August 29, 2016
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Side Effects


The following serious adverse reactions with the use of STAXYN (vardenafil) are discussed elsewhere in the labeling:

Clinical Studies Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

STAXYN: Safety of STAXYN was evaluated in two identical multi-national, randomized, double-blind, placebo-controlled trials. In both pivotal studies, enrollment was stratified so that approximately 50% of patients were ≥ 65 years old. Approximately 8% (n=29) were ≥ 75 years old. An integrated analysis of both studies included a total of 355 subjects that received STAXYN compared to 340 subjects that received placebo (mean age was 61.7, range 21.0 to 88.0; 68% White, 5% Black, 6% Asian, 11% Hispanic and 11% Other). The discontinuation rates due to adverse reactions were 1.4% for STAXYN compared to 0.6% for placebo. Table 1 below details the most frequently reported adverse reactions.

Table 1: Adverse drug reactions reported by ≥ 2% of the patients treated with STAXYN and more frequent on drug than placebo in controlled trials

Adverse Drug Reaction STAXYN
Headache 14.4% 1.8%
Flushing 7.6% 0.6%
Nasal Congestion 3.1% 0.3%
Dyspepsia 2.8% 0%
Dizziness 2.3% 0%
Back Pain 2% 0.3%

Adverse drug reactions reported in the STAXYN placebo controlled trials were comparable to the adverse drug reactions reported in earlier vardenafil film-coated tablets placebo controlled trials.

All Vardenafil Studies

Vardenafil film-coated tablets and STAXYN has been administered to over 17,000 men (mean age 54.5, range 18–89 years; 70% White, 5% Black, 13% Asian, 4% Hispanic and 8% Other) during controlled and uncontrolled clinical trials worldwide. The number of patients treated for 6 months or longer was 3357, and 1350 patients were treated for at least 1 year.

In the placebo-controlled clinical trials for vardenafil film-coated tablets and STAXYN, the discontinuation rate due to adverse events was 1.9% for vardenafil compared to 0.8% for placebo.

Placebo-controlled trials suggested a dose effect in the incidence of some adverse reactions (for example, dizziness, headache, flushing, dyspepsia, nausea, nasal congestion) over the 5 mg, 10 mg, and 20 mg doses of vardenafil film-coated tablets.

The following section identifies additional, less frequent adverse reactions ( < 2%) reported during the clinical development of vardenafil film-coated tablets and STAXYN. Excluded from this list are those adverse reactions that are infrequent and minor, those events that may be commonly observed in the absence of drug therapy, and those events that are not reasonably associated with the drug:

Body as a whole: allergic edema and angioedema, feeling unwell, allergic reactions, chest pain

Auditory: tinnitus, vertigo

Cardiovascular: palpitation, tachycardia, angina pectoris, myocardial infarction, ventricular tachyarrhythmias, hypotension

Digestive: nausea, gastrointestinal and abdominal pain, dry mouth, diarrhea, gastroesophageal reflux disease, gastritis, vomiting, increase in transaminases

Musculoskeletal: increase in creatine phosphokinase (CPK), increased muscle tone and cramping, myalgia

Nervous: paresthesia and dysesthesia, somnolence, sleep disorder, syncope, amnesia, seizure

Respiratory: dyspnea, sinus congestion

Skin and appendages: erythema, rash

Ophthalmologic: visual disturbance, ocular hyperemia, visual color distortions, eye pain and eye discomfort, photophobia, increase in intraocular pressure, conjunctivitis

Urogenital: increase in erection, priapism

Postmarketing Experience

The following adverse reactions have been identified during post approval use of vardenafil in the film-coated tablet formulation. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency or establish a causal relationship to drug exposure.


Non-arteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, has been reported rarely postmarketing in temporal association with the use of PDE5 inhibitors, including vardenafil. Most, but not all, of these patients had underlying anatomic or vascular risk factors for development of NAION, including but not necessarily limited to: low cup to disc ratio (“crowded disc”), age over 50, diabetes, hypertension, coronary artery disease, hyperlipidemia and smoking. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors, to the patient's underlying vascular risk factors or anatomical defects, to a combination of these factors, or to other factors [see WARNINGS AND PRECAUTIONS and PATIENT INFORMATION].

Visual disturbances including vision loss (temporary or permanent), such as visual field defect, retinal vein occlusion, and reduced visual acuity, have also been reported rarely in postmarketing experience. It is not possible to determine whether these events are related directly to the use of vardenafil.


Seizure, seizure recurrence and transient global amnesia have been reported postmarketing in temporal association with vardenafil.


Cases of sudden decrease or loss of hearing have been reported postmarketing in temporal association with the use of PDE5 inhibitors, including vardenafil. In some cases, medical conditions and other factors were reported that may have also played a role in the otologic adverse events. In many cases, medical follow-up information was limited. It is not possible to determine whether these reported events are related directly to the use of vardenafil, to the patient's underlying risk factors for hearing loss, a combination of these factors, or to other factors [see PATIENT INFORMATION].

Read the Staxyn (vardenafil hydrochloride orally disintegrating tablets) Side Effects Center for a complete guide to possible side effects


The drug interaction studies described below were conducted using vardenafil film-coated tablets.

Potential For Pharmacodynamic Interactions With STAXYN


Concomitant use of STAXYN and nitrates is contraindicated. The blood pressure lowering effects of sublingual nitrates (0.4 mg) taken 1 and 4 hours after vardenafil and increases in heart rate when taken at 1, 4 and 8 hours after vardenafil were potentiated by a 20 mg dose of vardenafil in healthy middle-aged subjects. These effects were not observed when vardenafil 20 mg was taken 24 hours before the nitroglycerin (NTG). Potentiation of the hypotensive effects of nitrates for patients with ischemic heart disease has not been evaluated, and concomitant use of STAXYN and nitrates is contraindicated [see CONTRAINDICATIONS and CLINICAL PHARMACOLOGY].


Patients taking alpha-blockers should not initiate vardenafil therapy with STAXYN. Patients treated with alpha-blockers who have previously used vardenafil film-coated tablets may be switched to STAXYN at the advice of their healthcare provider. Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including STAXYN and alpha-adrenergic blocking agents are both vasodilators with blood-pressure-lowering effects. When vasodilators are used in combination, an additive effect on blood pressure may be anticipated. Clinical pharmacology studies have been conducted with co-administration of vardenafil with alfuzosin, terazosin or tamsulosin. [See DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS, and CLINICAL PHARMACOLOGY]


STAXYN may add to the blood pressure lowering effect of antihypertensive agents. In a clinical pharmacology study of patients with erectile dysfunction, single doses of 20 mg vardenafil caused a mean maximum decrease in supine blood pressure of 7 mmHg systolic and 8 mmHg diastolic (compared to placebo), accompanied by a mean maximum increase of heart rate of 4 beats per minute. The maximum decrease in blood pressure occurred between 1 and 4 hours after dosing. Following multiple dosing for 31 days, similar blood pressure responses were observed on Day 31 as on Day 1.


Vardenafil 20 mg did not potentiate the hypotensive effects of alcohol during the 4-hour observation period in healthy volunteers when administered with alcohol (0.5 g/kg body weight: approximately 40 mL of absolute alcohol in a 70 kg person). Alcohol and vardenafil plasma levels were not altered when dosed simultaneously.

Effect Of Other Drugs On Vardenafil

In vitro studies

Studies in human liver microsomes showed that vardenafil is metabolized primarily by cytochrome P450 (CYP) isoforms 3A4/5, and to a lesser degree by CYP2C9. Therefore, inhibitors of these enzymes are expected to reduce vardenafil clearance [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS].

In Vivo Studies

Do not use STAXYN with moderate and potent CYP3A4 inhibitors such as erythromycin, grapefruit juice, clarithromycin, ketoconazole, itraconazole, indinavir, saquinavir, atazanavir, ritonavir as the systemic concentration of vardenafil is increased in their presence [see WARNINGS AND PRECAUTIONS and DOSAGE AND ADMINISTRATION].

Potent CYP3A4 Inhibitors

Ketoconazole (200 mg once daily) produced a 10-fold increase in vardenafil area under the curve (AUC) and a 4-fold increase in maximum concentration (Cmax) when co-administered with vardenafil 5 mg in healthy volunteers. [See DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS]

Indinavir (800 mg t.i.d.) co-administered with vardenafil 10 mg resulted in a 16-fold increase in vardenafil AUC, a 7-fold increase in vardenafil Cmax and a 2-fold increase in vardenafil half-life. [See DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS]

Ritonavir (600 mg b.i.d.) co-administered with vardenafil 5 mg resulted in a 49-fold increase in vardenafil AUC and a 13fold increase in vardenafil Cmax. The interaction is a consequence of blocking hepatic metabolism of vardenafil by ritonavir, a HIV protease inhibitor and a highly potent CYP3A4 inhibitor, which also inhibits CYP2C9. [See DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS]

Moderate CYP3A4 Inhibitors

Erythromycin (500 mg t.i.d.) produced a 4-fold increase in vardenafil AUC and a 3-fold increase in vardenafil Cmax when co-administered with vardenafil 5 mg in healthy volunteers [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS].

Other Drug Interactions

No pharmacokinetic interactions were observed between vardenafil and the following drugs: glyburide, warfarin, digoxin, an antacid based on magnesium-aluminum hydroxide, and ranitidine. In the warfarin study, vardenafil had no effect on the prothrombin time or other pharmacodynamic parameters.

Cimetidine (400 mg b.i.d.) had no effect on AUC and Cmax of vardenafil when co-administered with 20 mg vardenafil in healthy volunteers.

Effects Of Vardenafil On Other Drugs

In Vitro Studies

Vardenafil and its metabolites had no effect on CYP1A2, 2A6, and 2E1 (Ki > 100 micromolar). Weak inhibitory effects toward other isoforms (CYP2C8, 2C9, 2C19, 2D6, 3A4) were found, but Ki values were in excess of plasma concentrations achieved following dosing. The most potent inhibitory activity was observed for vardenafil metabolite M1, which had a Ki of 1.4 micromolar toward CYP3A4, which is about 20 times higher than the M1 Cmax values after an 80 mg vardenafil dose.

In Vivo Studies

Nifedipine: Vardenafil 20 mg, when co-administered with slow-release nifedipine 30 mg or 60 mg once daily, did not affect the relative AUC or Cmax of nifedipine, a drug that is metabolized via CYP3A4. Nifedipine did not alter the plasma levels of vardenafil when taken in combination. In these patients whose hypertension was controlled with nifedipine, vardenafil 20 mg produced mean additional supine systolic/diastolic blood pressure reductions of 6/5 mmHg compared to placebo.

Ritonavir and Indinavir: Upon concomitant administration of 5 mg vardenafil with 600 mg b.i.d. ritonavir, the Cmax and AUC of ritonavir were reduced by approximately 20%. Upon administration of 10 mg of vardenafil (film-coated tablets) with 800 mg t.i.d. indinavir, the Cmax and AUC of indinavir were reduced by 40% and 30%, respectively.

Aspirin: Vardenafil 10 mg and 20 mg did not potentiate the increase in bleeding time caused by aspirin (two 81 mg tablets).

Other Interactions: Vardenafil had no effect on the pharmacodynamics of glyburide (glucose and insulin concentrations) and warfarin (prothrombin time or other pharmacodynamic parameters).

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 10/2/2015

Side Effects

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