Viagra side effects range from headaches to heart attack
September 1, 1999
Viagra side effects range from headaches to heart attack
Viagra is popular, so learn about these possible dangers
The impotence drug Viagra has become a household word, but it can be dangerous for many patients, stresses Odette Comeau-Luis, RN, MS, CCRN, coordinator of the Emergency Cardiac Care Center at Loma Linda (CA) University Medical Center and Children’s Hospital. "There are side effects and interactions to consider when treating patients who are taking Viagra."
Sildenafil citrate (Viagra), manufactured by Pfizer in New York City, has become a widely prescribed pharmacological treatment option for erectile dysfunction. Serious cardiovascular side effects including myocardial infarction, sudden death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, and hypertension have been reported with Viagra. (See related story on addressing risks at triage, p. 136.)
"Many of these events were reported to occur during or shortly after sexual activity, and few were reported to have occurred hours or days after Viagra use and sexual activity," notes Clyde Miyagawa, PharmD, clinical pharmacy specialist in critical care at University Hospital in Cincinnati. Other potential adverse effects include headache (16%), dyspepsia (7%), and flushing (10%).
Document addresses effect on heart
Because of reports of side effects, an Expert Consensus Document, Use of Sildenafil (Viagra) in Patients with Cardiovascular Disease, was developed by the Bethesda, MD-based American College of Cardiology and the Washington, DC-based American Heart Association. (See ordering information in Source Box; also see excerpt, both on p. 133.)
Here are some things you should know about Viagra’s potential side effects:
• There have been reports of cardiovascular side effects with the use of Viagra in the normal, healthy population. Those have been minor effects, however, and include vasodilatory effects such as headache, flushing, and small decreases in systolic and diastolic blood pressure, says Comeau-Luis. There have been no reports of effects on heart rate or cardiac index, she adds.
• Patients may experience visual disturbances. Mild, transient dose-related impairment of color discrimination (blue/green) can occur with high doses of Viagra, with peak effects near the time of peak plasma levels, notes Miyagawa. "This finding is consistent with the inhibition of PDE6, which is involved in phototransduction in the retina."
• Patients seeking treatment for erectile dysfunction may actually have coronary artery disease. "The arterial system is affected in both," explains Comeau-Luis. "The coronary artery disease may be diagnosed or undiagnosed."
It has even been suggested that the risk factors for atherosclerotic heart disease, including smoking, hypertension, high total cholesterol, low high-density lipoprotein cholesterol, and diabetes are also risk factors for erectile dysfunction, Comeau-Luis adds.
Sexual dysfunction in men after the diagnosis of myocardial infarction is common. While most may be due to the fear that exertion may precipitate another myocardial infarction, as much as 10% to 15% is due to organic causes, notes Comeau-Luis.
Are patients using nitrates?
• Know which patients are at risk. There are many populations in whom the use of Viagra may be hazardous. "Concurrent use of nitrates with Viagra can lead to large and sudden drops in systemic blood pressure," warns Christine Clare, RN, MN, CEN, CNA, nurse manager for express care/industrial medicine and employee health at Loma Linda. (See story on risks of nitrate therapy and Viagra, p. 135.)
Other patients at risk include the following, according to Comeau-Luis:
— individuals receiving any form of nitrate therapy;
— patients with active coronary ischemia;
— patients with congestive heart failure, borderline low blood pressure, and low blood volume status;
— patients with complicated, multidrug, antihypertensive therapy regimens;
— patients taking medications that may affect the metabolic clearance of Viagra.
• Patients with impaired renal or hepatic function may have a reduced clearance of Viagra, notes Comeau-Luis. "Plasma levels of Viagra will increase in these patients. In patients with renal impairment, it may be twice that of those without renal impairment," she explains. "Therefore, the duration of effect will be prolonged, and the effect may be enhanced at any given dose of medication."
Patients with compromised renal and liver function will be predisposed to adverse effects if their dose is not modified, warns Miyagawa.
Red flag: anti-hypertensive meds
• Caution is needed for patients taking anti-hypertensive medications. "This may be a teaching point for a patient with multiple anti-hypertensive medications," says Comeau-Luis. "This could also be a consideration if a patient presents with unexplained hypotension who is on multiple antihypertensives, and has been on them for a long time and has never had problems before."
Patients taking multiple medications for hypotension must be cautioned about the possibility of hypotension induced by Viagra, notes Comeau-Luis.
• Non-prescription use of Viagra can be dangerous. Due to the action of Viagra, there is a large underground market, reports Clare. "Due to this fact, many individuals may use the medication without a physician prescription and will be wary to disclose this fact."
• Side effects can take place during, immediately after, or days after use of Viagra. Many of the side effects/complications occurred during or shortly after sexual activity, reports Comeau-Luis. "A few reported shortly after the use of Viagra but without sexual activity, and some occur hours to days after use of Viagra and sexual activity."
• Know side effects associated with Viagra. Flushing, dyspepsia, and headache are the most common side effects, says Clare. "In both the pre-hospital and ED setting, patients have been severely hypotensive. This had been a result of a nitrate, primarily nitroglycerin, being administered to a patient who had taken Viagra."
Some patients also have complained of dizziness and lightheadedness, and some have had syncopal or near syncopal episodes. "The cardiac neurological complications can be life threatening, and deaths have occurred," says Clare.
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