Nairem (Tadalafil)

Tadalafil is a phosphodiesterase type 5 inhibitor used to manage conditions related to vascular smooth‑muscle relaxation.

• Erectile dysfunction: Improves ability to achieve and maintain an erection sufficient for sexual activity.
• Pulmonary arterial hypertension: Reduces pulmonary vascular resistance and improves exercise capacity.
• Benign prostatic hyperplasia: Relieves lower urinary tract symptoms by relaxing smooth muscle in the prostate and bladder neck.

• Tadalafil selectively inhibits the enzyme phosphodiesterase type 5, preventing the breakdown of cyclic guanosine monophosphate (cGMP) in smooth‑muscle cells. Elevated cGMP levels lead to relaxation of the corpus cavernosum and pulmonary vasculature, enhancing blood flow. Its dose‑dependent, reversible inhibition provides sustained vasodilation for up to 36 hours after dosing.

Tadalafil may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Headache: mild to moderate pain often occurring shortly after dosing.
• Flushing: transient warmth and redness of the face or neck.
• Dyspepsia: indigestion or upset stomach.
• Nasal congestion: blocked or runny nose.
• Back pain: muscle aches, typically appearing 12–24 hours post‑dose.
• Vision changes: mild color perception alterations.

Serious or Rare Side Effects

• Sudden vision loss: may indicate non‑arteritic anterior ischemic optic neuropathy.
• Priapism: prolonged erection lasting more than 4 hours requiring medical attention.
• Severe hypotension: marked drop in blood pressure, especially with nitrate use.
• Hearing loss: sudden, unexplained decrease in auditory function.
• Allergic reaction: rash, itching, swelling, or anaphylaxis.
• Myocardial infarction: chest pain suggestive of heart attack.

When prescribing or dispensing tadalafil, consider the following safety measures.

• Cardiovascular assessment: evaluate for recent heart attack, unstable angina, or severe heart failure.
• Nitrate use: avoid concurrent use with any nitrate medication due to risk of profound hypotension.
• Blood pressure monitoring: caution in patients with uncontrolled hypertension or hypotension.
• Renal or hepatic impairment: dose adjustment may be required in moderate to severe dysfunction.
• Visual disorders: use with caution in patients with retinitis pigmentosa or other retinal diseases.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Tadalafil can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin): combined use can cause dangerous drops in blood pressure.
• Guanylate cyclase stimulators (e.g., riociguat): additive vasodilatory effect may lead to severe hypotension.

Moderate Interactions (Monitor Closely)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): may increase tadalafil plasma concentrations.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce tadalafil effectiveness.
• Alpha‑blockers (e.g., doxazosin, tamsulosin): may cause additive blood pressure lowering; monitor for dizziness.