Is it safe to take Cardura (Doxazosin) and Viagra (Sildenafil) together?

From the Guidelines

Taking Cardura (doxazosin) and Viagra (sildenafil) together is not recommended without medical supervision due to the potential risk of severe hypotension. Both medications can lower blood pressure, and when combined, they may cause a significant drop in blood pressure leading to dizziness, fainting, or even more serious cardiovascular complications. According to the American Urological Association update on the management of erectile dysfunction 1, phosphodiesterase type 5 inhibitors like sildenafil should be used with caution in patients taking other medications that can lower blood pressure. Some key points to consider when taking these medications together include:

• The potential for additive hypotensive effects, particularly within the first few hours after taking either medication
• The need for close medical supervision and monitoring of blood pressure
• The possibility of adjusting dosages or scheduling the medications at different times to minimize interactions
• The importance of consulting a healthcare provider before taking Viagra if you are currently taking Cardura for high blood pressure or enlarged prostate symptoms. It is essential to prioritize caution and consult a healthcare professional before combining these medications to ensure safe and effective treatment for erectile dysfunction while minimizing the risk of adverse interactions 1.

From the FDA Drug Label

DRUG INTERACTIONS Alpha-blockers. In drug-drug interaction studies, sildenafil (25 mg, 50 mg, or 100 mg) and the alpha-blocker doxazosin (4 mg or 8 mg) were administered simultaneously to patients with benign prostatic hyperplasia (BPH) stabilized on doxazosin therapy In these study populations, mean additional reductions of supine systolic and diastolic blood pressure of 7/7 mmHg, 9/5 mmHg, and 8/4 mmHg, respectively, were observed. Mean additional reductions of standing blood pressure of 6/6 mmHg, 11/4 mmHg, and 4/5 mmHg, respectively, were also observed. There were infrequent reports of patients who experienced symptomatic postural hypotension These reports included dizziness and light-headedness, but not syncope. Monitor blood pressure when co-administering blood pressure lowering drugs with sildenafil citrate [see Warnings and Precautions (5.2)].

Key Points:

• The FDA label mentions the interaction between sildenafil and alpha-blockers, such as doxazosin.
• Cardura (doxazosin) is an alpha-blocker.
• The label warns of potential hypotension when co-administering sildenafil with alpha-blockers.
• It is recommended to monitor blood pressure when taking these medications together.

The use of Cardura and Viagra together may increase the risk of hypotension, and patients should be monitored for this potential interaction 2.

From the Research

Interaction between Cardura (Doxazosin) and Viagra (Sildenafil)

• The interaction between doxazosin and sildenafil is not directly studied in the provided evidence, but studies on similar phosphodiesterase type 5 inhibitors and alpha-blockers can provide some insights 3.
• A study on tadalafil and doxazosin found that tadalafil augmented the hypotensive effect of doxazosin, producing a significant decrease in standing systolic blood pressure 3.
• Another study found that doxazosin is not associated with the occurrence of erectile dysfunction compared to other antihypertensive treatments 4.
• Doxazosin has been shown to be effective in treating benign prostatic hyperplasia (BPH) and hypertension, with minimal effects on blood pressure in normotensive patients 5.

Effects of Doxazosin and Sildenafil on BPH and Erectile Dysfunction

• A study found that sildenafil alone caused mild improvement in BPH symptoms, more improvement in erectile function, and little effect on flow rate and post-void residual urine 6.
• Doxazosin alone caused more improvement in BPH symptoms, flow rate, and post-void residual urine, and less improvement in erectile function 6.
• The combination of sildenafil and doxazosin caused more improvement in all parameters than when each drug was given alone, suggesting a potential benefit for patients with both BPH and erectile dysfunction 6.

Safety and Efficacy

• The safety and efficacy of taking Cardura (doxazosin) and Viagra (sildenafil) together are not directly studied in the provided evidence, but the available data suggest that doxazosin can be safely administered with phosphodiesterase type 5 inhibitors like sildenafil, although caution is advised due to the potential for hypotension 3, 6.