Lanrektan (Tadalafil)

Lanrektan, a PDE5 inhibitor, is used in several conditions that involve smooth‑muscle relaxation.

• Erectile dysfunction: improves the ability to achieve and maintain an erection during sexual activity.
• Benign prostatic hyperplasia: reduces urinary frequency, urgency and weak stream associated with prostate enlargement.
• Pulmonary arterial hypertension: enhances exercise capacity and delays disease progression in patients with elevated pulmonary arterial pressure.

• Tadalafil selectively inhibits phosphodiesterase type 5, the enzyme responsible for degrading cyclic guanosine monophosphate (cGMP) in the corpus cavernosum and pulmonary vasculature. By preventing cGMP breakdown, intracellular levels rise, leading to smooth‑muscle relaxation, increased blood flow, and improved erectile function or pulmonary vascular tone, depending on the therapeutic indication.

Adverse reactions may vary in frequency and severity.

Common Side Effects

• Headache: mild to moderate pain often described as tension‑type.
• Flushing: transient warmth and redness, typically on the face and neck.
• Dyspepsia: occasional indigestion or upset stomach.
• Nasal congestion: mild blockage or runny nose.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring urgent medical attention.
• Sudden vision loss: may indicate non‑arteritic anterior ischemic optic neuropathy.
• Sudden hearing loss: unexplained decrease or loss of hearing.
• Severe hypotension: marked drop in blood pressure, especially when combined with nitrates.

Before prescribing Lanrektan, clinicians should consider several safety aspects.

• Cardiovascular assessment: evaluate history of heart disease, recent myocardial infarction or unstable angina.
• Concomitant nitrate therapy: avoid due to risk of profound hypotension.
• Renal or hepatic impairment: dose may need adjustment in moderate to severe dysfunction.
• Visual disturbances: discontinue if sudden vision loss or visual field defects occur.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture.

Tadalafil can interact with several medication classes, requiring careful management.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin, isosorbide dinitrate): may cause severe hypotension.
• Alpha‑blockers (e.g., doxazosin, prazosin): risk of additive blood‑pressure lowering effects.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (ketoconazole, erythromycin): can increase tadalafil plasma concentrations.
• CYP3A4 inducers (rifampin, carbamazepine): may reduce tadalafil effectiveness.
• Antihypertensives (ACE inhibitors, ARBs): monitor blood pressure for additive effects.
• Alcohol: excessive intake may enhance hypotensive response.