Dutasteride

Oral
Benign prostatic hyperplasia
Adult: As monotherapy or in combination with β-1 adrenergic antagonist: 0.5 mg once daily. Assess treatment after at least 6 months; treatment duration depends on patient's clinical response.
Hepatic impairment: Severe: Contraindicated.

Dutaster: Should be taken with food.
Tamsulosin hydrochloride: May be taken with or without food.
Tamsulosin hydrochloride: Should be taken with food.

Severe hepatic impairment. Women, children and adolescents. Pregnancy and lactation.

Patient with large post-void residual urine volume or severely reduced urinary flow. Mild to moderate hepatic impairment. Not indicated for the prevention of prostate cancer. Patient Counselling Avoid donating blood during treatment and for at least 6 months following treatment cessation. Women of child-bearing potential or who are pregnant should not handle crushed or broken tab. Excreted in semen therefore use of condom is recommended. Monitoring Parameters Evaluate patients for prostate cancer (e.g. digital rectal examinations) prior to treatment and periodically thereafter. Monitor prostate-specific antigen (PSA) levels (new baseline after 6 months from treatment initiation then regularly thereafter); urinalysis (baseline). Assess for signs and symptoms of changes in breast tissue (e.g. pain, nipple discharge, lumps).

Significant: Cardiac failure; reduction in total sperm count, semen volume, and sperm motility. Rarely, breast cancer. Immune system disorders: Allergic reactions (e.g. rash, pruritus, urticaria, localised oedema, angioedema). Investigations: Increased LH, testosterone, TSH. Nervous system disorders: Dizziness. Psychiatric disorders: Depression. Reproductive system and breast disorders: Testicular pain and swelling, impotence, decreased libido, ejaculation disorders, breast disorders (e.g. tenderness, enlargement). Skin and subcutaneous tissue disorders: Alopecia (primarily body hair loss), hypertrichosis.

Increased serum concentrations with moderate CYP3A4 inhibitors (e.g. verapamil, diltiazem), or potent CYP3A4 inhibitors (e.g. ritonavir, indinavir, nefazodone, itraconazole, ketoconazole).

Decrease PSA level by approx 50% within 3-6 months of use.

Dutasteride, a 4-azo analog of testosterone, is a competitive, selective inhibitor of both type 1 (skin and liver) and type 2 (reproductive tissues) 5α-reductase, resulting in the inhibition of the conversion of testosterone to dihydrotestosterone thus reducing levels of circulating dihydrotestosterone.
Absorption: Absorbed from the gastrointestinal tract. Bioavailability: Approx 60%. Time to peak plasma concentration: 1-3 hours.
Distribution: Volume of distribution: 300-500 L. Plasma protein binding: 99% to albumin.
Metabolism: Extensively metabolised in the liver by CYP3A4 and CYP3A5 isoenzymes into 6-hydroxydutasteride (same activity with dutasteride); 4'-hydroxydutasteride and 1,2-dihydrodutasteride (less potent than dutasteride).
Excretion: Via faeces (40% as metabolites, approx 5% as unchanged drug); urine (<1% as unchanged drug). Elimination half-life: Approx 3-5 weeks.

Oral: Store between 15-30°C. Follow applicable procedures for receiving, handling, administration, and disposal.

Drugs for Bladder & Prostate Disorders

G04CB02 - dutasteride ; Belongs to the class of testosterone-5-alpha reductase inhibitors. Used in the treatment of benign prostatic hypertrophy.