Cardura (doxazosin mesylate) is an alpha-1 adrenergic blocker medication prescribed for the management of hypertension (high blood pressure) and the treatment of symptomatic benign prostatic hyperplasia (BPH). It functions by relaxing blood vessels and muscles in the prostate and bladder neck, facilitating smoother blood flow and improved urinary function. This dual-action mechanism makes it a versatile option in a clinician’s therapeutic arsenal for addressing these common, yet impactful, conditions. Proper diagnosis and ongoing medical supervision are essential for its safe and effective use.

Features

• Active Pharmaceutical Ingredient: Doxazosin mesylate.
• Drug Class: Quinazoline-derived alpha-1 adrenergic receptor antagonist.
• Available Formulations: Oral tablets in strengths of 1 mg, 2 mg, 4 mg, and 8 mg.
• Mechanism of Action: Selectively blocks postsynaptic alpha-1 adrenergic receptors.
• Onset of Action: Antihypertensive effects are typically observed within 1-2 hours post-dose.
• Duration of Action: Provides 24-hour hemodynamic and urinary symptom control with once-daily dosing.

Benefits

• Achieves significant reduction in both systolic and diastolic blood pressure, lowering the risk of cardiovascular events.
• Provides rapid and sustained improvement in urinary flow rates and reduction in BPH symptoms like hesitancy, weak stream, and nocturia.
• Offers a convenient once-daily dosing regimen, enhancing patient adherence and compliance with long-term therapy.
• Functions through a mechanism distinct from other antihypertensive classes (e.g., diuretics, beta-blockers), making it suitable for combination therapy.
• Does not adversely affect blood lipid profiles or glucose metabolism, which is beneficial for patients with metabolic syndrome.

Common use

Cardura is primarily indicated for two conditions. First, for the management of hypertension, either as monotherapy or in combination with other antihypertensive agents such as diuretics, beta-blockers, ACE inhibitors, or calcium channel blockers. Second, for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH). It is effective in relieving urinary obstruction and irritative symptoms associated with BPH, such as poor stream, dribbling, straining, and bladder emptying difficulties. Treatment is intended for long-term management of these chronic conditions.

Dosage and direction

The dosage of Cardura must be individualized based on the patient’s therapeutic response and tolerability. For hypertension, the initial dose is 1 mg administered once daily. The dose may be increased gradually, typically at 1-2 week intervals, to 2 mg, 4 mg, 8 mg, and finally to a maximum of 16 mg once daily to achieve the desired blood pressure response. The majority of patients respond to a dose of 4 mg daily or less. For BPH, the recommended initial dose is also 1 mg once daily. The dose should be titrated upwards to 2 mg, 4 mg, and 8 mg once daily, as needed, based on the patient’s clinical response and tolerability. The maximum recommended dose for BPH is 8 mg daily. The tablet should be taken with a glass of water, with or without food, at approximately the same time each day. The initial dose must be taken at bedtime to minimize the potential for first-dose hypotension (a sudden drop in blood pressure).

Precautions

Patients should be advised about the potential for syncope (fainting) and symptomatic hypotension (dizziness, lightheadedness), especially at the initiation of therapy or during dosage titration. A slow titration schedule is crucial to minimize this risk. Patients should avoid driving or operating hazardous machinery for 12-24 hours after the first dose or any dose increase until their response has been established. Caution is advised in patients with severe hepatic impairment. Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in patients treated with alpha-1 blockers like doxazosin. Ophthalmologists should be informed of a patient’s use of Cardura prior to surgery. Regular monitoring of blood pressure and, for BPH patients, prostate-specific antigen (PSA) levels is recommended.

Contraindications

Cardura is contraindicated in patients with a known hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any component of the formulation. Its use is also contraindicated in patients with a history of orthostatic hypotension (a form of low blood pressure that happens when standing up from sitting or lying down) and in those with benign prostatic hyperplasia who have concomitant gastrointestinal obstruction, ileus, or atonic bowel.

Possible side effect

Like all medications, Cardura can cause side effects, although not everybody gets them. Common side effects include dizziness, fatigue, headache, somnolence (drowsiness), nausea, and edema (swelling, particularly of the feet and ankles). Postural hypotension and syncope (fainting) are less common but are important dose-limiting effects, particularly at therapy initiation. Other reported side effects include rhinitis (stuffy or runny nose), abdominal pain, diarrhea, dyspnea (shortness of breath), hypotension, non-specific chest pain, and tachycardia (rapid heart rate). Priapism (a painful and prolonged erection) is a rare but serious side effect that requires immediate medical attention to prevent permanent damage.

Drug interaction

The hypotensive (blood pressure-lowering) effect of Cardura can be potentiated by concomitant use of other antihypertensive agents, phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil), and other medications that can induce hypotension. Concurrent administration with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir) may increase doxazosin plasma concentrations and should be approached with caution. Non-steroidal anti-inflammatory drugs (NSAIDs) and sympathomimetics (e.g, decongestants) may decrease and increase blood pressure, respectively, potentially interfering with the efficacy of Cardura.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. If it is not remembered until the next day, the patient should skip the missed dose and take only the regularly scheduled dose. Do not take a double dose to make up for a missed one, as this increases the risk of hypotension and dizziness.

Overdose

In the event of an overdose, the primary expected manifestation is exaggerated pharmacological effects, leading to profound hypotension, sometimes accompanied by shock. Symptoms may include extreme dizziness, lightheadedness, fainting, and a rapid heartbeat. In cases of suspected overdose, supportive care is paramount. The patient should be placed in a supine position (lying down, head flat) with their legs elevated. This position helps manage hypotension. Vital signs and electrolyte balance should be monitored and supported. Gastric lavage or the administration of activated charcoal may be considered if ingestion was recent. Since doxazosin is highly protein-bound, dialysis is not likely to be of benefit.

Storage

Store Cardura tablets at room temperature, between 20°C to 25°C (68°F to 77°F), in a dry place protected from light and moisture. Excursions are permitted between 15°C and 30°C (59°F and 86°F). Keep the medication in its original container, tightly closed, and out of reach of children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed through a medicine take-back program or by following FDA guidelines.

Disclaimer

This information is for educational and informational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting, stopping, or changing any prescribed part of your care plan. Never disregard professional medical advice or delay in seeking it because of something you have read here. The information provided is based on the drug’s prescribing information but may not be exhaustive.

Reviews

“Cardura has been a cornerstone in my practice for managing patients with concomitant hypertension and BPH. The titration process is key, but once an optimal dose is reached, the dual benefits on blood pressure and urinary symptoms are consistently reliable. Patient adherence is high due to the once-daily dosing.” – Urologist, 15 years of experience.

“Initiating therapy at 1 mg at bedtime is a critical step we emphasize to our nursing staff to prevent first-dose syncope events. For the right patient, it’s an effective agent, though we monitor closely during the first few weeks of treatment.” – Clinical Pharmacist, Cardiology Unit.

“As a patient, the difference in my urinary flow was noticeable within a couple of weeks. The dizziness was a bit strong the first day, but it faded quickly after that. It’s much more convenient than taking multiple pills throughout the day.” – Anonymous patient feedback.