Tadalafil

1. Introduction

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH). It enhances blood flow by relaxing blood vessels, improving erectile function, relieving urinary symptoms in BPH, and reducing pulmonary artery pressure in PAH.

2. Indications

  • Erectile Dysfunction (ED): Improves the ability to achieve and maintain an erection.
  • Benign Prostatic Hyperplasia (BPH): Relieves urinary symptoms due to an enlarged prostate.
  • Pulmonary Arterial Hypertension (PAH): Lowers pulmonary blood pressure, improving exercise capacity.

3. Dosage

Adults:

  • Erectile Dysfunction (As Needed):
    • 10 mg at least 30 minutes before sexual activity.
    • May increase to 20 mg based on response.
    • Maximum: One dose per day.
  • Erectile Dysfunction (Daily Use):
    • 2.5 mg to 5 mg once daily at the same time each day.
    • Allows for spontaneous sexual activity.
  • Benign Prostatic Hyperplasia (BPH):
    • 5 mg once daily.
  • Erectile Dysfunction + BPH:
    • 5 mg once daily.
  • Pulmonary Arterial Hypertension (PAH):
    • 40 mg once daily.

Elderly:

  • No dosage adjustment required, but monitor for hypotension.

Children:

  • Not approved for use.

Renal Impairment:

  • Mild to Moderate (CrCl 30–50 mL/min): Max 10 mg every 48 hours.
  • Severe (CrCl <30 mL/min): Avoid use.

Hepatic Impairment:

  • Mild to Moderate: Maximum 10 mg once daily.
  • Severe: Avoid use.

4. Administration

  • Take with or without food.
  • Swallow whole with water; do not crush or split.
  • Avoid excessive alcohol intake to reduce the risk of hypotension.

5. Forms Available

  • Tablets: 2.5 mg, 5 mg, 10 mg, 20 mg

6. Side Effects

6.1 Common Side Effects:

  • Headache
  • Flushing
  • Indigestion
  • Back pain
  • Nasal congestion

6.2 Less Common Side Effects:

  • Dizziness
  • Muscle pain
  • Blurred vision

6.3 Rare but Serious Side Effects:

  • Priapism (prolonged erection >4 hours; medical emergency)
  • Sudden hearing loss
  • Non-arteritic anterior ischaemic optic neuropathy (NAION)
  • Severe hypotension (low blood pressure)

7. Warnings

  • Cardiovascular Risk: Avoid in patients with significant heart disease or recent stroke.
  • Priapism: If an erection lasts >4 hours, seek immediate medical help.
  • Sudden Vision Loss: Risk of NAION in patients with existing eye conditions.
  • Severe Hypotension: Especially when taken with nitrates or alpha-blockers.

8. Precautions

  • Avoid use in severe kidney or liver disease.
  • Caution in patients with a history of heart attack or stroke.
  • Do not combine with other PDE5 inhibitors (e.g., sildenafil, vardenafil).
  • Avoid grapefruit juice as it may increase tadalafil levels.

9. Interactions

  • Nitrates (e.g., nitroglycerin, isosorbide): Severe hypotension; contraindicated.
  • Alpha-blockers (e.g., tamsulosin, doxazosin): Risk of low blood pressure.
  • CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): May increase tadalafil levels.
  • CYP3A4 inducers (e.g., rifampin, carbamazepine): May decrease tadalafil effectiveness.
  • Alcohol: May worsen dizziness and hypotension.

10. Monitoring Parameters

  • Blood pressure: Monitor for hypotension.
  • Cardiovascular function: Evaluate before prescribing to high-risk patients.
  • Vision and hearing changes: Discontinue if sudden loss occurs.

11. Use in Children

  • Not recommended; safety and efficacy not established.

12. Use in Pregnancy

  • Category B: Not indicated for use in women.

13. Use in Elderly

  • Safe, but monitor for hypotension and drug interactions.

14. Use in Kidney Disease

  • Dose adjustment required for moderate impairment.
  • Avoid in severe renal disease.

15. Use in Liver Disease

  • Avoid in severe hepatic impairment.

16. Patient Counselling Points

  • Take tadalafil at least 30 minutes before sexual activity if using on-demand.
  • Daily-use tadalafil does not require timing with sexual activity.
  • Do not take more than one dose per day.
  • Avoid nitrates or excessive alcohol to prevent severe hypotension.
  • If experiencing vision or hearing loss, seek medical help immediately.
  • Report erections lasting >4 hours (priapism) to a doctor immediately.

17. Table of Brand Names, Manufacturer, and Prices in USD

Brand NameManufacturerStrength/Dosage FormPrice (USD)
CialisEli Lilly20 mg Tablet$70 (1 tablet)
AdcircaEli Lilly40 mg Tablet (PAH)$120 (1 tablet)
Generic TadalafilVarious20 mg Tablet$10 (1 tablet)

18. 15 FAQs (Frequently Asked Questions)

1. What is Tadalafil used for?
Tadalafil treats erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension.

2. How does Tadalafil work?
It inhibits PDE5, allowing increased blood flow to the penis and relaxing blood vessels in the lungs and prostate.

3. How long does Tadalafil last?
Effects last up to 36 hours after a single dose.

4. Can I take Tadalafil daily?
Yes, 2.5 mg or 5 mg daily can be taken for continuous effect.

5. Can Tadalafil cause high blood pressure?
No, but it can lower blood pressure, so caution is needed with antihypertensives.

6. Can Tadalafil be taken with alcohol?
Alcohol may increase dizziness and hypotension, so limit intake.

7. How quickly does Tadalafil work?
It starts working within 30–60 minutes.

8. Can I take Tadalafil with food?
Yes, but high-fat meals do not affect absorption significantly.

9. Can women take Tadalafil?
It is not approved for use in women.

10. Can I take Tadalafil with other ED medications?
No, do not combine with sildenafil or vardenafil.

11. What should I do if Tadalafil doesn’t work?
Consult your doctor; dose adjustments or alternative treatments may be needed.

12. Can Tadalafil be taken by diabetics?
Yes, it is safe but requires monitoring for low blood pressure.

13. Can Tadalafil cause headaches?
Yes, headache is a common side effect due to vasodilation.

14. Is Tadalafil safe for long-term use?
Yes, but regular health monitoring is recommended.

15. What should I do if I miss a daily dose?
Take it as soon as possible, but skip it if close to the next dose.