Simenafil Hydrochloride

TPN171, a novel, highly selective, and potent phosphodiesterase type 5 (PDE5) inhibitor, is currently under clinical development for the treatment of pulmonary arterial hypertension (PAH) and erectile dysfunction (ED). The drug is mainly metabolized by the cytochrome P450 (CYP) enzyme 3A4. We evaluated the pharmacokinetic (PK) profile and safety of TPN171, both alone and in combination with itraconazole (a CYP3A4 potent inhibitor) or rifampin (a CYP3A4 potent inducer), in healthy Chinese volunteers.

In this open-label, fixed-sequence study, TPN171 (10 mg) was administered orally once daily on Days 1 and 6 in Cohort 1, followed by oral itraconazole (200 mg) once daily from Days 3 to 6. Cohort 2 received oral TPN171 (20 mg) once daily on Days 1 and 10, with concurrent oral rifampin (600 mg) once daily administered from Days 3 to 10. Twenty-four healthy subjects were enrolled (12 per cohort). The PK parameters of TPN171 were estimated through noncompartmental analysis with its plasma concentration detection. Comparisons of the maximum plasma concentration (C_max) and the area under the concentration-time curve extrapolated to infinity (AUC_0-∞) for TPN171 were conducted between conditions with and without coadministration of itraconazole or rifampin.

The C_max and AUC_0-∞ for TPN171 were increased by 76.00% (least squares geometric mean ratios (LSGMR), 176.00% [90% CI, 160.37%-193.15%]) and 185.67% (LSGMR, 285.67% [90% CI, 261.87%-311.64%]) when combined with itraconazole versus TPN171 alone. The C_max and AUC_0-∞ of TPN171 were reduced by 74.53% (LSGMR, 25.47% [90% CI, 21.98%-29.50%]) and 90.14% when combined with rifampin versus TPN171 alone (LSGMR, 9.86% [90% CI, 9.08%-10.71%]). Spontaneous penile erection was the most frequently reported adverse event, occurring in 17 (70.83%) of the 24 subjects.

CYP3A4 potent inhibitors and inducers can significantly affect the exposure level of TPN171, especially the inducers. Therefore, when taking TPN171, it is recommended to avoid concomitant administration with CYP3A4 potent inhibitors or potent/moderate inducers, or adjust the dosage of TPN171.

Simenafil, a potent and highly selective oral phosphodiesterase type 5 (PDE5) inhibitor, is currently under investigation for erectile dysfunction (ED) treatment.

To evaluate the efficacy and safety of simenafil for ED treatment.

This was a multicenter, randomized, double-blind, placebo-controlled, parallel group, phase 3 study in men aged 18-75 years with a history of ED of 6 months or more. The subjects were randomized in a ratio of 1:1:1:1 to on-demand receive fixed-dose either placebo or simenafil (2.5 mg, 5 mg or 10 mg) for 12 weeks.

Primary efficacy endpoints were the least square mean (LSM) changes from baseline to week 12 in the erectile function (EF) domain of the International Index of Erectile Function (IIEF), percentages of “yes” responses to sexual encounter profile (SEP) diary question 2 (SEP Q2: Were you able to insert your penis into your partner’s vagina?) and question 3 (SEP Q3: Did your erection last long enough for you to have successful intercourse?)

A total of 765 patients were randomized and 92.3% completed the study. The mean age of subjects was 41.3 years and 81.6% had moderate to severe ED (mean overall International Index of Erectile Function–Erectile Function (IIEF-EF) domain score 13.4). After 12 weeks of treatment, doses of 2.5, 5, and 10 mg of simenafil exhibited substantial increases than placebo in IIEF-EF score (12.3, 12.3, 12.7 vs. 9.6), the percentages of “yes” responses to SEP Q2 (40.58%, 42.43%, 43.98% vs. 32.05%), and SEP Q3 (61.91%, 63.70%, 65.19% vs. 46.70%) (all P < .001). Adverse drug reactions (ADRs) occurred in 36.2% of patients who received simenafil (32.6% in simenafil 5 mg group, the clinically recommended dose) and in 30.9% of those who received placebo. The most common (≥2%) ADRs were dizziness, headache, flushing, nasal congestion, and dry mouth, and most were mild or moderate. Furthermore, abnormal vision (PDE6 related) and myalgia (PDE11 related) did not occur in patients who received simenafil.

Simenafil is highly effective in all 3 dose groups and has a low effective dose and good safety profile, providing a novel, favorable treatment option for patients with ED.

The efficacy and safety evaluation of simenafil in difficult-to-treat patients with ED, ED patients with other concomitant diseases, and other ethnic populations was not performed.

Simenafil is an effective and well-tolerated therapy for patients with ED.