A prospective randomized study to optimize the dosage of trimix ingredients and compare its efficacy and safety with prostaglandin E1

Abstract

Intracavernous injection of Trimix (Tx) is indicated for patients unsuitable for prostaglandin E 1 (PgE 1 ) injection due to lack of response, pain or cost. We believe that the ideal ratio of ingredient doses in Tx is yet to be found. We postulated that increasing the doses of individual drug components in an orderly manner would convey important data on penile hemodynamic response. Such information is needed to choose an effective and less costly alternative to PgE 1 with least side effects. We set out to evaluate the impact of varying the ingredient dosage on response and shortterm safety of Tx compared with PgE 1 . We prospectively randomized 180 consecutive patients with erectile dysfunction into nine equal groups and each group received a different dose of Tx, namely phentolamine (1 mg) plus one dose of PgE 1 (2.5, 5 or 10 lg) and one dose of papaverine (5, 10 or 20 mg). Each patient was injected with 20 lg PgE 1 and one dose of Tx in two clinic visits 1 week apart. Following injection, duplex ultrasound of cavernous arteries and axial rigidometry were carried out. Patients ranked the quality of erection, estimated overall satisfaction and reported time to detumescence and side effects. Patients' mean age was 50.5711.7 y with underlying organic condition in 91.1%. There were no significant differences between PgE 1 and Tx with regard to peak cavernous artery flow, time to erection, patients' satisfaction, average axial rigidity and pain. PgE 1 produced higher end diastolic velocity, shorter duration of erection and less priapism. Patients did not show a preference for either drug or any particular dosage. We conclude that even at the smallest dose of ingredients of Tx, there are no significant differences in hemodynamic effects, rigidity, pain and self-satisfaction between the two drugs. However, Tx produces a longer duration of erection and more priapism than PgE 1 .

Mechanisms of Penile Erection and Basis for Pharmacological Treatment of Erectile Dysfunction

“…Bechara et al (1996) reported better results with the combination than with PGE 1 alone. However, Seyam et al (2005) compared trimix using a 1-mg dose of phentolamine and different doses of papaverine and PGE 1 with a 20-g dose of PGE1, found no significant differences in hemodynamic effects, rigidity, pain, and self-satisfaction between the two drugs. However, trimix produced a longer duration of erection and more priapism than PGE 1 .…”

Standardization of Vascular Assessment of Erectile Dysfunction

“…Inner diameter of intracavernosal arteries (both left and right) and occasionally the peak systolic velocities (PSVs) in both arteries are then measured using the Doppler blood‐flow mode. Although recent studies claim a good predictive value of PSV measurement in this flaccid state , the universal consensus is to perform the study under pharmacologically induced erection [10–15]. For this, an ICI of a single or combination of vasoactive agents (e.g., PGE1, phentolamine, and papaverine) is administered [1–3].…”

“… The following parameters commonly used in vascular diagnostics for the blood‐flow quantification are useful in ED evaluation [5–16]: …”

Pharmacotherapy for Erectile Dysfunction: Recommendations From the Fourth International Consultation for Sexual Medicine (ICSM 2015)

“…287 Currently, tri-mix is an option for severe veno-occlusive dysfunction or in the aftermath of radical pelvic surgery. 274,288 Pain or tenderness after PGE 1 is accentuated by an underlying cavernous nerve injury; therefore, bi-mix or tri-mix would be more suitable in such patients.…”