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Dutasteride (Monograph)

Brand name: Avodart
Drug class: 5-alpha-Reductase Inhibitors

Medically reviewed by Drugs.com on Jun 10, 2024. Written by ASHP.

Introduction

Selective inhibitor of steroid 5α-reductase isoenzymes, which are necessary for conversion of testosterone to 5α-dihydrotestosterone (DHT).1 4 9 14

Uses for Dutasteride

Benign Prostatic Hyperplasia (BPH)

Used as monotherapy for treatment of symptomatic benign prostatic hyperplasia(BPH) in men with an enlarged prostate to improve symptoms, reduce the risk of acute urinary retention, and reduce the risk of the need for surgery.1 3 12 14 Used alone or in combination with tamsulosin.1 3 12 13 14 15 17

A fixed-dose combination preparation containing dutasteride and tamsulosin hydrochloride is commercially available for the treatment of symptomatic BPH in men with an enlarged prostate.26

The American Urological Association (AUA) guidelines consider 5α-reductase inhibitor monotherapy an appropriate option for symptomatic treatment of lower urinary tract symptoms in patients with BPH who have evidence of prostatic enlargement.25 A 5α-reductase inhibitor, alone or in combination with an α1-adrenergic blocker, is recommended as a treatment option to prevent progression of lower urinary tract symptoms/BPH and/or reduce risks of urinary retention and need for future prostate-related surgery in patients with demonstrable prostatic enlargement.25

Not indicated for use in women and pediatric patients.1

Not approved for prevention of prostate cancer.1

Dutasteride Dosage and Administration

Administration

Oral Administration

Administer orally without regard to meals.1 14

Swallow capsules whole; do not chew or open.1 14 Contact with the capsule contents may irritate oropharyngeal mucosa.1

Dosage

Adults

Benign Prostatic Hyperplasia
Oral

0.5 mg once daily, alone or in combination with tamsulosin (0.4 mg once daily).1 12 13 14 17

While early symptomatic improvement (e.g., within 3 months) may occur, ≥6 months of therapy may be necessary to determine clinical benefit.17 Generally, therapy is continued for life.9 10

When the fixed-dose combination preparation of dutasteride and tamsulosin is used, the recommended dosage is 0.5 mg of dutasteride and 0.4 mg of tamsulosin hydrochloride taken once daily approximately 30 minutes after the same meal each day.26

Special Populations

Hepatic Impairment

No specific dosage recommendations.1

Renal Impairment

Dosage adjustment not required.1 14

Geriatric Patients

Dosage adjustment not required.1 14

Cautions for Dutasteride

Contraindications

Warnings/Precautions

Effects on Prostate Specific Antigen (PSA)

Decreases PSA concentrations; may interfere with interpretation of serum PSA determinations.1 7 14 17 Concurrent use of tamsulosin does not substantially alter dutasteride’s effect on PSA concentrations.1 12 14 17

May decrease serum PSA concentrations in men with prostate cancer; however, clinical benefit has not been demonstrated in patients with prostate cancer treated with dutasteride.1

Carefully evaluate any confirmed increase in serum PSA concentration during therapy, even if PSA value is within normal range for men not receiving 5α-reductase inhibitor therapy.1 18

Noncompliance may affect PSA concentrations; consider when evaluating test results.1

High-grade Prostate Cancer

5α-Reductase inhibitors may increase risk of development of high-grade prostate cancer.1 18

In 2 placebo-controlled trials evaluating dutasteride (0.5 mg daily for 4 years) or finasteride (5 mg daily for 7 years) for prevention of prostate cancer, overall occurrence of prostate cancer was reduced (due to reduction in lower-grade tumors) but incidence of high-grade tumors (Gleason score 8–10) was increased in men receiving dutasteride or finasteride.1 14 Not known whether detection bias (e.g., drug-induced reduction in prostate volume might have aided biopsy detection) or study-related factors influenced results.1 20 22

Not FDA labeled for prevention of prostate cancer.1 18

Consideration of Other Urological Conditions

Evaluate candidates for dutasteride therapy for other urologic conditions that might mimic BPH, such as infection,4 prostate 1 4 or bladder cancer,4 stricture disease,4 uncontrolled diabetes mellitus,4 neurogenic bladder,4 or CHF.4 7

BPH and prostate cancer may co-exist.1

Risk to Male Fetus

May cause fetal harm; teratogenicity demonstrated in animals.1 Animal studies indicate adverse effects on embryofetal development of male fetuses exposed to the drug during pregnancy (e.g., abnormalities of the external genitalia, decreased prostatic and seminal vesicular weights, distended preputial glands, nipple development).1

Because of the potential for absorption through the skin and the subsequent potential risk to a male fetus, pregnant women or women who may become pregnant should not handle the capsules.1 13 If contact is made with leaking capsules, wash the affected area immediately with soap and water.1

If used during pregnancy or if pregnancy occurs, apprise the pregnant woman of potential fetal hazard to the male fetus.1

Seminal drug concentrations not sufficient to warrant the use of condoms to prevent exposure to dutasteride.10

Blood Donation

To prevent potential fetal exposure, men receiving the drug should not donate blood during dutasteride therapy and for at least 6 months following discontinuance of the drug.1

Effects on Semen Characteristics

Reductions in sperm count, semen volume, and sperm motility reported;1 14 sperm concentration and morphology not altered.1 Clinical relevance not established.1

Specific Populations

Pregnancy

Not indicated for use in women and contraindicated in women who are pregnant.1

If used during pregnancy or if pregnancy occurs, apprise the pregnant woman of potential fetal hazard to a male fetus.1

Because 5α-reductase inhibitors inhibit conversion of testosterone to DHT, dutasteride may cause abnormalities of the external genitalia of male fetuses exposed to the drug during pregnancy.1

Because of the possibility of absorption through skin and subsequent risk to a male fetus, women who are pregnant or who potentially may be pregnant should not handle dutasteride capsules; if contact with a leaking dutasteride capsule occurs during pregnancy, wash affected area immediately with soap and water.1

Lactation

Not known whether dutasteride is distributed into human milk or if drug has any effects on breastfed infant or on milk product; not indicated for use in women.1 10

Females and Males of Reproductive Potential

Reductions in total sperm count, semen volume, and sperm motility observed; sperm concentration and morphology unaffected.1 Clinical significance of such effects on individual patient's fertility not known.1

Pediatric Use

Safety and efficacy not established; not indicated for use in pediatric patients.1

Geriatric Use

No substantial differences in safety and efficacy relative to younger men, but increased sensitivity cannot be ruled out.1

Hepatic Impairment

Not studied in patients with hepatic impairment.1 14 Increased exposure to the drug is probable.1 14 Use with caution.14

Renal Impairment

Dosage adjustment not necessary in renal impairment.1 14

Common Adverse Effects

Impotence, decreased libido, ejaculation disorder, breast disorders (tenderness, enlargement).1 14 Ejaculation disorders reported more frequently with combined therapy (dutasteride plus tamsulosin) than either drug alone.1 12 13

Drug Interactions

Metabolized by CYP isoenzymes 3A4 and 3A5 to active metabolites; not metabolized by CYP isoenzymes 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, or 2E1.1

Drugs Affecting Hepatic Microsomal Enzymes

Potential pharmacokinetic interaction with inhibitors of CYP3A4 and CYP3A5 (decreased clearance and increased serum concentrations of dutasteride).1 14 Use with caution in patients receiving chronic therapy with potent CYP3A4 inhibitors.1 14

Specific Drugs and Laboratory Tests

Drug or Test

Interaction

Comments

Amlodipine

Pharmacokinetic interaction unlikely1

Cholestyramine

Pharmacokinetic or pharmacodynamic interaction unlikely1 14

Cimetidine

Possible decreased clearance and increased serum concentrations of dutasteride1 14

Use concomitantly with care1 14

Ciprofloxacin

Possible decreased clearance and increased serum concentrations of dutasteride1 14

Use concomitantly with care1 14

Digoxin

Effect on digoxin pharmacokinetics unlikely1 14

Diltiazem

Decreased clearance and increased serum concentrations of dutasteride1 14

Not considered clinically important1 14

Ketoconazole

Possible decreased clearance and increased serum concentrations of dutasteride1 14

Use concomitantly with care1 14

Ritonavir

Possible decreased clearance and increased serum concentrations of dutasteride1 14

Use concomitantly with care1 14

Tamsulosin

Effect on tamsulosin pharmacokinetics unlikely1

Terazosin

Effect on terazosin pharmacokinetics unlikely1

Test for PSA

50% decrease in serum PSA concentration within 3–6 months of treatment1 3 6 9 10

No substantial change in ratio of free to total PSA (percentage of free PSA)1

Do not interpret decrease in PSA value as a therapeutic effect on prostate cancer1

Establish a new baseline PSA 3–6 months after initiation of treatment1 14

For clinical interpretation of isolated PSA values in men receiving dutasteride for ≥3 months, double the reported PSA value for comparison with normal values in men not receiving the drug1 3 14 17

No adjustment of reported value of ratio appears to be necessary1

Verapamil

Decreased clearance and increased serum concentrations of dutasteride1 14

Not considered clinically important1 14

Warfarin

Effect on warfarin pharmacokinetics or pharmacodynamics unlikely1 14

Dutasteride Pharmacokinetics

Absorption

Bioavailability

Absolute bioavailability is approximately 60%.1

Onset

Reduces serum and prostatic 5α-dihydroxytestosterone (DHT) concentrations maximally within 1–2 weeks of initiation of therapy.1

Duration

Serum drug concentrations are detectable for up to 4–6 months following discontinuance of therapy.1

Food

Decreases peak serum concentrations.1 Not considered clinically important.1

Distribution

Extent

Widely distributed; volume of distribution is 300–500 L.1

Distributes into semen.1

Plasma Protein Binding

Highly bound to albumin (99%) and α-1 acid glycoprotein (96.6%).1

Elimination

Metabolism

Metabolized by CYP3A4 and CYP3A5 to active metabolites.1

Elimination Route

Excreted in the feces (45%) and urine (<1%) mainly as metabolites; approximately 55% remained unaccounted.1

Half-life

Terminal half-life is approximately 5 weeks at steady state.1

Special Populations

In patients with hepatic impairment, pharmacokinetics not studied.1 Metabolized extensively in the liver, and increased exposure to the drug is probable in hepatic impairment.1

In adolescents (<18 years of age), pharmacokinetics not studied.1

In patients with renal impairment, pharmacokinetics not studied; however, <0.1% of a dose is excreted in urine in healthy individuals.1

In women, pharmacokinetics not studied; use contraindicated.1

Effects of race on pharmacokinetics not studied.1

Stability

Storage

Oral

Capsules

25°C (may be exposed to 15–30°C).1

Actions

Advice to Patients

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Dutasteride

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Capsules, liquid-filled

0.5 mg*

Avodart

Waylis Therapeutics

Dutasteride Capsules

Dutasteride Combinations

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Capsules

0.5 mg of dutasteride with 0.4 mg of tamsulosin hydrochloride

Jalyn

GlaxoSmithKline

AHFS DI Essentials™. © Copyright 2024, Selected Revisions June 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

References

1. Waylis Therapeutics. Avodart (dutasteride) soft gelatin capsules prescribing information. Wixom, MI; 2023 Oct.

3. Roehrborn CG, Boyle P, Nickel JC et al. Efficacy and safety of a dual inhibitor of 5-alpha-reductase types 1 and 2 (dutasteride) in men with benign prostatic hyperplasia. Urology. 2002 60:434-41.

4. Dull P, Reagan RW, Bahnson RR. Managing benign prostatic hyperplasia. Am Fam Physician. 2002; 66:77-84, 87-8. http://www.ncbi.nlm.nih.gov/pubmed/12126034?dopt=AbstractPlus

5. Roehrborn CG, McConnell JD, Lieber M et al. Serum prostate-specific antigen concentration is a powerful predictor of acute urinary retenion and need for surgery in men with clinical benign prostatic hyperplasia. PLESS study group. Urology. 1999; 53:473-80. http://www.ncbi.nlm.nih.gov/pubmed/10096369?dopt=AbstractPlus

6. Potts JM. Prospective identification of National Institutes of Health category IV prostatitis in men with elevated prostate specific antigen. J Urol. 2000; 164:1550-3. http://www.ncbi.nlm.nih.gov/pubmed/11025702?dopt=AbstractPlus

7. de la Rossette JJ, Alivizatos G, Madersbacher S et al. EAU guidelines on benign prostatic hyperplasia (BPH). Eur Urol. 2001; 40:256-63. http://www.ncbi.nlm.nih.gov/pubmed/11684840?dopt=AbstractPlus

9. Anon. Dutasteride (avodart) for benign prostatic hyperplasia. Med Lett Drugs Ther. 2002; 44:109-10. http://www.ncbi.nlm.nih.gov/pubmed/12500154?dopt=AbstractPlus

10. GlaxoSmithKline. Research Triangle Park, NC: Personal communication.

12. Roehrborn CG, Siami P, Barkin J et al. The effects of dutasteride, tamsulosin and combination therapy on lower urinary tract symptoms in men with benign prostatic hyperplasia and prostatic enlargement: 2-year results from the CombAT study. J Urol. 2008; 179:616-21; discussion 621. http://www.ncbi.nlm.nih.gov/pubmed/18082216?dopt=AbstractPlus

13. Anon. Dutasteride (Avodart) with tamsulosin (Flomax) for benign prostatic hyperplasia. Med Lett Drugs Ther. 2008; 50:79-80. http://www.ncbi.nlm.nih.gov/pubmed/18833033?dopt=AbstractPlus

14. Keam SJ, Scott LJ. Dutasteride: a review of its use in the management of prostate disorders. Drugs. 2008; 68:463-85. http://www.ncbi.nlm.nih.gov/pubmed/18318566?dopt=AbstractPlus

15. Siami P, Roehrborn CG, Barkin J et al. Combination therapy with dutasteride and tamsulosin in men with moderate-to-severe benign prostatic hyperplasia and prostate enlargement: the CombAT (Combination of Avodart and Tamsulosin) trial rationale and study design. Contemp Clin Trials. 2007; 28:770-9. http://www.ncbi.nlm.nih.gov/pubmed/17761460?dopt=AbstractPlus

17. Barkin J, Guimaráes M, Jacobi G et al. Alpha-blocker therapy can be withdrawn in the majority of men following initial combination therapy with the dual 5alpha-reductase inhibitor dutasteride. Eur Urol. 2003; 44:461-6. http://www.ncbi.nlm.nih.gov/pubmed/14499682?dopt=AbstractPlus

18. Food and Drug Administration. FDA drug safety communication: 5-alpha reductase inhibitors (5-ARIs) may increase the risk of a more serious form of prostate cancer. Rockville, MD; 2011 Jun 9. From FDA website. https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-5-alpha-reductase-inhibitors-5-aris-may-increase-risk-more-serious

19. Roehrborn CG, Siami P, Barkin J et al. The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study. Eur Urol. 2010; 57:123-31. http://www.ncbi.nlm.nih.gov/pubmed/19825505?dopt=AbstractPlus

20. Andriole GL, Bostwick DG, Brawley ON et al. Effect of dutasteride on the risk of prostate cancer. N Enlg J Med. 2010; 362:1192-202.

22. Theoret MR, Ning YM, Zhang JJ et al. The risks and benefits of 5α-reductase inhibitors for prostate-cancer prevention. N Engl J Med. 2011; 365:97-9. http://www.ncbi.nlm.nih.gov/pubmed/21675880?dopt=AbstractPlus

25. Sandhu JS, Bixler BR, Dahm P, et al. Management of lower urinary tract symptoms attributed to benign prostatic hyperplasia (BPH): AUA Guideline amendment 2023. J Urol. 2023;10.1097/JU.0000000000003698. From the AUA website. http://www.auanet.org

26. GlaxoSmithKline. Jalyn (dutasteride and tamsulosin hydrochloride) capsules prescribing information. Research Triangle Park, NC; 2020 Dec.