Rapaflo 4mg Capsules
It is used to treat the signs of an enlarged prostate. If you have been given this drug for some other reason, talk with your doctor for more information.
Drug Class
Benign Prostatic Hyperplasia (BPH) Agent
Pharmacologic Class
Selective Alpha-1A Adrenergic Antagonist
Pregnancy Category
Not available
FDA Approved
Oct 2008
DEA Schedule
Not Controlled
Overview
What is this medicine?
Rapaflo (silodosin) is a medication used to treat symptoms of an enlarged prostate, also known as Benign Prostatic Hyperplasia (BPH). It works by relaxing the muscles in the prostate and bladder, which helps to improve urine flow and reduce urinary symptoms like frequent urination, urgency, and difficulty starting urination.
How to Use This Medicine
Taking Your Medication
To take this medication correctly, follow your doctor's instructions and read all the information provided. Take the medication with a meal to help your body absorb it properly. If you have trouble swallowing the capsule, you can sprinkle its contents onto a small amount of applesauce. However, do not chew the mixture. Instead, swallow it immediately and follow with a glass of cool water. It's essential to use cool applesauce, as warm applesauce can affect the medication. Avoid mixing the medication with other liquids or foods.
Storing and Disposing of Your Medication
To maintain the medication's effectiveness, store it at room temperature, away from direct light and moisture. Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Ensure that all medications are kept out of the reach of children and pets to prevent accidental ingestion. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or participate in a local drug take-back program.
Missing a Dose
If you miss a dose, take it as soon as you remember, with a meal. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To take this medication correctly, follow your doctor's instructions and read all the information provided. Take the medication with a meal to help your body absorb it properly. If you have trouble swallowing the capsule, you can sprinkle its contents onto a small amount of applesauce. However, do not chew the mixture. Instead, swallow it immediately and follow with a glass of cool water. It's essential to use cool applesauce, as warm applesauce can affect the medication. Avoid mixing the medication with other liquids or foods.
Storing and Disposing of Your Medication
To maintain the medication's effectiveness, store it at room temperature, away from direct light and moisture. Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Ensure that all medications are kept out of the reach of children and pets to prevent accidental ingestion. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or participate in a local drug take-back program.
Missing a Dose
If you miss a dose, take it as soon as you remember, with a meal. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take this medication once daily with a meal to help reduce the risk of dizziness or lightheadedness.
- Avoid activities that require mental alertness, such as driving or operating machinery, until you know how this medication affects you, especially after the first dose or if your dose is changed.
- Be aware of the possibility of retrograde ejaculation (semen going into the bladder instead of out of the penis during orgasm), which is a common side effect and is not harmful.
- Stand up slowly from a sitting or lying position to minimize dizziness or lightheadedness.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
8 mg orally once daily with a meal
Dose Range:
8 - 8 mg
Condition-Specific Dosing:
Benign Prostatic Hyperplasia (BPH):
8 mg orally once daily with a meal
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment necessary (CrCl 50-80 mL/min)
Moderate:
Reduce dose to 4 mg orally once daily with a meal (CrCl 30-50 mL/min)
Severe:
Contraindicated (CrCl < 30 mL/min)
Dialysis:
Contraindicated
Hepatic Impairment:
Mild:
No dosage adjustment necessary
Moderate:
No dosage adjustment necessary
Severe:
Not recommended (not studied)
Pharmacology
Mechanism of Action
Silodosin is a selective antagonist of alpha-1A adrenergic receptors, which are predominantly located in the human prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra. By blocking these receptors, silodosin causes relaxation of the smooth muscle in these tissues, leading to an increase in urinary flow rate and a reduction in the symptoms of benign prostatic hyperplasia (BPH).
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 32%
Tmax:
Approximately 2.5 hours
FoodEffect:
A high-fat meal decreases Cmax by 18% and AUC by 4%, but it is recommended to take with a meal to reduce the incidence of orthostatic hypotension.
Distribution:
Vd:
Approximately 49.5 L
ProteinBinding:
Approximately 96.6% (silodosin), 97.9% (KMD-3213)
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 13.3 hours (silodosin), 24 hours (KMD-3213)
Clearance:
Not available
ExcretionRoute:
Urine (33.5%), feces (54.9%)
Unchanged:
Approximately 3.4% (in urine)
Pharmacodynamics
OnsetOfAction:
Symptom improvement may be observed within 1 week of starting therapy.
PeakEffect:
Not precisely defined, but related to steady-state concentrations achieved within a few days.
DurationOfAction:
24 hours (once daily dosing)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Other Possible Side Effects
Like all medications, this drug can cause side effects. Although many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or persist, contact your doctor for guidance:
Orgasm with reduced or absent semen
Dizziness
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Other Possible Side Effects
Like all medications, this drug can cause side effects. Although many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or persist, contact your doctor for guidance:
Orgasm with reduced or absent semen
Dizziness
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or fainting (syncope)
- Prolonged, painful erection (priapism) lasting more than 4 hours â seek immediate medical attention
- Chest pain or worsening angina
- Signs of an allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
Existing health conditions, such as kidney disease or liver disease.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because certain medications, including those used to treat HIV, infections, depression, and other conditions, should not be taken with this drug. Your doctor or pharmacist can help you determine if any of your medications interact with this drug.
If you are taking a similar medication, as using multiple similar drugs can be harmful. If you are unsure, consult your doctor or pharmacist.
If you are pregnant, plan to become pregnant, or are breastfeeding. This medication is not approved for use in these situations, so it is vital to discuss your options with your doctor.
Please note that this is not an exhaustive list of all potential interactions or health concerns related to this medication. To ensure your safety, it is crucial to:
Inform your doctor and pharmacist about all your medications (prescription and OTC), natural products, vitamins, and health problems.
Verify that it is safe to take this medication with your existing medications and health conditions.
Never start, stop, or change the dose of any medication without consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
Existing health conditions, such as kidney disease or liver disease.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because certain medications, including those used to treat HIV, infections, depression, and other conditions, should not be taken with this drug. Your doctor or pharmacist can help you determine if any of your medications interact with this drug.
If you are taking a similar medication, as using multiple similar drugs can be harmful. If you are unsure, consult your doctor or pharmacist.
If you are pregnant, plan to become pregnant, or are breastfeeding. This medication is not approved for use in these situations, so it is vital to discuss your options with your doctor.
Please note that this is not an exhaustive list of all potential interactions or health concerns related to this medication. To ensure your safety, it is crucial to:
Inform your doctor and pharmacist about all your medications (prescription and OTC), natural products, vitamins, and health problems.
Verify that it is safe to take this medication with your existing medications and health conditions.
Never start, stop, or change the dose of any medication without consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
When starting this medication, avoid driving and other activities that require alertness until you understand how it affects you. To minimize the risk of dizziness or fainting, get up slowly from a sitting or lying position. Be cautious when climbing stairs.
If you are scheduled for cataract surgery or any other eye procedure, discuss this with your doctor beforehand. Follow your doctor's instructions for regular blood tests and other laboratory evaluations. Additionally, monitor your blood pressure as advised by your doctor.
Men should undergo a rectal exam to check the prostate gland and have a prostate-specific antigen (PSA) blood test as recommended by their doctor. It is crucial to discuss the results and any concerns with your doctor.
Before consuming alcohol, consult with your doctor to understand any potential interactions with this medication.
Animal studies have shown that this drug can cause fertility problems in male rats, which reversed after the medication was stopped. However, it is unknown whether this medication will have a similar effect on human fertility.
When starting this medication, avoid driving and other activities that require alertness until you understand how it affects you. To minimize the risk of dizziness or fainting, get up slowly from a sitting or lying position. Be cautious when climbing stairs.
If you are scheduled for cataract surgery or any other eye procedure, discuss this with your doctor beforehand. Follow your doctor's instructions for regular blood tests and other laboratory evaluations. Additionally, monitor your blood pressure as advised by your doctor.
Men should undergo a rectal exam to check the prostate gland and have a prostate-specific antigen (PSA) blood test as recommended by their doctor. It is crucial to discuss the results and any concerns with your doctor.
Before consuming alcohol, consult with your doctor to understand any potential interactions with this medication.
Animal studies have shown that this drug can cause fertility problems in male rats, which reversed after the medication was stopped. However, it is unknown whether this medication will have a similar effect on human fertility.
Overdose Information
Overdose Symptoms:
- Severe hypotension (low blood pressure)
- Dizziness
- Fainting
What to Do:
In case of overdose, contact a poison control center immediately. Call 1-800-222-1222. Management is supportive, focusing on cardiovascular support (e.g., keeping the patient supine, administering fluids, vasopressors if necessary). Dialysis is unlikely to be beneficial due to high protein binding.
Drug Interactions
Contraindicated Interactions
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir, clarithromycin)
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) - increased risk of symptomatic hypotension
- Other alpha-adrenergic blocking agents (e.g., prazosin, doxazosin, terazosin, tamsulosin, alfuzosin) - increased risk of symptomatic hypotension
Moderate Interactions
- Moderate CYP3A4 inhibitors (e.g., diltiazem, erythromycin)
- P-glycoprotein inhibitors (e.g., cyclosporine)
Monitoring
Baseline Monitoring
Blood pressure (sitting and standing)
Rationale: To assess for baseline orthostatic hypotension risk and establish a baseline for monitoring.
Timing: Prior to initiation of therapy
BPH symptom assessment (e.g., AUA Symptom Score)
Rationale: To establish baseline symptom severity and monitor treatment efficacy.
Timing: Prior to initiation of therapy
Routine Monitoring
Blood pressure (sitting and standing)
Frequency: Periodically, especially during initial titration or if symptoms of orthostatic hypotension occur.
Target: Maintain within patient's normal range, avoid symptomatic hypotension.
Action Threshold: Significant drop in standing BP (>20 mmHg systolic or >10 mmHg diastolic) or symptomatic hypotension (dizziness, lightheadedness, syncope) warrants re-evaluation of therapy.
BPH symptom assessment (e.g., AUA Symptom Score)
Frequency: Periodically (e.g., every 3-6 months or as clinically indicated)
Target: Reduction in symptom score
Action Threshold: Lack of symptom improvement or worsening symptoms may indicate need for alternative therapy.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Orthostatic hypotension
- Syncope (fainting)
- Retrograde ejaculation (decreased or absent semen during orgasm)
- Priapism (prolonged, painful erection)
- Blurred vision or other visual disturbances (related to Intraoperative Floppy Iris Syndrome)
Special Patient Groups
Pregnancy
Silodosin is not indicated for use in women. There are no adequate and well-controlled studies of silodosin in pregnant women.
Trimester-Specific Risks:
First Trimester:
Not applicable
Second Trimester:
Not applicable
Third Trimester:
Not applicable
Lactation
Silodosin is not indicated for use in women. It is unknown whether silodosin is excreted in human milk.
Infant Risk:
Not applicable
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Silodosin is not indicated for use in pediatric patients.
Geriatric Use
No overall differences in safety or effectiveness were observed between elderly (65 years and over) and younger patients. However, the incidence of orthostatic hypotension may be higher in the elderly, and caution should be exercised due to potential for falls.
Clinical Information
Clinical Pearls
- Silodosin is highly selective for alpha-1A receptors, which may contribute to its efficacy in BPH symptoms and potentially a lower incidence of cardiovascular side effects compared to non-selective alpha-blockers, though orthostatic hypotension is still a risk.
- Retrograde ejaculation is a very common and often bothersome side effect (occurring in up to 28% of patients in clinical trials). Patients should be counseled about this prior to initiation, as it is reversible upon discontinuation.
- Advise patients to take silodosin with a meal to help mitigate the risk of orthostatic hypotension.
- Caution should be exercised when co-administering with PDE5 inhibitors due to the risk of additive hypotensive effects. If co-administration is necessary, patients should be stable on alpha-blocker therapy before initiating a low dose of a PDE5 inhibitor.
- Patients undergoing cataract surgery should inform their ophthalmologist about silodosin use due to the risk of Intraoperative Floppy Iris Syndrome (IFIS).
Alternative Therapies
- Other alpha-adrenergic blockers (e.g., tamsulosin, alfuzosin, doxazosin, terazosin)
- 5-alpha reductase inhibitors (e.g., finasteride, dutasteride)
- Combination therapy (e.g., alpha-blocker + 5-alpha reductase inhibitor)
- Anticholinergics (for storage symptoms, often in combination)
- Beta-3 adrenergic agonists (e.g., mirabegron, for storage symptoms)
- Surgical interventions (e.g., TURP, laser prostatectomy)
- Minimally invasive procedures (e.g., UroLift, Rezum)
Cost & Coverage
Average Cost:
Varies, typically $100-$300+ per 30 capsules (8mg)
Generic Available:
Yes
Insurance Coverage:
Tier 2 or Tier 3 (for generic), Tier 3 or higher (for brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.