All patients with a clinical and instrumental diagnosis of lifelong PE according to the European Association of Urology (EAU) guidelines and the International Society for Sexual Medicine (ISSM) recommendations (3,4), attending three Italian tertiary Urological Institutions (Department of Urology of Santa Chiara Regional Hospital, Trento; University of Naples Federico II, Naples; University of Foggia, Foggia) from July to December 2014 were enrolled in this prospective, multicentre, phase I–II study. All patients underwent clinical and instrumental examinations and International Prostatic Symptom Score (IPSS), International Index of Erectile Function (IIEF-15), Premature Ejaculation Diagnostic Tool (PEDT) and Short Form (SF)-36 questionnaires were administered. Moreover, a stop-watch estimation of intravaginal ejaculation latency time (IELT) and all patient-reported outcomes (PROs) were collected. In addition, urine examination and urine culture were performed. Following enrolment, all patients received oral tablets of EndEP^® (one tablet/day) for 90 days.

PE was defined in accordance to the ISSM as follows: ‘A male sexual dysfunction characterised by ejaculation which always or nearly always occurs before or within about 1 min of vaginal penetration, and the inability to delay ejaculation on all or nearly all vaginal penetrations, and negative personal consequences, such as stress, bother, frustration and/or the avoidance of sexual intimacy’ (4). Patients were eligible for inclusion if they met all the following criteria: Aged between 18 and 45 years; in a stable relationship with a partner for ≥6 months and engaging in sexual intercourse once a week or more often; and affected by life-long PE (with a baseline IELT ≤60s) (4). All enrolled patients were naive to any therapy for PE. All patients affected by major concomitant diseases such as diabetes, liver and/or renal failure; with known anatomical abnormalities or malignancy of the urinary tract or bladder, upper tract stones, diverticula, foreign bodies, prostatitis, active urinary tract infection, chronic retention or polycystic kidney disease were excluded. All patients with concomitant pharmacological therapy for erectile dysfunction, with clinical suspicion of secondary PE and all patients in chronic therapy for depression (SSRIs) were also excluded. In cases of clinical suspicion of secondary PE due to urinary tract infections or sexually transmitted disease, such as Chlamydia trachomatis, Ureaplasma urealyticum or Neisseria gonorrhoeae, a Meares-Stamey test and urethral swab were performed, in line with Cai et al (11). All patients with positive microbiological culture were excluded. Moreover, all patients with an allergy to one or more of the components of EndEP^® were also excluded.

On arrival at each Centre, all eligible individuals signed a standard informed consent form for off-label therapy and new drugs under investigation, underwent a baseline questionnaire and urological examination with anamnestic interview, in accordance with the procedure described in EAU guidelines (3). All patients who met the inclusion criteria underwent oral therapy with EndEP^® (one tablet/day) for 90 days. All patients were contacted by telephone on day 30 of the therapy to ensure the dosing and timing of treatment was correct. Each subject was scheduled for follow-up examination at 90 days from starting therapy, with a urological visit, and IPSS, IIEF-15, PEDT and SF-36 questionnaires. Moreover, all PROs were collected. No placebo arm was included. The possible biases caused by the lack of placebo arm were considered in the analysis of the results. Figure 1 shows a flow-chart of the study protocol. Clinical failure was defined as the persistence of symptoms following the treatment, or the suspension of therapy for significant reported adverse effects. In addition, spontaneously reported adverse events, or those noted by the investigator, were recorded during the whole study period. All subjects gave written informed consent before entering the study. The study was conducted in line with Good Clinical Practice guidelines, with the ethical principles laid down in the latest version of the Declaration of Helsinki. Ethical approval was not required due to the fact that the compound is registered in the Italian Pharmacopeia for clinical use as a nutraceutical.

The validated Italian versions of the IPSS (12), IIEF-15 (13) and PEDT (14) were administered to each patient. In line with Jannini et al, a careful urological visit with disease history collection was performed at arrival at each Centre (15). Moreover, patient quality of life (QoL) was measured using an Italian version of the SF-36 Health Survey, a test particularly suitable for chronic conditions (16). The questionnaire was offered to each patient on arrival at the Centre. All questionnaires were also used when determining the efficacy of clinical therapy. The patients and their partners were interviewed individually and each was requested to give an independent estimation of IELT. Pre-treatment IELT was measured during a 4-week baseline period; the patients were provided with a stop watch and instructions on how to measure IELT, and were requested to experience coitus at least four times, as reported by Pastore et al (17). Couples were instructed not to use condoms or any topical anaesthetic cream, and not to pause during intercourse or have interrupted intromission. Furthermore, the patients were instructed that if intercourse took place more than once in a single session, only the first intercourse was to be measured (17).

All patients were orally administered EndEP^® once daily, as a tablet in the morning immediately after breakfast. Each EndEP^® tablet (450 mg) contained 200 mg Rhodiola rosea, 10 mg zinc, 200 µg folic acid and 50 µg biotin. All compound analyses were carried out according to the methods described by Fiamegos et al (18).

Normal distribution of the variables was assessed using the Kolmogorov-Smirnov test, histograms, and P-P plots. If necessary, the data were log (ln) transformed to achieve a normal distribution. Data were analysed based on the intention-to-treat approach. General characteristics of the study participants were expressed using descriptive statistics (means, standard deviation and ranges). For each dependent variable, changes from baseline were calculated by subtracting the baseline value from the end-of-trial value. Analysis of variance was used for comparing means, and the Bonferroni adjustment test was used at the second stage of the analysis of variance. The sample size was calculated prospectively under the following conditions: Difference between the groups=10% (reduction in PEDT questionnaire score), α error level=0.05 two-sided, statistical power = 80% and anticipated effect size (Cohen's d=0.5). The calculation yielded 72 individuals. Assuming a dropout rate of approximately 20%, 86 patients should be enrolled into the study. The main outcome measure was the difference from baseline in PEDT questionnaire, mean IELT and PROs at the end of the follow-up period. P<0.05 was considered to indicate a statistically significant difference. SPSS software, version 11.0 (SPSS Inc., Chicago, IL, USA) was used to conduct the statistical analyses.

From a total population of 95 enrolled patients, 3 patients were excluded for lack of information and 1 patient was lost during follow-up; thus, 91 patients (mean age, 33.6±9.4 years) were finally analysed. Anamnestic and clinical data at enrolment are presented in Table I.

Compliance was observed in 91 patients (95.8%). Accordingly, compliance to the study protocol was high. The EndEP^® formulation was well tolerated in all patients analysed and there were no significant drug-related side effects. Four of the 91 patients (4.4%) had mild adverse effects that did not require the treatment to be suspended. The most common adverse effects were mild nausea and mild headache.

At the follow-up examination (90 days after treatment initiation), statistically significant differences were identified between mean IELT time at enrolment and following treatment (73.6±46.9 vs. 102.3±60.0s; P<0.001), PEDT score (15.3±3.4 vs. 12.2±3.2; P<0.001) and SF-36 questionnaire score (98.2±0.5 vs. 99.4±0.1; P<0.001). Moreover, 55 out of 91 patients reported improvement in control of ejaculation (PRO evaluation; 60.4%). At the follow-up examination (3 months after treatment), no statistically significant differences were found in terms of IPSS or IIEF-15 scores (P=0.19 and P=0.64, respectively). Table II shows all questionnaire results at enrolment and at the follow-up visit.