TABLE 3.

Potencies for clinically used progestins, antiprogestins, endogenous steroid hormones and androgens to elicit calcium influx in human sperm

	#	Steroid	Steroid Alone				+30 µM Mibefradil
			pEC50	Emax, %	n	pEC50		Emax, %	n
Progestins and Anti-progestins	4	MPA	<5	17	3	—		<10	3
	5	LNG	<5	15	6	—		<10	2
	31	drospirenone	6.28 ± 0.22	115	5	—		<10	4
	32	ulipristal	5.45 ± 0.22	106	3	<5		12	5
	33	mifepristone (RU-486)	5.33 ± 0.30	109	4	—		<10	5
	34	ulipristal acetate	<5	27	3	—		<10	3
	35	segesterone acetate	<5	57	4	—		<10	4
Endogenous	6	ALDO	—	<10	3	—		<10	1
	36	testosterone	6.66 ± 0.22	114	3	<5		17	4
	37	17β-estradiol	6.53 ± 0.25	94	3	<5		37	1
Androgens	38	11β-methyl-19-nortestosterone	6.37 ± 0.32	85	6	6.27 ± 0.25		15	3
	39	7α-methyl-19-nortestosterone	6.25 ± 0.37	86	7	6.29		26	2
	40	7α,11β-dimethylandrolone	6.06 ± 0.49	80	9	<5		11	3
	41	7β,11β-dimethylandrolone	5.41 ± 0.24	42	5	<5		26	3

The potency (EC₅₀ values, mean ±SD) and maximum response (E_max) produced by each compound was determined in the absence and presence of 30 µM mibefradil. E_max is expressed as a percent of the response produced by a saturating concentration of PROG (3 µM). The number of independent experiments indicated by n. Fitted parameters were not calculated for compounds producing E_max < 10%.