Terazosin 1mg Capsules
It is used to treat high blood pressure.It is used to treat the signs of an enlarged prostate.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antihypertensive; Benign Prostatic Hyperplasia (BPH) agent
Pharmacologic Class
Alpha-1 adrenergic antagonist
Pregnancy Category
Category C
FDA Approved
Aug 1987
DEA Schedule
Not Controlled
Overview
What is this medicine?
Terazosin is a medication used to treat high blood pressure and symptoms of an enlarged prostate (BPH). It works by relaxing blood vessels and muscles in the prostate and bladder, making it easier for blood to flow and for urine to pass.
How to Use This Medicine
Taking Your Medication
To get the most benefit from this medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. It's recommended to take this medication at bedtime. Continue taking the medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the medication's effectiveness, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. 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. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. 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. If you miss two or more days of medication, contact your doctor for guidance on how to restart your treatment.
To get the most benefit from this medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. It's recommended to take this medication at bedtime. Continue taking the medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the medication's effectiveness, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a safe location, out of the reach of children and pets. 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. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. 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. If you miss two or more days of medication, contact your doctor for guidance on how to restart your treatment.
Lifestyle & Tips
- Take the first dose at bedtime to minimize the 'first-dose effect' (sudden drop in blood pressure).
- Avoid sudden changes in position (e.g., standing up quickly from sitting or lying down) to prevent dizziness or fainting.
- Avoid or limit alcohol consumption, as it can worsen dizziness and low blood pressure.
- Be cautious when driving or operating machinery, especially when starting treatment or increasing dose, until you know how the medication affects you.
- Report any persistent dizziness, lightheadedness, or fainting spells to your doctor.
- Continue to take the medication regularly as prescribed, even if you feel well.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Hypertension: Initial 1 mg once daily at bedtime; BPH: Initial 1 mg once daily at bedtime
Dose Range:
1 - 20 mg
Condition-Specific Dosing:
hypertension:
Initial 1 mg once daily at bedtime. Dosage may be slowly increased to 2 mg, 5 mg, 10 mg, and 20 mg once daily to achieve desired blood pressure reduction. Usual maintenance dose is 1-5 mg once daily.
benignProstaticHyperplasia:
Initial 1 mg once daily at bedtime. Dosage may be slowly increased to 2 mg, 5 mg, or 10 mg once daily to achieve desired symptom improvement. Usual maintenance dose is 5-10 mg once daily.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established for hypertension or BPH. Safety and efficacy not established.
Adolescent:
Not established for hypertension or BPH. Safety and efficacy not established.
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment generally required.
Moderate:
No dosage adjustment generally required.
Severe:
No dosage adjustment generally required, but use with caution due to potential for increased sensitivity to hypotensive effects.
Dialysis:
Terazosin is highly protein bound and not significantly removed by dialysis. No specific adjustment recommended, but monitor blood pressure closely.
Hepatic Impairment:
Mild:
Use with caution; consider lower initial doses and slower titration.
Moderate:
Use with caution; consider lower initial doses and slower titration. Monitor for exaggerated hypotensive response.
Severe:
Use with extreme caution; not recommended due to lack of data and potential for increased systemic exposure and adverse effects.
Pharmacology
Mechanism of Action
Terazosin is a selective alpha-1 adrenergic receptor antagonist. It causes vasodilation by blocking alpha-1 receptors on vascular smooth muscle, leading to a reduction in peripheral vascular resistance and blood pressure. In BPH, it relaxes smooth muscle in the prostate and bladder neck, reducing bladder outlet obstruction and improving urine flow.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 90%
Tmax:
Approximately 1 hour
FoodEffect:
Food has minimal effect on the extent of absorption, but may delay Tmax by about 1 hour.
Distribution:
Vd:
Approximately 25-30 L
ProteinBinding:
Approximately 90-94%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 9-12 hours
Clearance:
Approximately 80 mL/min
ExcretionRoute:
Approximately 60% via feces (primarily as metabolites), 40% via urine (approximately 10% as unchanged drug)
Unchanged:
Approximately 10%
Pharmacodynamics
OnsetOfAction:
Within 15-30 minutes (for blood pressure lowering)
PeakEffect:
1-2 hours
DurationOfAction:
Up to 24 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:
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
Changes in vision
Abnormal or rapid heartbeat
Swelling in the arms or legs
A painful erection (priapism) or an erection that lasts longer than 4 hours, which can occur even when you are not having sex. If left untreated, this condition may lead to permanent sexual dysfunction.
Other Possible Side Effects
Like all medications, this drug can cause side effects. While 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 symptoms that bother you or do not go away, contact your doctor or seek medical help:
Dizziness
Drowsiness
Fatigue
Weakness
Stuffy nose
Headache
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor for medical advice. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:
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
Changes in vision
Abnormal or rapid heartbeat
Swelling in the arms or legs
A painful erection (priapism) or an erection that lasts longer than 4 hours, which can occur even when you are not having sex. If left untreated, this condition may lead to permanent sexual dysfunction.
Other Possible Side Effects
Like all medications, this drug can cause side effects. While 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 symptoms that bother you or do not go away, contact your doctor or seek medical help:
Dizziness
Drowsiness
Fatigue
Weakness
Stuffy nose
Headache
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor for medical advice. 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 lightheadedness
- Fainting (syncope)
- Persistent headache
- Chest pain
- Swelling in hands or feet
- Priapism (prolonged erection lasting more than 4 hours - rare but serious)
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, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor and pharmacist identify potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions or exacerbate underlying health issues.
To ensure your safety, it is crucial to verify that this medication can be taken safely with all your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first 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, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor and pharmacist identify potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions or exacerbate underlying health issues.
To ensure your safety, it is crucial to verify that this medication can be taken safely with all your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first 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.
To ensure your safety, avoid driving or engaging in activities that require alertness for 12 hours after taking the first dose, after any dose increase, and if you restart the medication after stopping it. Before resuming these activities, make sure you understand how this medication 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 to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
Follow your doctor's instructions for monitoring your blood pressure.
If you are taking this medication for an enlarged prostate, adhere to your doctor's recommendations for regular rectal exams (to check the prostate gland) and blood tests (PSA tests).
If you have high blood pressure and are taking this medication, consult with your doctor before using over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and certain natural products or aids.
Discuss your alcohol consumption with your doctor before drinking.
Be aware that this medication may affect the results of certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are pregnant, plan to become pregnant, or are breastfeeding, consult with your doctor to discuss the potential benefits and risks to you and your baby.
To ensure your safety, avoid driving or engaging in activities that require alertness for 12 hours after taking the first dose, after any dose increase, and if you restart the medication after stopping it. Before resuming these activities, make sure you understand how this medication 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 to undergo cataract surgery or any other eye procedure, consult with your doctor beforehand.
Follow your doctor's instructions for monitoring your blood pressure.
If you are taking this medication for an enlarged prostate, adhere to your doctor's recommendations for regular rectal exams (to check the prostate gland) and blood tests (PSA tests).
If you have high blood pressure and are taking this medication, consult with your doctor before using over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and certain natural products or aids.
Discuss your alcohol consumption with your doctor before drinking.
Be aware that this medication may affect the results of certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are pregnant, plan to become pregnant, or are breastfeeding, consult with your doctor to discuss the potential benefits and risks to you and your baby.
Overdose Information
Overdose Symptoms:
- Profound hypotension (very low blood pressure)
- Dizziness
- Fainting
- Tachycardia (rapid heart rate)
What to Do:
Call 911 or your local emergency number immediately. For non-emergencies, call Poison Control at 1-800-222-1222. Management typically involves supporting blood pressure (e.g., IV fluids, vasopressors if needed) and general supportive measures.
Drug Interactions
Major Interactions
- PDE5 inhibitors (e.g., sildenafil, tadalafil, vardenafil): Potentiation of hypotensive effects, risk of symptomatic hypotension.
- Other alpha-blockers (e.g., prazosin, doxazosin): Additive hypotensive effects.
Moderate Interactions
- Antihypertensive agents (e.g., beta-blockers, diuretics, ACE inhibitors, calcium channel blockers): Additive hypotensive effects, requiring careful monitoring and dose adjustment.
- Alcohol: May enhance hypotensive effects and dizziness.
- NSAIDs: May reduce the antihypertensive effect of terazosin.
Monitoring
Baseline Monitoring
Blood Pressure (sitting and standing)
Rationale: To establish baseline and assess for orthostatic hypotension before initiating therapy.
Timing: Prior to first dose
BPH Symptom Score (e.g., AUA Symptom Index)
Rationale: To establish baseline symptom severity for BPH patients.
Timing: Prior to first dose (for BPH)
Routine Monitoring
Blood Pressure (sitting and standing)
Frequency: Regularly, especially during dose titration and periodically thereafter.
Target: Individualized based on treatment goals (e.g., <130/80 mmHg for hypertension).
Action Threshold: Significant orthostatic drop (>20 mmHg systolic or >10 mmHg diastolic) or symptomatic hypotension.
BPH Symptom Score
Frequency: Periodically (e.g., every 3-6 months) for BPH patients.
Target: Improvement in score.
Action Threshold: Lack of improvement or worsening symptoms.
Renal Function (BUN, Creatinine)
Frequency: Periodically, especially in patients with pre-existing renal impairment.
Target: Within normal limits.
Action Threshold: Significant decline in renal function.
Liver Function Tests (ALT, AST, Bilirubin)
Frequency: Periodically, especially in patients with pre-existing hepatic impairment.
Target: Within normal limits.
Action Threshold: Significant elevation indicating liver injury.
Symptom Monitoring
- Dizziness
- Lightheadedness
- Syncope (fainting)
- Palpitations
- Headache
- Nasal congestion
- Fatigue
- Edema
Special Patient Groups
Pregnancy
Category C. Animal studies have shown adverse effects, but there are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for fetal harm based on animal data; avoid if possible.
Second Trimester:
Limited human data; use with caution.
Third Trimester:
Limited human data; use with caution. Alpha-blockers may affect fetal circulation or neonatal blood pressure.
Lactation
L3 (Moderately Safe). It is not known whether terazosin is excreted in human milk. Use with caution in nursing mothers. Monitor infant for signs of hypotension or sedation.
Infant Risk:
Low to moderate risk. Potential for hypotension in the infant. Monitor for drowsiness, poor feeding, or signs of low blood pressure.
Pediatric Use
Safety and efficacy have not been established in pediatric patients for either hypertension or BPH. Not recommended for use in this population.
Geriatric Use
Use with caution in elderly patients due to an increased risk of orthostatic hypotension and associated falls. Consider lower initial doses and slower titration. Monitor blood pressure closely, especially standing blood pressure.
Clinical Information
Clinical Pearls
- The 'first-dose phenomenon' (marked hypotension, dizziness, or syncope) is a significant concern, especially with the initial dose or dose increases. Advise patients to take the first dose at bedtime.
- Titrate dose slowly to minimize adverse effects and allow for patient adaptation.
- Terazosin is effective for both hypertension and BPH, offering a dual benefit for some male patients.
- Unlike some other alpha-blockers, terazosin can be taken with or without food, but consistency is key.
- Patients should be advised about the potential for intraoperative floppy iris syndrome (IFIS) during cataract surgery and should inform their ophthalmologist if they are taking or have taken terazosin.
Alternative Therapies
- Other alpha-1 blockers (e.g., doxazosin, prazosin, tamsulosin, alfuzosin, silodosin)
- For Hypertension: Thiazide diuretics, ACE inhibitors, ARBs, beta-blockers, calcium channel blockers
- For BPH: 5-alpha reductase inhibitors (e.g., finasteride, dutasteride), anticholinergics (for overactive bladder symptoms), PDE5 inhibitors (e.g., tadalafil), surgical options
Cost & Coverage
Average Cost:
Varies widely, typically low for generic per 30 capsules
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (preferred generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea 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 emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.