Patients must skip Viagra 24 hours before surgery

Interacts with drugs that are nitric oxide donors

As the number of Viagra prescriptions exceeds six million, take note: Your patients shouldn’t take Viagra for at least 24 hours before a procedure involving anesthesia, especially if nitrates may be involved, warns the American Association of Nurse Anesthetists (AANA) in Park Ridge, IL .

Viagra needs 24 hours to be eliminated from the patient’s system, according to Bruce Schoneboom, CRNA. Schoneboom is scheduled to receive his PhD in neuroscience from the Uniformed Services University of Health Sciences in Bethesda, MD, in May.

The potential problem with Viagra is that it interacts with drugs that are nitric oxide donors such as nitrates, according to New York City-based Pfizer, which manufactures the drug. Viagra and nitric oxide work at different points on the same chemical pathway to cause smooth muscle relaxation and open blood vessels.

Certain drugs, including nitrates, also work by using nitric oxide to open blood vessels and are commonly used during surgical procedures to lower a patient’s blood pressure, according to the AANA.

"We commonly use those types of drugs in the OR to manage blood pressure," Schoneboom says. Two examples are nitroglycerin and sodium nitroprusside.

If Viagra is in the patient’s system, it could cause blood pressure to become dangerously low and initiate complications during the surgical procedure, the AANA says.

Viagra has side effects that can cause vasodilation to occur in body parts other than the penis, Schoneboom says. "It’s uncommon, and those types of drops in blood pressure are usually small. However, the drops in blood pressure can be dramatic and dangerous, particularly in patients that take the nitrate drugs, he adds. "Our concerns as nurse anesthetists, if patients have recently taken Viagra and we administer general anesthesia or a spinal, is that the combination of the two also could cause an exaggerated drop in blood pressure."

The AANA points out that there have been no documented deaths of Viagra users related to anesthesia complications. While no research has examined whether there are adverse reaction between anesthetics and Viagra, there have been other drug interactions with Viagra, particularly with the nitrate types of drugs, he says. For this reason, the AANA is publicizing Schoneboom’s recommendation. "This was essentially a warning to the public."

Pfizer says 24-hour advice is reasonable

Be cautious when administering any medication that is a nitric oxide donor, of which nitrates are the most common, with Viagra, says Richard Siegel, MD, medical director of sexual health at Pfizer. "Therefore, the recommendations given — including a minimum 24-hour interval after a person’s last dose of Viagra before receiving anesthesia — are reasonable just in case a nitrate-containing medication may need to be used during the procedure," he says.

Anesthesia providers need to ask patients about all drugs they are taking, even those that don’t appear to be medicine, the AANA suggests. Examples of poorly reported drugs include ginseng, ginger, and other herbal treatments, according to the association. (To obtain a brochure titled Considerations for Anesthesiologists: What You Should Know About Your Patients’ Use of Herbal Medicines, see resource box, below. For more information on herbal use, see Same-Day Surgery, August 1999, pp. 93 and 94; and patient assessment form that identifies herb use, SDS August 1999, insert.)

The Park Ridge-based American Society of Anesthesiologists is encouraging patients to tell their surgeons and anesthesiologists about all medications they are taking prior to surgery, says Rebecca S. Twersky, MD, medical director of the Ambulatory Surgery Unit at Long Island College Hospital in Brooklyn, NY. This disclosure should include prescription drugs, over-the-counter medications, herbal products, and recreational drugs. "The decision whether to stop a specific drug prior to surgery should be a medical decision and be made by the patient’s physician, in consultation with the surgeon and anesthesiologist, and be based on the medical needs of the patient."

Men often are reluctant to volunteer that they are taking Viagra, Schoneboom points out. To pinpoint which male patients might be taking Viagra, look for patients who are over 40 and might have a medical history that contributes to erectile dysfunction, such as hypertension, diabetes, or a history of prostate surgery, Schoneboom suggests.

"If the anesthesia provider is tuned into those types of patient profiles, they may be more likely to ask the questions: Do you have erectile dysfunction, and, if so, do you treat it with Viagra?" Schoneboom says. Many patients think that erectile dysfunction isn’t a medical condition and doesn’t need to be reported, he adds.

For more information on Viagra and potential interactions, contact:

Bruce Schoneboom, CRNA, 1401 17th St. N.W., No. 411, Washington, DC 20036. E-mail: bschoneboom@aol.com. Fax: (301) 295-1996.

Richard Siegel, MD, Medical Director, Sexual Health, Pfizer, 235 E. 42nd St., 219-3-4, New York, NY 10017. Telephone: (212) 573-2798. Fax: (212) 672-7885. E-mail: sieger@pfizer. com. For information on all Pfizer products, call (800) 438-1985.

The American Society of Anesthesiology has a publication titled Considerations for Anesthesiologists: What You Should Know About Your Patients’ Use of Herbal Medicines. The brochure can be downloaded from the ASA Web site: ww.asahq.org/ProfInfo/herb/ herbbro.html. Or, for a free single copy, contact: American Society of Anesthesiologists, Publications Department, 520 N. Northwest Highway, Park Ridge, IL 60068-2573. Tele-phone: (847) 825-5586. E-mail: publications @asahq.org.