Sildenafil, commonly known as Viagra, is a medication used to treat erectile dysfunction (ED) and pulmonary arterial hypertension (PAH). As a phosphodiesterase-5 inhibitor (PDE5-I), sildenafil has been proven highly effective in treating ED, with a rapid onset of action and a good safety profile. However, its duration of action has yet to be thoroughly investigated.
Indications and Mechanism of Action
Sildenafil was the first PDE5 inhibitor approved for erectile dysfunction, receiving US Food and Drug Administration (FDA) approval in 1998. It is also FDA-approved for treating Group I pulmonary hypertension (PAH) in adults to improve exercise tolerance and delay clinical worsening.
Off-label uses of sildenafil include the treatment of secondary Raynaud phenomenon, female sexual arousal disorder, and as an adjunct in treating altitude-induced hypoxemia.
The molecular structure of sildenafil mimics that of cyclic guanosine monophosphate (cGMP), protecting it from degradation and acting as a competitive inhibitor of cGMP-specific PDE-5.
This leads to increased cGMP levels, causing smooth muscle relaxation in the corpus cavernosum and the pulmonary artery, ultimately resulting in penile erection and reduced pulmonary arterial pressure.
Sildenafil: Time to Take Effect
Generally, sildenafil takes approximately 30 to 60 minutes to start working after oral consumption. The time it takes for the medication to take effect may vary depending on several factors, including the individual’s overall health, metabolism, and underlying conditions.
It is essential to note that sildenafil will not work independently; sexual arousal is necessary for the medication to be effective.
Duration of Sildenafil’s Effects
On average, sildenafil lasts between 2 and 3 hours before its effects diminish. However, the medication can last up to 5 hours or longer, depending on dosage, metabolism, and external influences. Some individuals may be able to achieve an erection multiple times while sildenafil is in their system. Still, it should be noted that the drug does not definitively increase the duration of sexual activity.
Factors Affecting Sildenafil’s Duration
Several factors can influence how long sildenafil lasts in the body:
The amount of sildenafil taken affects the duration of its presence in the body. The smallest available dose, 25 milligrams (mg), may last less time than the largest available dose, 100 mg. However, a higher dose is only sometimes recommended, as it may not be safe for some individuals.
As metabolism slows, sildenafil may last longer in older individuals. Generally, the drug’s effectiveness may last longer for those aged 65 or older.
Diet and Lifestyle
Consuming a large or high-fat meal before taking sildenafil can delay its absorption, potentially reducing its effectiveness or prolonging its duration in the body. Similarly, alcohol consumption or smoking can decrease blood flow to the penis, making sildenafil less effective or shorter-lasting.
Certain medications, particularly antibiotics like erythromycin, clarithromycin, and ciprofloxacin, can interact with sildenafil and affect its duration in the body.
Existing health conditions can affect the duration and effectiveness of sildenafil. Diabetes, nervous system conditions like multiple sclerosis (MS), and heart conditions like atherosclerosis can all make sildenafil less effective and shorter-lasting. Some kidney conditions may also cause sildenafil to last longer due to its impact on metabolism.
An individual’s psychological state, including anxiety, stress, and depression, can influence how their body responds to sexual stimulation. If an individual is not relaxed or comfortable during sex or experiences performance anxiety due to past experiences, sildenafil may not be as effective or last as long.
Efficacy in Subpopulations and Difficult-to-Treat Cases
Sildenafil is effective in various subpopulations, including those with diabetes mellitus, after radical prostatectomy, and in men of older age groups. Efficacy rates may be lower in these difficult-to-treat subpopulations, but sildenafil remains a valuable treatment option for many men with ED.
The Bottom Line
Sildenafil typically starts working within 30 to 60 minutes of consumption and lasts 2 to 3 hours. However, the duration of the drug’s effects can vary depending on several factors, such as dosage, metabolism, and overall health.
It is crucial to consult a doctor before starting sildenafil or any related medication for ED to ensure safety and effectiveness. If an individual experiences an erection lasting longer than 4 hours, they should seek medical attention immediately.