1. Study design of the 23 included trials.

Study	Number of participants Study design Patient focus	Mean age (yrs)	Female	Male	F: M ratio	Quinine dose (mg)	Treatment period (d)	Washout period (d)	Treatment comparisons
BioDesign 1984a	n = 24 Study design = C Patient focus = I	57	11	13	0.8	260	7	7	Quinine‐vitamin E combination (Q‐Vel®)b ✓
Bottner 1984a	n = 69 Study design = C Patient focus = I	51	66	3	22.0	260	14	14	Placebo ✓
CIBA 1988a	n = 556 Study design = P Patient focus = I	45	393	163	2.4	260	14	n/a	Placebo ✓ Vitamin E ✓ Quinine‐vitamin E combination (Q‐Vel®) ✓
Connolly 1992	n = 30 Study design = C Patient focus = I	59	0	30	0.0	500	28	28	Placebo ✓ Vitamin E ✓c
Dunn 1993	n = 28 Study design = C Patient focus = I	67	17	11	1.5	300	30	3	Placebo ✓
Diener 2002	n = 94 Study design = P Patient focus = I	49	66	32	2.1	400	14	n/a	Placebo ✓
Fung 1989	n = 9 Study design = C Patient focus = I	63	7	1	7.0	200	28	7	Placebo ✓
Gorlich 1991	n = 164 Study design = P Patient focus = I	56	119	45	2.6	260	14	n/a	Placebo ✓ Quinine‐theophylline combination (Limptar®)b ✓
Hays 1986a	n = 62 Study design = C Patient focus = I	47	49	13	3.8	325	14	14	Placebo ✓
Jansen 1994	n = 20 Study design = P Patient focus = I	55	14	6	2.3	300	14	n/a	Placebo ✓
Jansen 1997	n = 106 Study design = P Patient focus = I	51	68	44	1.5	300	14	n/a	Placebo ✓
Jones 1983	n = 9 Study design = C Patient focus = I	_	_	_	_	300	14	14	Placebo ✓
Kaji 1976	n = 9 Study design = C Patient focus = H	_	_	_	_	320d	42d	0	Placebo ✓
Lee 1991	n = 31 Study design = P Patient focus = L	62	5	26	0.2	400	28	n/a	Placebo ✓
Leo Winter 1986a	n = 205 Study design = C Patient focus = I	44	173	32	5.4	260	5	2	Placebo ✓ Vitamin E ✓ Quinine‐vitamin E combination (Q‐Vel®) ✓
Lim 1986	n = 25 Study design = P Patient focus = I	_	_	_	_	300	≤ 14	n/a	Placebo ✓
Maule 1990	n = 16 Study design = C Patient focus = I	76	10	6	1.7	300	21	0	Placebo ✓
Prateepavanich 1999	n = 24 Study design = P Patient focus = Ie	64	21	3	7.0	300	28	n/a	Xylocaine injection ✓
Roca 1992	n = 30 Study design = P Patient focus = H	48	10	19	0.5	325	60f	n/a	Vitamin E ✓
Sidorov 1993	n = 19 Study design = C Patient focus = I	58	14	2	7.0	200	14	14	Placebo ✓
Smith 1985	n = 21 Study design = C Patient focus = I	73	_	_	_	300	21	0	Placebo ✓
Warburton 1987	n = 22 Study design = C Patient focus = I	74	16	6	2.7	300	21	0	Placebo ✓
Woodfield 2005	n = 13 Study design = N‐of‐1 Patient focus = I	75	7	6	1.2	200 to 300	42	0	Placebo ✓

Abbreviations: C: cross‐over, P: parallel, H: haemodialysis‐induced cramps, I: idiopathic, L: patients with liver cirrhosis; n/a: not available

^aUnpublished.
 ^bQ‐Vel^®: trade name for quinine‐vitamin E combination; Limptar^®:trade name for quinine‐theophylline combination.
 ^cConnolly 1992 did not directly compare quinine versus vitamin E ‐ using the data provided we were able to draw comparison.
 ^dQuinine dose given at beginning of each dialysis session (3 times per wk) and not daily.
 ^eInclusion criteria included presence of myofascial trigger point in gastrocnemius.
 ^fA 60‐day trial but results only reported from first month of treatment.