		Rifampicin
	Omeprazole		Omeprazole		Omeprazole
Parameter [unit]	Geometric mean	95% CI	Geometric mean	95% CI	Geometric mean	95% CI
Cmax [ng/mL]	4.48	3.59–5.60	13.6 *	11.5–16.1	1.31 *	0.95–1.81
tmax [min] (harmonic mean)	14.8	12.5–18.2	21.8 *	17.4–29.3	10.6 *	17.4–29.3
AUCtot [ng/mL min]	264	188–371	3405 *	2845–4075	45.4 *	33.0–62.4
t1/2 [min]	51.8	42.4–63.3	212 *	200–224	36.0 *	28.1–46.0
VSS [L]	26.1	21.3–31.9	8.80 *	7.50–10.3	93.1 *	67.6–128
VZ [L]	28.3	22.7–35.3	8.97 *	7.54–10.7	114 *	78.3–167
Cl/F [mL/min]	379	269–533	29.4 *	24.5–35.1	2205 *	1603–3034
	5-OH-omeprazole		5-OH-omeprazole		5-OH-omeprazole
Parameter [unit]	Geometric mean	95% CI	Geometric mean	95% CI	Geometric mean	95% CI
Cmax [ng/mL]	1.14	0.88–1.49	0.16 *	0.13–0.19	0.97	0.84–1.13
AUCtot [ng/mL min]	107	96.2–118	77.0 *	66.4–89.2	46.9 *	42.1–52.2
t1/2 [min]	70.4	61.1–81.0	239 *	221–261	47.2 *	43.4–51.4

Test baseline vs. fluconazole or rifampicin: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001

AUC_tot area under the concentration–time curve, Cl/F apparent oral clearance, C_max maximum plasma concentration, t_max time to reach C_max, t_1/2 terminal elimination half-life, V_SS apparent volume of distribution at steady state, V_Z apparent volume of distribution associated with the terminal phase