Objective and Subjective Measures of Premature Ejaculation: How Closely Do They Correspond and How Well Are the Subjective Measures Recalled?

BACKGROUND: Clinical trials evaluating new treatments for premature ejaculation (PE) should ideally include both objective end points and patient reported outcomes (PROs), but there is no consensus currently over the optimal measures or combination of outcomes. In addition, many PROs use a 1-month recall period, despite concerns about potential recall bias. AIMS: Data from a clinical trial of men with lifelong PE were used to examine the consistency of 2 core items of the Premature Ejaculation Profile (PEP), a widely used PRO for assessing subjective aspects of PE. The specific aim was to assess the level of agreement between the original 1-month recall version compared with a new event-based version of the scale in men meeting current definitions of lifelong PE. A further aim was to investigate the convergent validity between an objective end point of intravaginal ejaculatory latency time (IELT), subjective PEP responses, and a patient's Clinical Global Impression of Change (CGIC) measure. METHODS: For assessment of consistency of PEP responses (short-term [ie, sexual event driven] vs 1-month recall), descriptive statistics, correlation coefficients (Pearson and Spearman), and Bland-Altman plots are presented for each time interval. For assessment of convergent validity, descriptive statistics and correlation coefficients (Pearson and Spearman) are presented for each assessment with geometric mean IELT values. Results are also depicted graphically. Geometric mean IELT over the last 4 weeks of treatment and change from baseline (absolute and fold change) were estimated via a general linear model for each category of change in PEP and CGIC, adjusting for baseline IELT. OUTCOMES: PEP items administered via 1-month recall and short-term event-driven responses gave virtually identical results. There was a strong correlation (very good convergent validity) between IELT and responses to PEP and the CGIC. CLINICAL TRANSLATION: Men with lifelong PE can accurately recall their level of sexual functioning over the previous month. The PEP and CGIC are appropriate instruments to measure the subjective response of men with PE to new treatments. STRENGTHS AND LIMITATIONS: Our analyses address gaps in previously published research on PE assessment methodology. Men with acquired PE, men without partners, and men in homosexual relationships were not studied. CONCLUSIONS: In a clinical trial setting, PEP and CGIC are appropriate end points and are likely the optimal combination of PROs for use with IELT to enable a global assessment of patient response to new PE treatments. Althof S, Rosen R, Harty B, et al. Objective and Subjective Measures of Premature Ejaculation: How Closely Do They Correspond and How Well Are the Subjective Measures Recalled? J Sex Med 2020;17:634-644.

The Oxytocin Antagonist Cligosiban Prolongs Intravaginal Ejaculatory Latency and Improves Patient-Reported Outcomes in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Proof-of-Concept Trial (PEPIX).

INTRODUCTION: Cligosiban is an orally administered oxytocin receptor antagonist being developed to treat premature ejaculation (PE). AIM: To determine the safety and efficacy of cligosiban capsules (dose range 400-800 mg) to improve intravaginal ejaculation latency time (IELT) and patient-reported outcomes in men with severe lifelong PE. METHODS: Patients recorded details of at least 4 sexual intercourse events during a 4-week run-in period, after which they underwent baseline assessments. Patients were eligible for the study if they rated their control of ejaculation as poor/very poor and their stopwatch-assessed IELT was ≤1 minute in ≥75% of intercourse attempts. Eligible patients were randomized to an 8-week treatment period with double-blind cligosiban or placebo (to be taken 1 to 6 hours prior to sexual activity). The starting dose was 400 mg (not more than 1 dose per day) which could be increased to 800 mg after 2 and/or 4 weeks of treatment. Assessments were conducted at 2, 4, and 8 weeks. MAIN OUTCOME MEASURE: Efficacy measures were comprised of IELT, self-rating of ejaculation control and ejaculation-related distress (recorded in an electronic diary after each intercourse attempt), premature ejaculation profile, and the Clinical Global Impression of Change. RESULTS: The mean ratio of fold change from baseline in IELT to the last 4 weeks of treatment (cligosiban/placebo) was 1.9 compared to a baseline of 1.0 (P = .0079). The mean increase in IELT from baseline to the last 4 weeks of treatment was 61.0 seconds for cligosiban, which was significantly different from (and 3.6-fold greater than) the mean increase of 16.4 seconds for placebo (P = .0086). Statistically significant improvements in ejaculation control and ejaculation-related personal distress scores were also observed for cligosiban compared to little or no change with placebo. Cligosiban was generally well tolerated, with no serious or severe adverse events or other safety parameters. CLINICAL IMPLICATIONS: This proof-of-concept study demonstrated the potential for cligosiban, an oxytocin antagonist, to successfully treat symptoms of severe lifelong PE. STRENGTHS AND LIMITATIONS: This was a Phase II, randomized, double-blind, placebo-controlled study that was adequately powered to detect a clinically meaningful difference in change in IELT between cligosiban and placebo. Larger studies will be needed to confirm these findings, determine the optimal dose of cligosiban and assess efficacy in men with acquired PE. CONCLUSIONS: Cligosiban was well tolerated, and resulted in significant benefits in both objective and subjective measures of ejaculatory control in men with lifelong PE and therefore offers significant potential as an on-demand, orally administered agent for the treatment of PE. McMahon C, Althof S, Rosen R, et al. The Oxytocin Antagonist Cligosiban Prolongs Intravaginal Ejaculatory Latency and Improves Patient-Reported Outcomes in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Proof-of-Concept Trial (PEPIX). J Sex Med 2019; 16:1178-1187.

The Oxytocin Antagonist Cligosiban Fails to Prolong Intravaginal Ejaculatory Latency in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Phase IIb trial (PEDRIX).

INTRODUCTION: Cligosiban is an orally administered, centrally penetrant oxytocin receptor antagonist being developed to treat premature ejaculation (PE). AIM: To determine the efficacy of 3 dose levels of cligosiban caplets to prolong intravaginal ejaculation latency time (IELT) and improve patient-reported outcomes in men with lifelong PE. METHODS: Patients recorded details of at least 4 sexual intercourse events during a 4-week run-in period, after which they underwent baseline assessments. Patients were eligible for the study if their stopwatch-assessed IELT was ≤1 minute in ≥75% of intercourse attempts and if they met other diagnostic criteria for lifelong PE. Eligible patients (target 220 evaluable) were randomized to double-blind cligosiban 400, 800, or 1200 mg or matching placebo caplets (to be taken 1 to 6 hours prior to sexual activity). Assessments were conducted at 2, 4, and 8 weeks. MAIN OUTCOME MEASURE: Efficacy measures were comprised of IELT, self-rating of ejaculation control and ejaculation-related distress (recorded in an electronic diary after each intercourse attempt), premature ejaculation profile, Patient's Global Impression of Severity, and the Clinical Global Impression of Change. RESULTS: There were no clinically or statistically significant differences between cligosiban (at any dose level) and placebo for the primary endpoint (change in geometric IELT) or any of the secondary endpoints. Cligosiban was well tolerated with a side-effect profile similar to placebo. CLINICAL IMPLICATIONS: This Phase IIb study failed to demonstrate the potential for cligosiban, an oxytocin antagonist, to successfully treat symptoms of severe lifelong PE at doses up to 1200 mg. STRENGTHS AND LIMITATIONS: This was a Phase IIb, randomized, double-blind, placebo-controlled study that was adequately powered but failed to detect a clinically meaningful or statistical difference in change in IELT between cligosiban at 3 dose levels and placebo. This is in contrast to a similarly designed proof-of-concept study where cligosiban was flexibly dosed at doses up to 800 mg and did demonstrate clinically meaningful and statistically significant changes in efficacy parameters. The reasons for this disparity are not known. CONCLUSIONS: Cligosiban was well tolerated but failed to demonstrate efficacy for the treatment of men with lifelong PE at doses up to 1200 mg. Althof S, Osterloh IH, Muirhead GJ, et al. The Oxytocin Antagonist Cligosiban Fails to Prolong Intravaginal Ejaculatory Latency in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Phase IIb trial (PEDRIX). J Sex Med 2019; 16:1188-1198.

Content Validity of the Premature Ejaculation Profile, Original and Per-Event Formats, in Men with Lifelong Premature Ejaculation.

BACKGROUND: The Premature Ejaculation Profile (PEP) is a patient-reported outcome (PRO) measure that is widely used in clinical research in men with premature ejaculation (PE) but has not been fully validated for men meeting the current International Society for Sexual Medicine (ISSM) definition of lifelong PE. AIM: To explore the content validity of the PEP (original 1-month recall version and new event-driven version) in men meeting current definitions of lifelong PE and to understand the relevance of the concept of ejaculation control. METHODS: In-depth individual interviews were conducted with 24 men in a stable heterosexual relationship, including 15 with lifelong PE, 4 with acquired PE (with intravaginal ejaculation latency time values confirmed during a 4-week period of no treatment), and 5 with no sexual dysfunction. Initial concept elicitation explored individual experiences of having PE (in those with PE), experiences of control, and impact on sexual life. This was followed by a cognitive debriefing of the PEP versions. MAIN OUTCOME MEASURE: Thematic analysis was used to identify key concepts of PE, understand the experience of control in men with and without PE, and confirm understanding and relevance of questions from original and event-driven versions of the PEP. RESULTS: The interviews confirmed substantial negative consequences for men with lifelong PE. Men with and without PE could describe ejaculation control (or lack of it). The PEP was shown to cover the key concepts in PE, and the questions were easily understood in both the original or event-driven versions. The items were comprehensive, and the concept of ejaculation control was confirmed. A 1- or 2-category change in each item of the PEP was considered clinically meaningful. CLINICAL IMPLICATIONS: The PEP (original and per-event) has strong content validity for use in clinical research studies of men meeting the ISSM definition of lifelong PE. STRENGTHS & LIMITATIONS: This study addressed gaps in previously published research on the development and validation of the PEP and also confirmed that a new event-driven version is also suitable for use in research. However, the study was limited mainly to men meeting a strict definition of lifelong PE; in addition, homosexual men and those not in stable long-term relationships were not studied. CONCLUSION: Both the original and per-event PEP versions were shown to have strong content validity and be acceptable for use in men with lifelong PE. Burbridge C, Symonds T, Osterloh IH, et al. Content Validity of the Premature Ejaculation Profile, Original and Per-Event Formats, in Men with Lifelong Premature Ejaculation. J Sex Med 2019;16:569-576.

Pharmacokinetics, Safety, and Tolerability of Multiple Doses of the Novel Oxytocin Receptor Antagonist Cligosiban in Development for Premature Ejaculation: Two Randomized Clinical Trials in Healthy Subjects.

BACKGROUND: Cligosiban (formerly IX-01) is a selective oxytocin receptor antagonist being developed for the treatment of premature ejaculation (PE). AIM: To investigate the plasma pharmacokinetics, safety, and tolerability of multiple oral doses of cligosiban in healthy male subjects; measure the amount of cligosiban in semen; and evaluate the potential of cligosiban to modulate CYP3A4. METHODS: Both studies were double-blind, placebo-controlled, parallel group designs involving sequential cohorts of 12 subjects each. Cligosiban dosage regimens were 100 mg, 400 mg, 800 mg, 1200 mg, 1,600 mg and 2,400 mg once daily for 10 days, administered as an aqueous dispersion. OUTCOMES: Blood samplings for cligosiban assays and safety assessments were performed throughout both studies. Semen was collected on day 9 at 2-4 hours postdose in study 1 only. Safety assessments included monitoring of adverse events, 12-lead electrocardiography, vital signs, and laboratory safety assessments. Urine samples for assessment of the 6ß-hydroxycortisol/cortisol ratio were collected before dosing on days 1 and 10. RESULTS: Cligosiban was rapidly absorbed after both single and multiple dosing, with maximum plasma concentrations typically measured at 1-3 hours postdose. The terminal half-life was approximately 12 hours, and steady state was achieved by day 3. Exposure increased approximately proportionally to dose after single dosing but less than proportionally after multiple dosing. Accumulation ratios were higher at the lower doses compared with higher doses (2.3 at 100 mg vs 1.1 at 2,400 mg). The mean amount of cligosiban in semen ranged from 0.22 to 2.01 µg over the 100-1,200 mg dose range (<0.0003% of the administered dose). There were no meaningful differences in the urinary 6ß-hydroxycortisol/cortisol ratio after multiple dosing with cligosiban. Cligosiban appeared to be well tolerated at all dose levels. CLINICAL IMPLICATIONS: Cligosiban is well tolerated following once-daily dosing over a wide dose range and does not appear to modulate CYP3A4 activity, suggesting limited potential for perpetrating drug-drug interactions via this mechanism. STRENGTHS & LIMITATIONS: The 2 controlled trials show good toleration and pharmacokinetic data, including negligible amounts of cligosiban in semen at doses expected to be therapeutic. Toleration of cligosiban will need to be confirmed in studies in patients with PE. CONCLUSION: Cligosiban showed a good safety profile at doses predicted to be therapeutic or supratherapeutic along with a pharmacokinetic profile appropriate for as-required or once-daily dosing. There was no evidence that cligosiban inhibited or induced CYP3A4 at doses up to 2,400 mg. Muirhead GJ, Osterloh IH, Whaley S, et al. Pharmacokinetics, Safety, and Tolerability of Multiple Doses of the Novel Oxytocin Receptor Antagonist Cligosiban in Development for Premature Ejaculation: Two Randomized Clinical Trials in Healthy Subjects. J Sex Med 2019;16:213-222.

Pharmacokinetics, Safety, and Tolerability of Single Oral Doses of a Novel Oxytocin Receptor Antagonist-Cligosiban-in Development for Premature Ejaculation: Three Randomized Clinical Trials in Healthy Subjects.

INTRODUCTION: Cligosiban is a selective oxytocin receptor antagonist being developed for the treatment of premature ejaculation (PE). AIM: Three clinical studies investigated the pharmacokinetics (including effect of food and formulation), central penetration, safety, and tolerability of single oral doses of cligosiban in healthy subjects. METHODS: Study 1 was a double-blind, randomized, placebo-controlled, crossover design in 3 cohorts of 10 subjects each. Single doses of 0.3-2,400 mg cligosiban were administered as aqueous solutions or dispersions under fasting and fed (800 mg only) conditions. Studies 2 and 3 were open-label, randomized, crossover designs in 12 subjects each. Study 2 investigated 800 mg cligosiban administered as capsules and aqueous dispersion under fasting conditions, and capsules under fed conditions. Study 3 investigated 1,600 mg cligosiban administered as caplets and aqueous dispersion under fasting conditions, and caplets under fed conditions. MAIN OUTCOME MEASURES: Blood sampling for cligosiban assay and safety assessments were conducted throughout all studies. Cerebrospinal fluid (CSF) samples for cligosiban assay were collected in study 2. RESULTS: Cligosiban was rapidly absorbed under fasting conditions with peak concentrations generally occurring within 1-2 hours post-dose regardless of formulation. Maximum observed plasma concentration (Cmax) and area under the concentration time curve extrapolated to infinity (AUC0-∞) increased approximately dose-proportionally from 0.3-10 mg, but sub-proportionally from 30-2,400 mg. Cligosiban exposure was similar when administered as a dispersion or capsule (800 mg) under fasted conditions, but higher (87% increase) when administered as a caplet compared to the dispersion (1,600 mg). Food decreased the rate of absorption for all 3 formulations (median time to Cmax 3-6 hours compared to 1-2 hours fasted) but increased the extent of absorption (Cmax and AUC0-∞ increased by 75-149% and 33-49%, respectively). Cligosiban was detected in CSF at concentrations approximately 40% of unbound plasma concentrations. Cligosiban was well tolerated at all doses. CLINICAL IMPLICATIONS: Cligosiban is well tolerated over a wide dose range, and has the pharmacokinetic properties to be taken as required prior to sexual intercourse in men with PE and to antagonize the oxytocin receptor in the brain and spinal cord. STRENGTHS & LIMITATIONS: Three controlled trials show similar toleration and pharmacokinetic data. Cligosiban in CSF indicates its likely presence in all central nervous system tissue. These data need to be investigated and confirmed in multiple-dose studies prior to investigation in phase-II studies in men with PE. CONCLUSION: Cligosiban had a good safety/tolerability profile at doses predicted to be therapeutic or supra-therapeutic and a pharmacokinetic profile appropriate for "as-needed" dosing for men with PE. Osterloh IH, Muirhead GJ, Sultana S, et al. Pharmacokinetics, Safety, and Tolerability of Single Oral Doses of a Novel Oxytocin Receptor Antagonist-Cligosiban-in Development for Premature Ejaculation: Three Randomized Clinical Trials in Healthy Subjects. J Sex Med 2018;15:1547-1557.

Sildenafil: from angina to erectile dysfunction to pulmonary hypertension and beyond.

In less than 20 years, the first selective type 5 phosphodiesterase inhibitor, sildenafil, has evolved from a potential anti-angina drug to an on-demand oral treatment for erectile dysfunction (Viagra), and more recently to a new orally active treatment for pulmonary hypertension (Revatio). Here we describe the key milestones in the development of sildenafil for these diverse medical conditions, discuss the advances in science and clinical medicine that have accompanied this journey and consider possible future indications for this versatile drug.