Uses

Erectile Dysfunction (ED)

Erectile Dysfunction (ED) is a condition where it is difficult for a man to achieve or maintain an erection that is sufficient to have sexual intercourse. This condition may be occasional or chronic. The main underlying factor of ED is age, which increases the chances of this condition. Apart from this, there might be several factors for ED, such as metabolic, neurological, psychological, etc. Chronic diseases such as diabetes mellitus, cardiovascular disease, and /or lifestyle factors like tobacco use, alcohol, certain drugs, or psychological/relationship issues (stress, anxiety), can contribute to the progression of ED. Treatment of ED generally constitutes medical interventions and lifestyle changes. Viagra is indicated for the treatment of ED, as it can improve the body’s natural reaction to sexual stimulation. For ED, Viagra is a supportive measure and improves the quality of life.

Legality

Sildenafil Citrate (Brand name: Viagra) was officially approved by the U.S. Food and Drug Administration (FDA) in 1998 for the treatment of ED. 

Based on the FDA rules, Viagra is a prescription (Rx-only) medication, i.e., it can only be prescribed by a licensed healthcare provider. This drug cannot be sold as an over-the-counter (OTC) drug. Unauthorized sale, purchase, or sharing of Viagra will be considered a violation of federal law. Viagra can only be prescribed for the treatment of ED, at the officially indicated levels only. Dose adjustments can be made within the specified range of dosage. 

For a Sildenafil Citrate product to be legal for consumption, the product must be manufactured according to FDA-approved Good Manufacturing Practices (GMP). Any product not meeting the GMP standards will be identified as an adulterated or misbranded product. 

Products containing undeclared Sildenafil Citrate or those claiming to have similar effects as Sildenafil Citrate (such as “Herbal Viagra”) are classified as counterfeit products and are illegal.

Online pharmaceutical websites engaging in the sale, purchase, or distribution of Sildenafil Citrate products must have an FDA-approved license. The sale of Viagra can only be done with a valid prescription from a licensed medical specialist.

FDA can update the regulatory requirements, dosage changes, manufacturing rules, etc., which must be complied with, for legal purposes.

Dosage Information

Recommended dose

• Standard dose: 50 mg of Sildenafil Citrate (on an on-demand basis) 
• This drug can be consumed 30 minutes to 4 hours before the intended sexual activity.
• Dose adjustment must be done based on drug response and the patient’s tolerance:
  • Increase: Up to 100 mg of Sildenafil Citrate
  • Decrease: 25 mg Sildenafil Citrate
• This drug can be consumed with or without food

Special populations 

In such patients, the starting dose must be 25 mg. These populations include:

• Patients on alpha-blockers (must be stable first)
• Patients taking strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin)
• Patients aged over 65 years
• Patients with hepatic impairment (e.g., cirrhosis)
• Patients with severe renal impairment (CrCl levels less than 30 mL/min)
• Patients on Ritonavir therapy

Maximum dose limit:

• In general populations: 100 mg of Sildenafil Citrate in 24 hours
• Special population patients: 25 mg of Sildenafil Citrate in 24 hours
• Patients on Ritonavir therapy: 25 mg of Sildenafil Citrate in 48 hours

Missed dose instructions:

• As Viagra is consumed on an on-demand basis, missed dose instructions are not applicable for this drug.
• Individuals must maintain an adequate time gap between two consecutive doses (as explained above) to maintain a safe amount of the drug level in the blood.

Overdose instructions:

• In case of a Viagra overdose, individuals must report to their healthcare provider.
• If symptoms like sudden vision loss, sudden loss of hearing, dizziness, or priapism (prolonged erection over 4 hours) occur, immediate medical attention is required.

How Viagra 100mg Works

The process for a penile erection involves several neurovascular processes, specifically, the NO-cGMP pathway. Normally, the nerve endings present in the penile tissue (corpus cavernosum) release nitric oxide (NO) in response to an external stimulus (in this case, sexual arousal). NO activates the enzyme guanylate cyclase, which drives the production of cGMPs, which is a key secondary messenger. 

As the cGMP levels in the corpus cavernosum are increased, they prompt smooth muscle cell relaxation of the penile arteries, thus causing these arteries to dilate (vasodilation). As a result, the blood flow in this region is increased, which gives rise to an erection.

After a certain period of time (usually after ejaculation), an enzyme called PDE5 is released as a feedback response to high cGMP concentration in the penile tissues. This enzyme degrades the cGMP molecules, thus reversing the effects of cGMP. As PDE-5 is released, the smooth blood vessels get constricted, thus reducing the blood flow in the penis, restoring the body to its normal state. 

Viagra (Sildenafil Citrate) works by selectively inhibiting phosphodiesterase type 5 (PDE5), which is responsible for breaking down cGMP into inactive products. Compared to other PDEs, Sildenafil Citrate has the strongest affinity for PDE5. It does not react with the same efficiency to other PDE5s. This makes it selective for penile reaction. This drug prevents the breakdown of the cGMP molecules by blocking PDE5. In this way, the drug improves erectile function and keeps the smooth muscle cells relaxed for a longer time by boosting the natural NO-cGMP signalling pathway. 

It must be noted that Viagra does not trigger the NO-cGMP pathway. Hence, individuals do not procure an erection spontaneously after consuming this drug. For its effectiveness, sexual stimulation is essential. Viagra enhances the body’s natural processes involved in erection formation. The effects of Viagra can remain in the body for up to 4 hours.

Possible Side Effects

Common Side Effects (More than 2% chances)

These side effects are the most frequently reported:

• Headache
• Flushing (warmth/redness of face)
• Dyspepsia (indigestion)
• Abnormal vision (color tinge, blurred vision, light sensitivity)
• Nasal congestion
• Back pain
• Myalgia (muscle pain)
• Nausea
• Dizziness
• Rash

Less Common Side Effects (Less than 2% chances)

General 

• Face edema
• Photosensitivity reaction
• Shock
• Asthenia (weakness)
• Pain
• Chills
• Accidental fall/injury
• Abdominal pain
• Allergic reaction
• Chest pain

Cardiovascular

• Angina pectoris
• AV block
• Migraine
• Syncope (fainting)
• Tachycardia
• Palpitations
• Hypotension / postural hypotension
• Myocardial ischemia
• Cerebral thrombosis
• Cardiac arrest
• Heart failure
• Abnormal ECG
• Cardiomyopathy

Digestive

• Vomiting
• Glossitis (tongue inflammation)
• Colitis
• Dysphagia (difficulty swallowing)
• Gastritis
• Gastroenteritis
• Esophagitis
• Stomatitis
• Dry mouth
• Abnormal liver function tests
• Rectal hemorrhage
• Gingivitis

Hemic & Lymphatic

• Anemia
• Leukopenia

Metabolic & Nutritional

• Thirst
• Edema (including peripheral edema)
• Gout
• Unstable diabetes
• Unstable diabetes
• Hyperglycemia
• Hyperuricemia
• Hypoglycemic reactions
• Hypernatremia

Musculoskeletal

• Arthritis
• Arthrosis
• Myalgia
• Tendon rupture
• Tenosynovitis
• Bone pain
• Myasthenia
• Synovitis

Nervous System

• Ataxia
• Hypertonia
• Neuralgia
• Neuropathy
• Paresthesia
• Tremor
• Vertigo
• Depression
• Insomnia
• Somnolence
• Abnormal dreams
• Decreased reflexes
• Hypesthesia

Respiratory

• Asthma
• Dyspnea (shortness of breath)
• Laryngitis
• Pharyngitis
• Sinusitis
• Bronchitis
• Increased sputum
• Increased cough

Skin & Appendages

• Urticaria (hives)
• Herpes simplex
• Pruritus (itching)
• Sweating
• Skin ulcer
• Contact dermatitis
• Exfoliative dermatitis

Special Senses

• Sudden hearing decrease or loss
• Mydriasis (pupil dilation)
• Conjunctivitis
• Photophobia
• Tinnitus
• Eye pain
• Ear pain
• Eye hemorrhage
• Cataract
• Dry eyes

Urogenital

• Cystitis
• Nocturia
• Urinary frequency
• Breast enlargement
• Urinary incontinence
• Abnormal ejaculation
• Genital edema
• Anorgasmia

Postmarketing (Serious/Rare Side Effects)

Cardiovascular & Cerebrovascular

• Myocardial infarction (heart attack)
• Sudden cardiac death
• Ventricular arrhythmia
• Cerebrovascular hemorrhage (stroke)
• Transient ischemic attack (TIA)
• Hypertension
• Subarachnoid/intracerebral hemorrhage
• Pulmonary hemorrhage

Hemic

• Vaso-occlusive crisis (especially in sickle cell disease patients)

Nervous System

• Seizures/seizure recurrence
• Anxiety
• Transient global amnesia

Respiratory

• Epistaxis (nosebleed)

Hearing

• Sudden decrease or loss of hearing

Ocular (Eye-related)

• Diplopia (double vision)
• Temporary vision loss or decreased vision
• Red/bloodshot eyes
• Ocular burning
• Eye swelling or pressure
• Increased intraocular pressure
• Retinal edema
• Retinal vascular disease or bleeding
• Vitreous detachment/traction
• Non-arteritic anterior ischemic optic neuropathy (NAION) (can cause permanent vision loss)

Urogenital

• Prolonged erection
• Priapism (painful, prolonged erection)
• Hematuria (blood in urine)

Red Flag Side Effects

These side effects require immediate medical attention:

• Priapism (erection lasting longer than 4 hours)
• Sudden vision loss (NAION)
• Sudden hearing loss
• Chest pain/heart attack symptoms
• Severe hypotension (fainting, dizziness)
• Stroke symptoms (weakness, slurred speech)

Precautions and Considerations

• Individuals must consume Viagra only if prescribed by a licensed healthcare professional.
• Clinicians must ensure that the individual is fit to engage in sexual activity before prescribing Viagra.
• Viagra is indicated only for on-demand use and is not to be consumed daily.
• Patients with cardiovascular, renal, hepatic, or neurological conditions must be cautious before taking this medication. Those with a history of stroke, myocardial infarction, or unstable cardiac conditions must be especially careful while consuming Viagra.
• If symptoms like priapism, sudden vision or hearing loss, or dizziness occur, immediate emergency measures are required.
• Individuals must avoid consuming Viagra with nitrates, alpha blockers, CYP3A4, or other PDE-5 inhibitors.
• Viagra is not intended for consumption by women or children under any circumstances. 

Viagra: Myths Vs Facts

Myth: Viagra creates an erectile reaction on its own.

Fact: Viagra doesn't make an individual get an erection spontaneously. The trigger (sexual arousal) is required for the medication to work.

Myth: A higher dose of Viagra guarantees better performance.

Fact: Just like any pharmaceutical, Viagra has its own “peak dosage” which gives the maximum effectiveness. Beyond this limit, there won’t be any additional effects of this medication; there will be an increased risk of side effects if an excessive dose is taken.

Myth: Viagra increases the libido of the individual

Fact: Viagra does not increase an individual’s libido. It only works on the neuromuscular pathways to improve erection quality.

Myth: Viagra can be taken with cardiovascular medicines.

Fact: If Viagra is consumed wth cardiovascular medicines like nitrates, it can cause a severe drop in blood pressure and can be fatal. 

Myth: Viagra can cause addiction
Fact: Based on the latest scientific evidence, Viagra doesn’t stimulate the reward circuit, which is responsible for causing addiction. 

Other Information

Frequently Asked Questions

1.What are the uses of Viagra?

Viagra is officially indicated for the treatment of erectile dysfunction (ED), on an on-demand basis. 

2.How much time must be maintained between a Viagra dose and sexual activity?

It is recommended to take a Viagra tablet at least 60 minutes before the intended sexual activity. However, individuals can consume this drug anywhere from 4 hours to 30 minutes before.

3.How long do the effects of Viagra last?

Typically, the effects of Viagra can last for up to 4 hours. It must be noted that this time does not constitute a constant state of erection. It means that the penile performance would be optimum within this period of time.

4.Does Viagra procure an erection from a resting state?

No. Viagra cannot spontaneously procure an erection. It requires the “trigger” (existing state of sexual arousal), without which, Viagra produces negligible effects. 

5.Can Viagra be consumed daily?

The formulation of Viagra is intended for on-demand use. Hence, individuals must not consume it daily unless explicitly instructed to do so by a medical specialist.

6.What are the most common side effects caused by Viagra?

The most common side effects caused by Viagra include headache, flushing, indigestion, nasal congestion, dizziness, and visual disturbances.

7.Can Viagra be consumed with meals?

Viagra can be consumed with or without meals. However, individuals must note that consuming heavy or fat-rich meals can delay the onset of the effects of sildenafil citrate.

8.What are some dangerous side effects of Viagra to watch out for?

Side effects like chest pain, sudden vision or hearing loss, and prolonged erection over 4 hours are some of the severe side effects. If patients observe any such side effects, they must immediately seek emergency care.

9.Can Viagra cause any cardiovascular problems?

Viagra has a vasodilatory effect, which can cause a drop in blood pressure. This effect can be detrimental in cardiovascular patients and can negatively affect the originally impaired cardiovascular health.

10.Can Viagra be consumed by women?

There is limited scientific evidence regarding the safety of Viagra in women. Moreover, the FDA does not approve the use of Viagra in women. Hence, it must not be consumed by women.