Here is something I copied from an MOS member, Bionic:
World J Urol. 2005 Dec;23(6):385-92. Epub 2005 Nov 5.
Treating erectile dysfunction by endothelial rehabilitation with phosphodiesterase 5 inhibitors.
Department of Men’s Health and Clinic of Urology, University Hospital Hamburg-Eppendorf, P.O. Box 202101, 20214, Hamburg, Germany. Frank.Sommer@me … and-health.info
A large body of evidence has accumulated demonstrating that a common pathway in conditions such as hypertension, atherosclerosis, hypercholesterolemia, diabetes mellitus, and erectile dysfunction (ED) is endothelial dysfunction. Although a complete pharmacological cure for ED is currently unavailable, the phosphodiesterase 5 (PDE5) inhibitors sildenafil, vardenafil, and tadalafil are efficacious oral therapy for ED. Results from recent studies suggest that regular treatment with a PDE5 inhibitor may lead to enhanced erectile function (EF) beyond that observed with on-demand usage, possibly through improvement of endothelial function. Such an effect may be viewed as rehabilitation of damaged erectile tissue. The present review focuses on several recent studies which provide evidence for the beneficial effect of regular PDE5 inhibitor administration on the improvement of EF by rehabilitation of vascular endothelium.
PMID: 16273418
J Sex Med. 2006 May;3(3):504-11.
Tolerance to the therapeutic effect of tadalafil does not occur during 6 months of treatment: A randomized, double-blind, placebo-controlled study in men with erectile dysfunction.
Australian Centre for Sexual Health, Sydney, Australia. Cmcmahon@acsh.com.au
INTRODUCTION: Tolerance can cause a decrease in drug efficacy during chronic therapy, possibly leading to treatment failures. AIM: The aim of this article is to determine whether tolerance developed to the effects of tadalafil on erectile function (EF) over a 6-month treatment period. METHODS AND MAIN OUTCOME MEASURES: Post hoc analysis of data from a multicenter, double-blind, randomized, placebo-controlled, parallel group study was performed. Men (> or =18 years of age) with erectile dysfunction (ED) were randomized to treatment with placebo (N = 47) or 20-mg tadalafil (N = 93) taken as needed for 6 months. This report focuses on efficacy assessed with the Sexual Encounter Profile (SEP) diary (diaries were collected after a 4-week treatment-free run-in period [baseline], and monthly for 6 months), and with the International Index of Erectile Function (IIEF) (administered at baseline, and at 3 and 6 months). RESULTS. The mean per-patient percentage "yes" response on SEP question 3 (SEP3, successful intercourse) was 33 +/- 4% at baseline, 74 +/- 4% after 1 month, and 78 +/- 4% after 6 months of tadalafil treatment. The IIEF EF domain score was 16.2 +/- 0.7 at baseline, 24.3 +/- 0.8 after 3 months, and 24.3 +/- 0.9 after 6 months of tadalafil treatment. In a subgroup of patients who took tadalafil > or =3 times per week (N = 24), the SEP3 score was 87 +/- 4% after 1 month and 93 +/- 3% after 6 months of treatment, and the IIEF EF domain score was 27.3 +/- 0.9 after 3 months and 28.5 +/- 0.4 after 6 months. Of 16 tadalafil-treated patients who discontinued, three cited a lack of efficacy. CONCLUSIONS: Tadalafil treatment significantly improved SEP3 and IIEF EF domain scores. The efficacy of tadalafil, taken as needed, was maintained over a 6-month treatment period in men with ED.
PMID: 16681476
Int J Impot Res. 2007 Mar-Apr;19(2):200-7. Epub 2006 Aug 31.
Relationship between chronic tadalafil administration and improvement of endothelial function in men with erectile dysfunction: a pilot study.
Medical Pathophysiology, University of Rome La Sapienza, Rome, Italy. Antonio.aversa@uniroma1.it
Men with erectile dysfunction (ED) frequently have a disproportionate burden of comorbid vascular disorders including atherosclerotic disease. We investigated whether scheduled tadalafil is better than on-demand (OD) in improving endothelium-dependent vasodilatation of cavernous arteries in men with ED and whether this effect is also exerted on markers of endothelial function. We did an open-label, randomized, crossover study including 20 male outclinic patients aged 18 years or older (mean age 54 years) who had at least a 3-month history of ED of any severity or etiology. Tadalafil (20 mg) on alternate days (ADs) or OD was administered for 4 weeks. Primary end points were variations of basal inflow (peak systolic velocity (PSV)) and flow-mediated dilatation (FMD) of cavernous arteries compared with baseline at penile Duplex ultrasound. Secondary end points were variations of Q13-SIEDY scores regarding morning erections and of markers of endothelial function, that is, vascular cell adhesion molecule (VCAM), intercellular cell adhesion molecule, endothelin-1 (ET-1), insulin and C-reactive protein (CRP). PSVs and FMD were higher after AD treatment when compared with OD and baseline, respectively (P=0.0001), and improvements were maintained from 2 weeks after discontinuation (P<0.005). Patients receiving tadalafil AD experienced a significant improvement of morning erections as compared to AD treatment (P<0.0001); ET1, VCAM and CRP showed a robust decrease after chronic vs OD regimes (P<0.05), with concomitant increase in insulin levels (P<0.05), without any variation in blood pressure and other laboratory parameters. Chronic but not OD tadalafil improves endothelial function with sustained effects from it’s discontinuation. Chronic treatment also produces a dramatic increase in morning erections, which determines better oxygenation to the penis, thus providing a rationale for vascular rehabilitation.
PMID: 16943794
http://www.life stages.com/heal … ction_2006.html
Bionic also stated:
"The take home message: a little daily tadalafil is pretty damned good for your Johnson and general health and does not create tolerance."