Drug–drug interaction potential and clinical pharmacokinetics of enerisant, a novel potent and selective histamine H₃ receptor antagonist

Figures & data

Figure 1. Chemical structure of [¹⁴C]enerisant. Asterisk donates the position of the ¹⁴C label.

Table 1. Marker reactions, the concentrations of probe substrates, and the reaction times for CYP inhibition studies.

Enzyme	Marker reaction	Concentration (µM)	Reaction time (min)
CYP1A2	Phenacetin O-deethylation	30	30
CYP2A6	Coumarin 7-hydroxylation	1	2
CYP2B6	Bupropion hydroxylation	100	30
CYP2C8	Amodiaquine N-deethylation	2	2
CYP2C9	Diclofenac 4′-hydroxylation	5	5
CYP2C19	(S)-Mephenytoin 4′-hydroxylation	20	30
CYP2D6	Bufuralol 1′-hydroxylation	10	20
CYP2E1	Chlorzoxazone 6-hydroxylation	40	30
CYP3A4	Midazolam 1′-hydroxylation	5	5
CYP3A4	Testosterone 6β-hydroxylation	50	10

Table 2. Probe substrates, the concentrations of probe substrates, and the incubation times for transporter inhibition studies

Transporter	Probe substrate	Concentration (μM)	Incubation time (min)
P-gp	[^3H]Digoxin	1	60
BCRP	[^3H]Prazosin	5	60
OATP1B1	[^3H]Oestrone 3-sulfate	0.05	0.25
OATP1B3	[^3H]Cholecystokinin octapeptide	0.03	1
OAT1	[^3H]p-Aminohippuric acid	1	0.5
OAT3	[^3H]Oestrone 3-sulfate	0.2	0.5
OCT2	[^3H]N-methyl-4-phenylpyridinium acetate	0.03	0.5
MATE1	[^14C]Tetraethylammonium bromide	30	2
MATE2-K	[^14C]Tetraethylammonium bromide	30	2

Table 3. Plasma protein binding of [¹⁴C]Enerisant in rat, dog, and human.

	Protein binding (%)
	0.05 µg/mL	0.5 µg/mL	5 µg/mL
Rat	36.9 ± 1.8	35.1 ± 0.7	33.3 ± 0.2
Dog	25.5 ± 0.9	25.9 ± 2.2	26.0 ± 0.1
Human	31.7 ± 0.9	31.1 ± 1.0	31.0 ± 0.8

Data are represented as mean ± SD of triplicate.

Table 4. Inhibition of enerisant for CYP activities in human liver microsomes.

CYP isoform	Inhibition (%) at 100 µM^a
CYP1A2	3.6
CYP2A6	2.1
CYP2B6	2.6
CYP2C8	−3.6
CYP2C9	−2.0
CYP2C19	1.0
CYP2D6	14.1
CYP2E1	3.3
CYP3A4	3.3
CYP3A4	5.5

^aCalculated from the mean activity data of triplicate incubation samples.

Table 5. Effects of enerisant and control inducers on mRNA of primary human hepatocytes after 72 h-exposure.

Enzyme	mRNA fold change^a
	Control (DMSO)	Enerisant			Control inducer
		1 µM	5 µM	20 µM
CYP1A2	1.00	0.964 ± 0.066	0.945 ± 0.112	1.13 ± 0.24	Omeprazole (50 µM)	92.2 ± 43.4
CYP2B6	1.00	1.16 ± 0.36	1.09 ± 0.25	1.23 ± 0.17	Phenobarbital (750 µM)	14.0 ± 2.4
CYP3A4	1.00	1.16 ± 0.14	1.05 ± 0.11	1.42 ± 0.52	Rifampicin (20 µM)	14.6 ± 5.4

Data are represented as the mean ± SD of three donors.

^amRNA fold change = mRNA level after treatment of substance/mRNA level after treatment of solvent control.

Table 6. [¹⁴C]Enerisant permeability and efflux ratio across P-gp-expressing MDCK cell and BCRP-expressing MDCK cell monolayers.

Cell line	Treatment	Papp (10^−6 cm/sec)		Efflux ratio
		A to B	B to A
P-gp-MDCK	[^14C]Enerisant (5 μM)	4.17 ± 0.22	45.9 ± 4.1	11.0
	[^14C]Enerisant (5 μM)+verapamil (100 μM)	24.7 ± 0.2	18.6 ± 1.6	0.753
BCRP-MDCK	[^14C]Enerisant (5 μM)	16.4 ± 0.6	27.9 ± 0.9	1.70

A to B, apical to basolateral; B to A, basolateral to apical. P_app values are represented as mean ± SD of triplicate.

Figure 2. Time-dependent uptake of [¹⁴C]enerisant by cells transfected with OATP1B1 (A), OATP1B3 (B), OAT1 (C), OAT3 (D), OCT2 (E), MATE1 (F), and MATE2-K (G) compared with control cells, which were transfected with vector only. Data are represented as mean ± SD of quadruplicate.

Table 7. IC₅₀ values of enerisant for transporter activities in transporter-expressing cells.

Transporter	Probe substrate (μM)	Inhibitor (μM)^a	% of control	IC50 (µM)
P-gp	[^3H]Digoxin (1)	Enerisant (100)	90.2	>100
		Verapamil (100)	19.0	–
BCRP	[^3H]Prazosin (5)	Enerisant (100)	97.9	>100
		Ko143 (1)	10.9	–
OATP1B1	[^3H]E3S (0.05)	Enerisant (100)	84.6	>100
		Rifampicin (100)	8.9	–
OATP1B3	[^3H]CCK8 (0.03)	Enerisant (100)	64.5	>100
		Rifampicin (100)	0.0	–
OAT1	[^3H]PAH (1)	Enerisant (100)	91.1	>100
		Probenicid (100)	13.5	–
OAT3	[^3H]E3S (0.2)	Enerisant (100)	86.3	>100
		Probenicid (100)	3.2	–
OCT2	[^3H]MPP (0.03)	Enerisant (100)	3.3	2.21
		Quinidine (100)	19.9	–
MATE1	[^14C]TEA (30)	Enerisant (100)	1.8	1.80
		Pyrimethamine (1)	5.9	–
MATE2-K	[^14C]TEA (30)	Enerisant (100)	3.9	2.15
		Pyrimethamine (1)	14.7	–

E3S: oestrone 3-sulphate; CCK8: cholecystokinin octapeptide; PAH: p-aminohippuric acid; MMP: N-methyl-4-phenylpyridinium acetate; TEA: tetraethylammonium bromide.

^aEnerisant concentrations were 1 to 100 μM, 100 μM results shown.

Figure 3. Plasma enerisant concentration–time profiles after a single oral administration of enerisant to healthy male subjects. Data are represented as mean ± SD of six subjects.

Table 8. Plasma pharmacokinetic parameters after a single oral administration of enerisant to healthy male subjects.

Dose (mg)	Parameter
	Cmax (ng/mL)	tmax^a(h)	t1/2 (h)	AUC0–48 h (ng·h/mL)	AUC0–∞ (ng·h/mL)
1	4.29 ± 0.82	1.50 (1.00, 2.00)	8.11 ± 0.65	44.8 ± 3.1	45.5 ± 3.1
3	10.3 ± 1.3	2.00 (1.00, 3.00)	8.54 ± 0.80	125 ± 10	128 ± 11
10	39.5 ± 5.3	1.75 (1.00, 4.00)	8.40 ± 0.88	449 ± 51	458 ± 55
30	113 ± 11	1.25 (1.00, 3.00)	8.40 ± 0.52	1320 ± 120	1340 ± 120
50	260 ± 75	1.00 (0.500, 2.00)	8.14 ± 0.73	2180 ± 390	2210 ± 410
100	560 ± 91	1.75 (1.00, 2.00)	8.24 ± 0.36	5170 ± 360	5250 ± 360
150	835 ± 212	1.00 (1.00, 2.00)	7.30 ± 0.37	8480 ± 1660	8570 ± 1690

^aMedian (minimum, maximum) values are presented.

C_max, maximum plasma concentration; t_max, time to maximum plasma concentration; t_1/2, half-life; AUC_0–48 h, area under the concentration–time curve from zero to 48 h; AUC_0–∞, area under the concentration-time curve from zero to infinity. Data are represented as mean ± SD of six subjects.

Table 9. Urinary excretion and renal clearance after a single oral administration of enerisant to healthy male subjects.

Dose (mg)	Parameter
	Urinary excretion (% of dose)		CLr (L/h)
	0–24 h	0–48 h
1	70.6 ± 3.9	78.3 ± 4.1	17.6 ± 1.6
3	66.9 ± 8.7	74.9 ± 9.4	18.0 ± 2.5
10	65.4 ± 3.6	73.1 ± 3.2	16.4 ± 1.8
30	56.5 ± 6.2	64.5 ± 8.1	14.7 ± 1.2
50	69.4 ± 7.8	76.1 ± 7.7	18.0 ± 3.9
100	81.0 ± 2.8	89.9 ± 2.8	17.4 ± 1.2
150	63.0 ± 5.1	70.6 ± 4.5	12.9 ± 2.7

CL_r: renal clearance. Data are represented as mean ± SD of six subjects.