PTCB Certified Pharmacy Technician (PTCE)Patient Safety and Quality AssuranceHard
A pharmacy technician is reviewing a patient's medication profile and notes that the patient is prescribed 'Tamsulosin 0.4 mg daily' for benign prostatic hyperplasia (BPH) and 'Sildenafil 50 mg as needed' for erectile dysfunction. The technician recognizes a potential drug interaction. What is the MOST likely adverse effect if these medications are taken concurrently?
- AEnhanced absorption of tamsulosin.
- BSignificant decrease in blood pressure.
- CDecreased efficacy of sildenafil.
- DIncreased risk of priapism.
Show answer & explanationAnswer & explanation
Correct answer: B. Significant decrease in blood pressure.
Both tamsulosin (an alpha-1 blocker) and sildenafil (a PDE5 inhibitor) can cause vasodilation and a drop in blood pressure. When taken concurrently, especially within a short timeframe, their hypotensive effects can be additive, leading to a significant and potentially dangerous decrease in blood pressure (orthostatic hypotension).
Why the other options are wrong
- A. The primary interaction is pharmacodynamic (additive BP lowering), not pharmacokinetic (enhanced absorption).
- C. The interaction primarily concerns blood pressure, not a decrease in sildenafil's efficacy; rather, it's an additive side effect.
- D. While priapism is a rare side effect of PDE5 inhibitors like sildenafil, it's not the primary interaction concern with tamsulosin.
Alpha-Blocker/PDE5 Inhibitor Interaction
Concurrent use of alpha-blockers (e.g., tamsulosin) and PDE5 inhibitors (e.g., sildenafil) can lead to a significant, additive decrease in blood pressure.
- Both drug classes cause vasodilation.
- Additive hypotensive effect is the main risk.
- Patients should be advised on timing and symptoms of hypotension.
Memory trick: Alpha-Blocker + PDE5 = BP Crash, Too Much Vasodilation in a Flash!