Assurans belongs to the phosphodiesterase 5 (PDE-5) inhibitor class of drugs. It is a prescription-only medication used in pulmonary arterial hypertension (PAH).
The active ingredient is also widely used to treat erectile dysfunction (ED). Sildenafil is the generic name for a popular ED drug, Viagra.
This article covers the mechanism of action, dose, usage, safety profile, and drug interaction of Assurans. Read on to find out all you need to know about the drug.
Assurans is a clinically proven and effective first-line oral therapy in adult male patients with ED and symptomatic PAH. It is a PDE-5 inhibitor that targets the nitric oxide pathway .
The recommended dose of sildenafil is 50 mg when treating ED.
The dose is 20 mg three times a day for pulmonary arterial hypertension. There’s no evidence of improved efficacy with higher dosages. If accidental overdosing occurs, immediately contact your physician.
For PAH, Assurans should be taken three times a day, each dose taken four to six hours apart. For ED, the dosage is as needed and should be taken when sexual activity is anticipated.
It can be taken with or without food. However, stick with lighter meals, as fatty foods delay the onset of the drug’s effect. The tablet should be swallowed whole with water, not crushed or chewed.
If you miss a dose, take the drug as soon as you remember. If you are close to taking your next dose, skip the missed dose and take the next dose at the scheduled time. Do not take more than one dose at a time.
Assurans tablet is rapidly absorbed following oral administration. The maximum plasma concentration is achieved within 30 minutes to 2 hours. The onset of action is delayed if the drug is taken after a heavy meal.
Sildenafil has a half-life of about four hours. For this reason, Assurans should be taken every 4 to 6 hours for PAH.
The cost of each tablet of Assurans is $0.27. Each strip contains ten tablets. Most Medicare and insurance plans do not cover Assurans.
The development of sildenafil began in 1986. Pfizer’s chemists were searching for a compound to treat hypertension and angina. The test compound inhibited the activity of PDE-5, which resulted in vasodilation and platelet inhibition.
The clinical trials of sildenafil in angina were disappointing. However, some patients reported penile erection, which was an unexpected and surprising side effect. Sildenafil was then marketed to treat impotence, which was then a major concern for older men.
In 1996, the drug was patented as Viagra. It was approved by the US Food and Drug Administration (FDA) in 1998. The approval of sildenafil for ED was followed by the discovery of several other drugs with similar chemical compositions.
As understanding of the mechanism of sildenafil grew, a role in the treatment of PAH was postulated. The drug eventually obtained FDA approval for this indication. Pfizer’s patent expired in 2017, after which sildenafil became available as a generic medication [1, 2].
The first case report demonstrating the clinical benefit of sildenafil in PAH was published in 2000. By that time, the utility of sildenafil in other cardiopulmonary conditions, including respiratory failure, was already demonstrated.
Multiple single-center studies were subsequently completed, which suggested significant clinical efficacy. Functional and hemodynamic improvements in PAH were also obtained in these clinical trials. Sildenafil, in a dose-dependent manner, had durable and sustained pulmonary vasodilator effects .
Assurans tablets are indicated in adults with ED. In PAH, it is taken to delay clinical worsening and improve exercise ability.
Off-label uses of sildenafil are in high altitude pulmonary edema, Raynaud’s phenomenon, female sexual arousal disorder, and for enhancing performance in athletes .
Before using the drug, consult your doctor about whether or not the drug is appropriate for you.
Assurans is an FDA-approved drug. Although approved by the FDA, there is still some risk of adverse effects. These effects do not occur in all individuals.
Some adverse effects that may be seen with Assurans include:
- Nasal congestion
- Vaso-occlusive crisis
Serious adverse effects that may rarely occur are:
- Myocardial infarction
- Sudden cardiac death
- Sudden loss of vision
- Ventricular arrhythmia
- Cerebrovascular hemorrhage
- Transient ischemic attack
- Pulmonary hemorrhage
- Subarachnoid and intracerebral hemorrhages
- Bleeding into the eye 
Certain medications with sildenafil can cause serious and potentially life-threatening side effects. Assurans has interactions with the following drugs and should be avoided:
Co-administration of Assurans and nitrates should be avoided. Combination therapy may enhance the blood-pressure-lowering effects of each other.
Drinking alcohol while taking Assurans could increase the risk of adverse side effects such as dizziness, flushing, and headache.
Drugs such as aluminum hydroxide or magnesium hydroxide may also affect the absorption of sildenafil.
Drugs such as calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, and alpha-blockers should be avoided. Vasodilatory effects may be common in patients on antihypertensive therapy. Co-administration may cause additive blood pressure lowering effects.
The safety and efficacy of the combination of Assurans with Viagra or other PDE-5 inhibitors have not been studied. It may potentially lead to symptomatic hypotension. Hence, co-administration is not recommended.
Drugs such as ketoconazole, itraconazole, erythromycin, carbamazepine, barbiturates, and Grapefruit juice decrease the metabolism of Assurnas and hence can abnormally potentiate its clinical effects [2, 5].
This drug is not recommended for use by:
- Women (pregnant, breastfeeding, or in labor)
- Pediatric populations
- Patients with a recent history of stroke or myocardial infarction
- Patients with a previous history of non-arteritic anterior ischemic optic neuropathy (NAION) in one eye
- Patients with known hypersensitivity to any of the constituents.
- Patients with liver disease
- Patients with underlying risk factors for hearing loss
- Patients with a bleeding disorder or active peptic ulceration
- Patients with severe hypotension (blood pressure < 90/50 mmHg) at initiation
- Patients currently on drugs that can potentially interact with sildenafil
- Patients with a history of priapism (prolonged erection)
- Patients with certain blood disorders (hemophilia, leukemia, sickle-cell anemia) [2,5].
Sildenafil is a potent and selective inhibitor of cyclic guanosine monophosphate (cGMP) specific phosphodiesterase type 5 (PDE-5) in the smooth muscle of the pulmonary vasculature. PDE-5 is responsible for the degradation of cGMP.
Sildenafil, therefore, increases cGMP within the pulmonary vascular smooth muscle cells. The endothelial cells and nerve endings also release Nitric Oxide (NO).
NO stimulates the synthesis of cGMP and mediates vascular relaxation. This leads to vasodilation of the pulmonary vascular bed allowing the blood to flow more easily, reducing blood pressure in the lungs. Vasodilatation in the systemic circulation is also noted.
The effect of sildenafil is more potent on PDE-5 than on other known phosphodiesterases. PDE5 is also present in the corpus cavernosum of the penis. This forms the basis of the use of sildenafil in ED. PDE-5 is also found in other tissues, including vascular and visceral smooth muscle and platelets [2, 5].
The SUPER-1 trial (Sildenafil Use in Pulmonary hypertension) was started in 2002, and randomized patients with PAH to treatment with either 20 mg, 40 mg, or 80 mg of sildenafil three times daily or placebo.
This was an international multicenter, blinded, controlled study involving 278 patients with symptomatic PAH that was idiopathic, associated with connective tissue disease, or repaired congenital systemic to pulmonary shunts .
The change in the distance walked in 6 minutes from baseline to twelve weeks was analyzed. The change in the mean pulmonary artery pressure, World Health Organization (WHO) functional class, and the incidence of clinical worsening were also assessed. An increase in the distance walked in six minutes was reported.
Sildenafil improved exercise capacity, hemodynamics, and WHO functional class in patients with symptomatic PAH. Sildenafil was approved for the treatment of PAH in 2005 in both the United States and Europe at 20 mg .
A meta-analysis of 4 clinical trials was carried out that involved 545 patients. In this systematic review, treatment with sildenafil for 12 weeks or more improved clinical symptoms of pulmonary hypertension.
Sildenafil was also found to help delay the progression of the disease in adults. It was associated with a higher incidence of adverse events, but these additional events were tolerable and mild to moderate in severity .
Assurans is not recommended for use in women.
Discuss with your physician before switching medications.
- Avanafil (Avaforce, Stendra, Avana)
- Mirodenafil (Mvix)
- Sildenafil (Viagra, Fildena, P-Force, Vygex)
- Tadalafil (Cialis, Tadagra, Tadovas, Tadact, Tadacip, Tadalip)
- Udenafil (Zydena)
- Vardenafil (Levitra, Vilitra, Savitra)
There are natural remedies for treating ED. These are helpful for people who cannot tolerate Assurans or are not responding to them, or want to try a natural route first. However, these alternatives are not approved by the FDA.
- Catuaba (Trichilia catigua or Erythroxylum Catuaba)
- Horny Goat Weed (Epimedium spp.)
Assurans can be purchased online or at local pharmacies. Many prefer purchasing the drug online as it is cost, time-saving, and discrete.
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- Goldstein, I., Burnett, A. L., Rosen, R. C., Park, P. W., & Stecher, V. J. (2019). The serendipitous story of sildenafil: an unexpected oral therapy for erectile dysfunction. Sexual medicine reviews, 7(1), 115-128.
- Ramani, G. V., & Park, M. H. (2010). Update on the clinical utility of sildenafil in the treatment of pulmonary arterial hypertension. Drug design, development, and therapy, 4, 61.
- Smith, B. P., & Babos, M. (2020). Sildenafil. StatPearls [Internet].
- CHMP. (n.d.). Annex I Summary of product characteristics.
- Galiè, N., Ghofrani, H. A., Torbicki, A., Barst, R. J., Rubin, L. J., Badesch, D., … & Simonneau, G. (2005). Sildenafil citrate therapy for pulmonary arterial hypertension. New England Journal of Medicine, 353(20), 2148-2157.
- Wang, R. C., Jiang, F. M., Zheng, Q. L., Li, C. T., Peng, X. Y., He, C. Y., … & Liang, Z. A. (2014). Efficacy and safety of sildenafil treatment in pulmonary arterial hypertension: a systematic review. Respiratory medicine, 108(3), 531-537.