Madhu 2010.

Methods	Study design: randomised controlled trial. Allocation generation: randomisation. Allocation concealment: sealed envelope technique Blinding: not described. Loss to follow‐up: Intervention: 2%. Control: 4%.
Participants	Total number of participants randomised: 150. Inclusion criteria: primi‐ and multigravidas, gestational age 37‐40 weeks, with low risk pregnancy, in spontaneous labour, cephalic presentation. Exclusion criteria: malpresentation, multiple pregnancy, intrauterine growth restriction, medical problems, previous caesarean section, antepartum haemorrhage, induction of labour, cervical dilatation of > 5 cm.
Interventions	Intervention: 1. Drotaverine hydrochloride 40 mg (2 mL) IMI at 4 cm dilation and every hour for a max of 3 doses n = 50. 2. Valethamate bromide 8 mg (1 mL) IMI at 4 cm dilation and every hour for a max of 3 doses. n = 50 Control: NaCl 0.9% 2 mL IMI at 4 cm dilation and every hour for a max of 3 doses. n = 50.
Outcomes	Primary outcomes: 1. Injection to delivery time. 2. Mean cervical dilatation rate (cm/h). 3. Duration of second stage. Secondary outcomes: Adverse maternal and neonatal events.
Notes	Ethics: ethics approval from medical research committee of the college. Location: India.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation by sealed envelope technique.Not described how random numbers were generated.
Allocation concealment (selection bias)	Unclear risk	Sealed envelope technique. Not clear how this was done and if allocation was concealed.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding due to lack of resources.
Blinding of outcome assessment (detection bias) All outcomes	High risk	No blinding due to lack of resources.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for.
Selective reporting (reporting bias)	High risk	Pre‐specified outcomes not reported: Duration of 2nd and 3rd stage of labour Apgar scores of newborns not reported No follow‐up report (mothers and babies were followed for 3 days and at day 10 postnatal).
Other bias	Low risk	The study appears to be free of other sources of bias. Confounding factors are not statistically significantly different between groups. Drug company sponsorship: no.