Viagra

Viagra (Sildenafil) is a well-known medication primarily used to treat erectile dysfunction (ED) by improving blood flow to the penis, enabling men to achieve and maintain an erection when sexually aroused.

How It Works:

• Inhibits PDE5 (phosphodiesterase type 5), an enzyme that normally breaks down cGMP (cyclic guanosine monophosphate).
• By inhibiting PDE5, sildenafil increases cGMP levels, which helps relax the smooth muscle in the blood vessels of the penis, improving blood flow and causing an erection in response to sexual stimulation.

Uses:

1. Erectile Dysfunction:

   • Viagra is most commonly used to treat ED in men, enabling them to have an erection when sexually aroused.

2. Pulmonary Arterial Hypertension (PAH):

   • Sildenafil (brand name Revatio) is used to treat PAH by relaxing the blood vessels in the lungs, improving blood flow and reducing strain on the heart.

Dosage:

• For ED:
  • Typical Dose: 50 mg taken about 1 hour before sexual activity.
  • Can be adjusted to 25–100 mg depending on effectiveness and side effects.
  • Maximum dose: 100 mg per day.
• For PAH:
  • Lower doses (usually 20 mg three times daily) are used.

Benefits:

• Effective for ED: Provides noticeable improvement in erectile function.
• Quick Onset: Effects begin within 30–60 minutes and last 4–6 hours.
• Safe: Well-tolerated by most men when taken as directed.

Side Effects:

• Common: Headaches, flushing, indigestion, nasal congestion, dizziness, and visual disturbances (blue-tinted vision).
• Serious: Rare but can include heart problems (e.g., chest pain, irregular heartbeat), prolonged erections (priapism), sudden vision or hearing loss, or allergic reactions.
• Interactions: Can interact with nitrates (used for chest pain) and certain other medications, leading to a dangerous drop in blood pressure.