Table 1.

Details of Included Studies.

Study	Study Design	Country	Treatment	Dosage	Sample Size	Scheme	Treatment Cycle	Inclusion Criteria	Sample Size Calculations
Mohammad RS (2006)	RCT	Iran	Tramadol; Placebo	50 mg	32; 32	2 hr before sexual activity	8 weeks	Potent married men aged 20–52 years who had an IELT of less than 2 min that occurred in more than 90% of coitus.	No
Emad AS (2008)	Single blind crossover study	USA	Tramadol; Placebo	25 mg	30; 30	1–2 hr before sexual activity	8 weeks	Patients were IELT <2 min in 80% of intercourse attempts, with at least one intercourse episode per week.	No
Moheiddin A (2010)	RCT	Egypt	Tramadol; Paroxetine	50 mg; 20 mg	17; 18	2–3 hr before sexual activity	6 weeks	Only cases with lifelong PE were included. PE was defined according to the definition of DSM-IV-RT.	No
David BO (2011)	RCT	USA	Tramadol; Tramadol; Placebo	62 mg; 89 mg	206; 198; 200	2–8 hr before sexual activity	12 weeks	The population baseline median IELT was <60 s in each treatment arm.	No
XIONG GG (2011)	RCT	China	Tramadol; Placebo	50 mg	36; 36	2 hr before intercourse	8 weeks	Potent married men who had an IELT of <2 min over a 3-month period had been in a stable relationship with uncontrolled ejaculation.	No
Eid MA (2011)	Single blind base study	Egypt	Tramadol; Paroxetine; Placebo	50 mg; 20 mg	50; 50; 50	3–4 hr before sexual activity	3 weeks	Patients with IELT of less than 2 min in 80% of intercourses for 3 weeks for at least 10 successive intercourses.	No
Mehmet K (2012)	Single blind crossover study	Turkey	Tramadol; Placebo	25 mg	30; 30	2 hr before intercourse	8 weeks	All participants had primary PE and stable relationship with a partner for 6 months and possible sexual attempts of once a week or more.	No
Amil HK (2013)	RCT	India	Tramadol; Placebo	100 mg	30; 30	Daily for 4 weeks and then 2 or 8 hr before intercourse for 4 weeks	8 weeks	Patients with IELT of less than 1 min with minimal sexual stimulation before or after ejaculation.	No
Bayoumy IE (2013)	RCT	Egypt	Tramadol; Tramadol; Tramadol;	25 mg; 50 mg; 100 mg	100; 100; 100	2–3 hr before intercourse	24weeks	Men aged 25–50 years with a stable monogamous heterosexual relationship with regular sexual intercourse at least twice per week with a cooperative female partner.	No
Tarek AG (2013)	RCT	Egypt	Tramadol; Paroxetine; Placebo	50 mg; 20 mg	30; 30; 30	2 hr before intercourse; 4 hr before intercourse	4 weeks	Patients included were those with PE for >1 year and who had an IELT of <2 min in >75% of episodes of vaginal sexual intercourse over a 2-week period.	Yes
Adel K (2015)	RCT	Egypt	Tramadol; Tramadol; Placebo	50 mg; 100 mg	60; 60; 60	2–3 hr before intercourse	8 weeks	Participants were potent with no history of erectile dysfunction, and had a stable, regular (≥1 sexual attempts per week), single‑partner heterosexual relationship for ≥1 year.	Yes
Seyyed HS (2015)	RCT	Iran	Tramadol; Placebo	100 mg	20; 20	2 hr before intercourse	3 weeks	Men who had an IELT of <1 min had a stable relationship with uncontrolled ejaculation.	Yes
Ali HM (2018)	RCT	Iran	Tramadol; Paroxetine; Placebo	50 mg; 20 mg	50; 50; 50	2–3 hr before intercourse	12 weeks	Men were between 18 to 55 years old, married, and had a stable relationship for at least 6 months with uncontrolled ejaculation that occurred before or within 1 min of vaginal intercourse.	No
Muhammad FUR (2020)	RCT	PAK	Tramadol; Paroxetine	50 mg; 20 mg	53; 53	2 hr before intercourse; 4 hr before intercourse	8 weeks	Potent married men aged 30 to 40 years who had been in a relationship for at least 6 months with uncontrolled ejaculation within 1 min of vaginal intromission.	Yes

Note. RCT = randomized controlled trial; PE = premature ejaculation; IELT = intravaginal ejaculatory latency time; DSM-IV-TR = Diagnostic and Statistical Manual, Fourth Edition, Text Revision.