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CAMBER PHARMACE
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31722013190

dutasteride 0.5 mg capsule (generic avodart)

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Uses

Benign Prostatic Hyperplasia

Dutasteride is used to reduce prostatic size, urinary obstruction and associated manifestations (e.g., urinary hesitancy and/or urgency, nocturia), the risk of acute urinary retention, and the risk of the need for surgery in patients with symptomatic benign prostatic hyperplasia (BPH, benign prostatic hypertrophy).

Benign prostatic hyperplasia, a noncancerous abnormal enlargement of the prostate gland that occurs in most men older than 50 years of age, produces lower urinary tract symptoms such as a weak urinary stream, difficulty in initiating urination, urinary frequency and urgency, and nocturia. Urinary flow obstruction secondary to BPH generally is treated with surgical correction of the hyperplasia (e.g., transurethral resection of the prostate [TURP], transurethral incision of the prostate [TUIP], open prostatectomy) or other procedures (e.g., transurethral microwave thermotherapy [TUMT], transurethral needle ablation [TUNA]) in patients who fail medical treatment or catheter removal or in those who have refractory urinary retention, recurrent urinary tract infections, persistent hematuria, bladder stones, or renal insufficiency. However, medical therapy with steroid 5α-reductase inhibitors (e.g., dutasteride, finasteride), which shrink the prostate gland, and/or other drugs (e.g., α1-adrenergic blocking agents such as alfuzosin, doxazosin, tamsulosin, or terazosin), which reduce symptoms, may be a useful alternative to surgery in patients with obstructive manifestations who are unwilling to undergo surgical correction of BPH. Medical therapy may aid those who may be at increased risk from, but not necessarily candidates for, prostate surgery.

Pooled data from a number of placebo-controlled clinical trials evaluating dutasteride (0.5 mg daily) in patients with BPH indicate that treatment with the drug reduces prostate volume and obstructive manifestations (e.g., interrupted or weak stream, sensation of incomplete bladder emptying or straining, urinary urgency and/or frequency, nocturia), reduces the incidence of acute urinary retention and the need for surgery, and increases maximum urinary flow. Therapy with dutasteride in patients with BPH appears to prevent the progression of the disease.

Combination Therapy

Dutasteride is used in combination with tamsulosin for the treatment of symptomatic BPH. In a long-term (mean follow-up: 4 years), multicenter, randomized, double-blind, parallel-group study (Combination of Avodart and Tamsulosin [CombAT]) in men 50 years of age or older with moderate to severe BPH and prostate enlargement, interim analysis showed that combined therapy with dutasteride (0.5 mg daily) and tamsulosin (0.4 mg daily) was more effective than either drug alone in relieving lower urinary tract symptoms; a difference in symptom control was apparent within 9 months and persisted following 4 years of treatment. However, following 4 years of treatment, combined therapy with dutasteride and tamsulosin provided no additional benefit over dutasteride alone in reducing the incidence of acute urinary retention or the need for BPH-related surgery. In addition, although combined therapy was more effective than either drug alone in improving maximum urinary flow at 2 years, the difference between combined therapy and dutasteride alone was no longer significant after 4 years of treatment.

Most experts state that combined therapy with a 5α-reductase inhibitor and an α1-adrenergic blocker may be considered for men with symptomatic moderate to severe BPH and demonstrable prostate enlargement. Men at risk for BPH progression are most likely to benefit from combined therapy. Studies show that combined therapy with a 5α-reductase inhibitor and an α1-blocker is more effective than therapy with either drug alone in preventing long-term BPH symptom progression.

For further information on the use of 5α-reductase inhibitors in the management of BPH,

Dosage and Administration

Administration

Dutasteride is administered orally without regard to meals. Dutasteride capsules should be swallowed whole and not chewed or opened, since contact with the capsule contents may result in irritation of the oropharyngeal mucosa.

Dosage

Benign Prostatic Hyperplasia

Oral

For the treatment of symptomatic benign prostatic hyperplasia (BPH), the usual dosage of dutasteride is 0.5 mg once daily. The duration of dutasteride therapy depends on the clinical response of the patient. While early symptomatic improvement (e.g., within 3 months) may occur with dutasteride, a minimum of 6 months of therapy may be necessary to determine whether therapy with the drug will be of clinical benefit. Generally, therapy with dutasteride is continued for life.

When dutasteride is used in combination with tamsulosin for the treatment of symptomatic BPH, 0.5 mg of dutasteride combined with 0.4 mg of tamsulosin once daily is recommended.

Special Populations

Dosage adjustment based on age or renal function is not necessary. The effects of hepatic impairment on the pharmacokinetics of dutasteride have not been elucidated, and the manufacturer makes no specific recommendations for modification of dutasteride dosage in patients with hepatic impairment.(See Specific Populations: Hepatic Impairment, in Cautions.)

Cautions

Contraindications

Known or suspected pregnancy.

Use in women of childbearing potential.

Use in children.

History of clinically important hypersensitivity reactions (e.g., serious skin reactions, angioedema) to dutasteride, any ingredient in the formulation, or other 5α-reductase inhibitors. Immune system disorders, including hypersensitivity reactions, rash, pruritus, urticaria, localized edema, serious skin reactions, and angioedema, have been reported with dutasteride therapy during postmarketing surveillance.

Warnings/Precautions

Fetal Morbidity

Because of the ability of 5α-reductase inhibitors to inhibit the conversion of testosterone to dihydrotestosterone (DHT), dutasteride may cause abnormalities of the external genitalia of a male fetus exposed to the drug during pregnancy. In animal studies, adverse effects on embryofetal development of male fetuses (e.g., abnormalities of the external genitalia) and male offspring that were exposed to the drug during pregnancy (e.g., decreased prostatic weights, distended preputial glands, nipple development) have been demonstrated. Dutasteride is contraindicated during pregnancy and in women of childbearing potential. If dutasteride is administered during pregnancy, the pregnant woman should be apprised of the potential fetal hazard.

Because of the potential for absorption of dutasteride 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. If contact is made with leaking capsules, the affected area should be washed immediately with soap and water.

Dutasteride has been detected in the semen of men receiving the drug. However, the manufacturer states that seminal concentrations of dutasteride are not sufficient to warrant the use of condoms to prevent exposure to dutasteride.

Blood Donation

Because of the teratogenic potential of dutasteride and the possibility that the drug may be present in blood for long periods (i.e., serum dutasteride concentrations are detectable for up to 4-6 months following discontinuance of treatment), men receiving the drug should not donate blood during dutasteride therapy and for at least 6 months following discontinuance of the drug.

Patient Assessment

Candidates for dutasteride therapy should be evaluated for other urologic conditions that might mimic benign prostatic hyperplasia (BPH), such as infection, prostate or bladder cancer, stricture disease, uncontrolled diabetes mellitus, neurogenic bladder, or congestive heart failure. Digital rectal examinations, as well as other screening tests for prostate cancer, also should be performed during initial assessment of men with lower urinary tract symptoms suggestive of BPH.

High-grade Prostate Cancer

5α-Reductase inhibitors may increase the risk of development of high-grade prostate cancer. The efficacy of dutasteride for prevention of prostate cancer occurrence was evaluated in a 4-year placebo-controlled trial (Reduction by Dutasteride of Prostate Cancer Events; REDUCE) in men 50-75 years of age with a baseline serum prostate-specific antigen (PSA) concentration of 2.5-10 ng/mL and a prior (within 6 months) negative prostate biopsy. Although results showed that dutasteride (0.5 mg daily) was associated with an overall reduction in prostate cancer occurrence (which reflected a reduction in lower-grade [Gleason score of 6 or less] tumors), high-grade tumors (Gleason score of 8-10) were detected more frequently in men receiving dutasteride (1%) than in those receiving placebo (0.5%). Similar results were reported for a 7-year placebo-controlled trial (Prostate Cancer Prevention Trial; PCPT) evaluating preventive therapy with the 5α-reductase inhibitor finasteride; in this trial, high-grade prostate cancer occurred in 1.8% of men receiving finasteride compared with 1.1% of those receiving placebo, and the reduction in risk of prostate cancer was limited to tumors with a Gleason score of 6 or less. It is not known whether detection bias (e.g., 5α-reductase inhibitors potentially could increase the number of biopsy-detected tumors by reducing prostate volume, since this would result in a greater proportion of the prostate being sampled) or study-related factors influenced the results of these studies. Patients should be informed of the results of these studies. Dutasteride is not labeled by the US Food and Drug Administration (FDA) for prevention of prostate cancer.

Effects on Serum Prostate-specific Antigen

The possibility that dutasteride could interfere with interpretation of serum PSA determinations should be considered. Serum concentrations of PSA may be elevated in patients with BPH, prostate cancer, or other prostatic disease. Dutasteride causes a predictable decrease in serum PSA concentrations, although there is evidence of interindividual variation. In controlled clinical trials, dutasteride reduced serum concentrations of PSA by approximately 50% within 3-6 months following initiation of therapy; the mean decrease in serum total PSA concentration in patients receiving dutasteride was about 40% after 3 months of treatment and about 50% after 6, 12, 24, and 48 months of treatment. Administration of dutasteride in combination with tamsulosin results in changes in serum total PSA concentration similar to those observed with dutasteride therapy alone. Median decreases in PSA concentration in men receiving combined therapy with dutasteride and tamsulosin in controlled clinical trials were about 50% after 9 months and 56% after 24 months of treatment. Decreases in serum PSA concentration can occur even in those with prostate cancer. However, treatment with dutasteride has not been demonstrated to provide clinical benefit in patients with prostate cancer.

To allow assessment of potentially cancer-related changes in PSA values, a new baseline PSA concentration should be established 3-6 months after initiation of treatment with dutasteride, and PSA concentrations should be monitored periodically thereafter. Any confirmed increase in serum PSA concentration during dutasteride therapy should be evaluated carefully, even if PSA values are within the normal range for men not receiving 5α-reductase inhibitor therapy. Noncompliance with dutasteride may affect PSA concentrations and should be considered when evaluating test results. For clinical interpretation of isolated PSA values in men who have been receiving dutasteride monotherapy or combined therapy with dutasteride and tamsulosin for 3 months or more, the reported PSA value should be doubled for comparison with normal values in men not receiving the drug.

Dutasteride does not substantially alter the ratio of free to total PSA (percentage of free PSA). If clinicians elect to use this ratio in the detection of prostate cancer, no adjustment of the reported value of the ratio appears to be necessary.

Effects on Semen Characteristics

In a placebo-controlled study in healthy men, reductions in sperm count, semen volume, and sperm motility were reported in individuals receiving dutasteride for 52 weeks. At 24 weeks following drug discontinuance, mean sperm count remained below baseline. Although mean values for each of these parameters remained within normal ranges at all time points and did not meet criteria for a clinically important change (defined as a change of at least 30% from baseline), 2 men receiving dutasteride had reductions in sperm count of more than 90%, with partial recovery reported at 24 weeks following discontinuance of the drug. Sperm concentration and morphology were not altered by dutasteride treatment. The clinical relevance of the reported changes in semen characteristics to the fertility of individuals receiving the drug has not been established.

Breast Neoplasia

Combined data from 3 placebo-controlled clinical trials of dutasteride, each 4 years in duration, revealed 2 cases of breast cancer (one case involving a placebo-treated patient and one involving a patient receiving dutasteride). No cases of breast cancer were reported in the 4-year CombAT and REDUCE trials. Whether a causal relationship exists between long-term dutasteride use and breast neoplasia in men has not been established.

Specific Populations

Pregnancy

Category X.(See Fetal Morbidity and also see Blood Donation under Cautions: Warnings/Precautions.)

Lactation

Not known whether dutasteride is distributed into milk in humans, but the drug should not be used in nursing women.

Pediatric Use

Safety and efficacy not established in children, but the drug is contraindicated for use in children.

Geriatric Use

No substantial differences in safety and efficacy relative to younger men in clinical studies or experience to date, but increased sensitivity cannot be ruled out.

Renal Impairment

Dosage adjustment not necessary in patients with renal impairment.

Hepatic Impairment

Dutasteride has not been studied in patients with hepatic impairment. However, the drug is metabolized extensively in the liver, and increased exposure to the drug is probable in patients with hepatic impairment. Therefore, although administration of dutasteride at a dosage of 5 mg daily (10 times the usual recommended dosage) for 24 weeks in healthy men did not result in unusual adverse effects, dutasteride should be used with caution in patients with hepatic impairment.

Common Adverse Effects

Adverse effects reported in at least 1% of patients receiving dutasteride and more frequently than with placebo include impotence, decreased libido, ejaculation disorder, and breast disorders (including breast tenderness and enlargement). Ejaculation disorders have been reported more frequently with combined therapy with dutasteride and tamsulosin than with either drug alone.

Drug Interactions

α-Adrenergic Blocking Agents

Concomitant administration of dutasteride with α-adrenergic blocking agents (i.e., tamsulosin, terazosin) has no effect on the steady-state pharmacokinetics of either α-adrenergic blocker. However, the effect of tamsulosin or terazosin on dutasteride pharmacokinetic parameters has not been evaluated.

Calcium-channel Blocking Agents

Concomitant administration of dutasteride with calcium-channel blocking agents that inhibit the cytochrome P-450 (CYP) 3A4 isoenzyme (i.e., diltiazem, verapamil) decreases dutasteride clearance resulting in increased exposure to dutasteride. However, dosage adjustment of dutasteride is not recommended since the change in dutasteride exposure is not considered to be clinically important.

Drugs Affecting Hepatic Microsomal Enzymes

Potential pharmacokinetic interaction (decreased clearance and increased serum concentrations of dutasteride) with potent, chronic inhibitors of the CYP3A4 and CYP3A5 isoenzymes. However, the clinical effect of potent CYP3A inhibitors on dutasteride has not been studied. Because of the potential for drug interactions, care should be taken if dutasteride is administered with such drugs (e.g., ritonavir, ketoconazole, verapamil, diltiazem, cimetidine, ciprofloxacin).

Cholestyramine

Administration of a single 5-mg dose of dutasteride followed by a 12-g dose of cholestyramine one hour later did not affect the relative bioavailability of dutasteride.

Digoxin

Concomitant administration of dutasteride at a dosage of 0.5 mg daily for 3 weeks with digoxin did not alter the steady-state pharmacokinetics of digoxin.

Warfarin

Concomitant administration of dutasteride at a dosage of 0.5 mg daily for 3 weeks with warfarin did not alter the steady-state pharmacokinetics of R- or S-warfarin or alter the effect of warfarin on prothrombin time.

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