Viagra/Sildenafil Clinical Trials

Clinical trials are conducted to investigate the practical efficacy of drugs and they reveal the true picture of its effectiveness over a large patient base composed of people with different bodily attributes.

Most clinical trial reports are often not in simple language and people don't find it easy to sift through those journal papers. We aim to put forward the clinical trial report in a simple format.

There have been many clinical trials conducted by Pfizer to prove the efficacy of sildenafil citrate(Viagra) as a potent erectile dysfunction oral medication. The following report is constructed based on one of the well-documented randomized, placebo-controlled, fixed dose clinical study.

his particular clinical study pool consisted of 1797 patients initially. They were asked various questions corresponding to their frequency and quality of erections and intercourse. Based on this, they were given a grading categorized as IIEF score. IIEF stands for "International Index of Erectile Function". An IIEF score of 5 was considered good while 1 was categorized as a case of severe erectile dysfunction. In all, 349 people were excluded from this study as they were deemed to have normal or near-normal erectile function.

This left the pool with 1448 men who together had an average baseline IIEF score of 2. After this, further diagnosis was made to ascertain the causes of erctile dysfunction. Finally it was estimated that 58% of the men has erectile propblems due to complications from other diseases(organic), 17% had psychogenic ED while the remaining 25% had ED caused by a mix of conditions.

Men reporting positive results

The results were conclusive. An impressive 312 men taking 100mg dose of Viagra (sildenafil) out of the whole 380 reported an overall improvement in the quality of erections. 18% of men on 100mg dose unfortunately couldnt benefit from it. The efficacy was progressively lower for men on the 50mg and 25mg doses.

It is also interesting to note that 24% of the people who were under the placebo (pills with no active ingredient) also reported better erections. This underlines the possibility that for some men(especially ones with psychogenic ED), the very prospect of taking the medicine improves the erections as it builds much needed confidence in men thereby reducing stress levels.

The study went a step further and also attempted to determine the number of times the men in the study actually succeeded in satisfactory intercourse. It came to light that overaall on average 66% of the times, men succeeded in intercourse after having a dose of 100mg. Some men achieved success 90% of the time and some below 50%, but the mean-average was 66%. Pretty good result!

It was also noticed that men who were dose-optimized later on were showing better responses to the medicine. Dose optimization is a process of starting with a lower dose and only upping the dose if necessary. This ensures that one who doesnt need higher doses doesnt take them. Not surprisingly this method led to better efficacy and reduced side effects.

Side effects are almost always mild and temporary. Less than 2% of patients quit due to side effects. In addition to the side effects show in the chart above, a small percentage of men reported slight blue tinge to the vision at the time of peak sildenafil plasma concentration. This did not affect visual accuity and the effect was seen to be temporary.

References:
pfizer.com/files/products/uspi_viagra.pdf
ncbi.nlm.nih.gov/pubmed/15126148
ncbi.nlm.nih.gov/pubmed/9647940