See the end of this leaflet for a complete list of ingredients in SILDENAFIL CITRATE TABLETS. What should I tell my healthcare provider before taking SILDENAFIL CITRATE TABLETS? Before you take SILDENAFIL CITRATE TABLETS, tell your healthcare provider if you: have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve or heart failure have had heart surgery within the last 6 months have low blood pressure, or high blood pressure that is not controlled have had an erection that lasted for more than 4 hours have problems with your blood cells such as sickle cell anemia, multiple myeloma, or leukemia have retinitis pigmentosa, a rare genetic (runs in families) eye disease have ever had severe vision loss, including an eye problem called non-arteritic anterior ischemic optic neuropathy (NAION) have kidney problems or are having kidney dialysis Tell your healthcare provider about all the medicines you take1, including prescription and over-the-counter medicines, vitamins, and herbal supplements. SILDENAFIL CITRATE TABLETS may affect the way other medicines work, and other medicines may affect the way SILDENAFIL CITRATE TABLETS works causing side effects. Especially tell your healthcare provider if you take any of the following: medicines called nitrates (see "What is the most important information I should know about SILDENAFIL CITRATE TABLETS?") medicines called guanylate cyclase stimulators, such as riociguat (Adempas) medicines called alpha blockers such as Hytrin (terazosin HCl), Flomax (tamsulosin HCl), Cardura (doxazosin mesylate), Minipress (prazosin HCl), Uroxatral (alfuzosin HCl), Jalyn (dutasteride and tamsulosin HCl), or Rapaflo (silodosin). Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. In some patients, the use of SILDENAFIL CITRATE TABLETS with alpha-blockers can lead to a drop in blood pressure or to fainting. medicines called HIV protease inhibitors, such as ritonavir (Norvir), indinavir sulfate (Crixivan), saquinavir (Fortovase or Invirase) or atazanavir sulfate (Reyataz) some types of oral antifungal medicines, such as ketoconazole (Nizoral), and itraconazole (Sporanox) some types of antibiotics, such as clarithromycin (Biaxin), telithromycin (Ketek), or erythromycin other medicines that treat high blood pressure SILDENAFIL CITRATE TABLETS contains sildenafil, which is the same medicine found in another drug called SILDENAFIL TABLETS. SILDENAFIL TABLETS is used to treat a rare disease called pulmonary arterial hypertension (PAH).
- Sildenafil 100 mg can be used for pulmonary arterial hypertension in some cases.
- It is not intended for use in women or children.
- Regular use of sildenafil does not cure erectile dysfunction but manages symptoms.
SILDENAFIL CITRATE TABLETS should not be used with SILDENAFIL TABLETS or with other PAH treatments containing sildenafil or any other PDE5 inhibitors (such as Adcirca [tadalafil]).
Proper Use
50 mg PO ~1 hr before sexual activity; however, may be taken anywhere from 30 min to 4 hr before sexual activity Maximum dosing frequency is once per day Based on effectiveness and toleration, may increase dose to maximum of 100 mg or decrease to 25 mg Indicated for treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) to improve exercise ability and delay clinical worsening Revatio (PO), Liqrev: 20 mg PO TID; may titrate up to 80 mg TID, if required, based on symptoms and tolerability Revatio (IV): 10 mg IV bolus TID 10-mg IV predicted to provide pharmacologic effect equivalent to 10-mg oral dose Do not exceed recommended PO/IV dose Viagra, VibriqueSevere (eg, cirrhosis): Consider initial dose of 25 mg Severe (eg, cirrhosis): Consider initial dose of 25 mg RevatioMild or moderate (Child-Pugh A or B): No dose adjustment requiredSevere (Child-Pugh C): Not studied Mild or moderate (Child-Pugh A or B): No dose adjustment required Viagra, VibriqueMild or moderate (CrCl 30-80 mL/min): No dose adjustment requiredSevere (CrCl <30 mL/min): Consider initial dose of 25 mg Mild or moderate (CrCl 30-80 mL/min): No dose adjustment required Severe (CrCl <30 mL/min): Consider initial dose of 25 mg RevatioAny severity, including severe (CrCl <30 mL/min): No dose adjustment required Any severity, including severe (CrCl <30 mL/min): No dose adjustment required Indicated in children aged 1-17 years for treatment of pulmonary arterial hypertension (PAH) (WHO Group I) to improve exercise ability and, in pediatric patients too young to perform standard exercise testing, pulmonary hemodynamics thought to underly improvements in exercise 20-45 kg: 20 mg PO TID Maximum dose in pediatric patients not identified Based on experience in adults, dose may be titrated up to 40 mg TID, if required, based on symptoms and tolerability Mild or moderate (Child-Pugh A or B): No dose adjustment required Any severity, including severe (CrCl <30 mL/min): No dose adjustment required ≥65 years: 25 mg PO initially ~1 hr before sexual activity; however, may be taken anywhere from 30 min to 4 hr before sexual activity Maximum dosing frequency is once per day Based on effectiveness and toleration, may increase dose to maximum of 100 mg or decrease to 25 mg Indicated for treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) to improve exercise ability and delay clinical worsening PO: 20 mg PO TID; may titrate up to 80 mg TID, if required , based on symptoms and tolerability 10-mg IV predicted to provide pharmacologic effect equivalent to 10-mg oral dose Recommended PO/IV dose not to be exceeded Adding Revatio to bosentan does not have any beneficial effect on exercise capacity Clinical trials found no significant difference in response between elderly patients and younger adults; however, cautious dose selection should be considered in elderly because of greater frequency of decreased hepatic, renal, and cardiac function, as well as comorbid conditions and concomitant pharmacotherapy Compared with healthy younger volunteers, healthy elderly volunteers (≥65 years) had reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively atazanaviratazanavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Ask your healthcare provider or pharmacist for a list of these medicines, if you are not sure.
| Product | Dosage | Quantity + Bonus | Price | |
|---|---|---|---|---|
| Kamagra Oral Jelly | 100mg | 110 + 9 Sachets | 334.87€ 318.92€ | |
| Kamagra Oral Jelly | 100mg | 30 + 5 Sachets | 136.20€ 129.71€ | |
| Viagra Generic | 150mg | 20 Pills | 55.02€ 52.40€ | |
| Kamagra Oral Jelly | 100mg | 90 + 8 Sachets | 303.56€ 289.10€ | |
| Viagra Generic | 150mg | 60 + 4 Pills | 111.25€ 105.95€ | |
| Viagra Generic | 100mg | 270 + 10 Pills | 270.47€ 257.59€ | |
| Viagra Generic | 150mg | 30 + 2 Pills | 72.32€ 68.88€ | |
| Kamagra | 100mg | 84 + 6 Pills | 264.44€ 251.85€ | |
| Viagra Generic | 150mg | 120 + 8 Pills | 177.58€ 169.12€ | |
| Viagra Generic | 50mg | 270 + 8 Pills | 198.48€ 189.03€ | |
| Viagra Generic | 50mg | 30 + 4 Pills | 54.26€ 51.68€ | |
| Kamagra Oral Jelly | 100mg | 63 + 7 Sachets | 224.18€ 213.50€ | |
| Viagra Generic | 200mg | 60 + 4 Pills | 125.19€ 119.23€ | |
| Kamagra | 100mg | 60 + 4 Pills | 201.34€ 191.75€ | |
| Viagra Generic | 100mg | 120 + 6 Pills | 149.50€ 142.38€ | |
| Viagra Generic | 50mg | 60 + 4 Pills | 83.93€ 79.93€ |
Keep a list of them to show to your healthcare provider and pharmacist when you get a new medicine. How should I take SILDENAFIL CITRATE TABLETS? Take SILDENAFIL CITRATE TABLETS exactly as your healthcare provider tells you to sildenafil oral strips take it.
- People with heart problems should consult a doctor before using sildenafil 100 mg.
- Sildenafil is contraindicated in patients with severe liver or kidney impairment.
- Allergic reactions, though rare, may include rash, itching, or swelling.
Your healthcare provider will tell you how much SILDENAFIL CITRATE TABLETS to take and when to take it. Your healthcare provider may change your dose if needed. Take SILDENAFIL CITRATE TABLETS about 1 hour before sexual activity. You may take SILDENAFIL CITRATE TABLETS between 30 minutes to 4 hours before sexual activity if needed. SILDENAFIL CITRATE TABLETS can be taken with or without food.
Usual Pediatric Dose for Pulmonary Hypertension
Your healthcare provider may change your dose if needed. Take SILDENAFIL CITRATE TABLETS about 1 hour before sexual activity. You may take SILDENAFIL CITRATE TABLETS between 30 minutes to 4 hours before sexual activity if needed. SILDENAFIL CITRATE TABLETS can be taken with or without food. If you take SILDENAFIL CITRATE TABLETS after a high fat meal (such as a cheeseburger and french fries), SILDENAFIL CITRATE TABLETS may take a little longer to start working Do not take SILDENAFIL CITRATE TABLETS more than 1 time a day.
IV Administration
If you accidentally take too much SILDENAFIL CITRATE TABLETS, call your doctor or go to the nearest hospital emergency room right away. What are the possible side effects of SILDENAFIL CITRATE TABLETS? SILDENAFIL CITRATE TABLETS can cause serious side effects. an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away.
Dosage for erectile dysfunction (ED)
If it is not treated right away, priapism can permanently damage your penis. sudden vision loss in one or both eyes. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). It is uncertain whether PDE5 inhibitors directly cause the vision loss. Stop taking SILDENAFIL CITRATE TABLETS and call your healthcare provider right away if you have sudden vision loss in one or both eyes. If you take SILDENAFIL CITRATE TABLETS after a high fat meal (such as a cheeseburger and french fries), SILDENAFIL CITRATE TABLETS may take a little longer to start working Do not take SILDENAFIL CITRATE TABLETS more than 1 time a day.
- Sildenafil citrate 100 mg is a medication primarily used to treat erectile dysfunction.
- The typical recommended dose of sildenafil citrate is 50 to 100 mg.
- It works by increasing blood flow to the penis for improved erections.
If you accidentally take too much SILDENAFIL CITRATE TABLETS, call your doctor or go to the nearest hospital emergency room right away. What are the possible side effects of SILDENAFIL CITRATE TABLETS? SILDENAFIL CITRATE TABLETS can cause serious side effects. an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away.
Other uses for this medicine
regulations. USP is not responsible for the accuracy or completeness of the information furnished. 2USP procures materials worldwide and most foreign materials do not undergo a fundamental change during the packaging process at USP that would substantially transform the item resulting in a country of origin change from the foreign origin to the United States. Under the Rules of Origin the original foreign country of origin would remain. Animal, Plant, Fish) may require special country importation requirements.USP recommends you contact your country competent authorities to determine if any certifications, permits or licenses may be required prior to ordering.Material Origins are found within the Product under Origin Information. If it is not treated right away, priapism can permanently damage your penis. sudden vision loss in one or both eyes.
Liver Dose Adjustments
Some people may also have ringing in their ears (tinnitus) or dizziness. If you have these symptoms, stop taking SILDENAFIL CITRATE TABLETS and contact a doctor right away. The most common side effects of SILDENAFIL CITRATE TABLETS are: abnormal vision, such as changes in color vision (such as having a blue color tinge) and blurred vision In addition, heart attack, stroke, irregular heartbeats and death have happened rarely in men taking SILDENAFIL CITRATE TABLETS. Most, but not all, of these men had heart problems before taking SILDENAFIL CITRATE TABLETS. It is not known if SILDENAFIL CITRATE TABLETS caused these problems.
Related treatment guides
Tell your healthcare provider if you have any side effect that bothers you or does not go away. These are not all the possible side effects of SILDENAFIL CITRATE TABLETS. For more information, ask your healthcare provider or pharmacist. You sildenafil softgel capsule may report side effects to FDA at 1-800-FDA-1088. How should I store SILDENAFIL CITRATE TABLETS?
Interactions that increase your risk for side effects
Store SILDENAFIL CITRATE TABLETS at room temperature between 68°F to 77°F (20°C to 25°C). Keep SILDENAFIL CITRATE TABLETS and all medicines out of the reach of children. General information about the safe and effective use of SILDENAFIL CITRATE TABLETS. Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use SILDENAFIL CITRATE TABLETS for a condition for which it was not prescribed. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). It is uncertain whether PDE5 inhibitors directly cause the vision loss. Stop taking SILDENAFIL CITRATE TABLETS and call your healthcare provider right away if you have sudden vision loss in one or both eyes. Some people may also have ringing in their ears (tinnitus) or dizziness.
Drug Interactions
Do not give SILDENAFIL CITRATE TABLETS to other people, even if they have the same symptoms that you have. This Patient Information leaflet summarizes the most important information about SILDENAFIL CITRATE TABLETS. If you would like more information, talk with your healthcare provider. You can ask your healthcare sildenafil citrate 120 mg provider or pharmacist for information about SILDENAFIL CITRATE TABLETS that is written for health professionals. For more information, go to or call 1-800-438-1985 What are the ingredients in SILDENAFIL CITRATE TABLETS?
Other Interactions
This Patient Information has been approved by the U.S. Food and Drug Administration. This product's label may have been updated. For current full prescribing information, please visit Cardura (doxazosin mesylate), and Minipress (prazosin HCl) are registered trademarks of Pfizer Inc. The other brands listed are trademarks of their respective owners and are not trademarks of Pfizer Inc.
Sildenafil Tablets or Oral Suspension for PAH
The makers of these brands are not affiliated with and do not endorse Pfizer Inc or its products. USP Certificates/Product Information Sheets and Valid Use Dates View the USP Certificate or Product Information Sheet in the table above to view additional product details, including available label text and storage information. View the USP Certificate or Product Information Sheet in the table above to view additional product details, including available label text and storage information. 1The Harmonized System (HS) code provided on this webpage is for informational purposes only and is subject to change without notice. The exporter and/or importer of record is responsible for determining the accuracy of items at the time of export/import per U.S. If you have these symptoms, stop taking SILDENAFIL CITRATE TABLETS and contact a doctor right away. The most common side effects of SILDENAFIL CITRATE TABLETS are: abnormal vision, such as changes in color vision (such as having a blue color tinge) and blurred vision In addition, heart attack, stroke, irregular heartbeats and death have happened rarely in men taking SILDENAFIL CITRATE TABLETS. Most, but not all, of these men had heart problems before taking SILDENAFIL CITRATE TABLETS. It is not known if SILDENAFIL CITRATE TABLETS caused these problems.
| Patient Type | Recommended Dose | Notes |
|---|---|---|
| Adult Men | 50-100 mg approximately 1 hour before activity | Max dose per event; not to exceed 100 mg |
| Elderly Patients | Start at lower end, 25-50 mg | Increased sensitivity and risk of side effects |
| Patients with Kidney or Liver Disease | Dose adjustment may be necessary | Consult healthcare provider |
Tell your healthcare provider if you have any side effect that bothers you or does not go away. These are not all the possible side effects of SILDENAFIL CITRATE TABLETS. For more information, ask your healthcare provider or pharmacist. You sildenafil softgel capsule may report side effects to FDA at 1-800-FDA-1088. How should I store SILDENAFIL CITRATE TABLETS? Store SILDENAFIL CITRATE TABLETS at room temperature between 68°F to 77°F (20°C to 25°C). Keep SILDENAFIL CITRATE TABLETS and all medicines out of the reach of children. General information about the safe and effective use of SILDENAFIL CITRATE TABLETS. Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use SILDENAFIL CITRATE TABLETS for a condition for which it was not prescribed. Do not give SILDENAFIL CITRATE TABLETS to other people, even if they have the same symptoms that you have. This Patient Information leaflet summarizes the most important information about SILDENAFIL CITRATE TABLETS. If you would like more information, talk with your healthcare provider. You can ask your healthcare sildenafil citrate 120 mg provider or pharmacist for information about SILDENAFIL CITRATE TABLETS that is written for health professionals. For more information, go to or call 1-800-438-1985 What are the ingredients in SILDENAFIL CITRATE TABLETS?
- Sildenafil 100 mg is not a cure for erectile dysfunction but helps temporarily.
- Lifestyle changes like exercise and diet can enhance treatment effectiveness.
- Open communication with a partner can improve the sexual experience and treatment satisfaction.
This Patient Information has been approved by the U.S. Food and Drug Administration. This product's label may have been updated. For current full prescribing information, please visit Cardura (doxazosin mesylate), and Minipress (prazosin HCl) are registered trademarks of Pfizer Inc. The other brands listed are trademarks of their respective owners and are not trademarks of Pfizer Inc. The makers of these brands are not affiliated with and do not endorse Pfizer Inc or its products. USP Certificates/Product Information Sheets and Valid Use Dates View the USP Certificate or Product Information Sheet in the table above to view additional product details, including available label text and storage information. View the USP Certificate or Product Information Sheet in the table above to view additional product details, including available label text and storage information. 1The Harmonized System (HS) code provided on this webpage is for informational purposes only and is subject to change without notice. The exporter and/or importer of record is responsible for determining the accuracy of items at the time of export/import per U.S. regulations.
12.1 Mechanism of Action
See the end of this leaflet for a complete list of ingredients in SILDENAFIL CITRATE TABLETS. What should I tell my healthcare provider before taking SILDENAFIL CITRATE TABLETS? Before you take SILDENAFIL CITRATE TABLETS, tell your healthcare provider if you: have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve or heart failure have had heart surgery within the last 6 months have low blood pressure, or high blood pressure that is not controlled have had an erection that lasted for more than 4 hours have problems with your blood cells such as sickle cell anemia, multiple myeloma, or leukemia have retinitis pigmentosa, a rare genetic (runs in families) eye disease have ever had severe vision loss, including an eye problem called non-arteritic anterior ischemic optic neuropathy (NAION) have kidney problems or are having kidney dialysis Tell your healthcare provider about all the medicines you take1, including prescription and over-the-counter medicines, vitamins, and herbal supplements. SILDENAFIL CITRATE TABLETS may affect the way other medicines work, and other medicines may affect the way SILDENAFIL CITRATE TABLETS works causing side effects. Especially tell your healthcare provider if you take any of the following: medicines called nitrates (see "What is the most important information I should know about SILDENAFIL CITRATE TABLETS?") medicines called guanylate cyclase stimulators, such as riociguat (Adempas) medicines called alpha blockers such as Hytrin (terazosin HCl), Flomax (tamsulosin HCl), Cardura (doxazosin mesylate), Minipress (prazosin HCl), Uroxatral (alfuzosin HCl), Jalyn (dutasteride and tamsulosin HCl), or Rapaflo (silodosin).
Alcohol interaction warning
Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. In some patients, the use of SILDENAFIL CITRATE TABLETS with alpha-blockers can lead to a drop in blood pressure or to fainting. medicines called HIV protease inhibitors, such as ritonavir (Norvir), indinavir sulfate (Crixivan), saquinavir (Fortovase or Invirase) or atazanavir sulfate (Reyataz) some types of oral antifungal medicines, such as ketoconazole (Nizoral), and itraconazole (Sporanox) some types of antibiotics, such as clarithromycin (Biaxin), telithromycin (Ketek), or erythromycin other medicines that treat high blood pressure SILDENAFIL CITRATE TABLETS contains sildenafil, which is the same medicine found in another drug called SILDENAFIL TABLETS. SILDENAFIL TABLETS is used to treat a rare disease called pulmonary arterial hypertension (PAH). SILDENAFIL CITRATE TABLETS should not be used with SILDENAFIL TABLETS or with other PAH treatments containing sildenafil or any other PDE5 inhibitors (such as Adcirca [tadalafil]).
Cite this article
Ask your healthcare provider or pharmacist for a list of these medicines, if you are not sure. Keep a list of them to show to your healthcare provider and pharmacist when you get a new medicine. How should I take SILDENAFIL CITRATE TABLETS? Take SILDENAFIL CITRATE TABLETS exactly as your healthcare provider tells you to sildenafil oral strips take it. Your healthcare provider will tell you how much SILDENAFIL CITRATE TABLETS to take and when to take it. USP is not responsible for the accuracy or completeness of the information furnished. 2USP procures materials worldwide and most foreign materials do not undergo a fundamental change during the packaging process at USP that would substantially transform the item resulting in a country of origin change from the foreign origin to the United States. Under the Rules of Origin the original foreign country of origin would remain. Animal, Plant, Fish) may require special country importation requirements.USP recommends you contact your country competent authorities to determine if any certifications, permits or licenses may be required prior to ordering.Material Origins are found within the Product under Origin Information. 50 mg PO ~1 hr before sexual activity; however, may be taken anywhere from 30 min to 4 hr before sexual activity Maximum dosing frequency is once per day Based on effectiveness and toleration, may increase dose to maximum of 100 mg or decrease to 25 mg Indicated for treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) to improve exercise ability and delay clinical worsening Revatio (PO), Liqrev: 20 mg PO TID; may titrate up to 80 mg TID, if required, based on symptoms and tolerability Revatio (IV): 10 mg IV bolus TID 10-mg IV predicted to provide pharmacologic effect equivalent to 10-mg oral dose Do not exceed recommended PO/IV dose Viagra, VibriqueSevere (eg, cirrhosis): Consider initial dose of 25 mg Severe (eg, cirrhosis): Consider initial dose of 25 mg RevatioMild or moderate (Child-Pugh A or B): No dose adjustment requiredSevere (Child-Pugh C): Not studied Mild or moderate (Child-Pugh A or B): No dose adjustment required Viagra, VibriqueMild or moderate (CrCl 30-80 mL/min): No dose adjustment requiredSevere (CrCl <30 mL/min): Consider initial dose of 25 mg Mild or moderate (CrCl 30-80 mL/min): No dose adjustment required Severe (CrCl <30 mL/min): Consider initial dose of 25 mg RevatioAny severity, including severe (CrCl <30 mL/min): No dose adjustment required Any severity, including severe (CrCl <30 mL/min): No dose adjustment required Indicated in children aged 1-17 years for treatment of pulmonary arterial hypertension (PAH) (WHO Group I) to improve exercise ability and, in pediatric patients too young to perform standard exercise testing, pulmonary hemodynamics thought to underly improvements in exercise 20-45 kg: 20 mg PO TID Maximum dose in pediatric patients not identified Based on experience in adults, dose may be titrated up to 40 mg TID, if required, based on symptoms and tolerability Mild or moderate (Child-Pugh A or B): No dose adjustment required Any severity, including severe (CrCl <30 mL/min): No dose adjustment required ≥65 years: 25 mg PO initially ~1 hr before sexual activity; however, may be taken anywhere from 30 min to 4 hr before sexual activity Maximum dosing frequency is once per day Based on effectiveness and toleration, may increase dose to maximum of 100 mg or decrease to 25 mg Indicated for treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) to improve exercise ability and delay clinical worsening PO: 20 mg PO TID; may titrate up to 80 mg TID, if required , based on symptoms and tolerability 10-mg IV predicted to provide pharmacologic effect equivalent to 10-mg oral dose Recommended PO/IV dose not to be exceeded Adding Revatio to bosentan does not have any beneficial effect on exercise capacity Clinical trials found no significant difference in response between elderly patients and younger adults; however, cautious dose selection should be considered in elderly because of greater frequency of decreased hepatic, renal, and cardiac function, as well as comorbid conditions and concomitant pharmacotherapy Compared with healthy younger volunteers, healthy elderly volunteers (≥65 years) had reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively atazanaviratazanavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism.