Tadalafil

Tadalafil is commonly sold under the brand names Cialis and Adcirca.

It is a well-known phosphodiesterase type-5 (PDE-5) inhibitor primarily used to treat erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH).

Information About Tadalafil

• Chemical Structure & Formula: Tadalafil has the molecular formula C22H19N3O4 and belongs to the class of PDE-5 inhibitors that enhance blood flow by relaxing blood vessels.

Discovery & Development

• Tadalafil was discovered by GlaxoSmithKline in collaboration with ICOS Corporation in the 1990s. Later, Eli Lilly and Company took over the development and commercialized it under the brand name Cialis.

Approval & Regulatory Status

• The FDA approved Tadalafil for erectile dysfunction in 2003 and later for pulmonary arterial hypertension. It is also recognized by EMA and WHO for medical use.

Mode of Action

• Tadalafil works by inhibiting the PDE-5 enzyme. This, in turn, increases the levels of a molecule named cGMP (cyclic guanosine monophosphate), which results in the relaxation of smooth muscle in blood vessels.

This leads to increased blood flow to the penile region, aiding in erection. Tadalafil also has other therapeutic uses, including the treatment of benign prostatic hyperplasia (BPH) and pulmonary arterial hypertension (PAH).

Uses of Tadalafil

Primary Uses

• Erectile Dysfunction (ED): Tadalafil helps men achieve and maintain an erection. ED, or impotence, is a condition where a man is unable to achieve or maintain an erection firm enough for sexual intercourse. Tadalafil works by relaxing the muscles in the blood vessels of the penis, allowing for increased blood flow, which helps achieve and maintain an erection when combined with sexual stimulation.
• Benign Prostatic Hyperplasia (BPH): It improves urinary symptoms related to prostate enlargement. BPH is a non-cancerous enlargement of the prostate gland, which can cause urinary symptoms such as frequent urination, urgency, and difficulty emptying the bladder. Tadalafil helps by relaxing the muscles in the prostate and bladder, improving urine flow and reducing the symptoms associated with BPH. In fact, this is the only drug that has been shown to simultaneously treat ED and BPH in older men.
• Pulmonary Arterial Hypertension (PAH): Tadalafil is also approved to treat PAH, a condition characterized by high blood pressure in the arteries of the lungs. By relaxing the blood vessels in the lungs, tadalafil helps improve exercise ability and decrease symptoms like shortness of breath and fatigue associated with PAH.

Off-Label Uses

• Raynaud’s Phenomenon: Some studies suggest tadalafil helps in reducing symptoms of this vascular condition.
• Altitude Sickness: Research indicates that Tadalafil can provide possible benefits in improving oxygenation at high altitudes.

How Tadalafil Works

Tadalafil inhibits PDE-5, an enzyme that breaks down cGMP, which is responsible for muscle relaxation and enhanced blood flow. By blocking PDE-5, tadalafil maintains sustained cGMP levels, improving blood flow.

The tadalafil 5 mg dose starts to work within 30-60 minutes of consumption.

Factors Affecting Its Effectiveness

• Food Intake: Consuming a high-fat meal before taking tadalafil can slow down its absorption, delaying its onset of action. While the medication will still take effect, it may take longer to work compared to when taken on an empty stomach or with a light meal.
• Metabolism: The speed at which an individual’s body processes tadalafil affects its duration and potency. Those with a slower metabolism may experience prolonged effects, meaning the medication remains active for a longer period. Conversely, individuals with a faster metabolism may find that the drug’s effects wear off more quickly.
• Genetic Variations: Differences in enzyme activity, particularly in how the liver metabolizes tadalafil, can lead to varied responses among individuals. Some people may experience a stronger or longer-lasting effect, while others may find the drug less effective due to genetic factors influencing drug breakdown and absorption.
• Alcohol and Drug Interactions: Excessive alcohol consumption can reduce the effectiveness of tadalafil and increase the risk of side effects such as dizziness. Tadalafil can also interact with certain medications, particularly nitrates (used for chest pain) and alpha-blockers (used for high blood pressure or BPH), leading to potentially dangerous drops in blood pressure. Always tell your doctor about any medications you are currently taking.
• Heart Health: Since tadalafil affects blood vessels, individuals with heart conditions should be cautious and consult their healthcare provider before using it. It is generally not recommended for people with severe heart problems or those who have had a recent heart attack or stroke.

Common Side Effects of Tadalafil

There can be a few side effects with the tadalafil usage. Always consult your doctor when you feel something is beyond normal.

Mild Side Effects

• Headache
• Flushing
• Nasal congestion
• Indigestion
• Muscle pain

Moderate to Severe Side Effects

• Blurred vision
• Sudden hearing loss
• Priapism (prolonged erection)
• Hypotension (low blood pressure)

When to Seek Medical Help

If you experience any of the following, consult a doctor immediately:

• An erection lasting longer than four hours.
• Severe chest pain or dizziness.
• Sudden loss of vision or hearing.

Available Medicines for Tadalafil

Brand Names

Tadalafil is available under various brand names and generic versions.

Tadalafil Dosage & Strengths

Tadalafil is available in various strengths, including 2.5 mg, 5 mg, 10 mg, 20 mg, and higher strengths as required. Always consult your doctor before starting a dosage.

Erectile Dysfunction (ED)

The recommended starting tadalafil dosage for erectile dysfunction is 10 mg, taken as needed. However, your doctor may adjust it based on its effectiveness and your body's response.

• Standard dose: 10 mg before sexual activity
• Maximum dose of tadalafil in 24 hours: One tablet (10 mg or 20mg)
• Effects can last more than 24 hours, so daily use of the 10mg or 20mg tablet is not advised
• Requires sexual stimulation to work effectively

Benign Prostate Enlargement

• Dosage: Tadalafil 5 mg once daily.
• If treating both benign prostate enlargement and erectile dysfunction, the recommended dose remains 5 mg per day.

Pulmonary Hypertension

• Standard dosage: 40 mg per day (two 20 mg tadalafil tablets).
• For individuals with kidney or liver conditions, the doctor may adjust the starting dose to 10 mg or 20 mg.

How Long Does Tadalafil Last?

• The onset of tadalafil usually takes 30-60 minutes. But the peak effectiveness is reached in 2 hours and can last up to 36 hours.
• The effects of tadalafil can last up to 36 hours, making it a preferred choice for many users compared to other ED treatments. However, always follow your prescribed tadalafil dosage to avoid complications.
• The maximum recommended dose is 20 mg once daily for ED. Taking more than this increases the risk of severe side effects.

FAQs

Q1: How long does tadalafil last?

A: Tadalafil’s effects can last up to 36 hours, making it a popular choice over other ED medications.

Q2: What is tadalafil used for?

A: It is primarily used for erectile dysfunction, BPH, and pulmonary arterial hypertension.

Q3: Is tadalafil safe for daily use?

A: Yes, tadalafil 5 mg is commonly prescribed for daily use, especially for BPH and mild ED.

Q4: Can I take tadalafil with other medications?

A: Avoid combining it with nitrates, alpha-blockers, and some antibiotics, as it can cause dangerous interactions. Always consult your doctor before starting a dosage.

Disclaimer

This content is for informational purposes only and should not replace professional medical advice. Always consult a healthcare provider before starting any new medication.

References

1. https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021368s20s21lbl.pdf
2. https://www.mayoclinic.org/drugs-supplements/tadalafil-oral-route/description/drg-20067204
3. https://www.drugs.com/tadalafil.html
4. https://www.webmd.com/drugs/2/drug-77875/tadalafil-oral/details
5. https://pubmed.ncbi.nlm.nih.gov/14521415/