ViagraŽ and Spinal Cord Injury

Issue 2, Fall, 1999

In 1998 the drug, ViagraŽ (sildenafil), was approved by the Food and Drug Administration (FDA) for use in the treatment of erectile dysfunction in males. Erectile dysfunction (ED) is defined as the consistent inability to achieve and/or maintain an erection sufficient for satisfactory sexual activity.(1) Viagra quickly drew the interest of males with spinal cord injury (SCI) as many experience difficulty in achieving or maintaining an erection due to the effects of their injury.

In clinical studies the drug manufacturer, Pfizer, evaluated the effects of Viagra on over 3000 patients aged 19 to 87 with ED of various etiologies (organic, psychogenic, mixed) with an average duration of 5 years. They also conducted a randomized study of patients with erectile dysfunction resulting from SCI (n=178). Of those individuals with SCI responding to the global improvement question, 83% reported improved erections while taking Viagra versus 12% on the placebo. The diary data kept by individuals with SCI indicated that for those on Viagra, 59% of attempts at sexual intercourse were successful as compared to 13% on the placebo.(1)

Dr. Francois Giulano from Paris reported on this study at the 8th World Meeting on Impotence Research in August, 1998. Dr. Giulano concluded that Viagra is well tolerated and highly effective for men with erection problems caused by SCI.(2) Dr. Claes Hultling from Sweden presented his results that evaluated quality of life issues on participants from this same study. He found that treatment with sildenafil resulted in statistically significant improvements in key quality of life parameters in individuals with SCI who experience ED.(3)

As for adverse reactions to the drug, Pfizer reported in their studies that 16% experienced headache, 10% flushing and 7% dyspepsia (digestive problems).1 A report in the New England Journal of Medicine tells of 3 different studies on various dosages and their adverse effects. Depending on the dosage, the adverse effects ranged from 14%-30% for headache, 13%-27% for flushing; and 1%-16% for dispepsia.(4)

The information presented in these reports does not indicate the level of injury of the participants in the study. The Product Monograph produced by Pfizer indicates that the majority of patients had severe lesions, classified as A (Complete) or B (Incomplete: sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5) on the American Spinal Injury Association (ASIA) Impairment Scale.

A different study on Viagra , A two-part pilot study of sildenafil (Viagra) in men with erectile dysfunction caused by spinal cord injury, reports that "Sildenafil is an effective, well-tolerated oral treatment for ED in SCI subjects".(5) Another article, Efficacy and safety of oral sildenafil (Viagra) in men with erectile dysfunction caused by spinal cord injury, reports on the same study. It concluded, "Oral sildenafil, taken as required (not more than once daily), significantly improves the quality of erections and satisfaction with sex life in men with erectile dysfunction caused by a spinal cord injury between T6 and L5."(6) In reviewing the results of this study one must keep in mind that the sample size was small (27 patients), it was funded by Pfizer Inc, the company manufacturing the drug, and it was conducted in England. This study used only individuals with a level of injury at or below T7 who had incomplete lesions.

Clinical Applications

Jane Brown, MA, an AASECT Certified Sex Therapist at the UAB Sexual Health Clinic, works with Keith Lloyd, MD, Urologist for the Neurogenic Bladder Clinic, Department of Physical Medicine and Rehabilitation at UAB. They report that "Viagra is being prescribed for males with SCI who are experiencing impotency, but in doing so we address several issues. What is their level of injury? While we are prescribing its use for all levels of injury, we do not use it with anyone who experiences severe signs of dysreflexia. We also note what are other medical complications the individual has such as low or high blood pressure or vascular disease? These conditions disqualify an individual for use of Viagra."

"All patients seen at our Clinic are told to monitor any side effects that they may experience, such as flushing in the face, headaches, nasal congestion, or vision changes. These may be signs of autonomic dysreflexia that can be a life-threatening event. It is also important for us to know who is not getting a good response from the drug."

"Other advice that we give our patients is that Pfizer warns not to use Viagra with any other medical treatment for ED, such as injection therapy. If an individual has been using injection therapy, such as papaverine or triple mix, they must stop using it when taking Viagra."

"The patients whom we have seen at the general Urology Clinic, who do not have spinal cord injury, report that Viagra works best when taken on an empty stomach. We also remind individuals that alcohol and drug use can keep one from having a good response from Viagra. Avoid using drugs or alcohol use if one plans to use Viagra."

Another concern of individuals with SCI relates to age. Can older men with SCI use Viagra? "At this time there are no studies on this specific population with Viagra. At our clinic we see similar results with the use of Viagra in older men with SCI as in the general population. This mainly is that it can take longer for the Viagra to have an effect. Again the doctor needs to be aware of any prior health problems such as hypertension or vascular disease."

It is understandable that males with SCI are calling their physicians and urologists to get prescriptions for Viagra. There are articles in many popular publications, including magazines for individuals with SCI, on the success of this drug. Pfizer includes a man using a wheelchair in one of their television commercials advertising Viagra for treatment of erectile dysfunction (ED).

"Our main concern is that individuals with SCI receive the proper information for their situation. Some of what is presented to the public is mis-information in that it is not complete. Often the report does not include complete facts and conditions of the study or contain adequate warning signs. One such article, in a magazine for individuals with SCI, reported successful use of Viagra by some individuals with tetraplegia (level of injury at C5 and C 6). However, it did not explain that this was not the group used in clinical trials nor that individuals with tetraplegia need to be aware of certain side effects that could be signs of dysreflexia.

Other New Medications for Treatment of Erectile Dysfunction

There are several other drugs for treating ED that are still under clinical trials.(7) Uprima (apomorphine) is in clinical trials by the manufacturer, TAP Pharmaceuticals, Inc (Abbott Laboratories and Takeda Chemical Industries). Uprima is in pill form that is dissolved under the tongue. It is different from Viagra in that it acts through the central nervous system for sexual response. Results of the phase III studies were recently reported at the American Urological Association meeting in May, 1999. (8,9, 10) None of the reports indicated the involvement of individuals with spinal cord injuries in their studies at this time.

Vasomax (phentolamine) has been in clinical testing by drugmaker Zonagen, Inc. Vasomax was originally used for treatment of impotence by injection and has been reformulated as an oral medication. Their partner, Schering-Plough Corp., is conducting additional studies before submitting their clinical test data to the FDA for approval. It is expected that it will be mid-2000 before final approval is received from FDA. (11,12)

Recommendations for Viagra use by individuals with SCI

Before using Viagra for ED, individuals with SCI should